SAMPLE: Drawing to a Memory Bitmap for Faster Performance

• Microsoft Windows Software Development Kit (SDK) for Windows version 3.1
• Microsoft Win32 Application Programming Interface (API) included with:

      - Microsoft Windows NT version 3.5
      - Microsoft Windows 95 version 4.0
      - Microsoft Win32s version 1.2
  

An application whose client area is a complex image can realize a performance benefit from drawing to a memory bitmap. The complex, time consuming drawing code need only be performed once - to initialize the offscreen bitmap. During the handling of the WM_PAINT message, the only work that needs to be done is a simple BitBlt from the memory bitmap to the screen.

Sample code demonstrating this technique is available in the Microsoft Software Library. The MemDC sample code draws a complex pattern on its client area. A menu option toggle allows the user to see the speed difference between using and not using the offscreen bitmap.

Download MEMDC.EXE, a self-extracting file, from the Microsoft Software Library (MSL) on the following services:

• Microsoft Download Service (MSDL)

        Dial (206) 936-6735 to connect to MSDL
        Download MEMDC.EXE (size: 23553 bytes) 
  

• Internet (anonymous FTP)

        ftp ftp.microsoft.com
        Change to the \SOFTLIB\MSLFILES directory
        Get MEMDC.EXE (size: 23553 bytes)