wxWidgets学习笔记——在屏幕上画简单的图形和文字

在屏幕上画简单图形和显示图片、处理简单鼠标键盘事件

/***************************************************************
 * Name:      MyApp.h
 * Purpose:   Defines Application Class
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#ifndef WXTESTAPP_H
#define WXTESTAPP_H

#include <wx/app.h>

class MyApp : public wxApp          //应用程序类，应用程序的入口点
{
    public:
        virtual bool OnInit(void);  //在应用程序启动时调用，如果返回false，退出应用程序
};

#endif // WXTESTAPP_H

/***************************************************************
 * Name:      MyApp.cpp
 * Purpose:   Code for Application Class
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#include <wx/wx.h>
//(*AppHeaders
#include "MyApp.h"
#include "MyFrame.h"
//*)

DECLARE_APP(MyApp);
IMPLEMENT_APP(MyApp);

bool MyApp::OnInit(void)
{
    MyFrame * frame = new MyFrame(NULL, wxT("wxWidgets"));    //为新窗口分配空间，设定标题

    frame->Show();

    return wxOK;
}

/***************************************************************
 * Name:      MyFrame.h
 * Purpose:   Defines Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#ifndef WXTESTMAIN_H
#define WXTESTMAIN_H

#include <wx/frame.h>

class MyFrame : public wxFrame  //窗体类
{
    public:
        //Constructor
        MyFrame(wxWindow * parent, const wxString & title); //窗体的构造函数
        //Destructor
        ~MyFrame() {};

        //Event handlers
        void OnAbout    (wxCommandEvent & event);
        void OnQuit     (wxCommandEvent & event);
        void OnMotion   (wxMouseEvent   & event);
        void OnPaint    (wxPaintEvent   & event);
        void OnMousePrc (wxMouseEvent   & event);
        void OnKeyPrc   (wxKeyEvent     & event);

    private:
        DECLARE_EVENT_TABLE();
};

#endif // WXTESTMAIN_H

/***************************************************************
 * Name:      MyFrame.cpp
 * Purpose:   Code for Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#include <wx/wx.h>
#include <wx/dcbuffer.h>
//(*FrameHeaders
#include "MyApp.h"
#include "MyFrame.h"
#include "wxPingGe.h"
//*)

//事件表：（类，基类）
BEGIN_EVENT_TABLE(MyFrame,wxFrame)
    //(*EventTable(MyFrame)
    EVT_MENU        (wxID_ABOUT,    MyFrame::OnAbout)      //把wxID_ABOUT和OnAbout关联
    EVT_MENU        (wxID_EXIT,     MyFrame::OnQuit)       //把wxID_EXIT和OnQuit关联
    EVT_MOTION      (               MyFrame::OnMotion)     //鼠标事件
    EVT_PAINT       (               MyFrame::OnPaint)      //刷屏消息
    EVT_MOUSE_EVENTS(               MyFrame::OnMousePrc)   //鼠标事件
    EVT_KEY_DOWN    (               MyFrame::OnKeyPrc)     //键盘事件
    //*)
END_EVENT_TABLE()


#include "wx.xpm"
MyFrame::MyFrame(wxWindow * parent, const wxString & title)
       : wxFrame(NULL, wxID_ANY, title)
{
    SetIcon(wxIcon(wx_xpm));

    wxMenu * fileMenu = new wxMenu;             //建立“文件”菜单
    wxMenu * helpMenu = new wxMenu;             //建立“帮助”菜单

    //增加菜单项（标识、文本、帮助字符）
    helpMenu->Append(wxID_ABOUT, wxT("&About...	F2"),   wxT("Show about dialog"));
    fileMenu->Append(wxID_EXIT,  wxT("&Exit...	Alt-X"), wxT("Quit this programe"));

    wxMenuBar * menuBar = new wxMenuBar();      //建立一个菜单条
    menuBar->Append(fileMenu, wxT("&File"));    //将"文件"菜单加入到菜单条
    menuBar->Append(helpMenu, wxT("&Help"));    //将“帮助”菜单加入到菜单条

