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 = new GD::Image(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/local/bin/perl
69
70               use GD;
71
72               # create a new image
73               $im = new GD::Image(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 or XBM file.
106       2. Next you will ordinarily add colors to the image's color table.
107       colors are added using a colorAllocate() method call.  The three
108       parameters in each call are the red, green and blue (rgb) triples for
109       the desired color.  The method returns the index of that color in the
110       image's color table.  You should store these indexes for later use.
111       3. Now you can do some drawing!  The various graphics primitives are
112       described below.  In this example, we do some text drawing, create an
113       oval, and create and draw a polygon.
114       4. Polygons are created with a new() message to GD::Polygon.  You can
115       add points to the returned polygon one at a time using the addPt()
116       method. The polygon can then be passed to an image for rendering.
117       5. When you're done drawing, you can convert the image into PNG format
118       by sending it a png() message.  It will return a (potentially large)
119       scalar value containing the binary data for the image.  Ordinarily you
120       will print it out at this point or write it to a file.  To ensure
121       portability to platforms that differentiate between text and binary
122       files, be sure to call "binmode()" on the file you are writing the
123       image to.
124

Object Constructors: Creating Images

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

GD::Image Methods

295       Once a GD::Image object is created, you can draw with it, copy it, and
296       merge two images.  When you are finished manipulating the object, you
297       can convert it into a standard image file format to output or save to a
298       file.
299
300   Image Data Output Methods
301       The following methods convert the internal drawing format into standard
302       output file formats.
303
304       $pngdata = $image->png([$compression_level])
305           This returns the image data in PNG format.  You can then print it,
306           pipe it to a display program, or write it to a file.  Example:
307
308                   $png_data = $myImage->png;
309                   open (DISPLAY,"| display -") || die;
310                   binmode DISPLAY;
311                   print DISPLAY $png_data;
312                   close DISPLAY;
313
314           Note the use of "binmode()".  This is crucial for portability to
315           DOSish platforms.
316
317           The optional $compression_level argument controls the amount of
318           compression to apply to the output PNG image.  Values range from
319           0-9, where 0 means no compression (largest files, highest quality)
320           and 9 means maximum compression (smallest files, worst quality).  A
321           compression level of -1 uses the default compression level selected
322           when zlib was compiled on your system, and is the same as calling
323           png() with no argument.  Be careful not to confuse this argument
324           with the jpeg() quality argument, which ranges from 0-100 and has
325           the opposite meaning from compression (higher numbers give higher
326           quality).
327
328       $gifdata = $image->gifanimbegin([$GlobalCM [, $Loops]])
329           For libgd version 2.0.33 and higher, this call begins an animated
330           GIF by returning the data that comprises animated gif image file
331           header.  After you call this method, call gifanimadd() one or more
332           times to add the frames of the image. Then call gifanimend(). Each
333           frame must be the same width and height.
334
335           A typical sequence will look like this:
336
337             my $gifdata = $image->gifanimbegin;
338             $gifdata   .= $image->gifanimadd;    # first frame
339             for (1..100) {
340                # make a frame of right size
341                my $frame  = GD::Image->new($image->getBounds);
342                add_frame_data($frame);              # add the data for this frame
343                $gifdata   .= $frame->gifanimadd;     # add frame
344             }
345             $gifdata   .= $image->gifanimend;   # finish the animated GIF
346             print $gifdata;                     # write animated gif to STDOUT
347
348           If you do not wish to store the data in memory, you can print it to
349           stdout or a file.
350
351           The image that you call gifanimbegin on is used to set the image
352           size, color resolution and color map.  If argument $GlobalCM is 1,
353           the image color map becomes the GIF89a global color map.  If $Loops
354           is given and >= 0, the NETSCAPE2.0 application extension is
355           created, with looping count.  Looping count 0 means forever.
356
357       $gifdata = $image->gifanimadd([$LocalCM [, $LeftOfs [, $TopOfs [,
358       $Delay [, $Disposal [, $previm]]]]]])
359           Returns the data that comprises one animated gif image frame.  You
360           can then print it, pipe it to a display program, or write it to a
361           file.  With $LeftOfs and $TopOfs you can place this frame in
362           different offset than (0,0) inside the image screen.  Delay between
363           the previous frame and this frame is in 1/100s units.  Disposal is
364           usually and by default 1.  Compression is activated by giving the
365           previous image as a parameter.  This function then compares the
366           images and only writes the changed pixels to the new frame in
367           animation.  The Disposal parameter for optimized animations must be
368           set to 1, also for the first frame.  $LeftOfs and $TopOfs
369           parameters are ignored for optimized frames.
370
371       $gifdata = $image->gifanimend()
372           Returns the data for end segment of animated gif file.  It always
373           returns string ';'.  This string must be printed to an animated gif
374           file after all image frames to properly terminate it according to
375           GIF file syntax.  Image object is not used at all in this method.
376
377       $jpegdata = $image->jpeg([$quality])
378           This returns the image data in JPEG format.  You can then print it,
379           pipe it to a display program, or write it to a file.  You may pass
380           an optional quality score to jpeg() in order to control the JPEG
381           quality.  This should be an integer between 0 and 100.  Higher
382           quality scores give larger files and better image quality.  If you
383           don't specify the quality, jpeg() will choose a good default.
384
385       $gifdata = $image->gif().
386           This returns the image data in GIF format.  You can then print it,
387           pipe it to a display program, or write it to a file.
388
389       $gddata = $image->gd
390           This returns the image data in GD format.  You can then print it,
391           pipe it to a display program, or write it to a file.  Example:
392
393                   binmode MYOUTFILE;
394                   print MYOUTFILE $myImage->gd;
395
396       $gd2data = $image->gd2
397           Same as gd(), except that it returns the data in compressed GD2
398           format.
