XCreateImage(3X) XCreateImage(3X)
NAME
XCreateImage, XGetPixel, XPutPixel, XSubImage,
XAddPixel, XDestroyImage - image utilities
SYNOPSIS
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;
int 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;
int 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.
- 1 -
XCreateImage(3X) XCreateImage(3X)
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 a pointer to 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 a pointer to the visual.
width Specifies the width of the image, in pixels.
ximage Specifies a pointer to 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
- 2 -
XCreateImage(3X) XCreateImage(3X)
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 offset to a Z
format 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 Programming Manual
- 3 -