1GD(3)                 User Contributed Perl Documentation                GD(3)
2
3
4

NAME

6       GD.pm - Interface to Gd Graphics Library
7

SYNOPSIS

9           use GD;
10
11           # create a new image
12           $im = GD::Image->new(100,100);
13
14           # allocate some colors
15           $white = $im->colorAllocate(255,255,255);
16           $black = $im->colorAllocate(0,0,0);
17           $red = $im->colorAllocate(255,0,0);
18           $blue = $im->colorAllocate(0,0,255);
19
20           # make the background transparent and interlaced
21           $im->transparent($white);
22           $im->interlaced('true');
23
24           # Put a black frame around the picture
25           $im->rectangle(0,0,99,99,$black);
26
27           # Draw a blue oval
28           $im->arc(50,50,95,75,0,360,$blue);
29
30           # And fill it with red
31           $im->fill(50,50,$red);
32
33           # make sure we are writing to a binary stream
34           binmode STDOUT;
35
36           # Convert the image to PNG and print it on standard output
37           print $im->png;
38

DESCRIPTION

40       GD.pm is a Perl interface to Thomas Boutell's gd graphics library
41       (version 2.01 or higher; see below). GD allows you to create color
42       drawings using a large number of graphics primitives, and emit the
43       drawings as PNG files.
44
45       GD defines the following four classes:
46
47       "GD::Image"
48            An image class, which holds the image data and accepts graphic
49            primitive method calls.
50
51       "GD::Font"
52            A font class, which holds static font information and used for
53            text rendering.
54
55       "GD::Polygon"
56            A simple polygon object, used for storing lists of vertices prior
57            to rendering a polygon into an image.
58
59       "GD::Simple"
60            A "simple" class that simplifies the GD::Image API and then adds a
61            set of object-oriented drawing methods using turtle graphics,
62            simplified font handling, ability to work in polar coordinates,
63            HSV color spaces, and human-readable color names like "lightblue".
64            Please see GD::Simple for a description of these methods.
65
66       A Simple Example:
67
68               #!/usr/bin/perl
69
70               use GD;
71
72               # create a new image
73               $im = GD::Image->new(100,100);
74
75               # allocate some colors
76               $white = $im->colorAllocate(255,255,255);
77               $black = $im->colorAllocate(0,0,0);
78               $red = $im->colorAllocate(255,0,0);
79               $blue = $im->colorAllocate(0,0,255);
80
81               # make the background transparent and interlaced
82               $im->transparent($white);
83               $im->interlaced('true');
84
85               # Put a black frame around the picture
86               $im->rectangle(0,0,99,99,$black);
87
88               # Draw a blue oval
89               $im->arc(50,50,95,75,0,360,$blue);
90
91               # And fill it with red
92               $im->fill(50,50,$red);
93
94               # make sure we are writing to a binary stream
95               binmode STDOUT;
96
97               # Convert the image to PNG and print it on standard output
98               print $im->png;
99
100       Notes:
101
102       1. To create a new, empty image, send a new() message to GD::Image,
103       passing it the width and height of the image you want to create.  An
104       image object will be returned.  Other class methods allow you to
105       initialize an image from a preexisting JPG, PNG, GD, GD2, XBM or other
106       supported image files.
107       2. Next you will ordinarily add colors to the image's color table.
108       colors are added using a colorAllocate() method call.  The three
109       parameters in each call are the red, green and blue (rgb) triples for
110       the desired color.  The method returns the index of that color in the
111       image's color table.  You should store these indexes for later use.
112       3. Now you can do some drawing!  The various graphics primitives are
113       described below.  In this example, we do some text drawing, create an
114       oval, and create and draw a polygon.
115       4. Polygons are created with a new() message to GD::Polygon.  You can
116       add points to the returned polygon one at a time using the addPt()
117       method. The polygon can then be passed to an image for rendering.
118       5. When you're done drawing, you can convert the image into PNG format
119       by sending it a png() message (or any other supported image format).
120       It will return a (potentially large) scalar value containing the binary
121       data for the image.  Ordinarily you will print it out at this point or
122       write it to a file.  To ensure portability to platforms that
123       differentiate between text and binary files, be sure to call
124       "binmode()" on the file you are writing the image to.
125

Object Constructors: Creating Images

127       See GD::Image for the current list of supported Image formats.
128
129       The following class methods allow you to create new GD::Image objects.
130
131       $image = GD::Image->new([$width,$height],[$truecolor])
132       $image = GD::Image->new(*FILEHANDLE)
133       $image = GD::Image->new($filename)
134       $image = GD::Image->new($data)
135           The new() method is the main constructor for the GD::Image class.
136           Called with two integer arguments, it creates a new blank image of
137           the specified width and height. For example:
138
139                   $myImage = GD::Image->new(100,100) || die;
140
141           This will create an image that is 100 x 100 pixels wide.  If you
142           don't specify the dimensions, a default of 64 x 64 will be chosen.
143
144           The optional third argument, $truecolor, tells new() to create a
145           truecolor GD::Image object.  Truecolor images have 24 bits of color
146           data (eight bits each in the red, green and blue channels
147           respectively), allowing for precise photograph-quality color usage.
148           If not specified, the image will use an 8-bit palette for
149           compatibility with older versions of libgd.
150
151           Alternatively, you may create a GD::Image object based on an
152           existing image by providing an open filehandle, a filename, or the
153           image data itself.  The image formats automatically recognized and
154           accepted are: GIF, PNG, JPEG, XBM, XPM, GD2, TIFF, WEBP, HEIF or
155           AVIF. Other formats, including WBMP, and GD version 1, cannot be
156           recognized automatically at this time.
157
158           If something goes wrong (e.g. insufficient memory), this call will
159           return undef.
160
161       $image = GD::Image->trueColor([0,1])
162           For backwards compatibility with scripts previous versions of GD,
163           new images created from scratch (width, height) are palette based
164           by default.  To change this default to create true color images
165           use:
166
167                   GD::Image->trueColor(1);
168
169           before creating new images.  To switch back to palette based by
170           default, use:
171
172                   GD::Image->trueColor(0);
173
174       $image = GD::Image->newPalette([$width,$height])
175       $image = GD::Image->newTrueColor([$width,$height])
176           The newPalette() and newTrueColor() methods can be used to
177           explicitly create an palette based or true color image regardless
178           of the current setting of trueColor().
179
180       $image = GD::Image->newFromPng($file, [$truecolor])
181       $image = GD::Image->newFromPngData($data, [$truecolor])
182           The newFromPng() method will create an image from a PNG file read
183           in through the provided filehandle or file path.  The filehandle
184           must previously have been opened on a valid PNG file or pipe.  If
185           successful, this call will return an initialized image which you
186           can then manipulate as you please.  If it fails, which usually
187           happens if the thing at the other end of the filehandle is not a
188           valid PNG file, the call returns undef.  Notice that the call
189           doesn't automatically close the filehandle for you.  But it does
190           call "binmode(FILEHANDLE)" for you, on platforms where this
191           matters.
192
193           You may use any of the following as the argument:
194
195             1) a simple filehandle, such as STDIN
196             2) a filehandle glob, such as *PNG
197             3) a reference to a glob, such as \*PNG
198             4) an IO::Handle object
199             5) the pathname of a file
200
201           In the latter case, newFromPng() will attempt to open the file for
202           you and read the PNG information from it.
203
204             Example1:
205
206             open (PNG,"barnswallow.png") || die;
207             $myImage = GD::Image->newFromPng(\*PNG) || die;
208             close PNG;
209
210             Example2:
211             $myImage = GD::Image->newFromPng('barnswallow.png');
212
213           To get information about the size and color usage of the
214           information, you can call the image query methods described below.
215           Images created by reading PNG images will be truecolor if the image
216           file itself is truecolor. To force the image to be palette-based,
217           pass a value of 0 in the optional $truecolor argument.
218
219           The newFromPngData() method will create a new GD::Image initialized
220           with the PNG format data contained in $data.
221
222       $image = GD::Image->newFromJpeg($file, [$truecolor])
223       $image = GD::Image->newFromJpegData($data, [$truecolor])
224           These methods will create an image from a JPEG file.  They work
225           just like newFromPng() and newFromPngData(), and will accept the
226           same filehandle and pathname arguments.
227
228           Images created by reading JPEG images will always be truecolor.  To
229           force the image to be palette-based, pass a value of 0 in the
230           optional $truecolor argument.
231
232       $image = GD::Image->newFromGif($file, [$truecolor])
233       $image = GD::Image->newFromGifData($data)
234           These methods will create an image from a GIF file.  They work just
235           like newFromPng() and newFromPngData(), and will accept the same
236           filehandle and pathname arguments.
237
238           Images created from GIFs are always 8-bit palette images. To
239           convert to truecolor, you must create a truecolor image and then
240           perform a copy.
241
242       $image = GD::Image->newFromXbm($file, [$truecolor])
243           This works in exactly the same way as "newFromPng", but reads the
244           contents of an X Bitmap (black & white) file:
245
246                   open (XBM,"coredump.xbm") || die;
247                   $myImage = GD::Image->newFromXbm(\*XBM) || die;
248                   close XBM;
249
250           There is no newFromXbmData() function, because there is no
251           corresponding function in the gd library.
252
253       $image = GD::Image->newFromWBMP($file, [$truecolor])
254           This works in exactly the same way as "newFromPng", but reads the
255           contents of an Windows BMP Bitmap file:
256
257                   open (BMP,"coredump.bmp") || die;
258                   $myImage = GD::Image->newFromWBMP(\*BMP) || die;
259                   close BMP;
260
261           There is no newFromWBMPData() function, because there is no
262           corresponding function in the gd library.
263
264       $image = GD::Image->newFromGd($file)
265       $image = GD::Image->newFromGdData($data)
266           NOTE: GD and GD2 support was dropped witn libgd 2.3.2.
267
268           These methods initialize a GD::Image from a Gd file, filehandle, or
269           data.  Gd is Tom Boutell's disk-based storage format, intended for
270           the rare case when you need to read and write the image to disk
271           quickly.  It's not intended for regular use, because, unlike PNG or
272           JPEG, no image compression is performed and these files can become
273           BIG.
274
275                   $myImage = GD::Image->newFromGd("godzilla.gd") || die;
276                   close GDF;
277
278       $image = GD::Image->newFromGd2($file)
279       $image = GD::Image->newFromGd2Data($data)
280           NOTE: GD and GD2 support was dropped witn libgd 2.3.2.
281
282           This works in exactly the same way as "newFromGd()" and
283           newFromGdData, but use the new compressed GD2 image format.
284
285       $image = GD::Image->newFromGd2Part($file,srcX,srcY,width,height)
286           This class method allows you to read in just a portion of a GD2
287           image file.  In addition to a filehandle, it accepts the top-left
288           corner and dimensions (width,height) of the region of the image to
289           read.  For example:
290
291                   open (GDF,"godzilla.gd2") || die;
292                   $myImage = GD::Image->newFromGd2Part(\*GDF,10,20,100,100) || die;
293                   close GDF;
294
295           This reads a 100x100 square portion of the image starting from
296           position (10,20).
297
298       $image = GD::Image->newFromXpm($filename)
299           This creates a new GD::Image object starting from a filename.  This
300           is unlike the other newFrom() functions because it does not take a
301           filehandle.  This difference comes from an inconsistency in the
302           underlying gd library.
303
304                   $myImage = GD::Image->newFromXpm('earth.xpm') || die;
305
306           This function is only available if libgd was compiled with XPM
307           support.
308
309           NOTE: The libgd library is unable to read certain XPM files,
310           returning an all-black image instead.
311
312       $bool = GD::supportsFileType($filename, $is_writing)
313           This returns a TRUE or FALSE value, if libgd supports reading or
314           when the 2nd argument is 1, if libgd supports writing the given
315           filetype, depending on the filename extension. Only with libgd
316           versions >= gd-2.1.1.
317
318           Assuming LibGD is compiled with support for these image types, the
319           following extensions are supported:
320
321               .gif
322               .gd, .gd2
323               .wbmp
324               .bmp
325               .xbm
326               .tga
327               .png
328               .jpg, .jpeg
329               .tiff, .tif
330               .webp
331               .heic, .heix
332               .avif
333               .xpm
334
335           Filenames are parsed case-insensitively.  .avifs is not yet
336           suppurted upstream in libavif.
337

