SAMPLE: How to Draw Cubic Bezier Curves in Windows and Win32s

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

      - Microsoft Windows 95 version 4.0
      - Microsoft Win32s version 1.3
  

SUMMARY

You can get the functionality provided by the Win32 PolyBezier() function on the Windows 3.1 and Win32s platforms. The Bezier sample code shows by example how to draw cubic Bezier curves as well as curves with other degrees on both Windows version 3.1 and Win32s.

Download BEZIER.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 BEZIER.EXE (size: 28704 bytes) 
  

• Internet (anonymous FTP)

        ftp ftp.microsoft.com
        Change to the SOFTLIB\MSLFILES directory
        Get BEZIER.EXE (size: 28704 bytes) 
  

MORE INFORMATION

The PolyBezier() function draws cubic Bezier curves by using the endpoints and control points specified by the lppt parameter. The first curve is drawn from the first point to the fourth point by using the second and third points as control points. Each subsequent curve in the sequence needs exactly three more points: the ending point of the previous curve is used as the starting point, the next two points in the sequence are control points, and the third is the ending point.

Steps to Using the Sample Code

1. Compile the sample code using the .mak file that corresponds to the platform you are running (Bezier.mak for Win32s and Bezier16.mak for Win16).

2. Run the compiled program.

3. Use the left mouse button to position the endpoints and the control points in the client area. As soon as you've positioned enough points to draw a curve with the current degree (the default is cubic so you'll need four points), the curve will be drawn. Keep in mind that if you set the degree to a higher value, you'll have to position degree+1 points before the curve can be calculated and displayed.