XInitImage(3X11)XInitImage(3X11)NAME
XInitImage, XCreateImage, XGetPixel, XPutPixel, XSubImage, XAddPixel,
XDestroyImage - image utilities
SYNOPSIS
Status XInitImage(image)
XImage *image;
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
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. Specifies
the number of bytes in the client image between the start of one scan‐
line and the start of the next. Specifies the image data. Specifies
the depth of the image. Specifies the connection to the X server.
Specifies the format for the image. You can pass XYBitmap, XYPixmap, or
ZPixmap. Specifies the height of the image, in pixels. Specifies the
number of pixels to ignore at the beginning of the scanline. Specifies
the new pixel value. Specifies the height of the new subimage, in pix‐
els. Specifies the width of the new subimage, in pixels. Specifies
the constant value that is to be added. Specifies the Visual struc‐
ture. Specifies the width of the image, in pixels. Specifies the
image. Specify the x and y coordinates.
DESCRIPTION
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, XInitIm‐
age will assume the image data is contiguous in memory and set the
bytes_per_line member to an appropriate value based on the other mem‐
bers; 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 spec‐
ified 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 struc‐
ture 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 subim‐
age, 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 for‐
mat (that is, the least significant byte of the long is the least sig‐
nificant byte of the pixel). The image must contain the x and y coordi‐
nates.
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 ALSOXPutImage(3X11)
Xlib -- C Language X Interface
XInitImage(3X11)
