Icon and Cursor Size Determined by Display Driver

 Last reviewed: January 5, 1995
Article ID: Q73674
The information in this article applies to:
  • Microsoft Windows Software Development Kit (SDK) for Windows versions 3.1 and 3.0

SUMMARY

The display driver determines the display size of an icon or a cursor. Display drivers for Microsoft Windows operating system version 3.0 specify icon- and cursor-compression factors, which are used to determine the size for a particular icon or cursor. Under Windows version 3.1, the method that the display driver uses for storing icon and cursor dimensions is different. The text below details the two methods of storing icon and cursor dimensions.

MORE INFORMATION

Each compression factor is the ratio of 64 to the icon or cursor size. In other words, the icon-width compression factor is 64 divided by the final width of an icon. Because each factor must be a whole number, the height or the width of an icon or a cursor must be 64, 32, or 16 pixels.

Four compression factors are stored as a resource in each display driver. The following table shows typical values: 

   Display             Icon/Cursor        Compression Factors
   Drivers             Dimensions         Width       Height
   ----------------------------------------------------------

   CGA                  32 x 16             2           4
   EGA, VGA, 8514       32 x 32             2           2
In Windows version 3.1, the display driver stores the actual icon dimensions. Therefore, for an icon 32 pixels wide, the driver stores 32 instead of 2. This removes the limitation that 64 by 64 is the largest possible icon size.

Display drivers for versions of Windows earlier than version 3.0 will continue to be supported. If Windows encounters an icon dimension less than 11, it treats the dimension as a compression factor and calculates the dimension accordingly.

Additional reference words: 3.00 3.10
KBCategory: kbprg
KBSubcategory: GdiCurico

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Last reviewed: January 5, 1995
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