GD::Image Methods

339       Once a GD::Image object is created, you can draw with it, copy it, and
340       merge two images.  When you are finished manipulating the object, you
341       can convert it into a standard image file format to output or save to a
342       file.
343
344   Image Data Output Methods
345       The following methods convert the internal drawing format into standard
346       output file formats.
347
348       $pngdata = $image->png([$compression_level])
349           This returns the image data in PNG format.  You can then print it,
350           pipe it to a display program, or write it to a file.  Example:
351
352                   $png_data = $myImage->png;
353                   open (DISPLAY,"| display -") || die;
354                   binmode DISPLAY;
355                   print DISPLAY $png_data;
356                   close DISPLAY;
357
358           Note the use of "binmode()".  This is crucial for portability to
359           DOSish platforms.
360
361           The optional $compression_level argument controls the amount of
362           compression to apply to the output PNG image.  Values range from
363           0-9, where 0 means no compression (largest files, highest quality)
364           and 9 means maximum compression (smallest files, worst quality).  A
365           compression level of -1 uses the default compression level selected
366           when zlib was compiled on your system, and is the same as calling
367           png() with no argument.  Be careful not to confuse this argument
368           with the jpeg() quality argument, which ranges from 0-100 and has
369           the opposite meaning from compression (higher numbers give higher
370           quality).
371
372       $gifdata = $image->gifanimbegin([$GlobalCM [, $Loops]])
373           For libgd version 2.0.33 and higher, this call begins an animated
374           GIF by returning the data that comprises animated gif image file
375           header.  After you call this method, call gifanimadd() one or more
376           times to add the frames of the image. Then call gifanimend(). Each
377           frame must be the same width and height.
378
379           A typical sequence will look like this:
380
381             my $gifdata = $image->gifanimbegin;
382             $gifdata   .= $image->gifanimadd;    # first frame
383             for (1..100) {
384                # make a frame of right size
385                my $frame  = GD::Image->new($image->getBounds);
386                add_frame_data($frame);              # add the data for this frame
387                $gifdata   .= $frame->gifanimadd;     # add frame
388             }
389             $gifdata   .= $image->gifanimend;   # finish the animated GIF
390             print $gifdata;                     # write animated gif to STDOUT
391
392           If you do not wish to store the data in memory, you can print it to
393           stdout or a file.
394
395           The image that you call gifanimbegin on is used to set the image
396           size, color resolution and color map.  If argument $GlobalCM is 1,
397           the image color map becomes the GIF89a global color map.  If $Loops
398           is given and >= 0, the NETSCAPE2.0 application extension is
399           created, with looping count.  Looping count 0 means forever.
400
401       $gifdata = $image->gifanimadd([$LocalCM [, $LeftOfs [, $TopOfs [,
402       $Delay [, $Disposal [, $previm]]]]]])
403           Returns the data that comprises one animated gif image frame.  You
404           can then print it, pipe it to a display program, or write it to a
405           file.  With $LeftOfs and $TopOfs you can place this frame in
406           different offset than (0,0) inside the image screen.  Delay between
407           the previous frame and this frame is in 1/100s units.  Disposal is
408           usually and by default 1.  Compression is activated by giving the
409           previous image as a parameter.  This function then compares the
410           images and only writes the changed pixels to the new frame in
411           animation.  The Disposal parameter for optimized animations must be
412           set to 1, also for the first frame.  $LeftOfs and $TopOfs
413           parameters are ignored for optimized frames.
414
415       $gifdata = $image->gifanimend()
416           Returns the data for end segment of animated gif file.  It always
417           returns string ';'.  This string must be printed to an animated gif
418           file after all image frames to properly terminate it according to
419           GIF file syntax.  Image object is not used at all in this method.
420
421       $jpegdata = $image->jpeg([$quality])
422           This returns the image data in JPEG format.  You can then print it,
423           pipe it to a display program, or write it to a file.  You may pass
424           an optional quality score to jpeg() in order to control the JPEG
425           quality.  This should be an integer between 0 and 100.  Higher
426           quality scores give larger files and better image quality.  If you
427           don't specify the quality, jpeg() will choose a good default.
428
429       $gifdata = $image->gif().
430           This returns the image data in GIF format.  You can then print it,
431           pipe it to a display program, or write it to a file.
432
433       $gddata = $image->gd
434           This returns the image data in GD format.  You can then print it,
435           pipe it to a display program, or write it to a file.  Example:
436
437                   binmode MYOUTFILE;
438                   print MYOUTFILE $myImage->gd;
439
440       $gd2data = $image->gd2
441           Same as gd(), except that it returns the data in compressed GD2
442           format.
443
444       $wbmpdata = $image->wbmp([$foreground])
445           This returns the image data in WBMP format, which is a black-and-
446           white image format.  Provide the index of the color to become the
447           foreground color.  All other pixels will be considered background.
448
449       $tiffdata = $image->tiff()
450           This returns the image data in TIFF format.
451
452       $webpdata = $image->webp([$quality])
453           This returns the image data in WEBP format, with the optional
454           quality argument.  The default is 80, also chosen by the value -1.
455           A quality value of >= 101 is considered Lossless.
456
457       $webpdata = $image->heif([$quality])
458           This returns the truecolor image data in HEIF format, with the
459           optional quality and speed arguments.  If truecolor is not set,
460           this fails.  The default quality is 80, also chosen by the value
461           -1.  A quality value of 200 is considered Lossless.
462
463       $webpdata = $image->avif([$quality,$speed])
464           This returns the truecolor image data in AVIF format, with the AVif
465           encoder and 444 chroma, and the optional quality argument.  If
466           truecolor is not set, this fails.  The default compression quality
467           1-100 is -1, the default speed 0-10 is 6.
468
469       $success = $image->_file($filename)
470           Writes an image to a file in the format indicated by the filename,
471           with libgd versions >= gd-2.1.1.
472
473           File type is determined by the extension of the file name.  See
474           "supportsFiletype" for an overview of the parsing.
475
476           For file types that require extra arguments, "_file" attempts to
477           use sane defaults:
478
479             C<gdImageGd2> chunk size = 0, compression is enabled.
480             C<gdImageJpeg>        quality = -1 (i.e. the reasonable default)
481             C<gdImageWBMP>        foreground is the darkest available color
482             C<gdImageWEBP>        quality default
483             C<gdImageHEIF>        quality default, codes = HEVC, chroma = 444
484             C<gdImageAVIF>        quality default, speed = 6
485
486           Everything else is called with the two-argument function and so
487           will use the default values.
488
489           "_file" and the underlying libgd "gdImageFile" has some rudimentary
490           error detection and will return FALSE (0) if a detectable error
491           occurred.  However, the image loaders do not normally return their
492           error status so a result of TRUE (1) does **not** mean the file was
493           saved successfully.
494
495   Color Control
496       These methods allow you to control and manipulate the GD::Image color
497       table for palette, non-truecolor images.
498
499       $index = $image->colorAllocate(red,green,blue)
500           This allocates a color with the specified red, green and blue
501           components and returns its index in the color table, if specified.
502           The first color allocated in this way becomes the image's
503           background color.  (255,255,255) is white (all pixels on).  (0,0,0)
504           is black (all pixels off).  (255,0,0) is fully saturated red.
505           (127,127,127) is 50% gray.  You can find plenty of examples in
506           /usr/X11/lib/X11/rgb.txt.
507
508           If no colors are allocated, then this function returns -1.
509
510           Example:
511
512                   $black = $myImage->colorAllocate(0,0,0); #background color
513                   $white = $myImage->colorAllocate(255,255,255);
514                   $peachpuff = $myImage->colorAllocate(255,218,185);
515
516       $index = $image->colorAllocateAlpha(reg,green,blue,alpha)
517           This allocates a color with the specified red, green, and blue
518           components, plus the specified alpha channel.  The alpha value may
519           range from 0 (opaque) to 127 (transparent).  The "alphaBlending"
520           function changes the way this alpha channel affects the resulting
521           image.
522
523       $image->colorDeallocate(colorIndex)
524           This marks the color at the specified index as being ripe for
525           reallocation.  The next time colorAllocate is used, this entry will
526           be replaced.  You can call this method several times to deallocate
