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