    SetMenuBar(menuBar);                        //将菜单条放到窗体上

    CreateStatusBar(2);                         //创建两个状态栏，并写上字符串
    SetStatusText(wxT("welcome to wxWidgets!"), 1);
}

void MyFrame::OnAbout(wxCommandEvent & event)
{
    wxString msg;
    msg.Printf(wxT("hello and welcome to %s"), wxVERSION_STRING);   //消息的字符串

    //消息框：（消息内容、标题、窗口类型、父窗口）
    wxMessageBox(msg, wxT("About Minimal"), wxOK | wxICON_INFORMATION, this);
}

void MyFrame::OnQuit(wxCommandEvent & event)
{
    Close();
}

void MyFrame::OnMotion(wxMouseEvent & event)
{
    if(event.Dragging())                        //鼠标拖动时为真
    {
        wxClientDC dc(this);                    //创建一个指向当前窗口的设备指针dc
        wxPen pen(*wxRED, 1);                   //创建画笔，颜色：红色，宽度：1
        dc.SetPen(pen);
        dc.DrawPoint(event.GetPosition());      //画点
        dc.SetPen(wxNullPen);
    }
}

void MyFrame::OnPaint(wxPaintEvent & event)     //刷屏消息处理函数
{
    wxBufferedPaintDC mydc(this);
    mydc.SetPen(*wxWHITE_PEN);

    //mydc.SetBrush(*wxRED_BRUSH);
    mydc.SetBrush(wxColor(255, 0, 0)/*wxRED_BRUSH*/);

    mydc.SetBackground(wxBrush(*wxWHITE, wxSOLID));

    wxSize sz = GetClientSize();                //获取窗口大小

    wxCoord w = 100, h = 50;                    //要绘制的矩形大小

    int x = wxMax(0, sz.x / 2) - w / 2;         //将矩形放置在窗口的正中间，但不为负
    int y = wxMax(0, sz.y / 2) - h / 2;

    wxRect rectToDraw(x, y, w, h);

    if(IsExposed(rectToDraw))                   //只有在需要的时候才重新画以便提高效率
    {
        //mydc.DrawRectangle(rectToDraw);                                 //画矩形

        //DrawTextString(mydc, wxT("test"), wxPoint(50, 50));             //画字符串

        //DrawRotatedTest(mydc, wxT("PingGe"), wxPoint(100, 100), 60);   //旋转字符串

        DrawSimpleShape(mydc);

        DrawMap(mydc);
    }
    /*
    窗口最大化后出现两个矩形，原因是窗口变大时原先部分没有刷新，
    只把新增部分刷新出来；
    */
}

void MyFrame::OnMousePrc(wxMouseEvent & event)
{
    wxPoint pt(event.GetPosition());    //获取当前坐标pt

    wxClientDC dc(this);                //设置一个设备上下文


    if((pt.x > 100) && (pt.y > 100) && (event.LeftDown()))
    {
        wxPen pen(*wxWHITE, 1);         //白色画笔
        dc.SetPen(pen);
        dc.DrawLine(0, 0, 1280, 1024);  //当鼠标左键点击位置在(100, 100)之后时用白色画笔画线
    }
    if(event.LeftUp())
    {
        wxPen pen(*wxRED, 1);           //红色画笔
        dc.SetPen(pen);
        dc.DrawLine(0, 100, 1024, 100); //当鼠标左键弹起时，用红色画笔画线
    }
}

void MyFrame::OnKeyPrc(wxKeyEvent & event)  //处理按键按下的消息
{
    wxClientDC dc(this);                    //设置一个设备上下文

    wxPen pen(*wxWHITE, 1);
    dc.SetPen(pen);                         //白色画笔

    if(event.ShiftDown())                   //按下shift键画一条直线
    {
        dc.DrawLine(0, 50, 1280, 50);
    }

    int code = event.GetKeyCode();          //获取按下按键的编码
    if(code == 65)
    {
        dc.DrawLine(0, 40, 1280, 40);       //当按下A键时画一条直线
    }
}