399
400       $wbmpdata = $image->wbmp([$foreground])
401           This returns the image data in WBMP format, which is a black-and-
402           white image format.  Provide the index of the color to become the
403           foreground color.  All other pixels will be considered background.
404
405   Color Control
406       These methods allow you to control and manipulate the GD::Image color
407       table.
408
409       $index = $image->colorAllocate(red,green,blue)
410           This allocates a color with the specified red, green and blue
411           components and returns its index in the color table, if specified.
412           The first color allocated in this way becomes the image's
413           background color.  (255,255,255) is white (all pixels on).  (0,0,0)
414           is black (all pixels off).  (255,0,0) is fully saturated red.
415           (127,127,127) is 50% gray.  You can find plenty of examples in
416           /usr/X11/lib/X11/rgb.txt.
417
418           If no colors are allocated, then this function returns -1.
419
420           Example:
421
422                   $white = $myImage->colorAllocate(0,0,0); #background color
423                   $black = $myImage->colorAllocate(255,255,255);
424                   $peachpuff = $myImage->colorAllocate(255,218,185);
425
426       $index = $image->colorAllocateAlpha(reg,green,blue,alpha)
427           This allocates a color with the specified red, green, and blue
428           components, plus the specified alpha channel.  The alpha value may
429           range from 0 (opaque) to 127 (transparent).  The "alphaBlending"
430           function changes the way this alpha channel affects the resulting
431           image.
432
433       $image->colorDeallocate(colorIndex)
434           This marks the color at the specified index as being ripe for
435           reallocation.  The next time colorAllocate is used, this entry will
436           be replaced.  You can call this method several times to deallocate
437           multiple colors.  There's no function result from this call.
438
439           Example:
440
441                   $myImage->colorDeallocate($peachpuff);
442                   $peachy = $myImage->colorAllocate(255,210,185);
443
444       $index = $image->colorClosest(red,green,blue)
445           This returns the index of the color closest in the color table to
446           the red green and blue components specified.  If no colors have yet
447           been allocated, then this call returns -1.
448
449           Example:
450
451                   $apricot = $myImage->colorClosest(255,200,180);
452
453       $index = $image->colorClosestHWB(red,green,blue)
454           This also attempts to return the color closest in the color table
455           to the red green and blue components specified. It uses a
456           Hue/White/Black color representation to make the selected color
457           more likely to match human perceptions of similar colors.
458
459           If no colors have yet been allocated, then this call returns -1.
460
461           Example:
462
463                   $mostred = $myImage->colorClosestHWB(255,0,0);
464
465       $index = $image->colorExact(red,green,blue)
466           This returns the index of a color that exactly matches the
467           specified red green and blue components.  If such a color is not in
468           the color table, this call returns -1.
469
470                   $rosey = $myImage->colorExact(255,100,80);
471                   warn "Everything's coming up roses.\n" if $rosey >= 0;
472
473       $index = $image->colorResolve(red,green,blue)
474           This returns the index of a color that exactly matches the
475           specified red green and blue components.  If such a color is not in
476           the color table and there is room, then this method allocates the
477           color in the color table and returns its index.
478
479                   $rosey = $myImage->colorResolve(255,100,80);
480                   warn "Everything's coming up roses.\n" if $rosey >= 0;
481
482       $colorsTotal = $image->colorsTotal object method
483           This returns the total number of colors allocated in the object.
484
485                   $maxColors = $myImage->colorsTotal;
486
487           In the case of a TrueColor image, this call will return undef.
488
489       $index = $image->getPixel(x,y) object method
490           This returns the color table index underneath the specified point.
491           It can be combined with rgb() to obtain the rgb color underneath
492           the pixel.
493
494           Example:
495
496                   $index = $myImage->getPixel(20,100);
497                   ($r,$g,$b) = $myImage->rgb($index);
498
499       ($red,$green,$blue) = $image->rgb($index)
500           This returns a list containing the red, green and blue components
501           of the specified color index.
502
503           Example:
504
505                   @RGB = $myImage->rgb($peachy);
506
507       $image->transparent($colorIndex)
508           This marks the color at the specified index as being transparent.
509           Portions of the image drawn in this color will be invisible.  This
510           is useful for creating paintbrushes of odd shapes, as well as for
511           making PNG backgrounds transparent for displaying on the Web.  Only
512           one color can be transparent at any time. To disable transparency,
513           specify -1 for the index.
514
515           If you call this method without any parameters, it will return the
516           current index of the transparent color, or -1 if none.
517
518           Example:
519
520                   open(PNG,"test.png");
521                   $im = newFromPng GD::Image(PNG);
522                   $white = $im->colorClosest(255,255,255); # find white
523                   $im->transparent($white);
524                   binmode STDOUT;
525                   print $im->png;
526
527   Special Colors
528       GD implements a number of special colors that can be used to achieve
529       special effects.  They are constants defined in the GD:: namespace, but
530       automatically exported into your namespace when the GD module is
531       loaded.
532
533       $image->setBrush($image)
534           You can draw lines and shapes using a brush pattern.  Brushes are
535           just images that you can create and manipulate in the usual way.
536           When you draw with them, their contents are used for the color and
537           shape of the lines.
538
539           To make a brushed line, you must create or load the brush first,
540           then assign it to the image using setBrush().  You can then draw in
541           that with that brush using the gdBrushed special color.  It's often
542           useful to set the background of the brush to transparent so that
543           the non-colored parts don't overwrite other parts of your image.
544
545           Example:
546
547                   # Create a brush at an angle
548                   $diagonal_brush = new GD::Image(5,5);
549                   $white = $diagonal_brush->colorAllocate(255,255,255);
550                   $black = $diagonal_brush->colorAllocate(0,0,0);
551                   $diagonal_brush->transparent($white);
552                   $diagonal_brush->line(0,4,4,0,$black); # NE diagonal
553
554                   # Set the brush
555                   $myImage->setBrush($diagonal_brush);
556
557                   # Draw a circle using the brush
