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API Reference

BITMAP SCALING TRANSPARENCY OPERATIONS

Brew Release
Brew MP 1.0.2
See Also
IBitmapScale_Scale()
Description
Specifies how transparency should be handled inside the scaling algorithm. These constants are passed to IBitmapScale_Scale() to govern how the alpha channel is treated while scaling.
IBitmapScale must rely on the caller to specify if the source image supports transparency. If it doesn't, IBitmapScale_Scale() can ignore the alpha channel and do the scale in less time. If it does, IBitmapScale_Scale() has to create an alpha channel if needed and consider it while combining pixels to make sure transparency is preserved.
Definition
  •    
       AEEBITMAPSCALE_OPAQUE: The source image does not support transparency
    
       AEEBITMAPSCALE_ALPHA: The source image has an alpha channel
    
       AEEBITMAPSCALE_KEYCOLOR: The source image has a transparent color
    
    
Comments
If AEEBITMAPSCALE_OPAQUE is specified, the source image is assumed to be opaque. The alpha channel is ignored and the image is simply copied to the destination bitmap. This mode provides the best performance. If AEEBITMAPSCALE_ALPHA is specified, IBitmapScale_Scale() combines the alpha channel for each pixel. The result is blended into the destination bitmap. This mode produces good results but is somewhat slower. If AEEBITMAPSCALE_KEYCOLOR is specified, IBitmapScale_Scale() builds an alpha channel from the source image using the transparency color specified in the image and combines it for each pixel. This is somewhat slower but is necessary to preserve transparency.