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Table of Contents
XInitImage, XCreateImage,
XGetPixel, XPutPixel, XSubImage, XAddPixel, XDestroyImage - image utilities
- Status XInitImage(XImage *image);
- XImage *XCreateImage(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 *ximage, int x, int
- y);
- int XPutPixel(XImage
*ximage, int x, int y,
- unsigned long pixel);
- XImage *XSubImage(XImage
*ximage, int x, int y,
- unsigned int subimage_width, unsigned int subimage_height);
- int XAddPixel(XImage *ximage, long value);
- int XDestroyImage(XImage *ximage);
- 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.
- 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.
The XInitImage function
initializes the internal image manipulation routines of an image structure,
based on the values of the various structure members. All fields other than
the manipulation routines must already be initialized. If the bytes_per_line
member is zero, XInitImage will assume the image data is contiguous in
memory and set the bytes_per_line member to an appropriate value based
on the other members; otherwise, the value of bytes_per_line is not changed.
All of the manipulation routines are initialized to functions that other
Xlib image manipulation functions need to operate on the type of image
specified by the rest of the structure.
This function must be called for
any image constructed by the client before passing it to any other Xlib
function. Image structures created or returned by Xlib do not need to be
initialized in this fashion.
This function returns a nonzero status if initialization
of the structure is successful. It returns zero if it detected some error
or inconsistency in the structure, in which case the image is not changed.
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 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.
XPutImage(3X11)
Xlib - C Language X Interface
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