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Q111865: BUG: StretchBlt()/StretchDIBits() Fail with Very Large Stretch

Article: Q111865
Product(s): Microsoft Windows Software Development Kit
Version(s): 
Operating System(s): 
Keyword(s): kbOSWin310 _IK kbOSWin300 kbSDKWin16
Last Modified: 22-DEC-1999

3.00 3.10
WINDOWS
kbprg kbbuglist

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) for Windows versions 3.0, 3.1 
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SYMPTOMS
========

If the stretching factor is large, for example, when stretching from a very
small to a large height, StretchDIBits() and StretchBlt() may return zero (0)
and display nothing. The same bitmap with a smaller stretch is displayed
correctly.

CAUSE
=====

Most display drivers do not implement their own StretchBlt() or StretchDIBits()
so GDI must simulate these calls. Part of the GDI simulation involves allocating
temporary work buffers, which are limited to 64K. If the size of the work buffer
is calculated to be greater than 64K, then the height of the source and
destination rectangles are halved until they are less than 64K. The problem is
that if GDI must continue to divide the height by two (2) to get a buffer less
than 64K, the source or destination height could eventually reach one scan line.
At this point, the call fails because it cannot break up a scan line into
subunits.

StretchBlt() and StretchDIBits() are not designed to provide unlimited
stretching. However, they may fail a bit more prematurely than their design
limitation.

RESOLUTION
==========

If StretchBlt() or StretchDIBits() fails on a large stretch, an application can
divide up the source bitmap, stretch the pieces individually, and position them
correctly once stretched. Another alternative is to do a smaller stretch. There
is no formula to determine exactly what bitmaps will fail at what stretch size.

STATUS
======

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

MORE INFORMATION
================

To reproduce the problem, create a bitmap approximately 2048 pixels wide by 16
pixels high. Then, display the bitmap with the DIBVIEW sample from the Windows
3.1 SDK. Choose Stretch To Window from DIBVIEW's Options menu, so that the
bitmap is stretched according to the size of the client window. When the height
is more than about 200 pixels, the bitmap will not be displayed.

Additional query words: buglist3.00 buglist3.10 3.00 3.10 fail zoom

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Keywords          : kbOSWin310 _IK kbOSWin300 kbSDKWin16 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Issue type        : kbbug
Solution Type     : kbpending

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