Read Pixels From Application

Question

Hi. I'm working on a project for fun in which I need the values associated with pixels at certain locations on a window of an application, which may or may not be changing.
I've been looking around, but have only been able to find support for reading in pixels from a saved image. One bad way to do it would be to write a script that takes a screen shot and accesses the pixel from the saved image. However, I was hoping for a more direct way to do this because I will want to run this script many times and at a very rapid rate (the higher frequency, the better). The way I suggested would waste both processing time and memory. Is there a way to just have a script pull off the pixel value corresponding to an (x,y) coordinate relative to the entire screen?
Any other suggestions?
Thanks,
Steve

Answer 1

Hi Steve--
This thread is a mess, because of all the formatting problems I was having -- not to mention that I somehow got the wrong idea of what you were after. Perhaps you could post your question again as a new thread, with whatever clarification you feel might help?
In the meantime, I've been trying to figure out exactly what you're up to and my guess is that it might be (probably is?) dynamic image editing for various animation effects. I can see that the code I posted might be useful for size animation, so I tried this with an open Preview window
(hope there are no formatting issues here):
set TargetWinName to "MyPicture.jpg"
-- you must enter the name of your window, or get script to enter it
set Wins_ to windows of application "Preview" -- you must enter relevant application
repeat with w_ from 1 to count items of Wins_
set WinName to name of item w_ of Wins_
if WinName contains " — " then set WinName to do shell script "echo " & quoted form of WinName & " | sed -e 's/(same note as before)*$//' -e 's/ — //'"
if WinName is TargetWinName then
repeat 100 times
set WinBounds to bounds of item w_ of Wins_
set bounds of item w_ of Wins_ to {item 1 of WinBounds, item 2 of WinBounds, (0.95 * (item 3 of WinBounds)), (0.95 * (item 4 of WinBounds))}
end repeat
exit repeat
end if
end repeat
For me, this essentially makes the image vanish into its upper left corner, but there are all kinds of things you might do. I'm a bit surprised that it works as well as it does, as Preview has limited scriptability.
I'm assuming (but may be wrong) that you want to do something like this with pixel color -- I don't know how to do that offhand, but I'm thinking about it. New post?
Message was edited by: osimp