Alaska Software Inc. - Problem saving PNG files on Windows XP
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AuthorTopic: Problem saving PNG files on Windows XP
Andreas Gehrs-Pahl

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Problem saving PNG files on Windows XP
on Thu, 19 Feb 2015 09:50:54 -0500
Till,

Saving bitmaps in the PNG format (in 2.0.570) on Windows XP will create 
invalid files that are missing most of the information, possibly because 
pixels are saved as being transparent? This works fine on Windows 7, though.

The attached images were created with a simple routine to copy the active 
dialog to the clipboard, and getting the bitmap from there, basically using:

oBitmap := oClipBoard:GetBuffer(XBPCLPBRD_BITMAP)

They were then saved with 1.9.355 and with 2.0.570 using basically:

oBitmap:SaveFile(cFileName, XBPBMP_FORMAT_PNG, nCompression)

Changing the Compression value has no effect on this particular issue, and 
saving in BMP or JGP formats will result in normal files without the issue. 
I believe the problem started with 2.0.502, but I can't verify that right 
now.

In 1.9.355 there was a problem with saving PNGs on Windows XP with a 
compression ratio greater than about 50% -- or the default value (-1) --  
resulting in (empty) PNG files that were just 77-bytes long, but this seems 
to have been fixed in 2.0.

Also, saving images in GIF format isn't working in either version and on any 
OS, always resulting in basically empty GIF87a files.

I didn't find any existing PDRs for those issues. If you need more details 
or a working demo program, please let me know.

Thanks,

Andreas

Andreas Gehrs-Pahl
Absolute Software, LLC

phone: (989) 723-9927
email: Andreas.GP@Charter.net
web:   http://www.Aerospace-History.net

Images.zip