527           multiple colors.  There's no function result from this call.
528
529           Example:
530
531                   $myImage->colorDeallocate($peachpuff);
532                   $peachy = $myImage->colorAllocate(255,210,185);
533
534       $index = $image->colorClosest(red,green,blue)
535           This returns the index of the color closest in the color table to
536           the red green and blue components specified.  If no colors have yet
537           been allocated, then this call returns -1.
538
539           Example:
540
541                   $apricot = $myImage->colorClosest(255,200,180);
542
543       $index = $image->colorClosestAlpha(red,green,blue,alpha)
544           This returns the index of the color closest in the color table to
545           the red green blue and alpha components specified.  If no colors
546           have yet been allocated, then this call returns -1.
547
548           Example:
549
550                   $apricot = $myImage->colorClosestAlpha(255,200,180,0);
551
552       $index = $image->colorClosestHWB(red,green,blue)
553           This also attempts to return the color closest in the color table
554           to the red green and blue components specified. It uses a
555           Hue/White/Black color representation to make the selected color
556           more likely to match human perceptions of similar colors.
557
558           If no colors have yet been allocated, then this call returns -1.
559
560           Example:
561
562                   $mostred = $myImage->colorClosestHWB(255,0,0);
563
564       $index = $image->colorExact(red,green,blue)
565           This returns the index of a color that exactly matches the
566           specified red green and blue components.  If such a color is not in
567           the color table, this call returns -1.
568
569                   $rosey = $myImage->colorExact(255,100,80);
570                   warn "Everything's coming up roses.\n" if $rosey >= 0;
571
572       $index = $image->colorExactAlpha(red,green,blue,alpha)
573           This returns the index of a color that exactly matches the
574           specified red green blue and alpha components.  If such a color is
575           not in the color table, this call returns -1.
576
577                   $rosey = $myImage->colorExactAlpha(255,100,80,0);
578                   warn "Everything's coming up roses.\n" if $rosey >= 0;
579
580       $index = $image->colorResolve(red,green,blue)
581           This returns the index of a color that exactly matches the
582           specified red green and blue components.  If such a color is not in
583           the color table and there is room, then this method allocates the
584           color in the color table and returns its index.
585
586                   $rosey = $myImage->colorResolve(255,100,80);
587                   warn "Everything's coming up roses.\n" if $rosey >= 0;
588
589       $index = $image->colorResolveAlpha(red,green,blue,alpha)
590           This returns the index of a color that exactly matches the
591           specified red green blue and alpha components.  If such a color is
592           not in the color table and there is room, then this method
593           allocates the color in the color table and returns its index.
594
595                   $rosey = $myImage->colorResolveAlpha(255,100,80,0);
596                   warn "Everything's coming up roses.\n" if $rosey >= 0;
597
598       $colorsTotal = $image->colorsTotal object method
599           This returns the total number of colors allocated in the object.
600
601                   $maxColors = $myImage->colorsTotal;
602
603           In the case of a TrueColor image, this call will return undef.
604
605       $index = $image->getPixel(x,y) object method
606           This returns the color table index underneath the specified point.
607           It can be combined with rgb() to obtain the rgb color underneath
608           the pixel.
609
610           Example:
611
612                   $index = $myImage->getPixel(20,100);
613                   ($r,$g,$b) = $myImage->rgb($index);
614
615       ($red,$green,$blue) = $image->rgb($index)
616           This returns a list containing the red, green and blue components
617           of the specified color index.
618
619           Example:
620
621                   @RGB = $myImage->rgb($peachy);
622
623       ($alpha) = $image->alpha($index)
624           This returns an item containing the alpha component of the
625           specified color index.
626
627           Example:
628
629                   @RGB = $myImage->rgb($peachy);
630
631       $image->transparent($colorIndex)
632           This marks the color at the specified index as being transparent.
633           Portions of the image drawn in this color will be invisible.  This
634           is useful for creating paintbrushes of odd shapes, as well as for
635           making PNG backgrounds transparent for displaying on the Web.  Only
636           one color can be transparent at any time. To disable transparency,
637           specify -1 for the index.
638
639           If you call this method without any parameters, it will return the
640           current index of the transparent color, or -1 if none.
641
642           Example:
643
644                   open(PNG,"test.png");
645                   $im = GD::Image->newFromPng(PNG);
646                   $white = $im->colorClosest(255,255,255); # find white
647                   $im->transparent($white);
648                   binmode STDOUT;
649                   print $im->png;
650
651   Special Colors
652       GD implements a number of special colors that can be used to achieve
653       special effects.  They are constants defined in the GD:: namespace, but
654       automatically exported into your namespace when the GD module is
655       loaded.
656
657       $image->setBrush($image)
658           You can draw lines and shapes using a brush pattern.  Brushes are
659           just palette, not TrueColor, images that you can create and
660           manipulate in the usual way. When you draw with them, their
661           contents are used for the color and shape of the lines.
662
663           To make a brushed line, you must create or load the brush first,
664           then assign it to the image using setBrush().  You can then draw in
665           that with that brush using the gdBrushed special color.  It's often
666           useful to set the background of the brush to transparent so that
667           the non-colored parts don't overwrite other parts of your image.
668
669           Example:
670
671                   # Create a brush at an angle
672                   $diagonal_brush = GD::Image->new(5,5);
673                   $white = $diagonal_brush->colorAllocate(255,255,255);
674                   $black = $diagonal_brush->colorAllocate(0,0,0);
675                   $diagonal_brush->transparent($white);
676                   $diagonal_brush->line(0,4,4,0,$black); # NE diagonal
677
678                   # Set the brush
679                   $myImage->setBrush($diagonal_brush);
680
681                   # Draw a circle using the brush
682                   $myImage->arc(50,50,25,25,0,360,gdBrushed);
683
684       $image->setThickness($thickness)
685           Lines drawn with line(), rectangle(), arc(), and so forth are 1
686           pixel thick by default.  Call setThickness() to change the line
687           drawing width.
688
689       $image->setStyle(@colors)
690           Styled lines consist of an arbitrary series of repeated colors and
691           are useful for generating dotted and dashed lines.  To create a
692           styled line, use setStyle() to specify a repeating series of
693           colors.  It accepts an array consisting of one or more color
694           indexes.  Then draw using the gdStyled special color.  Another
695           special color, gdTransparent can be used to introduce holes in the
696           line, as the example shows.
697
698           Example:
699
700                   # Set a style consisting of 4 pixels of yellow,
701                   # 4 pixels of blue, and a 2 pixel gap
702                   $myImage->setStyle($yellow,$yellow,$yellow,$yellow,
703                                      $blue,$blue,$blue,$blue,
704                                      gdTransparent,gdTransparent);
705                   $myImage->arc(50,50,25,25,0,360,gdStyled);
706
707           To combine the "gdStyled" and "gdBrushed" behaviors, you can
708           specify "gdStyledBrushed".  In this case, a pixel from the current
709           brush pattern is rendered wherever the color specified in
710           setStyle() is neither gdTransparent nor 0.
711
712       gdTiled
713           Draw filled shapes and flood fills using a pattern.  The pattern is
714           just another image.  The image will be tiled multiple times in
715           order to fill the required space, creating wallpaper effects.  You
716           must call "setTile" in order to define the particular tile pattern
717           you'll use for drawing when you specify the gdTiled color.
718           details.
719
720       gdStyled
721           The gdStyled color is used for creating dashed and dotted lines.  A
722           styled line can contain any series of colors and is created using
723           the setStyled() command.
724
725       gdAntiAliased
726           The "gdAntiAliased" color is used for drawing lines with
727           antialiasing turned on.  Antialiasing will blend the jagged edges
728           of lines with the background, creating a smoother look.  The actual
729           color drawn is set with setAntiAliased().
730
731       $image->setAntiAliased($color)
732           "Antialiasing" is a process by which jagged edges associated with
733           line drawing can be reduced by blending the foreground color with
734           an appropriate percentage of the background, depending on how much
735           of the pixel in question is actually within the boundaries of the
736           line being drawn. All line-drawing methods, such as line() and
737           polygon, will draw antialiased lines if the special "color"
738           gdAntiAliased is used when calling them.
