直线生成算法

voidCDrawLinesView::MenuDdaline()
...{
CDC*pDC=GetDC();

intxa=m_pnt1.x,ya=m_pnt1.y,xb=m_pnt2.x,yb=m_pnt2.y,c=RGB(255,0,0);

floatx,y;
floatdx,dy,k;
dx=(float)(xb-xa);
dy=(float)(yb-ya);
k=dy/dx;
y=ya;
x=xa;
if(abs(k)<1)
...{
if(xa<=xb)...{
for(x=xa;x<=xb;++x)
...{
pDC->SetPixel((int)x,int(y+0.5),c);
y+=k;
}
}
elseif(xa>xb)
...{
for(x=xa;x>=xb;--x)
...{
pDC->SetPixel((int)x,int(y+0.5),c);
y-=k;
}
}
}
if(abs(k)>=1)
...{
if(ya<=yb)...{
for(y=ya;y<=yb;++y)
...{
pDC->SetPixel(int(x+0.5),(int)y,c);
x+=1/k;
}
}
elseif(ya>yb)
...{
for(y=ya;y>=yb;--y)
...{
pDC->SetPixel(int(x+0.5),(int)y,c);
x-=1/k;
}
}
}
ReleaseDC(pDC);
}


voidCDrawLinesView::MenuMindlepoint()
...{
CDC*dc=GetDC();

intx0=m_pnt1.x,y0=m_pnt1.y,x1=m_pnt2.x,y1=m_pnt2.y,color=RGB(0,255,0);

intdx,dy,nexte,nextne,d,x,t,y;
floatm;
dx=x1-x0;
dy=y1-y0;
m=1.0*dy/dx;//¼ÆËãбÂÊ£¬²¢ÒÀ¾Ý´Ë½øÐÐÅжÏ
if(m<=1&&m>=0)
...{
if(x0>=x1)
...{
swap(x0,x1);
swap(y0,y1);
dx=-dx;dy=-dy;//½»»»×ø±êºódx,dy±äΪÏà·´µÄÊý
}
x=x0;y=y0;
d=dx-2*dy;//d0
nexte=-2*dy;//ÏÂÒ»¸ö×ø±ê¾àÀëÇ°Ò»¸ö×ø±êµÄÆ«ÒÆ
nextne=-2*dy+2*dx;
while(x<x1)
...{
if(d>0)
d+=nexte;
else
...{
d+=nextne;
y++;
}
x++;
dc->SetPixel(x,y,color);
}
}
elseif(m>=-1&&m<0)
...{
if(x0>=x1)
...{
swap(x0,x1);
swap(y0,y1);
dx=-dx;dy=-dy;
}
x=x0;y=y0;
d=-dx-2*dy;//d0
nexte=-2*dy;
nextne=-2*dy-2*dx;
while(x<x1)
...{
if(d>0)
...{
d+=nextne;
y--;
}
else
d+=nexte;
x++;
dc->SetPixel(x,y,color);
}
}
elseif(m>1)
...{
if(y0>=y1)
...{
swap(x0,x1);
swap(y0,y1);
dy=-dy;dx=-dx;
}
x=x0;
y=y0;
d=-dy+2*dx;//d0
nexte=2*dx;
nextne=-2*dy+2*dx;
while(y<y1)
...{
if(d>0)
...{
d+=nextne;
x++;
}
else
d+=nexte;
y++;
dc->SetPixel(x,y,color);
}
}
elseif(m<-1)
...{
if(y0>=y1)
...{
swap(x0,x1);
swap(y0,y1);
dx=-dx;dy=-dy;
}
x=x0;
y=y0;
d=2*dx+dy;//d0
nexte=2*dx;
nextne=2*dx+2*dy;
while(y<y1)
...{
if(d<0)
...{
d+=nextne;
x--;
}
else
d+=nexte;
y++;
dc->SetPixel(x,y,color);
}
}
ReleaseDC(dc);
}
voidswap(int&x1,int&x2)
...{
intt;
t=x1;
x1=x2;
x2=t;
}
voidCDrawLinesView::MenuBhline()
...{
CDC*dc=GetDC();

intx0=m_pnt1.x,y0=m_pnt1.y,x1=m_pnt2.x,y1=m_pnt2.y,color=RGB(0,0,255);

intx,y,dx,dy,sx,sy;
intf;
boolflag=false;
x=x0;
y=y0;
dx=abs(x0-x1);
dy=abs(y0-y1);
if(x1-x0>=0)
sx=1;
else
sx=-1;
if(y1-y0>=0)
sy=1;
else
sy=-1;
if(dy>dx)
...{
swap(dx,dy);
flag=true;
}
else
flag=false;

f=2*dy-dx;

for(inti=1;i<=dx;++i)
...{
dc->SetPixel(x,y,color);
if(f>=0)
...{
if(flag)
x+=sx;
else
y+=sy;
dc->SetPixel(x,y,color);
f-=2*dx;
}
else
...{
if(flag)
y+=sy;
else
x+=sx;
f+=2*dy;
}
}
}
voidCDrawLinesView::OnMenuDdaline()
...{
//TODO:Addyourcommandhandlercodehere
m_blDDA=true;
m_blMid=false;
m_blBre=false;
}

voidCDrawLinesView::OnMenuMindlepoint()
...{
//TODO:Addyourcommandhandlercodehere
m_blDDA=false;
m_blMid=true;
m_blBre=false;
}

voidCDrawLinesView::OnMenuBhline()
...{
//TODO:Addyourcommandhandlercodehere
m_blDDA=false;
m_blMid=false;
m_blBre=true;
}

voidCDrawLinesView::OnLButtonDown(UINTnFlags,CPointpoint)
...{
//TODO:Addyourmessagehandlercodehereand/orcalldefault

++m_pntCount;
if(m_pntCount==1)
m_pnt1=point;
elseif(m_pntCount==2)
...{
m_pnt2=point;
if(m_blDDA)
MenuDdaline();
if(m_blMid)
MenuMindlepoint();
if(m_blBre)
MenuBhline();
m_pntCount=0;
}

CView::OnLButtonDown(nFlags,point);
}