/***************************************************************
 * Name:      wxPingGe.h
 * Purpose:   Code for Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/
#ifndef _WXPINGGE_H_
#define _WXPINGGE_H_

#include <wx/wx.h>
#include <wx/dcbuffer.h>

//画字符函数：（DC，文本，位置）
void DrawTextString(wxDC & dc, const wxString & text, const wxPoint & pt);

//画旋转字符函数：（DC，文本，位置，旋转角度）
void DrawRotatedTest(wxDC & dc, const wxString & text, const wxPoint & pt, int angle = 0);

//画一些图形
void DrawSimpleShape(wxDC & dc);

//画图片
void DrawMap(wxDC & dc);

#endif //_WXPINGGE_H_

/***************************************************************
 * Name:      wxPingGe.cpp
 * Purpose:   Code for Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#include "wxPingGe.h"

void DrawTextString(wxDC & dc, const wxString & text, const wxPoint & pt)
{
    //定义一个wxFont类的对象font
    //构造函数wxFont::wxFont(字体大小、字体类型(书法、艺术)、斜体)
    wxFont font(50, wxFONTFAMILY_SCRIPT, wxNORMAL, wxBOLD);

    //利用DC类的成员函数SetFont设置字体
    dc.SetFont(font);

    //设置背景透或者不透
    dc.SetBackgroundMode(wxSOLID/*wxTRANSPARENT*/);

    //设置前景颜色
    dc.SetTextForeground(*wxRED);

    //设置背景颜色
    dc.SetTextBackground(*wxWHITE);

    //写字，文本wxString，位置wxPoint
    dc.DrawText(text, pt);
}

void DrawRotatedTest(wxDC & dc, const wxString & text, const wxPoint & pt, int angle)
{
    wxFont font(50, wxFONTFAMILY_SCRIPT, wxNORMAL, wxBOLD);

    dc.SetFont(font);

    dc.SetBackgroundMode(wxTRANSPARENT/*wxSOLID*/);

    dc.SetTextForeground(*wxWHITE);

    dc.SetTextBackground(*wxRED);

    dc.DrawRotatedText(text, pt, angle);
}

void DrawSimpleShape(wxDC & dc)
{
    //设置画笔画刷
    dc.SetPen(wxPen(*wxRED, 1, wxSOLID));

    dc.SetBrush(wxBrush(*wxGREEN, wxSOLID));

    //画抛物线
    dc.DrawSpline(0, 100, 100, 0, 200, 100);

    //画点
    dc.DrawPoint(5, 5);

    //画线：（注意，最后一个点不会画）
    dc.DrawLine(10, 10, 100, 100);

    //画矩形：（用画笔画边框，画刷填充内部）
    dc.DrawRectangle(50, 50, 150, 100);

    //设置画刷为红色
    dc.SetBrush(*wxRED_BRUSH);

    //画圆角矩形
    dc.DrawRoundedRectangle(150, 20, 100, 50, 10);

    //设置颜色
    dc.SetBrush(wxColor(255, 255, 0));

    //画圆
    dc.DrawCircle(100, 150, 60);
}

#include "1.xpm"
void DrawMap(wxDC & dc)
{
    wxBitmap bitmap(logo_xpm);
    dc.DrawBitmap(bitmap, 200, 100, wxBITMAP_TYPE_XPM);

    dc.SetTextBackground(*wxBLACK);
    dc.SetTextForeground(*wxWHITE);

    wxString msg = wxT("Some text is mixed in bmp shade.");

    for(int i = 0, step = 75; i < 10; i++, step += 20)
    {
        dc.DrawText(msg, 200, step);
    }
}

在屏幕上画普通文字和旋转的文字

/***************************************************************
 * Name:      MyApp.h
 * Purpose:   Defines Application Class
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#ifndef WXTESTAPP_H
#define WXTESTAPP_H

#include <wx/app.h>

class MyApp : public wxApp          //应用程序类，应用程序的入口点
{
    public:
        virtual bool OnInit(void);  //在应用程序启动时调用，如果返回false，退出应用程序
};

