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94 lines
2.5 KiB
C
94 lines
2.5 KiB
C
/*
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* GDI drawing functions.
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*
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* Copyright 1993, 1994 Alexandre Julliard
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* Copyright 1997 Bertho A. Stultiens
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* 1999 Huw D M Davies
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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/*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS GDI32
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* PURPOSE: LineDDA Function
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* FILE: win32ss/gdi/gdi32/objects/linedda.c
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* PROGRAMER: Steven Edwards
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* REVISION HISTORY: 2003/11/15 sedwards Created, 2009/04 gschneider Updated
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* NOTES: Adapted from Wine
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*/
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#include <precomp.h>
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#include <debug.h>
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/**********************************************************************
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* LineDDA (GDI32.@)
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* @implemented
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*/
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BOOL WINAPI LineDDA(INT nXStart, INT nYStart, INT nXEnd, INT nYEnd,
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LINEDDAPROC callback, LPARAM lParam )
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{
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INT xadd = 1, yadd = 1;
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INT err,erradd;
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INT cnt;
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INT dx = nXEnd - nXStart;
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INT dy = nYEnd - nYStart;
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if (dx < 0)
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{
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dx = -dx;
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xadd = -1;
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}
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if (dy < 0)
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{
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dy = -dy;
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yadd = -1;
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}
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if (dx > dy) /* line is "more horizontal" */
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{
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err = 2*dy - dx;
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erradd = 2*dy - 2*dx;
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for(cnt = 0; cnt < dx; cnt++)
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{
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callback(nXStart,nYStart,lParam);
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if (err > 0)
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{
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nYStart += yadd;
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err += erradd;
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}
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else err += 2*dy;
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nXStart += xadd;
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}
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}
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else /* line is "more vertical" */
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{
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err = 2*dx - dy;
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erradd = 2*dx - 2*dy;
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for(cnt = 0; cnt < dy; cnt++)
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{
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callback(nXStart,nYStart,lParam);
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if (err > 0)
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{
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nXStart += xadd;
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err += erradd;
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}
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else err += 2*dx;
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nYStart += yadd;
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}
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}
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return TRUE;
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}
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