558                   $myImage->arc(50,50,25,25,0,360,gdBrushed);
559
560       $image->setThickness($thickness)
561           Lines drawn with line(), rectangle(), arc(), and so forth are 1
562           pixel thick by default.  Call setThickness() to change the line
563           drawing width.
564
565       $image->setStyle(@colors)
566           Styled lines consist of an arbitrary series of repeated colors and
567           are useful for generating dotted and dashed lines.  To create a
568           styled line, use setStyle() to specify a repeating series of
569           colors.  It accepts an array consisting of one or more color
570           indexes.  Then draw using the gdStyled special color.  Another
571           special color, gdTransparent can be used to introduce holes in the
572           line, as the example shows.
573
574           Example:
575
576                   # Set a style consisting of 4 pixels of yellow,
577                   # 4 pixels of blue, and a 2 pixel gap
578                   $myImage->setStyle($yellow,$yellow,$yellow,$yellow,
579                                      $blue,$blue,$blue,$blue,
580                                      gdTransparent,gdTransparent);
581                   $myImage->arc(50,50,25,25,0,360,gdStyled);
582
583           To combine the "gdStyled" and "gdBrushed" behaviors, you can
584           specify "gdStyledBrushed".  In this case, a pixel from the current
585           brush pattern is rendered wherever the color specified in
586           setStyle() is neither gdTransparent nor 0.
587
588       gdTiled
589           Draw filled shapes and flood fills using a pattern.  The pattern is
590           just another image.  The image will be tiled multiple times in
591           order to fill the required space, creating wallpaper effects.  You
592           must call "setTile" in order to define the particular tile pattern
593           you'll use for drawing when you specify the gdTiled color.
594           details.
595
596       gdStyled
597           The gdStyled color is used for creating dashed and dotted lines.  A
598           styled line can contain any series of colors and is created using
599           the setStyled() command.
600
601       gdAntiAliased
602           The "gdAntiAliased" color is used for drawing lines with
603           antialiasing turned on.  Antialiasing will blend the jagged edges
604           of lines with the background, creating a smoother look.  The actual
605           color drawn is set with setAntiAliased().
606
607       $image->setAntiAliased($color)
608           "Antialiasing" is a process by which jagged edges associated with
609           line drawing can be reduced by blending the foreground color with
610           an appropriate percentage of the background, depending on how much
611           of the pixel in question is actually within the boundaries of the
612           line being drawn. All line-drawing methods, such as line() and
613           polygon, will draw antialiased lines if the special "color"
614           gdAntiAliased is used when calling them.
615
616           setAntiAliased() is used to specify the actual foreground color to
617           be used when drawing antialiased lines. You may set any color to be
618           the foreground, however as of libgd version 2.0.12 an alpha channel
619           component is not supported.
620
621           Antialiased lines can be drawn on both truecolor and palette-based
622           images. However, attempts to draw antialiased lines on highly
623           complex palette-based backgrounds may not give satisfactory
624           results, due to the limited number of colors available in the
625           palette. Antialiased line-drawing on simple backgrounds should work
626           well with palette-based images; otherwise create or fetch a
627           truecolor image instead. When using palette-based images, be sure
628           to allocate a broad spectrum of colors in order to have sufficient
629           colors for the antialiasing to use.
630
631       $image->setAntiAliasedDontBlend($color,[$flag])
632           Normally, when drawing lines with the special gdAntiAliased
633           "color," blending with the background to reduce jagged edges is the
634           desired behavior. However, when it is desired that lines not be
635           blended with one particular color when it is encountered in the
636           background, the setAntiAliasedDontBlend() method can be used to
637           indicate the special color that the foreground should stand out
638           more clearly against.
639
640           Once turned on, you can turn this feature off by calling
641           setAntiAliasedDontBlend() with a second argument of 0:
642
643            $image->setAntiAliasedDontBlend($color,0);
644
645   Drawing Commands
646       These methods allow you to draw lines, rectangles, and ellipses, as
647       well as to perform various special operations like flood-fill.
648
649       $image->setPixel($x,$y,$color)
650           This sets the pixel at (x,y) to the specified color index.  No
651           value is returned from this method.  The coordinate system starts
652           at the upper left at (0,0) and gets larger as you go down and to
653           the right.  You can use a real color, or one of the special colors
654           gdBrushed, gdStyled and gdStyledBrushed can be specified.
655
656           Example:
657
658                   # This assumes $peach already allocated
659                   $myImage->setPixel(50,50,$peach);
660
661       $image->line($x1,$y1,$x2,$y2,$color)
662           This draws a line from (x1,y1) to (x2,y2) of the specified color.
663           You can use a real color, or one of the special colors gdBrushed,
664           gdStyled and gdStyledBrushed.
665
666           Example:
667
668                   # Draw a diagonal line using the currently defined
669                   # paintbrush pattern.
670                   $myImage->line(0,0,150,150,gdBrushed);
671
672       $image->dashedLine($x1,$y1,$x2,$y2,$color)
673           DEPRECATED: The libgd library provides this method solely for
674           backward compatibility with libgd version 1.0, and there have been
675           reports that it no longer works as expected. Please use the
676           setStyle() and gdStyled methods as described below.
677
678           This draws a dashed line from (x1,y1) to (x2,y2) in the specified
679           color.  A more powerful way to generate arbitrary dashed and dotted
680           lines is to use the setStyle() method described below and to draw
681           with the special color gdStyled.
682
683           Example:
684
685                   $myImage->dashedLine(0,0,150,150,$blue);
686
687       $image->rectangle($x1,$y1,$x2,$y2,$color)
688           This draws a rectangle with the specified color.  (x1,y1) and
689           (x2,y2) are the upper left and lower right corners respectively.
690           Both real color indexes and the special colors gdBrushed, gdStyled
691           and gdStyledBrushed are accepted.
692
693           Example:
694
695                   $myImage->rectangle(10,10,100,100,$rose);
696
697       $image->filledRectangle($x1,$y1,$x2,$y2,$color)
698           This draws a rectangle filed with the specified color.  You can use
699           a real color, or the special fill color gdTiled to fill the polygon
700           with a pattern.
701
702           Example:
703
