Microsoft KB Archive/159427

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BUG: GetGlyphOutline Returns Corrupt Glyphs with GGO_BITMAP

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Q159427

4.00 WINDOWS NT kbgraphic kbbuglist

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The information in this article applies to:


 * Microsoft Win32 Software Development Kit (SDK), on platform(s):
 * the hardware: Intel x86

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SYMPTOMS
The function GetGlyphOutline occasionally returns corrupted bitmaps of TrueType glyphs when called with the GGO_BITMAP format. This problem occurs only on Windows NT 4.0. The corrupted bitmaps usually resemble a "Venetian" blind where every other scan line appears to have been inserted from some other source.

There is no practical workaround for this bug involving the use of GetGlyphOutline. The problem can be avoided by using TextOut on a memory DC and using the BitBlt function to copy a bitmap similar to the one to be returned by GetGlyphOutline.

Additionally, the problem can be avoided by specifying a rotation matrix in the call to GetGlyphOutline that would result in a rotation of 1 degree or more. This approach, however, suffers from the loss of hinting to the resulting bitmap glyph.

STATUS
Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.

Steps to Reproduce Problem
The problem can be reproduced by asking for glyph bitmaps for a series of characters over a range of Font heights. A specific case can be reproduced with a font height of -104 device units for the Wingdings font and the character code equivalent of the letter "i" in the ANSI character set.

Additional query words: 4.00 kbdsi

Keywords : kbOSWinNT400 kbSDKWin32 kbDSupport

Issue type : kbbug

Technology : kbWin32SDKSearch kbAudDeveloper kbSDKSearch kbWin32sSearch