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
89       inconsistency 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-
94       order, 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
110       object.  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
114       image.  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
122       coordinates.
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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
131       image.  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 1.6.7                  XCreateImage(3)
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