XCreateImage(3) XLIB FUNCTIONS XCreateImage(3)
XInitImage, XCreateImage, XGetPixel, XPutPixel, XSubImage, XAddPixel, XDestroyImage -
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
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
int XAddPixel(XImage *ximage, long value);
int XDestroyImage(XImage *ximage);
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 scan-
line by an integer multiple of this many bits.
Specifies the number of bytes in the client image between the start of one scan-
line 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
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.
Specifies the height of the new subimage, in pixels.
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.
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 initial-
izes 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 con-
stant 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
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 rec-
tangle 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.
Xlib - C Language X Interface
X Version 11 libX11 1.2.1 XCreateImage(3)