67 lines
1.5 KiB
C
67 lines
1.5 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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#include <stdlib.h>
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#include "windows.h"
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/**********************************************************************
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* LineDDA16 (GDI.100)
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*/
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void WINAPI LineDDA16( INT16 nXStart, INT16 nYStart, INT16 nXEnd, INT16 nYEnd,
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LINEDDAPROC16 callback, LPARAM lParam )
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{
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LineDDA32( nXStart, nYStart, nXEnd, nYEnd,
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(LINEDDAPROC32)callback, lParam );
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}
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/**********************************************************************
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* LineDDA32 (GDI32.248)
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*/
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BOOL32 WINAPI LineDDA32(INT32 nXStart, INT32 nYStart, INT32 nXEnd, INT32 nYEnd,
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LINEDDAPROC32 callback, LPARAM lParam )
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{
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INT32 xadd = 1, yadd = 1;
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INT32 err,erradd;
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INT32 cnt;
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INT32 dx = nXEnd - nXStart;
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INT32 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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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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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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return TRUE;
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}
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