739
740           setAntiAliased() is used to specify the actual foreground color to
741           be used when drawing antialiased lines. You may set any color to be
742           the foreground, however as of libgd version 2.0.12 an alpha channel
743           component is not supported.
744
745           Antialiased lines can be drawn on both truecolor and palette-based
746           images. However, attempts to draw antialiased lines on highly
747           complex palette-based backgrounds may not give satisfactory
748           results, due to the limited number of colors available in the
749           palette. Antialiased line-drawing on simple backgrounds should work
750           well with palette-based images; otherwise create or fetch a
751           truecolor image instead. When using palette-based images, be sure
752           to allocate a broad spectrum of colors in order to have sufficient
753           colors for the antialiasing to use.
754
755       $image->setAntiAliasedDontBlend($color,[$flag])
756           Normally, when drawing lines with the special gdAntiAliased
757           "color," blending with the background to reduce jagged edges is the
758           desired behavior. However, when it is desired that lines not be
759           blended with one particular color when it is encountered in the
760           background, the setAntiAliasedDontBlend() method can be used to
761           indicate the special color that the foreground should stand out
762           more clearly against.
763
764           Once turned on, you can turn this feature off by calling
765           setAntiAliasedDontBlend() with a second argument of 0:
766
767             $image->setAntiAliasedDontBlend($color,0);
768
769   Drawing Commands
770       These methods allow you to draw lines, rectangles, and ellipses, as
771       well as to perform various special operations like flood-fill.
772
773       $image->setPixel($x,$y,$color)
774           This sets the pixel at (x,y) to the specified color index.  No
775           value is returned from this method.  The coordinate system starts
776           at the upper left at (0,0) and gets larger as you go down and to
777           the right.  You can use a real color, or one of the special colors
778           gdBrushed, gdStyled and gdStyledBrushed can be specified.
779
780           Example:
781
782                   # This assumes $peach already allocated
783                   $myImage->setPixel(50,50,$peach);
784
785       $image->line($x1,$y1,$x2,$y2,$color)
786           This draws a line from (x1,y1) to (x2,y2) of the specified color.
787           You can use a real color, or one of the special colors gdBrushed,
788           gdStyled and gdStyledBrushed.
789
790           Example:
791
792                   # Draw a diagonal line using the currently defined
793                   # paintbrush pattern.
794                   $myImage->line(0,0,150,150,gdBrushed);
795
796       $image->dashedLine($x1,$y1,$x2,$y2,$color)
797           DEPRECATED: The libgd library provides this method solely for
798           backward compatibility with libgd version 1.0, and there have been
799           reports that it no longer works as expected. Please use the
800           setStyle() and gdStyled methods as described below.
801
802           This draws a dashed line from (x1,y1) to (x2,y2) in the specified
803           color.  A more powerful way to generate arbitrary dashed and dotted
804           lines is to use the setStyle() method described below and to draw
805           with the special color gdStyled.
806
807           Example:
808
809                   $myImage->dashedLine(0,0,150,150,$blue);
810
811       $image->rectangle($x1,$y1,$x2,$y2,$color)
812           This draws a rectangle with the specified color.  (x1,y1) and
813           (x2,y2) are the upper left and lower right corners respectively.
814           Both real color indexes and the special colors gdBrushed, gdStyled
815           and gdStyledBrushed are accepted.
816
817           Example:
818
819                   $myImage->rectangle(10,10,100,100,$rose);
820
821       $image->filledRectangle($x1,$y1,$x2,$y2,$color) =item
822       $image->setTile($otherimage)
823           This draws a rectangle filled with the specified color.  You can
824           use a real color, or the special fill color gdTiled to fill the
825           polygon with a pattern.
826
827           Example:
828
829                   # read in a fill pattern and set it
830                   $tile = GD::Image->newFromPng('happyface.png');
831                   $myImage->setTile($tile);
832
833                   # draw the rectangle, filling it with the pattern
834                   $myImage->filledRectangle(10,10,150,200,gdTiled);
835
836       $image->openPolygon($polygon,$color)
837           This draws a polygon with the specified color.  The polygon must be
838           created first (see below).  The polygon must have at least three
839           vertices.  If the last vertex doesn't close the polygon, the method
840           will close it for you.  Both real color indexes and the special
841           colors gdBrushed, gdStyled and gdStyledBrushed can be specified.
842
843           Example:
844
845                   $poly = GD::Polygon->new;
846                   $poly->addPt(50,0);
847                   $poly->addPt(99,99);
848                   $poly->addPt(0,99);
849                   $myImage->openPolygon($poly,$blue);
850
851       $image->unclosedPolygon($polygon,$color)
852           This draws a sequence of connected lines with the specified color,
853           without connecting the first and last point to a closed polygon.
854           The polygon must be created first (see below).  The polygon must
855           have at least three vertices.  Both real color indexes and the
856           special colors gdBrushed, gdStyled and gdStyledBrushed can be
857           specified.
858
859           You need libgd 2.0.33 or higher to use this feature.
860
861           Example:
862
863                   $poly = GD::Polygon->new;
864                   $poly->addPt(50,0);
865                   $poly->addPt(99,99);
866                   $poly->addPt(0,99);
867                   $myImage->unclosedPolygon($poly,$blue);
868
869       $image->filledPolygon($poly,$color)
870           This draws a polygon filled with the specified color.  You can use
871           a real color, or the special fill color gdTiled to fill the polygon
872           with a pattern.
873
874           Example:
875
876                   # make a polygon
877                   $poly = GD::Polygon->new;
878                   $poly->addPt(50,0);
879                   $poly->addPt(99,99);
880                   $poly->addPt(0,99);
881
882                   # draw the polygon, filling it with a color
883                   $myImage->filledPolygon($poly,$peachpuff);
884
885       $image->ellipse($cx,$cy,$width,$height,$color)
886       $image->filledEllipse($cx,$cy,$width,$height,$color)
887           These methods() draw ellipses. ($cx,$cy) is the center of the arc,
888           and ($width,$height) specify the ellipse width and height,
889           respectively.  filledEllipse() is like Ellipse() except that the
890           former produces filled versions of the ellipse.
891
892       $image->arc($cx,$cy,$width,$height,$start,$end,$color)
893           This draws arcs and ellipses.  (cx,cy) are the center of the arc,
894           and (width,height) specify the width and height, respectively.  The
895           portion of the ellipse covered by the arc are controlled by start
896           and end, both of which are given in degrees from 0 to 360.  Zero is
897           at the right end of the ellipse, and angles increase clockwise.  To
898           specify a complete ellipse, use 0 and 360 as the starting and
899           ending angles.  To draw a circle, use the same value for width and
900           height.
901
902           You can specify a normal color or one of the special colors
903           gdBrushed, gdStyled, or gdStyledBrushed.
904
905           Example:
906
907                   # draw a semicircle centered at 100,100
908                   $myImage->arc(100,100,50,50,0,180,$blue);
909
910       $image->filledArc($cx,$cy,$width,$height,$start,$end,$color
911       [,$arc_style])
912           This method is like arc() except that it colors in the pie wedge
913           with the selected color.  $arc_style is optional.  If present it is
914           a bitwise OR of the following constants:
915
916             gdArc           connect start & end points of arc with a rounded edge
917             gdChord         connect start & end points of arc with a straight line
918             gdPie           synonym for gdChord
919             gdNoFill        outline the arc or chord
920             gdEdged         connect beginning and ending of the arc to the center
921
922           gdArc and gdChord are mutually exclusive.  gdChord just connects
923           the starting and ending angles with a straight line, while gdArc
924           produces a rounded edge. gdPie is a synonym for gdArc. gdNoFill
925           indicates that the arc or chord should be outlined, not filled.
926           gdEdged, used together with gdNoFill, indicates that the beginning
927           and ending angles should be connected to the center; this is a good
928           way to outline (rather than fill) a "pie slice."
929
930           Example:
931
932             $image->filledArc(100,100,50,50,0,90,$blue,gdEdged|gdNoFill);
933
934       $image->fill($x,$y,$color)
935           This method flood-fills regions with the specified color.  The
936           color will spread through the image, starting at point (x,y), until
937           it is stopped by a pixel of a different color from the starting
938           pixel (this is similar to the "paintbucket" in many popular drawing
939           toys).  You can specify a normal color, or the special color
940           gdTiled, to flood-fill with patterns.
941
942           Example:
943
944                   # Draw a rectangle, and then make its interior blue
945                   $myImage->rectangle(10,10,100,100,$black);
