MFC中实现的画箭头算法 (Arrow in MFC)

在codeproject中寻找到一个这样的算法,在这里介绍一下

可以改变三角形大小,顶点角度,是否填充和填充颜色等

但是画出的箭头还是不够美观....呵呵,还好吧

其中填充是代表箭头内是否填充颜色 

先来看声明和实现

 

 

//使用一个结构体来存储相关的信息

//Defines the attributes of an arrow.

typedef struct tARROWSTRUCT {

int nWidth;     // width (in pixels) of the full base of the arrowhead

float fTheta;   // angle (in radians) at the arrow tip between the two

//  sides of the arrowhead

bool bFill;     // flag indicating whether or not the arrowhead should be

//  filled

} ARROWSTRUCT;

///

//函数声明

// Draws an arrow, using the current pen and brush, from the current position

//  to the passed point using the attributes defined in the ARROWSTRUCT.

void ArrowTo(HDC hDC, int x, int y, ARROWSTRUCT *pArrow);

void ArrowTo(HDC hDC, const POINT *lpTo, ARROWSTRUCT *pArrow);

///

//画箭头函数实现

void CMyDialog::ArrowTo(HDC hDC, int x, int y, ARROWSTRUCT *pA) {

POINT ptTo = {x, y};

ArrowTo(hDC, &ptTo, pA);

}

void CMyDialog::ArrowTo(HDC hDC, const POINT *lpTo, ARROWSTRUCT *pA) {

POINT pFrom;

POINT pBase;

POINT aptPoly[3];

float vecLine[2];

float vecLeft[2];

float fLength;

float th;

float ta;

// get from point

MoveToEx(hDC, 0, 0, &pFrom);

// set to point

aptPoly[0].x = lpTo->x;

aptPoly[0].y = lpTo->y;

// build the line vector

vecLine[0] = (float) aptPoly[0].x - pFrom.x;

vecLine[1] = (float) aptPoly[0].y - pFrom.y;

// build the arrow base vector - normal to the line

vecLeft[0] = -vecLine[1];

vecLeft[1] = vecLine[0];

// setup length parameters

fLength = (float) sqrt(vecLine[0] * vecLine[0] + vecLine[1] * vecLine[1]);

th = pA->nWidth / (2.0f * fLength);

ta = pA->nWidth / (2.0f * (tanf(pA->fTheta) / 2.0f) * fLength);

// find the base of the arrow

pBase.x = (int) (aptPoly[0].x + -ta * vecLine[0]);

pBase.y = (int) (aptPoly[0].y + -ta * vecLine[1]);

// build the points on the sides of the arrow

aptPoly[1].x = (int) (pBase.x + th * vecLeft[0]);

aptPoly[1].y = (int) (pBase.y + th * vecLeft[1]);

aptPoly[2].x = (int) (pBase.x + -th * vecLeft[0]);

aptPoly[2].y = (int) (pBase.y + -th * vecLeft[1]);

MoveToEx(hDC, pFrom.x, pFrom.y, NULL);

// draw we're fillin'...

if(pA->bFill) {

LineTo(hDC, aptPoly[0].x, aptPoly[0].y);

Polygon(hDC, aptPoly, 3);

}

// ... or even jes chillin'...

else {

LineTo(hDC, pBase.x, pBase.y);

LineTo(hDC, aptPoly[1].x, aptPoly[1].y);

LineTo(hDC, aptPoly[0].x, aptPoly[0].y);

LineTo(hDC, aptPoly[2].x, aptPoly[2].y);

LineTo(hDC, pBase.x, pBase.y);

MoveToEx(hDC, aptPoly[0].x, aptPoly[0].y, NULL);

}

}

再来看调用实现(加一层封装更加适用)

 

/

//封装调用函数实现(其实还是有很大的扩展空间的)

void CMyDialog::ArrowTo(

CDC *pDC,              //画刷

CPoint point,          //终点坐标

int nPenStyle,         //线样式

int nPenWidth,         //线宽度

COLORREF color, //颜色

int nWidth,            //三角形底边宽度

float fTheta,          //三角形顶角角度

bool bFill             //是否填充颜色

)

{

ARROWSTRUCT a;

a.nWidth = nWidth;     //三角形底边宽度

a.fTheta = fTheta;     //三角形顶角角度

a.bFill = bFill;       //是否填充颜色

CPen* pOldPen;

CPen pen(nPenStyle,nPenWidth,color);

pOldPen = pDC->SelectObject(&pen);

CBrush br,*pbrOld;

br.CreateSolidBrush(color);

pbrOld = pDC->SelectObject(&br);

ArrowTo(*pDC,point.x,point.y,&a);       //调用画箭头函数

pDC->SelectObject(pOldPen);

pDC->SelectObject(pbrOld);

}

 

 

转载于:https://www.cnblogs.com/wupingzsf/archive/2010/05/16/1736958.html

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