704                   # read in a fill pattern and set it
705                   $tile = newFromPng GD::Image('happyface.png');
706                   $myImage->setTile($tile);
707
708                   # draw the rectangle, filling it with the pattern
709                   $myImage->filledRectangle(10,10,150,200,gdTiled);
710
711       $image->openPolygon($polygon,$color)
712           This draws a polygon with the specified color.  The polygon must be
713           created first (see below).  The polygon must have at least three
714           vertices.  If the last vertex doesn't close the polygon, the method
715           will close it for you.  Both real color indexes and the special
716           colors gdBrushed, gdStyled and gdStyledBrushed can be specified.
717
718           Example:
719
720                   $poly = new GD::Polygon;
721                   $poly->addPt(50,0);
722                   $poly->addPt(99,99);
723                   $poly->addPt(0,99);
724                   $myImage->openPolygon($poly,$blue);
725
726       $image->unclosedPolygon($polygon,$color)
727           This draws a sequence of connected lines with the specified color,
728           without connecting the first and last point to a closed polygon.
729           The polygon must be created first (see below).  The polygon must
730           have at least three vertices.  Both real color indexes and the
731           special colors gdBrushed, gdStyled and gdStyledBrushed can be
732           specified.
733
734           You need libgd 2.0.33 or higher to use this feature.
735
736           Example:
737
738                   $poly = new GD::Polygon;
739                   $poly->addPt(50,0);
740                   $poly->addPt(99,99);
741                   $poly->addPt(0,99);
742                   $myImage->unclosedPolygon($poly,$blue);
743
744       $image->filledPolygon($poly,$color)
745           This draws a polygon filled with the specified color.  You can use
746           a real color, or the special fill color gdTiled to fill the polygon
747           with a pattern.
748
749           Example:
750
751                   # make a polygon
752                   $poly = new GD::Polygon;
753                   $poly->addPt(50,0);
754                   $poly->addPt(99,99);
755                   $poly->addPt(0,99);
756
757                   # draw the polygon, filling it with a color
758                   $myImage->filledPolygon($poly,$peachpuff);
759
760       $image->ellipse($cx,$cy,$width,$height,$color)
761       $image->filledEllipse($cx,$cy,$width,$height,$color)
762           These methods() draw ellipses. ($cx,$cy) is the center of the arc,
763           and ($width,$height) specify the ellipse width and height,
764           respectively.  filledEllipse() is like Ellipse() except that the
765           former produces filled versions of the ellipse.
766
767       $image->arc($cx,$cy,$width,$height,$start,$end,$color)
768           This draws arcs and ellipses.  (cx,cy) are the center of the arc,
769           and (width,height) specify the width and height, respectively.  The
770           portion of the ellipse covered by the arc are controlled by start
771           and end, both of which are given in degrees from 0 to 360.  Zero is
772           at the top of the ellipse, and angles increase clockwise.  To
773           specify a complete ellipse, use 0 and 360 as the starting and
774           ending angles.  To draw a circle, use the same value for width and
775           height.
776
777           You can specify a normal color or one of the special colors
778           gdBrushed, gdStyled, or gdStyledBrushed.
779
780           Example:
781
782                   # draw a semicircle centered at 100,100
783                   $myImage->arc(100,100,50,50,0,180,$blue);
784
785       $image->filledArc($cx,$cy,$width,$height,$start,$end,$color
786       [,$arc_style])
787           This method is like arc() except that it colors in the pie wedge
788           with the selected color.  $arc_style is optional.  If present it is
789           a bitwise OR of the following constants:
790
791             gdArc           connect start & end points of arc with a rounded edge
792             gdChord         connect start & end points of arc with a straight line
793             gdPie           synonym for gdChord
794             gdNoFill        outline the arc or chord
795             gdEdged         connect beginning and ending of the arc to the center
796
797           gdArc and gdChord are mutually exclusive.  gdChord just connects
798           the starting and ending angles with a straight line, while gdArc
799           produces a rounded edge. gdPie is a synonym for gdArc. gdNoFill
800           indicates that the arc or chord should be outlined, not filled.
801           gdEdged, used together with gdNoFill, indicates that the beginning
802           and ending angles should be connected to the center; this is a good
803           way to outline (rather than fill) a "pie slice."
804
805           Example:
806
807             $image->filledArc(100,100,50,50,0,90,$blue,gdEdged|gdNoFill);
808
809       $image->fill($x,$y,$color)
810           This method flood-fills regions with the specified color.  The
811           color will spread through the image, starting at point (x,y), until
812           it is stopped by a pixel of a different color from the starting
813           pixel (this is similar to the "paintbucket" in many popular drawing
814           toys).  You can specify a normal color, or the special color
815           gdTiled, to flood-fill with patterns.
816
817           Example:
818
819                   # Draw a rectangle, and then make its interior blue
820                   $myImage->rectangle(10,10,100,100,$black);
821                   $myImage->fill(50,50,$blue);
822
823       $image->fillToBorder($x,$y,$bordercolor,$color)
824           Like "fill", this method flood-fills regions with the specified
825           color, starting at position (x,y).  However, instead of stopping
826           when it hits a pixel of a different color than the starting pixel,
827           flooding will only stop when it hits the color specified by
828           bordercolor.  You must specify a normal indexed color for the
829           bordercolor.  However, you are free to use the gdTiled color for
830           the fill.
831
832           Example:
833
834                   # This has the same effect as the previous example
835                   $myImage->rectangle(10,10,100,100,$black);
836                   $myImage->fillToBorder(50,50,$black,$blue);
837
838   Image Copying Commands
839       Two methods are provided for copying a rectangular region from one
840       image to another.  One method copies a region without resizing it.  The
841       other allows you to stretch the region during the copy operation.
842
843       With either of these methods it is important to know that the routines
844       will attempt to flesh out the destination image's color table to match
845       the colors that are being copied from the source.  If the destination's
846       color table is already full, then the routines will attempt to find the
847       best match, with varying results.
848
849       $image->copy($sourceImage,$dstX,$dstY,
850                               $srcX,$srcY,$width,$height)
851
852           This is the simplest of the several copy operations, copying the
853           specified region from the source image to the destination image
