objects/linedda.c

   1 /*
   2  * LineDDA
   3  *
   4  * Copyright 1993 Bob Amstadt
   5  */
   6
   7 static char Copyright[] = "Copyright  Bob Amstadt, 1993";
   8
   9 #include <stdlib.h>
  10 #include "windows.h"
  11
  12 /**********************************************************************
  13  *              LineDDA         (GDI.100)
  14  */
  15 void LineDDA(short nXStart, short nYStart, short nXEnd, short nYEnd,
  16              FARPROC callback, long lParam)
  17 {
  18     int x, y;
  19     int b;
  20     int x_diff = nXEnd - nXStart;
  21     int y_diff = nYEnd - nYStart;
  22
  23     if (x_diff == 0 && y_diff == 0)
  24         return;
  25
  26     if ((abs(x_diff) < abs(y_diff) && x_diff != 0) || y_diff == 0)
  27     {
  28         b = (nXStart * y_diff) / x_diff - nYStart;
  29
  30         for (x = nXStart; x <= nXEnd; x++)
  31         {
  32             y = (x * y_diff) / x_diff + b;
  33             CallLineDDAProc(callback, x, y, lParam);
  34         }
  35     }
  36     else
  37     {
  38         b = (nYStart * x_diff) / y_diff - nXStart;
  39
  40         for (y = nYStart; y <= nYEnd; y++)
  41         {
  42             x = (y * x_diff) / y_diff + b;
  43             CallLineDDAProc(callback, x, y, lParam);
  44         }
  45     }
  46 }