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.