polygonclipview.cpp

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// PolygonClipView.cpp : implementation of the CPolygonClipView class
//

#include "stdafx.h"
#include "PolygonClip.h"

#include "PolygonClipDoc.h"
#include "PolygonClipView.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CPolygonClipView

IMPLEMENT_DYNCREATE(CPolygonClipView, CView)

BEGIN_MESSAGE_MAP(CPolygonClipView, CView)
	//{{AFX_MSG_MAP(CPolygonClipView)
	ON_WM_RBUTTONDOWN()
	ON_WM_LBUTTONDOWN()
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CPolygonClipView construction/destruction

CPolygonClipView::CPolygonClipView()
{
	// TODO: add construction code here
	outLength=new int;
	*outLength = 0;
	inLength = 0;
	count =1;//记录画线次数
	//初始化输出点列表
	for(int i=0;i<MAX;i++)
	{
		outVertexArray[i].x=0;
		outVertexArray[i].y=0;
	}

}

CPolygonClipView::~CPolygonClipView()
{
}

BOOL CPolygonClipView::PreCreateWindow(CREATESTRUCT& cs)
{
	// TODO: Modify the Window class or styles here by modifying
	//  the CREATESTRUCT cs

	return CView::PreCreateWindow(cs);
}

/////////////////////////////////////////////////////////////////////////////
// CPolygonClipView drawing

void CPolygonClipView::OnDraw(CDC* pDC)
{
	CPolygonClipDoc* pDoc = GetDocument();
	ASSERT_VALID(pDoc);
	// TODO: add draw code for native data here
	CPen Pen(PS_SOLID,1,RGB(0, 0, 0));
	CPen *pOldPen;
	pOldPen=pDC->SelectObject(&Pen);
	screen.left=200;
	screen.bottom=100;
	screen.right=500;
	screen.top=300;
	pDC->Rectangle(&screen);
	CString str;
	str.Format("请在屏幕上用左键点出%d个多边形顶点,点击右键执行剪裁",EdgeNum);
	pDC->TextOut(0,0,str);

}

/////////////////////////////////////////////////////////////////////////////
// CPolygonClipView diagnostics

#ifdef _DEBUG
void CPolygonClipView::AssertValid() const
{
	CView::AssertValid();
}

void CPolygonClipView::Dump(CDumpContext& dc) const
{
	CView::Dump(dc);
}

CPolygonClipDoc* CPolygonClipView::GetDocument() // non-debug version is inline
{
	ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CPolygonClipDoc)));
	return (CPolygonClipDoc*)m_pDocument;
}
#endif //_DEBUG

/////////////////////////////////////////////////////////////////////////////
// CPolygonClipView message handlers

void CPolygonClipView::Intersect(Vertex *s, Vertex *p, Edge clipBoundary, Vertex *I)
{//求多边形的边与剪裁边的交点I
	if(clipBoundary[0].y==clipBoundary[1].y)//水平剪裁边
	{
		I->y=clipBoundary[0].y;
		I->x=s->x+(clipBoundary[0].y - s->y)*(p->x - s->x)/(p->y - s->y);
	}
	else//竖直边剪裁
	{
		I->x = clipBoundary[0].x;
		I->y = s->y+(clipBoundary[0].x - s->x)*(p->y - s->y)/(p->x - s->x);
	}
}



bool CPolygonClipView::Inside(Vertex *testVertex, Edge clipBoundary)
{
	if(clipBoundary[1].x > clipBoundary[0].x)//剪裁边为窗口下边
	{
		if(testVertex->y >= clipBoundary[0].y)
			return true;
	}
	else if(clipBoundary[1].x < clipBoundary[0].x)//剪裁边为窗口上边
	{
		if(testVertex->y <= clipBoundary[0].y)
			return true;
	}
	else if(clipBoundary[1].y > clipBoundary[0].y)//剪裁边为窗口右边
	{
		if(testVertex->x <= clipBoundary[0].x)
			return true;
	}
	else if(clipBoundary[1].y < clipBoundary[0].y)//剪裁边为窗口左边
	{
		if(testVertex->x >= clipBoundary[0].x)
			return true;
	}
	return false;
}


void CPolygonClipView::Output(Vertex *newVertex, int *outLength, VertexArray outVertexArray)
{

	//将newVertex加入到结果多边形顶点表outVertexArray中
	outVertexArray[*outLength].x = newVertex->x;
	outVertexArray[*outLength].y = newVertex->y;
	
	(*outLength)++;