946                   $myImage->fill(50,50,$blue);
947
948       $image->fillToBorder($x,$y,$bordercolor,$color)
949           Like "fill", this method flood-fills regions with the specified
950           color, starting at position (x,y).  However, instead of stopping
951           when it hits a pixel of a different color than the starting pixel,
952           flooding will only stop when it hits the color specified by
953           bordercolor.  You must specify a normal indexed color for the
954           bordercolor.  However, you are free to use the gdTiled color for
955           the fill.
956
957           Example:
958
959                   # This has the same effect as the previous example
960                   $myImage->rectangle(10,10,100,100,$black);
961                   $myImage->fillToBorder(50,50,$black,$blue);
962
963   Image Copying Commands
964       Two methods are provided for copying a rectangular region from one
965       image to another.  One method copies a region without resizing it.  The
966       other allows you to stretch the region during the copy operation.
967
968       With either of these methods it is important to know that the routines
969       will attempt to flesh out the destination image's color table to match
970       the colors that are being copied from the source.  If the destination's
971       color table is already full, then the routines will attempt to find the
972       best match, with varying results.
973
974       $image->copy($sourceImage,$dstX,$dstY,$srcX,$srcY,$width,$height)
975           This is the simplest of the several copy operations, copying the
976           specified region from the source image to the destination image
977           (the one performing the method call).  (srcX,srcY) specify the
978           upper left corner of a rectangle in the source image, and
979           (width,height) give the width and height of the region to copy.
980           (dstX,dstY) control where in the destination image to stamp the
981           copy.  You can use the same image for both the source and the
982           destination, but the source and destination regions must not
983           overlap or strange things will happen.
984
985           Example:
986
987                   $myImage = GD::Image->new(100,100);
988                   ... various drawing stuff ...
989                   $srcImage = GD::Image->new(50,50);
990                   ... more drawing stuff ...
991                   # copy a 25x25 pixel region from $srcImage to
992                   # the rectangle starting at (10,10) in $myImage
993                   $myImage->copy($srcImage,10,10,0,0,25,25);
994
995       $image->clone()
996           Make a copy of the image and return it as a new object.  The new
997           image will look identical.  However, it may differ in the size of
998           the color palette and other nonessential details.
999
1000           Example:
1001
1002                   $myImage = GD::Image->new(100,100);
1003                   ... various drawing stuff ...
1004                   $copy = $myImage->clone;
1005
1006       $image->copyMerge($sourceImage,$dstX,$dstY,
1007                               $srcX,$srcY,$width,$height,$percent)
1008
1009           This copies the indicated rectangle from the source image to the
1010           destination image, merging the colors to the extent specified by
1011           percent (an integer between 0 and 100).  Specifying 100% has the
1012           same effect as copy() -- replacing the destination pixels with the
1013           source image.  This is most useful for highlighting an area by
1014           merging in a solid rectangle.
1015
1016           Example:
1017
1018                   $myImage = GD::Image->new(100,100);
1019                   ... various drawing stuff ...
1020                   $redImage = GD::Image->new(50,50);
1021                   ... more drawing stuff ...
1022                   # copy a 25x25 pixel region from $srcImage to
1023                   # the rectangle starting at (10,10) in $myImage, merging 50%
1024                   $myImage->copyMerge($srcImage,10,10,0,0,25,25,50);
1025
1026       $image->copyMergeGray($sourceImage,$dstX,$dstY,
1027                               $srcX,$srcY,$width,$height,$percent)
1028
1029           This is identical to copyMerge() except that it preserves the hue
1030           of the source by converting all the pixels of the destination
1031           rectangle to grayscale before merging.
1032
1033       $image->copyResized($sourceImage,$dstX,$dstY,
1034                               $srcX,$srcY,$destW,$destH,$srcW,$srcH)
1035
1036           This method is similar to copy() but allows you to choose different
1037           sizes for the source and destination rectangles.  The source and
1038           destination rectangle's are specified independently by (srcW,srcH)
1039           and (destW,destH) respectively.  copyResized() will stretch or
1040           shrink the image to accommodate the size requirements.
1041
1042           Example:
1043
1044                   $myImage = GD::Image->new(100,100);
1045                   ... various drawing stuff ...
1046                   $srcImage = GD::Image->new(50,50);
1047                   ... more drawing stuff ...
1048                   # copy a 25x25 pixel region from $srcImage to
1049                   # a larger rectangle starting at (10,10) in $myImage
1050                   $myImage->copyResized($srcImage,10,10,0,0,50,50,25,25);
1051
1052       $image->copyResampled($sourceImage,$dstX,$dstY,
1053                               $srcX,$srcY,$destW,$destH,$srcW,$srcH)
1054
1055           This method is similar to copyResized() but provides "smooth"
1056           copying from a large image to a smaller one, using a weighted
1057           average of the pixels of the source area rather than selecting one
1058           representative pixel. This method is identical to copyResized()
1059           when the destination image is a palette image.
1060
1061       $image->copyRotated($sourceImage,$dstX,$dstY,
1062                               $srcX,$srcY,$width,$height,$angle)
1063
1064           Like copyResized() but the $angle argument specifies an arbitrary
1065           amount to rotate the image counter clockwise (in degrees).  In
1066           addition, $dstX and $dstY species the center of the destination
1067           image, and not the top left corner.
1068
1069       $image->trueColorToPalette([$dither], [$colors])
1070           This method converts a truecolor image to a palette image. The code
1071           for this function was originally drawn from the Independent JPEG
1072           Group library code, which is excellent. The code has been modified
1073           to preserve as much alpha channel information as possible in the
1074           resulting palette, in addition to preserving colors as well as
1075           possible. This does not work as well as might be hoped. It is
1076           usually best to simply produce a truecolor output image instead,
1077           which guarantees the highest output quality.  Both the dithering
1078           (0/1, default=0) and maximum number of colors used (<=256, default
1079           = gdMaxColors) can be specified.
1080
1081       $image = $sourceImage->createPaletteFromTrueColor([$dither], [$colors])
1082           Creates a new palette image from a truecolor image. Same as above,
1083           but returns a new image.
1084
1085           Don't use these function -- write real truecolor PNGs and JPEGs.
1086           The disk space gain of conversion to palette is not great (for
1087           small images it can be negative) and the quality loss is ugly.
1088
1089       $error = $image->colorMatch($otherimage)
1090           Bring the palette colors in $otherimage to be closer to truecolor
1091           $image.  A negative return value is a failure.
1092
1093             -1 image must be True Color
1094             -2 otherimage must be indexed
1095             -3 the images are meant to be the same dimensions
1096             -4 At least 1 color in otherimage must be allocated
1097
1098           This method is only available with libgd >= 2.1.0
1099
1100       $image = $sourceImage->neuQuant($maxcolor=256,$samplefactor=5)
1101           Creates a new palette image from a truecolor image.
1102
1103           samplefactor   The quantization precision between 1 (highest
1104           quality) and 10 (fastest).
1105           maxcolor  The number of desired palette entries.
1106
1107           This is the same as createPaletteFromTrueColor with the
1108           quantization method GD_QUANT_NEUQUANT. This does not support
1109           dithering.  This method is only available with libgd >= 2.1.0
1110
1111   Image Transformation Commands
1112       Gd provides these simple image transformations, non-interpolated.
1113
1114       $image = $sourceImage->copyRotate90()
1115       $image = $sourceImage->copyRotate180()
1116       $image = $sourceImage->copyRotate270()
1117       $image = $sourceImage->copyFlipHorizontal()
1118       $image = $sourceImage->copyFlipVertical()
1119       $image = $sourceImage->copyTranspose()
1120       $image = $sourceImage->copyReverseTranspose()
1121           These methods can be used to rotate, flip, or transpose an image.
1122           The result of the method is a copy of the image.
1123
1124       $image->rotate180()
1125       $image->flipHorizontal()
1126       $image->flipVertical()
1127           These methods are similar to the copy* versions, but instead modify
1128           the image in place.
1129
1130   Image Interpolation Methods
1131       Since libgd 2.1.0 there are better transformation methods, with these
1132       interpolation methods:
1133
1134         GD_BELL                - Bell
1135         GD_BESSEL              - Bessel
1136         GD_BILINEAR_FIXED      - fixed point bilinear
1137         GD_BICUBIC             - Bicubic
1138         GD_BICUBIC_FIXED       - fixed point bicubic integer
1139         GD_BLACKMAN            - Blackman
1140         GD_BOX                 - Box
1141         GD_BSPLINE             - BSpline
1142         GD_CATMULLROM          - Catmullrom
1143         GD_GAUSSIAN            - Gaussian
