Screenshotting DLL Call failing on one computer

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softwareeater
Posts: 40
Joined: 31 Aug 2015, 11:33

Screenshotting DLL Call failing on one computer

17 Jan 2017, 12:33

So I have a script that takes screenshots and saves them silently, and it's worked on most of my computers. But now I've run into difficulty. A side-by side comparison of it working and not working showed that both computers got to the line "Loop, %encodersSize%" but the failing computer skipped right over it, presumably since the var ended up blank. Any thoughts on this would be super appreciated, I'm a bit in over my head with all this DLL call stuff.

A snippet of my code:

Code: Select all

	DllCall("gdiplus\GdipGetImageEncodersSize", "uint*", encodersCount, "uint*", encodersSize)
	
	VarSetCapacity(encodersDump, encodersSize)
	DllCall("gdiplus\GdipGetImageEncoders", "uint", encodersCount, "uint", encodersSize, "uint", &encodersDump)

	Loop, %encodersCount%
		{
		Location := NumGet(encodersDump, 76*(A_Index-1)+44)
		if !A_IsUnicode
			{
			encodersSize := DllCall("WideCharToMultiByte", "uint", 0, "uint", 0, "uint", Location, "int", -1, "uint", 0, "int",  0, "uint", 0, "uint", 0)
			VarSetCapacity(sString, encodersSize)
			DllCall("WideCharToMultiByte", "uint", 0, "uint", 0, "uint", Location, "int", -1, "str", sString, "int", encodersSize, "uint", 0, "uint", 0)
			if !InStr(sString, "*.png")
				{
				continue
				}
			}
		else
			{
			encodersSize := DllCall("WideCharToMultiByte", "uint", 0, "uint", 0, "uint", Location, "int", -1, "uint", 0, "int",  0, "uint", 0, "uint", 0)
			sString := ""
			Loop, %encodersSize%
				{
				sString .= Chr(NumGet(Location+0, 2*(A_Index-1), "char"))
				}
			if !InStr(sString, "*.png")
				{
				continue
				}
			}
		pCodec := &encodersDump+76*(A_Index-1)
		break
		}
kon
Posts: 1756
Joined: 29 Sep 2013, 17:11

Re: Screenshotting DLL Call failing on one computer

17 Jan 2017, 16:12

It looks like your code was originally based on Gdip.ahk. Have a look at the Gdip_All version of the Gdip_SaveBitmapToFile function to see a 64 bit compatible implementation.

32 Bit AHK: Ptr = 4 Bytes
64 Bit AHK: Ptr = 8 Bytes

Gdip_All.ahk goes out of its way to remain AHK v1.0 compatible, but you probably don't want to do that. For example, StrGet_Name := "StrGet" is only included because the built-in StrGet function would throw a "Call to nonexistent function." error in v1.0. Gdip_All.ahk calls StrGet dynamically to avoid the error.
gwarble
Posts: 240
Joined: 30 Sep 2013, 15:01

Re: Screenshotting DLL Call failing on one computer

17 Jan 2017, 23:23

It looks like gdi+ called directly, not with gdip ahk library, but the problem may be the same, check your bit-ness/unicodeness on each machine (or test by dragging directly to the 32bit and 64bit ahk version exes... )

to make the code universal enough to work on each, you probably have to adjust the widechartomultibyte call to be 64bit compatible, using a_ptrsize for the proper bit depth
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kon
Posts: 1756
Joined: 29 Sep 2013, 17:11

Re: Screenshotting DLL Call failing on one computer

17 Jan 2017, 23:45

gwarble wrote:It looks like gdi+ called directly, not with gdip ahk library, but the problem may be the same, check your bit-ness/unicodeness on each machine...
That's what I said. And you missed my main point. Look at Gdip_SaveBitmapToFile. It's almost exactly the same, but Gdip_all already shows a fully compatible version.

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