MFC GUI 编程

Greetings

Hello, World! class CGreetingsDoc : public CDocument { protected: // create from serialization only

char *m_pMessage;

// Attributes public: char *GetGreetings() { return m_pMessage; } … }

CGreetingsDoc::CGreetingsDoc() { m_pMessage = "Hello, world!"; }

void CGreetingsView::OnDraw(CDC* pDC) { CGreetingsDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc);

RECT ClientRect; GetClientRect(&ClientRect); pDC->DrawText( pDoc->GetGreetings(),

-1, &ClientRect, DT_CENTER ); }

Button void CGreetingsView::OnButtongreetings() { AfxMessageBox("Hello, world!"); }

MiniDraw

MiniDraw

用户可以画不同的图形元素 Line, rectangle, ellipse, polygon…

demo

1. 用鼠标画线

Member Variables class CMiniDrawView : public CView { private: int m_Dragging; CPoint m_PointOld; CPoint m_PointOrigin; }

CMiniDrawView::CMiniDrawView() { m_Dragging = 0; }

响应消息 ClassWizard (^W)

WM_LBUTTONDOWN void CMiniDrawView::OnLButtonDown(UINT

nFlags, CPoint point) { //AfxMessageBox("button down");

m_PointOrigin = point; m_PointOld = point; m_Dragging = 1;

CView::OnLButtonDown(nFlags, point); }

WM_MOUSEMOVE void CMiniDrawView::OnMouseMove(UINT nFlags, CPoint point) { if( !m_Dragging ) return;

CClientDC ClientDC( this );

ClientDC.SetROP2( R2_NOT ); ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( m_PointOld );

ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( point );

m_PointOld = point;

CView::OnMouseMove(nFlags, point); }

WM_LBUTTONUP void CMiniDrawView::OnLButtonUp(UINT nFlags, CPoint point) { if( !m_Dragging ) return ;

CClientDC ClientDC( this );

ClientDC.SetROP2( R2_NOT ); ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( m_PointOld );

ClientDC.SetROP2( R2_COPYPEN ); ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( point );

m_Dragging = 0;

CView::OnLButtonUp(nFlags, point); }

Problem

窗口更新后线段消失了

原因？ 没有存储数据

2. 存储数据

线段数据结构 class CLine { private: int m_X1, m_Y1, m_X2, m_Y2;

public: CLine(int X1, int Y1, int X2, int Y2 ) { m_X1 = X1; m_Y1 = Y1; m_X2 = X2; m_Y2 = Y2; }

void Draw( CDC *pDC ) { pDC->MoveTo( m_X1, m_Y1 ); pDC->LineTo( m_X2, m_Y2 ); } };

保存线段的数组 class CMiniDrawView : public CView { vector<CLine *> m_LineArray; … }

#include <vector> using namespace std;

保存线段数据 void CMiniDrawView::OnLButtonUp(UINT nFlags, CPoint point) { // TODO: Add your message handler code here and/or call default if( m_Dragging ) { CClientDC ClientDC( this );

ClientDC.SetROP2( R2_NOT ); ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( m_PointOld );

ClientDC.SetROP2( R2_COPYPEN ); ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( point );

m_Dragging = 0;

CLine *pLine = NULL; pLine = new CLine(m_PointOrigin.x, m_PointOrigin.y, point.x, point.y ); m_LineArray.push_back( pLine ); }

重画所有线段 void CMiniDrawView::OnDraw(CDC* pDC) { CMiniDrawDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc); // TODO: add draw code for native data

here

for( int i=0; i<m_LineArray.size(); i++) { m_LineArray.at(i)->Draw(pDC); } }

如何检测有无内存泄漏 Debug information

释放空间 CMiniDrawView::~CMiniDrawView() { for( int i=0; i<m_LineArray.size(); i++) { SAFEDELETE ( m_LineArray.at(i) ); } }

#define SAFEDELETE(p) {if(p){delete p; p=NULL;}}

3. 更多图形元素 不同类型图形元素如何存储？ 如何组织它们之间的关系？

椭圆图形及数据结构 class CEllipse { private: int m_X1, m_Y1, m_X2, m_Y2;

public: CEllipse(int X1, int Y1, int X2, int Y2 ) { m_X1 = X1; m_Y1 = Y1; m_X2 = X2; m_Y2 = Y2; }

void Draw( CDC *pDC ) { pDC->Ellipse( m_X1, m_Y1, m_X2, m_Y2 ); } };

???