#endif // WXTESTAPP_H

/***************************************************************
 * Name:      MyApp.cpp
 * Purpose:   Code for Application Class
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#include <wx/wx.h>
//(*AppHeaders
#include "MyApp.h"
#include "MyFrame.h"
//*)

DECLARE_APP(MyApp);
IMPLEMENT_APP(MyApp);

bool MyApp::OnInit(void)
{
    MyFrame * frame = new MyFrame(NULL, wxT("wxWidgets"));    //为新窗口分配空间，设定标题

    frame->Show();

    return wxOK;
}

/***************************************************************
 * Name:      MyFrame.h
 * Purpose:   Defines Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#ifndef WXTESTMAIN_H
#define WXTESTMAIN_H

#include <wx/frame.h>

class MyFrame : public wxFrame  //窗体类
{
    public:
        //Constructor
        MyFrame(wxWindow * parent, const wxString & title); //窗体的构造函数
        //Destructor
        ~MyFrame() {};

        //Event handlers
        void OnAbout    (wxCommandEvent & event);
        void OnQuit     (wxCommandEvent & event);
        void OnMotion   (wxMouseEvent   & event);
        void OnPaint    (wxPaintEvent   & event);

    private:
        DECLARE_EVENT_TABLE();
};

#endif // WXTESTMAIN_H

/***************************************************************
 * Name:      MyFrame.cpp
 * Purpose:   Code for Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#include <wx/wx.h>
#include <wx/dcbuffer.h>
//(*FrameHeaders
#include "MyApp.h"
#include "MyFrame.h"
#include "wxPingGe.h"
//*)

//事件表：（类，基类）
BEGIN_EVENT_TABLE(MyFrame,wxFrame)
    //(*EventTable(MyFrame)
    EVT_MENU    (wxID_ABOUT, MyFrame::OnAbout)
    EVT_MENU    (wxID_EXIT,  MyFrame::OnQuit)
    EVT_MOTION  (            MyFrame::OnMotion)
    EVT_PAINT   (            MyFrame::OnPaint)
    //*)
END_EVENT_TABLE()


#include "wx.xpm"
MyFrame::MyFrame(wxWindow * parent, const wxString & title)
       : wxFrame(NULL, wxID_ANY, title)
{
    SetIcon(wxIcon(wx_xpm));

    wxMenu * fileMenu = new wxMenu;             //建立“文件”菜单
    wxMenu * helpMenu = new wxMenu;             //建立“帮助”菜单

    //增加菜单项（标识、文本、帮助字符）
    helpMenu->Append(wxID_ABOUT, wxT("&About...	F2"),   wxT("Show about dialog"));
    fileMenu->Append(wxID_EXIT,  wxT("&Exit...	Alt-X"), wxT("Quit this programe"));

    wxMenuBar * menuBar = new wxMenuBar();      //建立一个菜单条
    menuBar->Append(fileMenu, wxT("&File"));    //将"文件"菜单加入到菜单条
    menuBar->Append(helpMenu, wxT("&Help"));    //将“帮助”菜单加入到菜单条

    SetMenuBar(menuBar);                        //将菜单条放到窗体上

    CreateStatusBar(2);                         //创建两个状态栏，并写上字符串
    SetStatusText(wxT("welcome to wxWidgets!"));
}

void MyFrame::OnAbout(wxCommandEvent & event)
{
    wxString msg;
    msg.Printf(wxT("hello and welcome to %s"), wxVERSION_STRING);   //消息的字符串