}

void CPolygonClipView::SHPolygonClip(int inLength, VertexArray inVertexArray, int *outLength, VertexArray outVertexArray, Edge clipBoundary)
{
	Vertex *s,*p,I;
	int j;
	
	*outLength = 0;
	s=&(inVertexArray[inLength-1]);
	for(j=0;j<inLength;j++)
	{
		p=&(inVertexArray[j]);
		if( Inside(p,clipBoundary) )
		{
			if(Inside(s,clipBoundary))
				Output(p,outLength,outVertexArray);//情况1
			else
			{
				Intersect(s,p,clipBoundary,&I);//情况4
				Output(&I,outLength,outVertexArray);
				Output(p,outLength,outVertexArray);
			}
		}
		else if(Inside(s,clipBoundary))
		{
			Intersect(s,p,clipBoundary,&I);//情况2
			Output(&I,outLength,outVertexArray);
		}//情况3无输出
		s=p;
	}
}

void CPolygonClipView::OnRButtonDown(UINT nFlags, CPoint point) 
{
	// TODO: Add your message handler code here and/or call default
	if(count==EdgeNum+1)
	{
		//剪裁左边
		clipBoundary[0].x=screen.left;
		clipBoundary[0].y=screen.top;
		clipBoundary[1].x=screen.left;
		clipBoundary[1].y=screen.bottom;
		SHPolygonClip(inLength,inVertexArray,outLength,outVertexArray,clipBoundary);
		
		
		//剪裁下边,注意此时输出多边形变为输入多边形!!
		clipBoundary[0].x=screen.left;
		clipBoundary[0].y=screen.bottom;
		clipBoundary[1].x=screen.right;
		clipBoundary[1].y=screen.bottom;
		inLength=*outLength;
		//初始化输出点列表
		for(int i=0;i<MAX;i++)
		{
			inVertexArray[i].x=0;
			inVertexArray[i].y=0;
		}
		SHPolygonClip(inLength,outVertexArray,outLength,inVertexArray,clipBoundary);
	
		
		//剪裁右边
		clipBoundary[0].x=screen.right;
		clipBoundary[0].y=screen.bottom;
		clipBoundary[1].x=screen.right;
		clipBoundary[1].y=screen.top;
		inLength=*outLength;
		//初始化输出点列表
		for(i=0;i<MAX;i++)
		{
			outVertexArray[i].x=0;
			outVertexArray[i].y=0;
		}
		SHPolygonClip(inLength,inVertexArray,outLength,outVertexArray,clipBoundary);
		
		
		//剪裁上边
		clipBoundary[0].x=screen.right;
		clipBoundary[0].y=screen.top;
		clipBoundary[1].x=screen.left;
		clipBoundary[1].y=screen.top;
		inLength=*outLength;
		//初始化输出点列表
		for(i=0;i<MAX;i++)
		{
			inVertexArray[i].x=0;
			inVertexArray[i].y=0;
		}
		SHPolygonClip(inLength,outVertexArray,outLength,inVertexArray,clipBoundary);
		
		
		//描出结果
		CDC *pDC=GetDC();
		CPen pen(PS_SOLID,3,RGB(100,220,253));
		CPen* pOldPen=pDC->SelectObject(&pen);
		//inVertexArray为最后的输出多变形
		for(i=1;inVertexArray[i].x!=0 && inVertexArray[i].y!=0;i++)
		{
			pDC->MoveTo(inVertexArray[i-1].x,inVertexArray[i-1].y);
			pDC->LineTo(inVertexArray[i].x,inVertexArray[i].y);
		}
		pDC->MoveTo(inVertexArray[i-1].x,inVertexArray[i-1].y);
		pDC->LineTo(inVertexArray[0].x,inVertexArray[0].y);
	}
	
	CView::OnRButtonDown(nFlags, point);
}

void CPolygonClipView::OnLButtonDown(UINT nFlags, CPoint point) 
{
	// TODO: Add your message handler code here and/or call default

//	startpoint=point;
//	lastendpoint=point;
//	SetCapture();
	CDC *pDC=GetDC();
	if(count<=EdgeNum)
	{
		inVertexArray[inLength].x=point.x;
		inVertexArray[inLength].y=point.y;
		if(count!=1)
		{
			pDC->MoveTo(inVertexArray[inLength-1].x,inVertexArray[inLength-1].y);
			pDC->LineTo(point);
		}
		if(count==EdgeNum)
		{
			pDC->MoveTo(point);
			pDC->LineTo(inVertexArray[0].x,inVertexArray[0].y);
		}

		inLength++;
		count++;
	}

	CView::OnLButtonDown(nFlags, point);
}