vector<CLine *> m_LineArray; vector<CEllipse *>

m_EllipseArray; …

4. 父类和继承 class CFigure { public: virtual void Draw( CDC *pDC ) {} //虚函数

};

class CLine: public CFigure

class CEllipse: public CFigure

5. 图形数组 class CMiniDrawView : public CView { vector<CFigure *> m_FigArray;

UINT m_CurrentTool; //图形类型 }

//数据初始化 CMiniDrawView::CMiniDrawView() { m_CurrentTool = ID_BUTTONLINE; }

替换m_LineArraym_FigArray CFigure *pFigure = NULL; pFigure = new CLine (m_PointOrigin.x, m_PointOrigin.y, point.x, point.y ); m_FigArray.push_back( pFigure );

图形类型

void CMiniDrawView::OnButtonline() { m_CurrentTool = ID_BUTTONLINE; }

void CMiniDrawView::OnButtonellipse() { m_CurrentTool = ID_BUTTONELLIPSE; }

OnMouseMove void CMiniDrawView::OnMouseMove(UINT nFlags, CPoint point) { if( !m_Dragging ) return ;

CClientDC ClientDC( this ); ClientDC.SelectStockObject (NULL_BRUSH); switch (m_CurrentTool) { case ID_BUTTONLINE: ClientDC.SetROP2( R2_NOT ); ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( m_PointOld ); ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( point ); break; case ID_BUTTONELLIPSE: ClientDC.SetROP2 (R2_NOT); ClientDC.Ellipse (m_PointOrigin.x, m_PointOrigin.y, m_PointOld.x,

m_PointOld.y ); ClientDC.Ellipse (m_PointOrigin.x, m_PointOrigin.y, point.x,

point.y ); break; }

m_PointOld = point; CView::OnMouseMove(nFlags, point); }

OnLButtonUp void CMiniDrawView::OnLButtonUp(UINT nFlags, CPoint point) { if( !m_Dragging ) return;

CClientDC ClientDC( this ); ClientDC.SelectStockObject (NULL_BRUSH);

CFigure *pFigure = NULL; switch (m_CurrentTool) { case ID_BUTTONLINE: ClientDC.SetROP2( R2_NOT ); ClientDC.MoveTo( m_PointOrigin ); ClientDC.LineTo( m_PointOld );

pFigure = new CLine(m_PointOrigin.x, m_PointOrigin.y, point.x, point.y );

break; case ID_BUTTONELLIPSE: ClientDC.SetROP2 (R2_NOT); ClientDC.Ellipse (m_PointOrigin.x, m_PointOrigin.y, m_PointOld.x,

m_PointOld.y ); pFigure = new CEllipse (m_PointOrigin.x, m_PointOrigin.y, point.x,

point.y); break; }

ClientDC.SetROP2 (R2_COPYPEN); pFigure->Draw (&ClientDC);

m_FigArray.push_back( pFigure ); m_Dragging = 0;

CView::OnLButtonUp(nFlags, point); }

6. 多态性 void CMiniDrawView::OnDraw(CDC* pDC) { CMiniDrawDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc); // TODO: add draw code for native data here

pDC->SelectStockObject (NULL_BRUSH);

for( int i=0; i<m_FigArray.size(); i++) { m_FigArray.at(i)->Draw(pDC); } }

线框画图模式 CMiniDrawView:: OnMouseMove() CMiniDrawView::OnLButtonUp()

CClientDC ClientDC( this ); ClientDC.SelectStockObject

(NULL_BRUSH); CMiniDrawView::OnDraw()

pDC->SelectStockObject (NULL_BRUSH);

类的分离 Figure.h/cpp

总结 STL vector GDI画图 鼠标交互 消息响应（鼠标） 按钮 类的继承和多态

作业 3--MiniDraw 完善MiniDraw画图程序 写一个画图小程序MiniDraw，要求画直线

(Line)，椭圆 (Ellipse)，矩形 (Rectangle)，多边形 (Polygon)等图形元素 ( 图元 )

每种图元需用一个类（对象）来封装，如CLine, CEllipse, CRect, CPolygon, CFreehand；

各种图元从一个父类 CFigure来继承； 学习类的继承和多态

要求 至少完成直线 (Line)，椭圆 (Ellipse)，矩形 (Rectangle)，多边形 (Polygon) ，自由手绘线 (Freehand)等图形元素

Deadline: 9:30a.m. April 6, 2011

如何学好 VC

需要有好的 C/C++基础 理解Windows的消息机制，窗口句柄和其他 GUI句柄的含义和用途

多使用 Online Help 记住一些常用的消息名称和参数的意义 学会看别人的代码 多练习，在实践中成长！

References

VC入门级书籍 Windows编程 《 MFC深入浅出》

Q&A