1144         GD_GENERALIZED_CUBIC   - Generalized cubic
1145         GD_HERMITE             - Hermite
1146         GD_HAMMING             - Hamming
1147         GD_HANNING             - Hannig
1148         GD_MITCHELL            - Mitchell
1149         GD_NEAREST_NEIGHBOUR   - Nearest neighbour interpolation
1150         GD_POWER               - Power
1151         GD_QUADRATIC           - Quadratic
1152         GD_SINC                - Sinc
1153         GD_TRIANGLE            - Triangle
1154         GD_WEIGHTED4           - 4 pixels weighted bilinear interpolation
1155         GD_LINEAR              - bilinear interpolation
1156
1157       $image->interpolationMethod( [$method] )
1158           Gets or sets the interpolation methods for all subsequent
1159           interpolations.  See above for the valid values.  Only available
1160           since libgd 2.2.0
1161
1162       $image->copyScaleInterpolated( width, height )
1163           Returns a copy, using interpolation.
1164
1165       $image->copyRotateInterpolated( angle, bgcolor )
1166           Returns a copy, using interpolation.
1167
1168   Image Filter Commands
1169       Gd also provides some common image filters, they modify the image in
1170       place and return TRUE if modified or FALSE if not.  Most of them need
1171       libgd >= 2.1.0, with older versions those functions are undefined.
1172
1173       $ok = $image->scatter($sub, $plus)
1174           if $sub and $plus are 0, nothing is changed, TRUE is returned.  if
1175           $sub >= $plus, nothing is changed, FALSE is returned.  else random
1176           pixels are changed.
1177
1178       $ok = $image->scatterColor($sub, $plus, @colors)
1179           Similar to scatter, but using the given array of colors, i.e.
1180           palette indices.
1181
1182       $ok = $image->pixelate($blocksize, $mode)
1183           if $blocksize <= 0, nothing is changed, FALSE is returned.  if
1184           $blocksize == 1, nothing is changed, TRUE is returned.  else the
1185           following modes are observed:
1186             GD_PIXELATE_UPPERLEFT
1187             GD_PIXELATE_AVERAGE
1188
1189       $ok = $image->negate()
1190       $ok = $image->grayscale()
1191       $ok = $image->brightness($add)
1192           $add: -255..255
1193
1194       $ok = $image->contrast($contrast)
1195           $contrast: a double value. The contrast adjustment value. Negative
1196           values increase, positive values decrease the contrast. The larger
1197           the absolute value, the stronger the effect.
1198
1199       $ok = $image->color($red,$green,$blue,$alpha)
1200           Change channel values of an image.
1201
1202             $red   - The value to add to the red channel of all pixels.
1203             $green - The value to add to the green channel of all pixels.
1204             $blue  - The value to add to the blue channel of all pixels.
1205             $alpha - The value to add to the alpha channel of all pixels.
1206
1207       $ok = $image->selectiveBlur()
1208       $ok = $image->edgeDetectQuick()
1209       $ok = $image->gaussianBlur()
1210       $ok = $image->emboss()
1211       $ok = $image->meanRemoval()
1212       $ok = $image->smooth($weight)
1213       $image = $sourceImage->copyGaussianBlurred($radius, $sigma)
1214           $radius: int, the blur radius (*not* diameter--range is 2*radius +
1215           1) a radius, not a diameter so a radius of 2 (for example) will
1216           blur across a region 5 pixels across (2 to the center, 1 for the
1217           center itself and another 2 to the other edge).
1218
1219           $sigma: the sigma value or a value <= 0.0 to use the computed
1220           default.  represents the "fatness" of the curve (lower == fatter).
1221
1222           The result is always truecolor.
1223
1224   Character and String Drawing
1225       GD allows you to draw characters and strings, either in normal
1226       horizontal orientation or rotated 90 degrees.  These routines use a
1227       GD::Font object, described in more detail below.  There are four built-
1228       in monospaced fonts, available in the global variables gdGiantFont,
1229       gdLargeFont, gdMediumBoldFont, gdSmallFont and gdTinyFont.
1230
1231       In addition, you can use the load() method to load GD-formatted bitmap
1232       font files at runtime. You can create these bitmap files from X11 BDF-
1233       format files using the bdf2gd.pl script, which should have been
1234       installed with GD (see the bdf_scripts directory if it wasn't).  The
1235       format happens to be identical to the old-style MSDOS bitmap ".fnt"
1236       files, so you can use one of those directly if you happen to have one.
1237
1238       For writing proportional scalable fonts, GD offers the stringFT()
1239       method, which allows you to load and render any TrueType font on your
1240       system.
1241
1242       $image->string($font,$x,$y,$string,$color)
1243           This method draws a string starting at position (x,y) in the
1244           specified font and color.  Your choices of fonts are gdSmallFont,
1245           gdMediumBoldFont, gdTinyFont, gdLargeFont and gdGiantFont.
1246
1247           Example:
1248
1249                   $myImage->string(gdSmallFont,2,10,"Peachy Keen",$peach);
1250
1251       $image->stringUp($font,$x,$y,$string,$color)
1252           Just like the previous call, but draws the text rotated
1253           counterclockwise 90 degrees.
1254
1255       $image->char($font,$x,$y,$char,$color)
1256       $image->charUp($font,$x,$y,$char,$color)
1257           These methods draw single characters at position (x,y) in the
1258           specified font and color.  They're carry-overs from the C
1259           interface, where there is a distinction between characters and
1260           strings.  Perl is insensible to such subtle distinctions.
1261
1262       $font = GD::Font->load($fontfilepath)
1263           This method dynamically loads a font file, returning a font that
1264           you can use in subsequent calls to drawing methods.  For example:
1265
1266              my $courier = GD::Font->load('./courierR12.fnt') or die "Can't load font";
1267              $image->string($courier,2,10,"Peachy Keen",$peach);
1268
1269           Font files must be in GD binary format, as described above.
1270
1271       @bounds =
1272       $image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string)
1273       @bounds =
1274       GD::Image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string)
1275       @bounds =
1276       $image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string,\%options)
1277           This method uses TrueType to draw a scaled, antialiased string
1278           using the TrueType vector font of your choice.  It requires that
1279           libgd to have been compiled with TrueType support, and for the
1280           appropriate TrueType font to be installed on your system.
1281
1282           The arguments are as follows:
1283
1284             fgcolor    Color index to draw the string in
1285             fontname   A path to the TrueType (.ttf) font file or a font pattern.
1286             ptsize     The desired point size (may be fractional)
1287             angle      The rotation angle, in radians (positive values rotate counter clockwise)
1288             x,y        X and Y coordinates to start drawing the string
1289             string     The string itself
1290
1291           If successful, the method returns an eight-element list giving the
1292           boundaries of the rendered string:
1293
1294            @bounds[0,1]  Lower left corner (x,y)
1295            @bounds[2,3]  Lower right corner (x,y)
1296            @bounds[4,5]  Upper right corner (x,y)
1297            @bounds[6,7]  Upper left corner (x,y)
1298
1299           In case of an error (such as the font not being available, or FT
1300           support not being available), the method returns an empty list and
1301           sets $@ to the error message.
1302
1303           The fontname argument is the name of the font, which can be a full
1304           pathname to a .ttf file, or if not the paths in $ENV{GDFONTPATH}
1305           will be searched or if empty the libgd compiled DEFAULT_FONTPATH.
1306           The TrueType extensions .ttf, .pfa, .pfb or .dfont can be omitted.
1307
1308           The string may contain UTF-8 sequences like: "&#192;"
1309
1310           You may also call this method from the GD::Image class name, in
1311           which case it doesn't do any actual drawing, but returns the
1312           bounding box using an inexpensive operation.  You can use this to
1313           perform layout operations prior to drawing.
1314
1315           Using a negative color index will disable antialiasing, as
1316           described in the libgd manual page at
1317           <http://www.boutell.com/gd/manual2.0.9.html#gdImageStringFT>.
1318
1319           An optional 8th argument allows you to pass a hashref of options to
1320           stringFT().  Several hashkeys are recognized: linespacing, charmap,
1321           resolution, and kerning.
1322
1323           The value of linespacing is supposed to be a multiple of the
1324           character height, so setting linespacing to 2.0 will result in
1325           double-spaced lines of text.  However the current version of libgd
1326           (2.0.12) does not do this.  Instead the linespacing seems to be
1327           double what is provided in this argument.  So use a spacing of 0.5
1328           to get separation of exactly one line of text.  In practice, a
1329           spacing of 0.6 seems to give nice results.  Another thing to watch
1330           out for is that successive lines of text should be separated by the
1331           "\r\n" characters, not just "\n".
1332
1333           The value of charmap is one of "Unicode", "Shift_JIS" and "Big5".
1334           The interaction between Perl, Unicode and libgd is not clear to me,
1335           and you should experiment a bit if you want to use this feature.
1336
1337           The value of resolution is the vertical and horizontal resolution,
1338           in DPI, in the format "hdpi,vdpi".  If present, the resolution will
