Q128637: HOWTO: How to Draw a Gradient Background

Article: Q128637
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1,95; winnt:3.5,3.51,4.0
Operating System(s): 
Keyword(s): kbOSWinNT350 kbOSWinNT351 kbOSWinNT400 kbOSWin2000 kbOSWin95 _IK kbSDKWin16
Last Modified: 12-MAY-2001

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) 3.1 
- Microsoft Win32 Application Programming Interface (API) 
- Microsoft Windows 2000 Advanced Server 
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SUMMARY
=======

This article provides source code for drawing a gradient background pattern
similar to the one used in Microsoft Setup applications. The code will compile
and run on Windows version 3.1, Win32s, Windows 95 and Windows NT.

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

WARNING: ANY USE BY YOU OF THE CODE PROVIDED IN THIS ARTICLE IS AT YOUR OWN
RISK. Microsoft provides this code "as is" without warranty of any kind, either
express or implied, including but not limited to the implied warranties of
merchantability and/or fitness for a particular purpose.

     /*************************************************************

     *                                                            *
     *  DrawBackgroundPattern()                                   *
     *                                                            *
     *  Purpose: This function draws a gradient pattern that      *
     *           transitions between blue and black. This is      *
     *           similar to the background used in Microsoft      *
     *           setup programs.                                  *
     *                                                            *
     *************************************************************/ 

     void DrawBackgroundPattern(HWND hWnd)

     {
     HDC hDC = GetDC(hWnd);  // Get the DC for the window
     RECT rectFill;          // Rectangle for filling band
     RECT rectClient;        // Rectangle for entire client area
     float fStep;            // How large is each band?
     HBRUSH hBrush;

     int iOnBand;  // Loop index

     // How large is the area you need to fill?

     GetClientRect(hWnd, &rectClient);

     // Determine how large each band should be in order to cover the
     // client with 256 bands (one for every color intensity level)

     fStep = (float)rectClient.bottom / 256.0f;

     // Start filling bands

     for (iOnBand = 0; iOnBand < 256; iOnBand++) {

      // Set the location of the current band
      SetRect(&rectFill,
              0,                           // Upper left X
              (int)(iOnBand * fStep),      // Upper left Y
              rectClient.right+1,          // Lower right X
              (int)((iOnBand+1) * fStep)); // Lower right Y

     // Create a brush with the appropriate color for this band
     hBrush = CreateSolidBrush(RGB(0, 0, (255 - iOnBand)));

     // Fill the rectangle
     FillRect(hDC, &rectFill, hBrush);

     // Get rid of the brush you created
     DeleteObject(hBrush);

     };

     // Give back the DC

     ReleaseDC(hWnd, hDC);
     }

Additional query words: 3.00 3.10 4.00 GRADIENT BACKGROUND DITHER

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Keywords          : kbOSWinNT350 kbOSWinNT351 kbOSWinNT400 kbOSWin2000 kbOSWin95 _IK kbSDKWin16 
Technology        : kbwin2000AdvServ kbwin2000AdvServSearch kbwin2000Search kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinAdvServSearch kbWin32sSearch kbWin32API kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1,95; winnt:3.5,3.51,4.0
Issue type        : kbhowto

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