1XCreateImage(3)                 XLIB FUNCTIONS                 XCreateImage(3)
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NAME

6       XInitImage,  XCreateImage,  XGetPixel, XPutPixel, XSubImage, XAddPixel,
7       XDestroyImage - image utilities
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SYNTAX

10       Status XInitImage(XImage *image);
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12       XImage *XCreateImage(Display *display,  Visual  *visual,  unsigned  int
13              depth,  int  format, int offset, char *data, unsigned int width,
14              unsigned int height, int bitmap_pad, int bytes_per_line);
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16       unsigned long XGetPixel(XImage *ximage, int x, int y);
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18       int XPutPixel(XImage *ximage, int x, int y, unsigned long pixel);
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20       XImage *XSubImage(XImage *ximage, int x, int  y,  unsigned  int  subim‐
21              age_width, unsigned int subimage_height);
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23       int XAddPixel(XImage *ximage, long value);
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25       int XDestroyImage(XImage *ximage);
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ARGUMENTS

28       bitmap_pad
29                 Specifies the quantum of a scanline (8, 16, or 32).  In other
30                 words, the start of one scanline is separated in client  mem‐
31                 ory  from the start of the next scanline by an integer multi‐
32                 ple of this many bits.
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34       bytes_per_line
35                 Specifies the number of bytes in the client image between the
36                 start of one scanline and the start of the next.
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38       data      Specifies the image data.
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40       depth     Specifies the depth of the image.
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42       display   Specifies the connection to the X server.
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44       format    Specifies  the  format for the image.  You can pass XYBitmap,
45                 XYPixmap, or ZPixmap.
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47       height    Specifies the height of the image, in pixels.
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49       offset    Specifies the number of pixels to ignore at the beginning  of
50                 the scanline.
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52       pixel     Specifies the new pixel value.
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54       subimage_height
55                 Specifies the height of the new subimage, in pixels.
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57       subimage_width
58                 Specifies the width of the new subimage, in pixels.
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60       value     Specifies the constant value that is to be added.
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62       visual    Specifies the Visual structure.
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64       width     Specifies the width of the image, in pixels.
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66       ximage    Specifies the image.
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68       x
69       y         Specify the x and y coordinates.
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DESCRIPTION

72       The  XInitImage  function  initializes  the internal image manipulation
73       routines of an image structure, based on  the  values  of  the  various
74       structure  members.   All  fields  other than the manipulation routines
75       must already be initialized.  If the  bytes_per_line  member  is  zero,
76       XInitImage  will  assume the image data is contiguous in memory and set
77       the bytes_per_line member to an appropriate value based  on  the  other
78       members; otherwise, the value of bytes_per_line is not changed.  All of
79       the manipulation routines are initialized to functions that other  Xlib
80       image manipulation functions need to operate on the type of image spec‐
81       ified by the rest of the structure.
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83       This function must be called for any image constructed  by  the  client
84       before passing it to any other Xlib function.  Image structures created
85       or returned by Xlib do not need to be initialized in this fashion.
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87       This function returns a nonzero status if initialization of the  struc‐
88       ture  is  successful.  It returns zero if it detected some error or in‐
89       consistency in the structure, in which case the image is not changed.
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91       The XCreateImage function allocates the memory  needed  for  an  XImage
92       structure for the specified display but does not allocate space for the
93       image itself.  Rather, it initializes the structure byte-order, bit-or‐
94       der,  and  bitmap-unit values from the display and returns a pointer to
95       the XImage structure.  The red, green, and blue mask values are defined
96       for  Z  format  images  only  and are derived from the Visual structure
97       passed in.  Other values also are passed in.  The  offset  permits  the
98       rapid  displaying  of  the  image without requiring each scanline to be
99       shifted into position.  If you pass a  zero  value  in  bytes_per_line,
100       Xlib assumes that the scanlines are contiguous in memory and calculates
101       the value of bytes_per_line itself.
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103       Note that when the image is created using XCreateImage,  XGetImage,  or
104       XSubImage,  the destroy procedure that the XDestroyImage function calls
105       frees both the image structure and the data pointed  to  by  the  image
106       structure.
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108       The  basic  functions used to get a pixel, set a pixel, create a subim‐
109       age, and add a constant value to an image are defined in the image  ob‐
110       ject.   The  functions  in this section are really macro invocations of
111       the functions in the image object and are defined in X11/Xutil.h.
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113       The XGetPixel function returns the specified pixel from the  named  im‐
114       age.   The  pixel  value is returned in normalized format (that is, the
115       least significant byte of the long is the least significant byte of the
116       pixel).  The image must contain the x and y coordinates.
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118       The XPutPixel function overwrites the pixel in the named image with the
119       specified pixel value.  The input pixel value  must  be  in  normalized
120       format  (that  is,  the least significant byte of the long is the least
121       significant byte of the pixel).  The image must contain the x and y co‐
122       ordinates.
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124       The  XSubImage  function creates a new image that is a subsection of an
125       existing one.  It allocates the memory necessary  for  the  new  XImage
126       structure  and  returns a pointer to the new image.  The data is copied
127       from the source image, and the image must contain the rectangle defined
128       by x, y, subimage_width, and subimage_height.
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130       The  XAddPixel  function adds a constant value to every pixel in an im‐
131       age.  It is useful when you have a base  pixel  value  from  allocating
132       color resources and need to manipulate the image to that form.
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134       The  XDestroyImage  function deallocates the memory associated with the
135       XImage structure.
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SEE ALSO

138       XPutImage(3)
139       Xlib - C Language X Interface
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143X Version 11                     libX11 1.8.1                  XCreateImage(3)
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