XCreateImage(3X11) X Version 11 (Release 5) XCreateImage(3X11)
NAME
XCreateImage, XGetPixel, XPutPixel, XSubImage, XAddPixel,
XDestroyImage - image utilities
SYNTAX
XImage *XCreateImage(display, visual, depth, format, offset,
data, width, height, bitmap_pad,
bytes_per_line)
Display *display;
Visual *visual;
unsigned int depth;
int format;
int offset;
char *data;
unsigned int width;
unsigned int height;
int bitmap_pad;
int bytes_per_line;
unsigned long XGetPixel(ximage, x, y)
XImage *ximage;
int x;
int y;
XPutPixel(ximage, x, y, pixel)
XImage *ximage;
int x;
int y;
unsigned long pixel;
XImage *XSubImage(ximage, x, y, subimage_width,
subimage_height)
XImage *ximage;
int x;
int y;
unsigned int subimage_width;
unsigned int subimage_height;
XAddPixel(ximage, value)
XImage *ximage;
long value;
XDestroyImage(ximage)
XImage *ximage;
ARGUMENTS
bitmap_pad
Specifies the quantum of a scanline (8, 16, or
32). In other words, the start of one scanline is
separated in client memory from the start of the
next scanline by an integer multiple of this many
bits.
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XCreateImage(3X11) X Version 11 (Release 5) XCreateImage(3X11)
bytes_per_line
Specifies the number of bytes in the client image
between the start of one scanline and the start of
the next.
data Specifies the image data.
depth Specifies the depth of the image.
display Specifies the connection to the X server.
format Specifies the format for the image. You can pass
XYBitmap, XYPixmap, or ZPixmap.
height Specifies the height of the image, in pixels.
offset Specifies the number of pixels to ignore at the
beginning of the scanline.
pixel Specifies the new pixel value.
subimage_height
Specifies the height of the new subimage, in
pixels.
subimage_width
Specifies the width of the new subimage, in
pixels.
value Specifies the constant value that is to be added.
visual Specifies the Visual structure.
width Specifies the width of the image, in pixels.
ximage Specifies the image.
x
y Specify the x and y coordinates.
DESCRIPTION
The XCreateImage function allocates the memory needed for an
XImage structure for the specified display but does not
allocate space for the image itself. Rather, it initializes
the structure byte-order, bit-order, and bitmap-unit values
from the display and returns a pointer to the XImage
structure. The red, green, and blue mask values are defined
for Z format images only and are derived from the Visual
structure passed in. Other values also are passed in. The
offset permits the rapid displaying of the image without
requiring each scanline to be shifted into position. If you
pass a zero value in bytes_per_line, Xlib assumes that the
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XCreateImage(3X11) X Version 11 (Release 5) XCreateImage(3X11)
scanlines are contiguous in memory and calculates the value
of bytes_per_line itself.
Note that when the image is created using XCreateImage,
XGetImage, or XSubImage, the destroy procedure that the
XDestroyImage function calls frees both the image structure
and the data pointed to by the image structure.
The basic functions used to get a pixel, set a pixel, create
a subimage, and add a constant value to an image are defined
in the image object. The functions in this section are
really macro invocations of the functions in the image
object and are defined in <X11/Xutil.h>.
The XGetPixel function returns the specified pixel from the
named image. The pixel value is returned in normalized
format (that is, the least-significant byte of the long is
the least-significant byte of the pixel). The image must
contain the x and y coordinates.
The XPutPixel function overwrites the pixel in the named
image with the specified pixel value. The input pixel value
must be in normalized format (that is, the least-significant
byte of the long is the least-significant byte of the
pixel). The image must contain the x and y coordinates.
The XSubImage function creates a new image that is a
subsection of an existing one. It allocates the memory
necessary for the new XImage structure and returns a pointer
to the new image. The data is copied from the source image,
and the image must contain the rectangle defined by x, y,
subimage_width, and subimage_height.
The XAddPixel function adds a constant value to every pixel
in an image. It is useful when you have a base pixel value
from allocating color resources and need to manipulate the
image to that form.
The XDestroyImage function deallocates the memory associated
with the XImage structure.
SEE ALSO
XPutImage(3X11)
Xlib - C Language X Interface
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