畫線算法的實現

衆所周知，VC++中畫圖算法封裝在一個重要的類CDC中。。。基本的像LineTo();MoveTo()等，

要說到畫線，其實底層的算法也不是很難。。。
在這裏貼幾個代碼分享一下!
(這裏只在MFC的view類OnDraw函數實現)

1、DDA（數值微分）法:

void CDDALineView::OnDraw(CDC* pDC) { CDDALineDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc); // TODO: add draw code for native data here int x,x0(200),y0(200),x1(500),y1(500); float dx,dy,y,k; dx=x1-x0; dy=y1-y0; k=dy/dx; y=y0; for(x=x0;x<=x1;x++) { pDC->SetPixel(x,(int)(y+0.5),RGB(255,0,0)); y+=k; } }

2、中點畫線算法

void CMidpointLineView::OnDraw(CDC* pDC) { CMidpointLineDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc); // TODO: add draw code for native data here int a,b,d1,d2,d,x,y; int x0(200),x1(500),y0(200),y1(500); a=y0-y1; b=x1-x0; d=2*a+b; d1=2*a; d2=2*(a+b); x=x0; y=y0; pDC->SetPixel(x,y,RGB(0,255,0)); while(x<x1) { if(d<0) { x++; y++; d+=d2; } else { x++; d+=d1; } pDC->SetPixel(x,y,RGB(0,255,0)); } }

3、Bresenham算法：

void CBresenhamline2View::OnDraw(CDC* pDC) { CBresenhamline2Doc* pDoc = GetDocument(); ASSERT_VALID(pDoc); // TODO: add draw code for native data here int x0(200),y0(200),x1(500),y1(500); int x,y,dx,dy; dx=x1-x0; dy=y1-y0; int e=-dx; x=x0; y=y0; for(int i=0;i<=dx;i++) { pDC->SetPixel(x,y,RGB(0,0,255)); x=x+1; e=e+2*dy; if(e>=0) { y++; e=e-2*dx; } } }