854           (the one performing the method call).  (srcX,srcY) specify the
855           upper left corner of a rectangle in the source image, and
856           (width,height) give the width and height of the region to copy.
857           (dstX,dstY) control where in the destination image to stamp the
858           copy.  You can use the same image for both the source and the
859           destination, but the source and destination regions must not
860           overlap or strange things will happen.
861
862           Example:
863
864                   $myImage = new GD::Image(100,100);
865                   ... various drawing stuff ...
866                   $srcImage = new GD::Image(50,50);
867                   ... more drawing stuff ...
868                   # copy a 25x25 pixel region from $srcImage to
869                   # the rectangle starting at (10,10) in $myImage
870                   $myImage->copy($srcImage,10,10,0,0,25,25);
871
872       $image->clone()
873           Make a copy of the image and return it as a new object.  The new
874           image will look identical.  However, it may differ in the size of
875           the color palette and other nonessential details.
876
877           Example:
878
879                   $myImage = new GD::Image(100,100);
880                   ... various drawing stuff ...
881                   $copy = $myImage->clone;
882
883       $image->copyMerge($sourceImage,$dstX,$dstY,
884                               $srcX,$srcY,$width,$height,$percent)
885
886           This copies the indicated rectangle from the source image to the
887           destination image, merging the colors to the extent specified by
888           percent (an integer between 0 and 100).  Specifying 100% has the
889           same effect as copy() -- replacing the destination pixels with the
890           source image.  This is most useful for highlighting an area by
891           merging in a solid rectangle.
892
893           Example:
894
895                   $myImage = new GD::Image(100,100);
896                   ... various drawing stuff ...
897                   $redImage = new GD::Image(50,50);
898                   ... more drawing stuff ...
899                   # copy a 25x25 pixel region from $srcImage to
900                   # the rectangle starting at (10,10) in $myImage, merging 50%
901                   $myImage->copyMerge($srcImage,10,10,0,0,25,25,50);
902
903       $image->copyMergeGray($sourceImage,$dstX,$dstY,
904                               $srcX,$srcY,$width,$height,$percent)
905
906           This is identical to copyMerge() except that it preserves the hue
907           of the source by converting all the pixels of the destination
908           rectangle to grayscale before merging.
909
910       $image->copyResized($sourceImage,$dstX,$dstY,
911                               $srcX,$srcY,$destW,$destH,$srcW,$srcH)
912
913           This method is similar to copy() but allows you to choose different
914           sizes for the source and destination rectangles.  The source and
915           destination rectangle's are specified independently by (srcW,srcH)
916           and (destW,destH) respectively.  copyResized() will stretch or
917           shrink the image to accommodate the size requirements.
918
919           Example:
920
921                   $myImage = new GD::Image(100,100);
922                   ... various drawing stuff ...
923                   $srcImage = new GD::Image(50,50);
924                   ... more drawing stuff ...
925                   # copy a 25x25 pixel region from $srcImage to
926                   # a larger rectangle starting at (10,10) in $myImage
927                   $myImage->copyResized($srcImage,10,10,0,0,50,50,25,25);
928
929       $image->copyResampled($sourceImage,$dstX,$dstY,
930                               $srcX,$srcY,$destW,$destH,$srcW,$srcH)
931
932           This method is similar to copyResized() but provides "smooth"
933           copying from a large image to a smaller one, using a weighted
934           average of the pixels of the source area rather than selecting one
935           representative pixel. This method is identical to copyResized()
936           when the destination image is a palette image.
937
938       $image->copyRotated($sourceImage,$dstX,$dstY,
939                               $srcX,$srcY,$width,$height,$angle)
940
941           Like copyResized() but the $angle argument specifies an arbitrary
942           amount to rotate the image clockwise (in degrees).  In addition,
943           $dstX and $dstY species the center of the destination image, and
944           not the top left corner.
945
946       $image->trueColorToPalette([$dither], [$colors])
947           This method converts a truecolor image to a palette image. The code
948           for this function was originally drawn from the Independent JPEG
949           Group library code, which is excellent. The code has been modified
950           to preserve as much alpha channel information as possible in the
951           resulting palette, in addition to preserving colors as well as
952           possible. This does not work as well as might be hoped. It is
953           usually best to simply produce a truecolor output image instead,
954           which guarantees the highest output quality.  Both the dithering
955           (0/1, default=0) and maximum number of colors used (<=256, default
956           = gdMaxColors) can be specified.
957
958   Image Transformation Commands
959       Gd also provides some common image transformations:
960
961       $image = $sourceImage->copyRotate90()
962       $image = $sourceImage->copyRotate180()
963       $image = $sourceImage->copyRotate270()
964       $image = $sourceImage->copyFlipHorizontal()
965       $image = $sourceImage->copyFlipVertical()
966       $image = $sourceImage->copyTranspose()
967       $image = $sourceImage->copyReverseTranspose()
968           These methods can be used to rotate, flip, or transpose an image.
969           The result of the method is a copy of the image.
970
971       $image->rotate180()
972       $image->flipHorizontal()
973       $image->flipVertical()
974           These methods are similar to the copy* versions, but instead modify
975           the image in place.
976
977   Character and String Drawing
978       GD allows you to draw characters and strings, either in normal
979       horizontal orientation or rotated 90 degrees.  These routines use a
980       GD::Font object, described in more detail below.  There are four built-
981       in monospaced fonts, available in the global variables gdGiantFont,
982       gdLargeFont, gdMediumBoldFont, gdSmallFont and gdTinyFont.
983
984       In addition, you can use the load() method to load GD-formatted bitmap
985       font files at runtime. You can create these bitmap files from X11 BDF-
986       format files using the bdf2gd.pl script, which should have been
987       installed with GD (see the bdf_scripts directory if it wasn't).  The
988       format happens to be identical to the old-style MSDOS bitmap ".fnt"
989       files, so you can use one of those directly if you happen to have one.
990
991       For writing proportional scaleable fonts, GD offers the stringFT()
992       method, which allows you to load and render any TrueType font on your
993       system.
994
995       $image->string($font,$x,$y,$string,$color)
996           This method draws a string starting at position (x,y) in the
