Drawing Reduced and Enlarged Bitmaps

This topic provides examples of using CGraphicsContext::DrawBitmap() to draw a bitmap that is stretched or compressed.

The bitmap blitting functions of the bitmapped graphics context (CBitmapContext) cannot be used to perform scaling of the bitmap. They always draws the bitmap using its dimensions in pixels. The overloaded GDI CGraphicsContext::DrawBitmap() function, however, can be used to draw a bitmap that is:

• stretched or compressed to a set size in twips

• stretched and/or compressed to fit a given rectangle.

Note: DrawBitmap() is slower than BitBlt(). You should therefore use BitBlt() in preference wherever possible.

These examples assume that bitmap is a pointer to a valid CFbsBitmap object.

// Set twips size 
TSize bmpSizeInTwips(2000,2000);
bitmap->SetSizeInTwips(bmpSizeInTwips);
gc.DrawBitmap(TPoint(50,50), bitmap);

// Draw bitmap stretched from the origin to 100,100
TRect rect(0,0,100,100);
gc.DrawBitmap(rect, bitmap);