AutoHotkey Community

Laszlo · Joined: 14 Feb 2005 Posts: 4710 Location: Boulder, CO

Show a Gui window with transparent background, but opaque controls. PixelGetColor returns the color of the pixel under the control (not the color of the control), which is not what we see on screen. It needs to be clarified in the help.

Chris · Site Admin Joined: 02 Mar 2004 Posts: 10716

PixelGetColor is simply a wrapper for the OS's GetPixel() function. Here is the code behind it (converted to DllCall). Maybe you can tweak it do better things by giving it a different HDC (such as a window's).

PhiLho · Posted: Mon Apr 17, 2006 9:03 am Post subject:

Interesting.
Actually, I am not sure if that is tied to transparency.
If I put, for example, w300 and remove transparency, I get random results over the GUI area (outside the button), and even outside the GUI.

PhiLho · Posted: Mon Apr 17, 2006 10:01 am Post subject:

I searched how others pick colors on screen.
I found a CodeProject article explaining one technique: it uses GetPixel, indeed, but it creates a DC using hDC = CreateDC("DISPLAY",0,0,0);. Perhaps that's the main difference.
I tested the provided exe and it works quite well, including over SciTE...

Chris · Site Admin Joined: 02 Mar 2004 Posts: 10716

It could be that the cursor is blocking the mouse somehow. You might try using PixelGetColor on a pixel that is definitely not under the mouse cursor.

If PixelGetColor is unreliable as you suggest, that would be a pretty big surprise because it has been a command since the beta versions of AHK in December 2003, yet there have been no complaints about its reliability (except in certain games, where a few have said it always gets a black pixel).

By contrast, there have been complaints about the performance of PixelGetColor. So I'd be hesitant to change it to a potentially slower method, especially if there's a chance it would break existing scripts by extracting different colors from games and other apps.

Laszlo · Joined: 14 Feb 2005 Posts: 4710 Location: Boulder, CO

PhiLho's script works more reliably than PixelgetColor in normal windows, but on the button in my partially transparent Gui window, it fails, too.

PhiLho · Posted: Mon Apr 17, 2006 6:20 pm Post subject:

I forgot to test again your GUI problem...
Well, it acts like all the GUI is transparent, including the title bar... Perhaps Windows see the whole window as transparent (for GetPixel at least), even if it displays some parts as opaque. Strange...
_________________

vPhiLho := RegExReplace("Philippe Lhoste", "^(\w{3})\w*\s+\b(\w{3})\w*$", "$1$2")

Chris · Site Admin Joined: 02 Mar 2004 Posts: 10716

Laszlo, I should clarify that my previous post was in response to PhiLho's two posts, not yours. Sorry if it caused any misunderstanding.

Micha · Joined: 15 Nov 2005 Posts: 537 Location: Germany

Hi PhiLho,
i've tried your script:

black -> 0 0 0
red ->00 00 ff
cyan ->00 ff ff
blue -> 00 00 ff
green ->00 00 80

Red and blue have the same values. When changing the tooltip to show

PhiLho · Posted: Tue Apr 18, 2006 11:43 am Post subject:

Micha, you were right, there was a strange bug I didn't care to fully understand. Anyway, I wanted to use a trick given by Laszlo, giving a simplier code, giving correct results.
I updated the code above. Thanks for pointing that out.
Mmm, I even updated the code to show in parallel the results of the DllCall and those of PixelGetColor.

cqcqcqn · Joined: 06 Jan 2010 Posts: 1

....俺一点也没看懂

svi · Joined: 09 Oct 2006 Posts: 236 Location: Finland

Since this old thread has been bumbed, I'd like to tell my opinion about the reliability of PixelGetColor:
It seems that no one of those famous posters didn't notice a simple thing although...