997           specified font and color.  Your choices of fonts are gdSmallFont,
998           gdMediumBoldFont, gdTinyFont, gdLargeFont and gdGiantFont.
999
1000           Example:
1001
1002                   $myImage->string(gdSmallFont,2,10,"Peachy Keen",$peach);
1003
1004       $image->stringUp($font,$x,$y,$string,$color)
1005           Just like the previous call, but draws the text rotated
1006           counterclockwise 90 degrees.
1007
1008       $image->char($font,$x,$y,$char,$color)
1009       $image->charUp($font,$x,$y,$char,$color)
1010           These methods draw single characters at position (x,y) in the
1011           specified font and color.  They're carry-overs from the C
1012           interface, where there is a distinction between characters and
1013           strings.  Perl is insensible to such subtle distinctions.
1014
1015       $font = GD::Font->load($fontfilepath)
1016           This method dynamically loads a font file, returning a font that
1017           you can use in subsequent calls to drawing methods.  For example:
1018
1019              my $courier = GD::Font->load('./courierR12.fnt') or die "Can't load font";
1020              $image->string($courier,2,10,"Peachy Keen",$peach);
1021
1022           Font files must be in GD binary format, as described above.
1023
1024       @bounds =
1025       $image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string)
1026       @bounds =
1027       GD::Image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string)
1028       @bounds =
1029       $image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string,\%options)
1030           This method uses TrueType to draw a scaled, antialiased string
1031           using the TrueType vector font of your choice.  It requires that
1032           libgd to have been compiled with TrueType support, and for the
1033           appropriate TrueType font to be installed on your system.
1034
1035           The arguments are as follows:
1036
1037             fgcolor    Color index to draw the string in
1038             fontname   A path to the TrueType (.ttf) font file or a font pattern.
1039             ptsize     The desired point size (may be fractional)
1040             angle      The rotation angle, in radians (positive values rotate counter clockwise)
1041             x,y        X and Y coordinates to start drawing the string
1042             string     The string itself
1043
1044           If successful, the method returns an eight-element list giving the
1045           boundaries of the rendered string:
1046
1047            @bounds[0,1]  Lower left corner (x,y)
1048            @bounds[2,3]  Lower right corner (x,y)
1049            @bounds[4,5]  Upper right corner (x,y)
1050            @bounds[6,7]  Upper left corner (x,y)
1051
1052           In case of an error (such as the font not being available, or FT
1053           support not being available), the method returns an empty list and
1054           sets $@ to the error message.
1055
1056           The string may contain UTF-8 sequences like: "&#192;"
1057
1058           You may also call this method from the GD::Image class name, in
1059           which case it doesn't do any actual drawing, but returns the
1060           bounding box using an inexpensive operation.  You can use this to
1061           perform layout operations prior to drawing.
1062
1063           Using a negative color index will disable antialiasing, as
1064           described in the libgd manual page at
1065           <http://www.boutell.com/gd/manual2.0.9.html#gdImageStringFT>.
1066
1067           An optional 8th argument allows you to pass a hashref of options to
1068           stringFT().  Several hashkeys are recognized: linespacing, charmap,
1069           resolution, and kerning.
1070
1071           The value of linespacing is supposed to be a multiple of the
1072           character height, so setting linespacing to 2.0 will result in
1073           double-spaced lines of text.  However the current version of libgd
1074           (2.0.12) does not do this.  Instead the linespacing seems to be
1075           double what is provided in this argument.  So use a spacing of 0.5
1076           to get separation of exactly one line of text.  In practice, a
1077           spacing of 0.6 seems to give nice results.  Another thing to watch
1078           out for is that successive lines of text should be separated by the
1079           "\r\n" characters, not just "\n".
1080
1081           The value of charmap is one of "Unicode", "Shift_JIS" and "Big5".
1082           The interaction between Perl, Unicode and libgd is not clear to me,
1083           and you should experiment a bit if you want to use this feature.
1084
1085           The value of resolution is the vertical and horizontal resolution,
1086           in DPI, in the format "hdpi,vdpi".  If present, the resolution will
1087           be passed to the Freetype rendering engine as a hint to improve the
1088           appearance of the rendered font.
1089
1090           The value of kerning is a flag.  Set it to false to turn off the
1091           default kerning of text.
1092
1093           Example:
1094
1095            $gd->stringFT($black,'/dosc/windows/Fonts/pala.ttf',40,0,20,90,
1096                         "hi there\r\nbye now",
1097                         {linespacing=>0.6,
1098                          charmap  => 'Unicode',
1099                         });
1100
1101           If GD was compiled with fontconfig support, and the fontconfig
1102           library is available on your system, then you can use a font name
1103           pattern instead of a path.  Patterns are described in fontconfig
1104           and will look something like this "Times:italic".  For backward
1105           compatibility, this feature is disabled by default.  You must
1106           enable it by calling useFontConfig(1) prior to the stringFT() call.
1107
1108              $image->useFontConfig(1);
1109
1110           For backward compatibility with older versions of the FreeType
1111           library, the alias stringTTF() is also recognized.
1112
1113       $hasfontconfig = $image->useFontConfig($flag)
1114           Call useFontConfig() with a value of 1 in order to enable support
1115           for fontconfig font patterns (see stringFT).  Regardless of the
1116           value of $flag, this method will return a true value if the
1117           fontconfig library is present, or false otherwise.
1118
1119       $result =
1120       $image-stringFTCircle($cx,$cy,$radius,$textRadius,$fillPortion,$font,$points,$top,$bottom,$fgcolor)>
1121           This draws text in a circle. Currently (libgd 2.0.33) this function
1122           does not work for me, but the interface is provided for
1123           completeness.  The call signature is somewhat complex.  Here is an
1124           excerpt from the libgd manual page:
1125
1126           Draws the text strings specified by top and bottom on the image,
1127           curved along the edge of a circle of radius radius, with its center
1128           at cx and cy. top is written clockwise along the top; bottom is
1129           written counterclockwise along the bottom. textRadius determines
1130           the "height" of each character; if textRadius is 1/2 of radius,
1131           characters extend halfway from the edge to the center. fillPortion
1132           varies from 0 to 1.0, with useful values from about 0.4 to 0.9, and
1133           determines how much of the 180 degrees of arc assigned to each
