objects/linedda.c

   1 /*
   2  * LineDDA
   3  *
   4  * Copyright 1993 Bob Amstadt
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <stdlib.h>
  22 #include "windef.h"
  23 #include "wingdi.h"
  24 #include "wine/wingdi16.h"
  25
  26 /* ### start build ### */
  27 extern WORD CALLBACK DDA_CallTo16_word_wwl(LINEDDAPROC16,WORD,WORD,LONG);
  28 /* ### stop build ### */
  29
  30 struct linedda16_info
  31 {
  32     LINEDDAPROC16 proc;
  33     LPARAM        param;
  34 };
  35
  36
  37 static void CALLBACK DDA_callback( INT x, INT y, LPARAM param )
  38 {
  39     const struct linedda16_info *info = (struct linedda16_info *)param;
  40     DDA_CallTo16_word_wwl( info->proc, x, y, info->param );
  41 }
  42
  43 /**********************************************************************
  44  *           LineDDA   (GDI32.@)
  45  */
  46 BOOL WINAPI LineDDA(INT nXStart, INT nYStart, INT nXEnd, INT nYEnd,
  47                         LINEDDAPROC callback, LPARAM lParam )
  48 {
  49     INT xadd = 1, yadd = 1;
  50     INT err,erradd;
  51     INT cnt;
  52     INT dx = nXEnd - nXStart;
  53     INT dy = nYEnd - nYStart;
  54
  55     if (dx < 0)  {
  56       dx = -dx; xadd = -1;
  57     }
  58     if (dy < 0)  {
  59       dy = -dy; yadd = -1;
  60     }
  61     if (dx > dy) { /* line is "more horizontal" */
  62       err = 2*dy - dx; erradd = 2*dy - 2*dx;
  63       for(cnt = 0;cnt <= dx; cnt++) {
  64         callback(nXStart,nYStart,lParam);
  65         if (err > 0) {
  66           nYStart += yadd;
  67           err += erradd;
  68         } else  {
  69           err += 2*dy;
  70         }
  71         nXStart += xadd;
  72       }
  73     } else  { /* line is "more vertical" */
  74       err = 2*dx - dy; erradd = 2*dx - 2*dy;
  75       for(cnt = 0;cnt <= dy; cnt++) {
  76         callback(nXStart,nYStart,lParam);
  77         if (err > 0) {
  78           nXStart += xadd;
  79           err += erradd;
  80         } else  {
  81           err += 2*dx;
  82         }
  83         nYStart += yadd;
  84       }
  85     }
  86     return TRUE;
  87 }
  88
  89
  90 /**********************************************************************
  91  *           LineDDA   (GDI.100)
  92  */
  93 void WINAPI LineDDA16( INT16 nXStart, INT16 nYStart, INT16 nXEnd,
  94                        INT16 nYEnd, LINEDDAPROC16 proc, LPARAM lParam )
  95 {
  96     struct linedda16_info info;
  97     info.proc  = proc;
  98     info.param = lParam;
  99     LineDDA( nXStart, nYStart, nXEnd, nYEnd, DDA_callback, (LPARAM)&info );
 100 }