1339           be passed to the Freetype rendering engine as a hint to improve the
1340           appearance of the rendered font.
1341
1342           The value of kerning is a flag.  Set it to false to turn off the
1343           default kerning of text.
1344
1345           Example:
1346
1347            $gd->stringFT($black,'/c/windows/Fonts/pala.ttf',40,0,20,90,
1348                         "hi there\r\nbye now",
1349                         {linespacing=>0.6,
1350                          charmap  => 'Unicode',
1351                         });
1352
1353           If GD was compiled with fontconfig support, and the fontconfig
1354           library is available on your system, then you can use a font name
1355           pattern instead of a path.  Patterns are described in fontconfig
1356           and will look something like this "Times:italic".  For backward
1357           compatibility, this feature is disabled by default.  You must
1358           enable it by calling useFontConfig(1) prior to the stringFT() call.
1359
1360              $image->useFontConfig(1);
1361
1362           For backward compatibility with older versions of the FreeType
1363           library, the alias stringTTF() is also recognized.
1364
1365       $hasfontconfig = $image->useFontConfig($flag)
1366           Call useFontConfig() with a value of 1 in order to enable support
1367           for fontconfig font patterns (see stringFT).  Regardless of the
1368           value of $flag, this method will return a true value if the
1369           fontconfig library is present, or false otherwise.
1370
1371           This method can also be called as a class method of GD::Image;
1372
1373       $result =
1374       $image->stringFTCircle($cx,$cy,$radius,$textRadius,$fillPortion,$font,$points,$top,$bottom,$fgcolor)
1375           This draws text in a circle. Currently (libgd 2.0.33) this function
1376           does not work for me, but the interface is provided for
1377           completeness.  The call signature is somewhat complex.  Here is an
1378           excerpt from the libgd manual page:
1379
1380           Draws the text strings specified by top and bottom on the image,
1381           curved along the edge of a circle of radius radius, with its center
1382           at cx and cy. top is written clockwise along the top; bottom is
1383           written counterclockwise along the bottom. textRadius determines
1384           the "height" of each character; if textRadius is 1/2 of radius,
1385           characters extend halfway from the edge to the center. fillPortion
1386           varies from 0 to 1.0, with useful values from about 0.4 to 0.9, and
1387           determines how much of the 180 degrees of arc assigned to each
1388           section of text is actually occupied by text; 0.9 looks better than
1389           1.0 which is rather crowded. font is a freetype font; see
1390           gdImageStringFT. points is passed to the freetype engine and has an
1391           effect on hinting; although the size of the text is determined by
1392           radius, textRadius, and fillPortion, you should pass a point size
1393           that "hints" appropriately -- if you know the text will be large,
1394           pass a large point size such as 24.0 to get the best results.
1395           fgcolor can be any color, and may have an alpha component, do
1396           blending, etc.
1397
1398           Returns a true value on success.
1399
1400   Alpha channels
1401       The alpha channel methods allow you to control the way drawings are
1402       processed according to the alpha channel. When true color is turned on,
1403       colors are encoded as four bytes, in which the last three bytes are the
1404       RGB color values, and the first byte is the alpha channel.  Therefore
1405       the hexadecimal representation of a non transparent RGB color will be:
1406       C=0x00(rr)(bb)(bb)
1407
1408       When alpha blending is turned on, you can use the first byte of the
1409       color to control the transparency, meaning that a rectangle painted
1410       with color 0x00(rr)(bb)(bb) will be opaque, and another one painted
1411       with 0x7f(rr)(gg)(bb) will be transparent. The Alpha value must be >= 0
1412       and <= 0x7f.
1413
1414       $image->alphaBlending($integer)
1415           The alphaBlending() method allows for two different modes of
1416           drawing on truecolor images. In blending mode, which is on by
1417           default (libgd 2.0.2 and above), the alpha channel component of the
1418           color supplied to all drawing functions, such as "setPixel",
1419           determines how much of the underlying color should be allowed to
1420           shine through. As a result, GD automatically blends the existing
1421           color at that point with the drawing color, and stores the result
1422           in the image. The resulting pixel is opaque. In non-blending mode,
1423           the drawing color is copied literally with its alpha channel
1424           information, replacing the destination pixel. Blending mode is not
1425           available when drawing on palette images.
1426
1427           Pass a value of 1 for blending mode, and 0 for non-blending mode.
1428
1429       $image->saveAlpha($saveAlpha)
1430           By default, GD (libgd 2.0.2 and above) does not attempt to save
1431           full alpha channel information (as opposed to single-color
1432           transparency) when saving PNG images. (PNG is currently the only
1433           output format supported by gd which can accommodate alpha channel
1434           information.) This saves space in the output file. If you wish to
1435           create an image with alpha channel information for use with tools
1436           that support it, call saveAlpha(1) to turn on saving of such
1437           information, and call alphaBlending(0) to turn off alpha blending
1438           within the library so that alpha channel information is actually
1439           stored in the image rather than being composited immediately at the
1440           time that drawing functions are invoked.
1441
1442   Miscellaneous Image Methods
1443       These are various utility methods that are useful in some
1444       circumstances.
1445
1446       $image->interlaced([$flag])
1447           This method sets or queries the image's interlaced setting.
1448           Interlace produces a cool venetian blinds effect on certain
1449           viewers.  Provide a true parameter to set the interlace attribute.
1450           Provide undef to disable it.  Call the method without parameters to
1451           find out the current setting.
1452
1453       ($width,$height) = $image->getBounds()
1454           This method will return a two-member list containing the width and
1455           height of the image.  You query but not change the size of the
1456           image once it's created.
1457
1458       $width = $image->width
1459       $height = $image->height
1460           Return the width and height of the image, respectively.
1461
1462       $is_truecolor = $image->isTrueColor()
1463           This method will return a Boolean representing whether the image is
1464           true color or not.
1465
1466       $flag = $image1->compare($image2)
1467           Compare two images and return a bitmap describing the differences
1468           found, if any.  The return value must be logically AND'ed with one
1469           or more constants in order to determine the differences.  The
1470           following constants are available:
1471
1472             GD_CMP_IMAGE             The two images look different
1473             GD_CMP_NUM_COLORS        The two images have different numbers of colors
1474             GD_CMP_COLOR             The two images' palettes differ
1475             GD_CMP_SIZE_X            The two images differ in the horizontal dimension
1476             GD_CMP_SIZE_Y            The two images differ in the vertical dimension
1477             GD_CMP_TRANSPARENT       The two images have different transparency
1478             GD_CMP_BACKGROUND        The two images have different background colors
1479             GD_CMP_INTERLACE         The two images differ in their interlace
1480             GD_CMP_TRUECOLOR         The two images are not both true color
1481
1482           The most important of these is GD_CMP_IMAGE, which will tell you
1483           whether the two images will look different, ignoring differences in
1484           the order of colors in the color palette and other invisible
1485           changes.  The constants are not imported by default, but must be
1486           imported individually or by importing the :cmp tag.  Example:
1487
1488             use GD qw(:DEFAULT :cmp);
1489             # get $image1 from somewhere
1490             # get $image2 from somewhere
1491             if ($image1->compare($image2) & GD_CMP_IMAGE) {
1492                warn "images differ!";
1493             }
1494
1495       $image->clip($x1,$y1,$x2,$y2)
1496       ($x1,$y1,$x2,$y2) = $image->clip
1497           Set or get the clipping rectangle.  When the clipping rectangle is
1498           set, all drawing will be clipped to occur within this rectangle.
1499           The clipping rectangle is initially set to be equal to the
1500           boundaries of the whole image. Change it by calling clip() with the
1501           coordinates of the new clipping rectangle.  Calling clip() without
1502           any arguments will return the current clipping rectangle.
1503
1504       $flag = $image->boundsSafe($x,$y)
1505           The boundsSafe() method will return true if the point indicated by
1506           ($x,$y) is within the clipping rectangle, or false if it is not.
1507           If the clipping rectangle has not been set, then it will return
1508           true if the point lies within the image boundaries.
1509
1510   Grouping Methods
1511       GD does not support grouping of objects, but GD::SVG does. In that
1512       subclass, the following methods declare new groups of graphical
1513       objects:
1514
1515       $image->startGroup([$id,\%style])
1516       $image->endGroup()
1517       $group = $image->newGroup
1518           See GD::SVG for information.
1519