1134           section of text is actually occupied by text; 0.9 looks better than
1135           1.0 which is rather crowded. font is a freetype font; see
1136           gdImageStringFT. points is passed to the freetype engine and has an
1137           effect on hinting; although the size of the text is determined by
1138           radius, textRadius, and fillPortion, you should pass a point size
1139           that "hints" appropriately -- if you know the text will be large,
1140           pass a large point size such as 24.0 to get the best results.
1141           fgcolor can be any color, and may have an alpha component, do
1142           blending, etc.
1143
1144           Returns a true value on success.
1145
1146   Alpha channels
1147       The alpha channel methods allow you to control the way drawings are
1148       processed according to the alpha channel. When true color is turned on,
1149       colors are encoded as four bytes, in which the last three bytes are the
1150       RGB color values, and the first byte is the alpha channel.  Therefore
1151       the hexadecimal representation of a non transparent RGB color will be:
1152       C=0x00(rr)(bb)(bb)
1153
1154       When alpha blending is turned on, you can use the first byte of the
1155       color to control the transparency, meaning that a rectangle painted
1156       with color 0x00(rr)(bb)(bb) will be opaque, and another one painted
1157       with 0x7f(rr)(gg)(bb) will be transparent. The Alpha value must be >= 0
1158       and <= 0x7f.
1159
1160       $image->alphaBlending($integer)
1161           The alphaBlending() method allows for two different modes of
1162           drawing on truecolor images. In blending mode, which is on by
1163           default (libgd 2.0.2 and above), the alpha channel component of the
1164           color supplied to all drawing functions, such as "setPixel",
1165           determines how much of the underlying color should be allowed to
1166           shine through. As a result, GD automatically blends the existing
1167           color at that point with the drawing color, and stores the result
1168           in the image. The resulting pixel is opaque. In non-blending mode,
1169           the drawing color is copied literally with its alpha channel
1170           information, replacing the destination pixel. Blending mode is not
1171           available when drawing on palette images.
1172
1173           Pass a value of 1 for blending mode, and 0 for non-blending mode.
1174
1175       $image->saveAlpha($saveAlpha)
1176           By default, GD (libgd 2.0.2 and above) does not attempt to save
1177           full alpha channel information (as opposed to single-color
1178           transparency) when saving PNG images. (PNG is currently the only
1179           output format supported by gd which can accommodate alpha channel
1180           information.) This saves space in the output file. If you wish to
1181           create an image with alpha channel information for use with tools
1182           that support it, call saveAlpha(1) to turn on saving of such
1183           information, and call alphaBlending(0) to turn off alpha blending
1184           within the library so that alpha channel information is actually
1185           stored in the image rather than being composited immediately at the
1186           time that drawing functions are invoked.
1187
1188   Miscellaneous Image Methods
1189       These are various utility methods that are useful in some
1190       circumstances.
1191
1192       $image->interlaced([$flag])
1193           This method sets or queries the image's interlaced setting.
1194           Interlace produces a cool venetian blinds effect on certain
1195           viewers.  Provide a true parameter to set the interlace attribute.
1196           Provide undef to disable it.  Call the method without parameters to
1197           find out the current setting.
1198
1199       ($width,$height) = $image->getBounds()
1200           This method will return a two-member list containing the width and
1201           height of the image.  You query but not change the size of the
1202           image once it's created.
1203
1204       $width = $image->width
1205       $height = $image->height
1206           Return the width and height of the image, respectively.
1207
1208       $is_truecolor = $image->isTrueColor()
1209           This method will return a Boolean representing whether the image is
1210           true color or not.
1211
1212       $flag = $image1->compare($image2)
1213           Compare two images and return a bitmap describing the differences
1214           found, if any.  The return value must be logically ANDed with one
1215           or more constants in order to determine the differences.  The
1216           following constants are available:
1217
1218             GD_CMP_IMAGE             The two images look different
1219             GD_CMP_NUM_COLORS        The two images have different numbers of colors
1220             GD_CMP_COLOR             The two images' palettes differ
1221             GD_CMP_SIZE_X            The two images differ in the horizontal dimension
1222             GD_CMP_SIZE_Y            The two images differ in the vertical dimension
1223             GD_CMP_TRANSPARENT       The two images have different transparency
1224             GD_CMP_BACKGROUND        The two images have different background colors
1225             GD_CMP_INTERLACE         The two images differ in their interlace
1226             GD_CMP_TRUECOLOR         The two images are not both true color
1227
1228           The most important of these is GD_CMP_IMAGE, which will tell you
1229           whether the two images will look different, ignoring differences in
1230           the order of colors in the color palette and other invisible
1231           changes.  The constants are not imported by default, but must be
1232           imported individually or by importing the :cmp tag.  Example:
1233
1234             use GD qw(:DEFAULT :cmp);
1235             # get $image1 from somewhere
1236             # get $image2 from somewhere
1237             if ($image1->compare($image2) & GD_CMP_IMAGE) {
1238                warn "images differ!";
1239             }
1240
1241       $image->clip($x1,$y1,$x2,$y2)
1242       ($x1,$y1,$x2,$y2) = $image->clip
1243           Set or get the clipping rectangle.  When the clipping rectangle is
1244           set, all drawing will be clipped to occur within this rectangle.
1245           The clipping rectangle is initially set to be equal to the
1246           boundaries of the whole image. Change it by calling clip() with the
1247           coordinates of the new clipping rectangle.  Calling clip() without
1248           any arguments will return the current clipping rectangle.
1249
1250       $flag = $image->boundsSafe($x,$y)
1251           The boundsSafe() method will return true if the point indicated by
1252           ($x,$y) is within the clipping rectangle, or false if it is not.
1253           If the clipping rectangle has not been set, then it will return
1254           true if the point lies within the image boundaries.
1255
1256   Grouping Methods
1257       GD does not support grouping of objects, but GD::SVG does. In that
1258       subclass, the following methods declare new groups of graphical
1259       objects:
1260
1261       $image->startGroup([$id,\%style])
1262       $image->endGroup()
1263       $group = $image->newGroup
1264           See GD::SVG for information.
1265

