linedda.c File Reference

#include <precomp.h>
#include <debug.h>

Include dependency graph for linedda.c:

Go to the source code of this file.

Functions
BOOL WINAPI	LineDDA (INT nXStart, INT nYStart, INT nXEnd, INT nYEnd, LINEDDAPROC callback, LPARAM lParam)

Function Documentation

LineDDA()

BOOL WINAPI LineDDA	(	INT	nXStart,
		INT	nYStart,
		INT	nXEnd,
		INT	nYEnd,
		LINEDDAPROC	callback,
		LPARAM	lParam
	)

Definition at line 40 of file linedda.c.

{
    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;
}