imgGrabArea

Usage

rval imgGrabArea(SESSION_ID sid, void** bufAddr, uInt32 waitForNext, uInt32 top, uInt32 left, uInt32 height, uInt32 width, uInt32 rowPixels);

Purpose

Performs a transfer from a continuous acquisition. This function operates similarly to imgGrab, but imgGrabArea only acquires a portion of the image. Call this function only after calling imgGrabSetup.

Parameters

Name	Type	Direction
sid	SESSION_ID	input
bufAddr	void**	input/output
waitForNext	uInt32	input
top	uInt32	input
left	uInt32	input
height	uInt32	input
width	uInt32	input
rowPixels	uInt32	input
rval	Int32	output

Parameter Discussion

sid: valid SESSION_ID.

bufAddr: pointer to a pointer to an area of memory in which to store the image. If bufAddr points to a NULL pointer, this call allocates a buffer, acquires an image, and returns the buffer address in the location specified by bufAddr. If bufAddr points to a non-NULL pointer, this function acquires into that buffer.

waitForNext: if zero, the function returns the most recently acquired image. If non-zero, the function waits for and returns the next acquired image.

top: top offset of the first pixel to acquire.

left: left offset of the first pixel to acquire.

height: height of the area to acquire.

width: width of the area to acquire.

rowPixels: total number of pixels in each image line. Passing a zero for this parameter causes the function to ignore the parameter and use the IMG_ATTR_ROWPIXELS attribute instead. Use this parameter for byte alignment or if the image buffer contains a border for image processing.

Return Value

This function returns 0 on success. On failure, this function returns an error code. For more information about the error code, call imgShowError.