Polygons

1521       A few primitive polygon creation and manipulation methods are provided.
1522       They aren't part of the Gd library, but I thought they might be handy
1523       to have around (they're borrowed from my qd.pl Quickdraw library).
1524       Also see GD::Polyline.
1525
1526       $poly = GD::Polygon->new
1527          Create an empty polygon with no vertices.
1528
1529                  $poly = GD::Polygon->new;
1530
1531       $poly->addPt($x,$y)
1532          Add point (x,y) to the polygon.
1533
1534                  $poly->addPt(0,0);
1535                  $poly->addPt(0,50);
1536                  $poly->addPt(25,25);
1537                  $myImage->fillPoly($poly,$blue);
1538
1539       ($x,$y) = $poly->getPt($index)
1540          Retrieve the point at the specified vertex.
1541
1542                  ($x,$y) = $poly->getPt(2);
1543
1544       $poly->setPt($index,$x,$y)
1545          Change the value of an already existing vertex.  It is an error to
1546          set a vertex that isn't already defined.
1547
1548                  $poly->setPt(2,100,100);
1549
1550       ($x,$y) = $poly->deletePt($index)
1551          Delete the specified vertex, returning its value.
1552
1553                  ($x,$y) = $poly->deletePt(1);
1554
1555       $poly->clear()
1556          Delete all vertices, restoring the polygon to its initial empty
1557          state.
1558
1559       $poly->toPt($dx,$dy)
1560          Draw from current vertex to a new vertex, using relative (dx,dy)
1561          coordinates.  If this is the first point, act like addPt().
1562
1563                  $poly->addPt(0,0);
1564                  $poly->toPt(0,50);
1565                  $poly->toPt(25,-25);
1566                  $myImage->fillPoly($poly,$blue);
1567
1568       $vertex_count = $poly->length
1569          Return the number of vertices in the polygon.
1570
1571                  $points = $poly->length;
1572
1573       @vertices = $poly->vertices
1574          Return a list of all the vertices in the polygon object.  Each
1575          member of the list is a reference to an (x,y) array.
1576
1577                  @vertices = $poly->vertices;
1578                  foreach $v (@vertices)
1579                     print join(",",@$v),"\n";
1580                  }
1581
1582       @rect = $poly->bounds
1583          Return the smallest rectangle that completely encloses the polygon.
1584          The return value is an array containing the (left,top,right,bottom)
1585          of the rectangle.
1586
1587                  ($left,$top,$right,$bottom) = $poly->bounds;
1588
1589       $poly->offset($dx,$dy)
1590          Offset all the vertices of the polygon by the specified horizontal
1591          (dh) and vertical (dy) amounts.  Positive numbers move the polygon
1592          down and to the right.
1593
1594                  $poly->offset(10,30);
1595
1596       $poly->map($srcL,$srcT,$srcR,$srcB,$destL,$dstT,$dstR,$dstB)
1597          Map the polygon from a source rectangle to an equivalent position in
1598          a destination rectangle, moving it and resizing it as necessary.
1599          See polys.pl for an example of how this works.  Both the source and
1600          destination rectangles are given in (left,top,right,bottom)
1601          coordinates.  For convenience, you can use the polygon's own
1602          bounding box as the source rectangle.
1603
1604                  # Make the polygon really tall
1605                  $poly->map($poly->bounds,0,0,50,200);
1606
1607       $poly->scale($sx,$sy, [$tx,$ty])
1608          Scale each vertex of the polygon by the X and Y factors indicated by
1609          sx and sy.  For example scale(2,2) will make the polygon twice as
1610          large.  For best results, move the center of the polygon to position
1611          (0,0) before you scale, then move it back to its previous position.
1612          Accepts an optional offset vector.
1613
1614       $poly->transform($sx,$rx,$ry,$sy, $tx,$ty)
1615          Run each vertex of the polygon through a 2D affine transformation
1616          matrix, where sx and sy are the X and Y scaling factors, rx and ry
1617          are the X and Y rotation factors, and tx and ty are X and Y offsets.
1618          See the Adobe PostScript Reference, page 154 for a full explanation,
1619          or experiment.
1620
1621          libgd:
1622
1623              The transformation matrix is created using 6 numbers:
1624              matrix[0] == xx
1625              matrix[1] == yx
1626              matrix[2] == xy
1627              matrix[3] == xy (probably meaning yy here)
1628              matrix[4] == x0
1629              matrix[5] == y0
1630              where the transformation of a given point (x,y) is given by:
1631
1632              x_new = xx * x + xy * y + x0;
1633              y_new = yx * x + yy * y + y0;
1634
1635   GD::Polyline
1636       Please see GD::Polyline for information on creating open polygons and
1637       splines.
1638

Font Utilities

1640       The libgd library (used by the Perl GD library) has built-in support
1641       for about half a dozen fonts, which were converted from public-domain X
1642       Windows fonts.  For more fonts, compile libgd with TrueType support and
1643       use the stringFT() call.
1644
1645       If you wish to add more built-in fonts, the directory bdf_scripts
1646       contains two contributed utilities that may help you convert X-Windows
1647       BDF-format fonts into the format that libgd uses internally.  However
1648       these scripts were written for earlier versions of GD which included
1649       its own mini-gd library.  These scripts will have to be adapted for use
1650       with libgd, and the libgd library itself will have to be recompiled and
1651       linked!  Please do not contact me for help with these scripts: they are
1652       unsupported.
1653
1654       Each of these fonts is available both as an imported global (e.g.
1655       gdSmallFont) and as a package method (e.g. GD::Font->Small).
1656
1657       gdSmallFont
1658       GD::Font->Small
1659            This is the basic small font, "borrowed" from a well known public
1660            domain 6x12 font.
1661
1662       gdLargeFont
1663       GD::Font->Large
1664            This is the basic large font, "borrowed" from a well known public
1665            domain 8x16 font.
1666
1667       gdMediumBoldFont
1668       GD::Font->MediumBold
1669            This is a bold font intermediate in size between the small and
1670            large fonts, borrowed from a public domain 7x13 font;
1671
1672       gdTinyFont
1673       GD::Font->Tiny
1674            This is a tiny, almost unreadable font, 5x8 pixels wide.
1675
1676       gdGiantFont
1677       GD::Font->Giant
1678            This is a 9x15 bold font converted by Jan Pazdziora from a sans
1679            serif X11 font.
1680
1681       $font->nchars
1682            This returns the number of characters in the font.
1683
1684                    print "The large font contains ",gdLargeFont->nchars," characters\n";
1685
1686       $font->offset
1687            This returns the ASCII value of the first character in the font
1688
1689       $width = $font->width
1690       $height = $font->height
1691       "height"
1692            These return the width and height of the font.
1693
1694              ($w,$h) = (gdLargeFont->width,gdLargeFont->height);
1695

Helper Functions

1697       GD::LIBGD_VERSION
1698           Returns a number of the libgd VERSION, like 2.0204, 2.0033 or 2.01.
1699
1700       GD::VERSION_STRING
1701           Returns the string of the libgd VERSION, like "2.2.4".
1702
1703       GD::constant
1704

Obtaining the C-language version of gd

1706       libgd, the C-language version of gd, can be obtained at URL
1707       http://libgd.org/  Directions for installing and using it can be found
1708       at that site.  Please do not contact me for help with libgd.
1709

AUTHOR

1711       The GD.pm interface is copyright 1995-2010, Lincoln D. Stein. This
1712       package and its accompanying libraries is free software; you can
1713       redistribute it and/or modify it under the terms of the GPL (either
1714       version 1, or at your option, any later version) or the Artistic
1715       License 2.0.  Refer to LICENSE for the full license text.  package for
1716       details.
1717
1718       The latest versions of GD.pm are available at
1719
1720         https://github.com/lstein/Perl-GD
1721

SEE ALSO

1723       GD::Polyline, GD::SVG, GD::Simple, Image::Magick
1724
1725
1726
1727perl v5.36.0                      2022-07-22                             GD(3)
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