Generates a checksum for a region of pixels.
PixelChecksum ( left, top, right, bottom [, step = 1 [, hwnd [, mode = 0]]] )
| left | left coordinate of rectangle. |
| top | top coordinate of rectangle. |
| right | right coordinate of rectangle. |
| bottom | bottom coordinate of rectangle. |
| step | [optional] Instead of checksumming each pixel use a value larger than 1 to skip pixels (for speed). E.g. A value of 2 will only check every other pixel. Default is 1. It is not recommended to use a step value greater than 1. |
| hwnd | [optional] Window handle to be used. Default is the desktop window. |
| mode | [optional] default 0 ADLER checksum, 1 CRC32 Checksum. |
| Success: | the checksum value of the region. |
| Failure: | 0. |
A checksum only allows you to see if "something" has changed in a region - it does not tell you exactly what has changed.
CRC32 checksum is a little slower than ADLDER but detects better pixel variation.
PixelCoordMode (Option), PixelGetColor, PixelSearch
#include <MsgBoxConstants.au3>
; Wait until something changes in the region 0,0 to 50,50
; Get initial checksum
Local $iCheckSum = PixelChecksum(0, 0, 50, 50)
; Wait for the region to change, the region is checked every 100ms to reduce CPU load
While $iCheckSum = PixelChecksum(0, 0, 50, 50)
Sleep(100)
WEnd
MsgBox($MB_SYSTEMMODAL, "", "Something in the region has changed!")