| /* |
| * LineDDA |
| * |
| * Copyright 1993 Bob Amstadt |
| */ |
| |
| #include <stdlib.h> |
| #include "wingdi.h" |
| |
| |
| /********************************************************************** |
| * LineDDA16 (GDI.100) |
| */ |
| void WINAPI LineDDA16( INT16 nXStart, INT16 nYStart, INT16 nXEnd, INT16 nYEnd, |
| LINEDDAPROC16 callback, LPARAM lParam ) |
| { |
| LineDDA( nXStart, nYStart, nXEnd, nYEnd, |
| (LINEDDAPROC)callback, lParam ); |
| } |
| |
| |
| /********************************************************************** |
| * LineDDA32 (GDI32.248) |
| */ |
| BOOL WINAPI LineDDA(INT nXStart, INT nYStart, INT nXEnd, INT nYEnd, |
| LINEDDAPROC callback, LPARAM 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++) { |
| 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++) { |
| callback(nXStart,nYStart,lParam); |
| if (err > 0) { |
| nXStart += xadd; |
| err += erradd; |
| } else { |
| err += 2*dx; |
| } |
| nYStart += yadd; |
| } |
| } |
| return TRUE; |
| } |