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.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.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.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_LineArraym_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.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 ); } 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); } 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

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References VC入门级书籍 Windows编程 《MFC深入浅出》

Q&A