objects/linedda.c

   1 /*
   2  * LineDDA
   3  *
   4  * Copyright 1993 Bob Amstadt
   5  */
   6
   7 #include <stdlib.h>
   8 #include "windef.h"
   9 #include "wingdi.h"
  10 #include "wine/wingdi16.h"
  11
  12 /* ### start build ### */
  13 extern WORD CALLBACK DDA_CallTo16_word_wwl(LINEDDAPROC16,WORD,WORD,LONG);
  14 /* ### stop build ### */
  15
  16 struct linedda16_info
  17 {
  18     LINEDDAPROC16 proc;
  19     LPARAM        param;
  20 };
  21
  22
  23 static void CALLBACK DDA_callback( INT x, INT y, LPARAM param )
  24 {
  25     const struct linedda16_info *info = (struct linedda16_info *)param;
  26     DDA_CallTo16_word_wwl( info->proc, x, y, info->param );
  27 }
  28
  29 /**********************************************************************
  30  *           LineDDA   (GDI32.@)
  31  */
  32 BOOL WINAPI LineDDA(INT nXStart, INT nYStart, INT nXEnd, INT nYEnd,
  33                         LINEDDAPROC callback, LPARAM lParam )
  34 {
  35     INT xadd = 1, yadd = 1;
  36     INT err,erradd;
  37     INT cnt;
  38     INT dx = nXEnd - nXStart;
  39     INT dy = nYEnd - nYStart;
  40
  41     if (dx < 0)  {
  42       dx = -dx; xadd = -1;
  43     }
  44     if (dy < 0)  {
  45       dy = -dy; yadd = -1;
  46     }
  47     if (dx > dy) { /* line is "more horizontal" */
  48       err = 2*dy - dx; erradd = 2*dy - 2*dx;
  49       for(cnt = 0;cnt <= dx; cnt++) {
  50         callback(nXStart,nYStart,lParam);
  51         if (err > 0) {
  52           nYStart += yadd;
  53           err += erradd;
  54         } else  {
  55           err += 2*dy;
  56         }
  57         nXStart += xadd;
  58       }
  59     } else  { /* line is "more vertical" */
  60       err = 2*dx - dy; erradd = 2*dx - 2*dy;
  61       for(cnt = 0;cnt <= dy; cnt++) {
  62         callback(nXStart,nYStart,lParam);
  63         if (err > 0) {
  64           nXStart += xadd;
  65           err += erradd;
  66         } else  {
  67           err += 2*dx;
  68         }
  69         nYStart += yadd;
  70       }
  71     }
  72     return TRUE;
  73 }
  74
  75
  76 /**********************************************************************
  77  *           LineDDA   (GDI.100)
  78  */
  79 void WINAPI LineDDA16( INT16 nXStart, INT16 nYStart, INT16 nXEnd,
  80                        INT16 nYEnd, LINEDDAPROC16 proc, LPARAM lParam )
  81 {
  82     struct linedda16_info info;
  83     info.proc  = proc;
  84     info.param = lParam;
  85     LineDDA( nXStart, nYStart, nXEnd, nYEnd, DDA_callback, (LPARAM)&info );
  86 }