objects/linedda.c

   1 /*
   2  * LineDDA
   3  *
   4  * Copyright 1993 Bob Amstadt
   5  *
   6 static char Copyright[] = "Copyright  Bob Amstadt, 1993";
   7 */
   8
   9 #include <stdlib.h>
  10 #include "windows.h"
  11 #include "if1632.h"
  12
  13 /**********************************************************************
  14  *              LineDDA         (GDI.100)
  15  */
  16 void LineDDA(short nXStart, short nYStart, short nXEnd, short nYEnd,
  17              FARPROC callback, long lParam)
  18 {
  19     int x, y;
  20     int b;
  21     int x_diff = nXEnd - nXStart;
  22     int y_diff = nYEnd - nYStart;
  23
  24     if (x_diff == 0 && y_diff == 0)
  25         return;
  26
  27     if ((abs(x_diff) < abs(y_diff) && x_diff != 0) || y_diff == 0)
  28     {
  29         b = (nXStart * y_diff) / x_diff - nYStart;
  30
  31         for (x = nXStart; x <= nXEnd; x++)
  32         {
  33             y = (x * y_diff) / x_diff + b;
  34             CallLineDDAProc(callback, x, y, lParam);
  35         }
  36     }
  37     else
  38     {
  39         b = (nYStart * x_diff) / y_diff - nXStart;
  40
  41         for (y = nYStart; y <= nYEnd; y++)
  42         {
  43             x = (y * x_diff) / y_diff + b;
  44             CallLineDDAProc(callback, x, y, lParam);
  45         }
  46     }
  47 }