Polygons

1267       A few primitive polygon creation and manipulation methods are provided.
1268       They aren't part of the Gd library, but I thought they might be handy
1269       to have around (they're borrowed from my qd.pl Quickdraw library).
1270       Also see GD::Polyline.
1271
1272       $poly = GD::Polygon->new
1273          Create an empty polygon with no vertices.
1274
1275                  $poly = new GD::Polygon;
1276
1277       $poly->addPt($x,$y)
1278          Add point (x,y) to the polygon.
1279
1280                  $poly->addPt(0,0);
1281                  $poly->addPt(0,50);
1282                  $poly->addPt(25,25);
1283                  $myImage->fillPoly($poly,$blue);
1284
1285       ($x,$y) = $poly->getPt($index)
1286          Retrieve the point at the specified vertex.
1287
1288                  ($x,$y) = $poly->getPt(2);
1289
1290       $poly->setPt($index,$x,$y)
1291          Change the value of an already existing vertex.  It is an error to
1292          set a vertex that isn't already defined.
1293
1294                  $poly->setPt(2,100,100);
1295
1296       ($x,$y) = $poly->deletePt($index)
1297          Delete the specified vertex, returning its value.
1298
1299                  ($x,$y) = $poly->deletePt(1);
1300
1301       $poly->clear()
1302          Delete all vertices, restoring the polygon to its initial empty
1303          state.
1304
1305       $poly->toPt($dx,$dy)
1306          Draw from current vertex to a new vertex, using relative (dx,dy)
1307          coordinates.  If this is the first point, act like addPt().
1308
1309                  $poly->addPt(0,0);
1310                  $poly->toPt(0,50);
1311                  $poly->toPt(25,-25);
1312                  $myImage->fillPoly($poly,$blue);
1313
1314       $vertex_count = $poly->length
1315          Return the number of vertices in the polygon.
1316
1317                  $points = $poly->length;
1318
1319       @vertices = $poly->vertices
1320          Return a list of all the vertices in the polygon object.  Each
1321          member of the list is a reference to an (x,y) array.
1322
1323                  @vertices = $poly->vertices;
1324                  foreach $v (@vertices)
1325                     print join(",",@$v),"\n";
1326                  }
1327
1328       @rect = $poly->bounds
1329          Return the smallest rectangle that completely encloses the polygon.
1330          The return value is an array containing the (left,top,right,bottom)
1331          of the rectangle.
1332
1333                  ($left,$top,$right,$bottom) = $poly->bounds;
1334
1335       $poly->offset($dx,$dy)
1336          Offset all the vertices of the polygon by the specified horizontal
1337          (dh) and vertical (dy) amounts.  Positive numbers move the polygon
1338          down and to the right.
1339
1340                  $poly->offset(10,30);
1341
1342       $poly->map($srcL,$srcT,$srcR,$srcB,$destL,$dstT,$dstR,$dstB)
1343          Map the polygon from a source rectangle to an equivalent position in
1344          a destination rectangle, moving it and resizing it as necessary.
1345          See polys.pl for an example of how this works.  Both the source and
1346          destination rectangles are given in (left,top,right,bottom)
1347          coordinates.  For convenience, you can use the polygon's own
1348          bounding box as the source rectangle.
1349
1350                  # Make the polygon really tall
1351                  $poly->map($poly->bounds,0,0,50,200);
1352
1353       $poly->scale($sx,$sy)
1354          Scale each vertex of the polygon by the X and Y factors indicated by
1355          sx and sy.  For example scale(2,2) will make the polygon twice as
1356          large.  For best results, move the center of the polygon to position
1357          (0,0) before you scale, then move it back to its previous position.
1358
1359       $poly->transform($sx,$rx,$sy,$ry,$tx,$ty)
1360          Run each vertex of the polygon through a transformation matrix,
1361          where sx and sy are the X and Y scaling factors, rx and ry are the X
1362          and Y rotation factors, and tx and ty are X and Y offsets.  See the
1363          Adobe PostScript Reference, page 154 for a full explanation, or
1364          experiment.
1365
1366   GD::Polyline
1367       Please see GD::Polyline for information on creating open polygons and
1368       splines.
1369

Font Utilities

1371       The libgd library (used by the Perl GD library) has built-in support
1372       for about half a dozen fonts, which were converted from public-domain X
1373       Windows fonts.  For more fonts, compile libgd with TrueType support and
1374       use the stringFT() call.
1375
1376       If you wish to add more built-in fonts, the directory bdf_scripts
1377       contains two contributed utilities that may help you convert X-Windows
1378       BDF-format fonts into the format that libgd uses internally.  However
1379       these scripts were written for earlier versions of GD which included
1380       its own mini-gd library.  These scripts will have to be adapted for use
1381       with libgd, and the libgd library itself will have to be recompiled and
1382       linked!  Please do not contact me for help with these scripts: they are
1383       unsupported.
1384
1385       Each of these fonts is available both as an imported global (e.g.
1386       gdSmallFont) and as a package method (e.g. GD::Font->Small).
1387
1388       gdSmallFont
1389       GD::Font->Small
1390            This is the basic small font, "borrowed" from a well known public
1391            domain 6x12 font.
1392
1393       gdLargeFont
1394       GD::Font->Large
1395            This is the basic large font, "borrowed" from a well known public
1396            domain 8x16 font.
1397
1398       gdMediumBoldFont
1399       GD::Font->MediumBold
1400            This is a bold font intermediate in size between the small and
1401            large fonts, borrowed from a public domain 7x13 font;
1402
1403       gdTinyFont
1404       GD::Font->Tiny
1405            This is a tiny, almost unreadable font, 5x8 pixels wide.
1406
1407       gdGiantFont
1408       GD::Font->Giant
1409            This is a 9x15 bold font converted by Jan Pazdziora from a sans
1410            serif X11 font.
1411
1412       $font->nchars
1413            This returns the number of characters in the font.
1414
1415                    print "The large font contains ",gdLargeFont->nchars," characters\n";
1416
1417       $font->offset
1418            This returns the ASCII value of the first character in the font
1419
1420       $width = $font->width
1421       $height = $font->height
1422       "height"
1423            These return the width and height of the font.
1424
1425              ($w,$h) = (gdLargeFont->width,gdLargeFont->height);
1426

Obtaining the C-language version of gd

1428       libgd, the C-language version of gd, can be obtained at URL
1429       http://www.boutell.com/gd/.  Directions for installing and using it can
1430       be found at that site.  Please do not contact me for help with libgd.
1431

AUTHOR

1433       The GD.pm interface is copyright 1995-2007, Lincoln D. Stein.  It is
1434       distributed under GPL and the Artistic License 2.0.
1435
1436       The latest versions of GD.pm are available at
1437
1438         http://stein.cshl.org/WWW/software/GD
1439

SEE ALSO

1441       GD::Polyline, GD::SVG, GD::Simple, Image::Magick
1442

POD ERRORS

1444       Hey! The above document had some coding errors, which are explained
1445       below:
1446
1447       Around line 463:
1448           You forgot a '=back' before '=head1'
1449
1450       Around line 475:
1451           '=item' outside of any '=over'
1452
1453
1454
1455perl v5.12.0                      2009-07-10                             GD(3)
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