56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
/*
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* LineDDA
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*
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* Copyright 1993 Bob Amstadt
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*
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*/
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#include <stdlib.h>
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#include "windows.h"
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#include "callback.h"
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/**********************************************************************
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* LineDDA (GDI.100)
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*/
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void LineDDA(short nXStart, short nYStart, short nXEnd, short nYEnd,
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FARPROC callback, long 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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dx = -dx; xadd = -1;
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}
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if (dy < 0) {
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dy = -dy; yadd = -1;
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}
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if (dx > dy) { /* line is "more horizontal" */
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err = 2*dy - dx; erradd = 2*dy - 2*dx;
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for(cnt = 0;cnt <= dx; cnt++) {
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CallLineDDAProc(callback,nXStart,nYStart,lParam);
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if (err > 0) {
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nYStart += yadd;
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err += erradd;
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} else {
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err += 2*dy;
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}
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nXStart += xadd;
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}
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} else { /* line is "more vertical" */
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err = 2*dx - dy; erradd = 2*dx - 2*dy;
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for(cnt = 0;cnt <= dy; cnt++) {
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CallLineDDAProc(callback,nXStart,nYStart,lParam);
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if (err > 0) {
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nXStart += xadd;
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err += erradd;
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} else {
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err += 2*dx;
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}
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nYStart += yadd;
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}
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}
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}
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