    //消息框：（消息内容、标题、窗口类型、父窗口）
    wxMessageBox(msg, wxT("About Minimal"), wxOK | wxICON_INFORMATION, this);
}

void MyFrame::OnQuit(wxCommandEvent & event)
{
    Close();
}

void MyFrame::OnMotion(wxMouseEvent & event)
{
    if(event.Dragging())                        //鼠标拖动时为真
    {
        wxClientDC dc(this);                    //创建一个指向当前窗口的设备指针dc
        wxPen pen(*wxRED, 1);                   //创建画笔，颜色：红色，宽度：1
        dc.SetPen(pen);
        dc.DrawPoint(event.GetPosition());      //画点
        dc.SetPen(wxNullPen);
    }
}

void MyFrame::OnPaint(wxPaintEvent & event)     //刷屏消息处理函数
{
    wxBufferedPaintDC mydc(this);
    mydc.SetPen(*wxBLACK_PEN);
    mydc.SetBrush(*wxRED_BRUSH);

    wxSize sz = GetClientSize();                //获取窗口大小

    wxCoord w = 100, h = 50;                    //要绘制的矩形大小

    int x = wxMax(0, sz.x / 2) - w / 2;         //将矩形放置在窗口的正中间，但不为负
    int y = wxMax(0, sz.y / 2) - h / 2;

    wxRect rectToDraw(x, y, w, h);

    if(IsExposed(rectToDraw))                   //只有在需要的时候才重新画以便提高效率
    {
        mydc.DrawRectangle(rectToDraw);

        DrawTextString(mydc, wxT("test"), wxPoint(50, 50));             //画字符串

        DrawRotatedTest(mydc, wxT("PingGe"), wxPoint(100, 100), 60);    //旋转字符串
    }
    /*
    窗口最大化后出现两个矩形，原因是窗口变大时原先部分没有刷新，
    只把新增部分刷新出来；
    */
}

/***************************************************************
 * Name:      wxPingGe.h
 * Purpose:   Code for Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/
#ifndef _WXPINGGE_H_
#define _WXPINGGE_H_

#include <wx/wx.h>
#include <wx/dcbuffer.h>

//画字符函数：（DC，文本，位置）
void DrawTextString(wxDC & dc, const wxString & text, const wxPoint & pt);

//画旋转字符函数：（DC，文本，位置，旋转角度）
void DrawRotatedTest(wxDC & dc, const wxString & text, const wxPoint & pt, int angle = 0);


#endif //_WXPINGGE_H_

/***************************************************************
 * Name:      wxPingGe.cpp
 * Purpose:   Code for Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#include "wxPingGe.h"

void DrawTextString(wxDC & dc, const wxString & text, const wxPoint & pt)
{
    //定义一个wxFont类的对象font
    //构造函数wxFont::wxFont(字体大小、字体类型(书法、艺术)、斜体)
    wxFont font(50, wxFONTFAMILY_SCRIPT, wxNORMAL, wxBOLD);

    //利用DC类的成员函数SetFont设置字体
    dc.SetFont(font);

    //设置背景透或者不透
    dc.SetBackgroundMode(wxSOLID/*wxTRANSPARENT*/);

    //设置前景颜色
    dc.SetTextForeground(*wxRED);

    //设置背景颜色
    dc.SetTextBackground(*wxWHITE);

    //写字，文本wxString，位置wxPoint
    dc.DrawText(text, pt);
}


void DrawRotatedTest(wxDC & dc, const wxString & text, const wxPoint & pt, int angle)
{
    wxFont font(50, wxFONTFAMILY_SCRIPT, wxNORMAL, wxBOLD);

    dc.SetFont(font);

    dc.SetBackgroundMode(wxTRANSPARENT/*wxSOLID*/);

    dc.SetTextForeground(*wxWHITE);

    dc.SetTextBackground(*wxRED);

    dc.DrawRotatedText(text, pt, angle);
}

在屏幕上画点和矩形

/***************************************************************
 * Name:      MyApp.h
 * Purpose:   Defines Application Class
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#ifndef WXTESTAPP_H
#define WXTESTAPP_H

#include <wx/app.h>

class MyApp : public wxApp
{
    public:
        virtual bool OnInit(void);
};

#endif // WXTESTAPP_H

/***************************************************************
 * Name:      MyApp.cpp
 * Purpose:   Code for Application Class
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#include "MyApp.h"

//(*AppHeaders
#include "wx/wx.h"
#include "MyFrame.h"
//*)

DECLARE_APP(MyApp);
IMPLEMENT_APP(MyApp);

bool MyApp::OnInit(void)
{
    MyFrame * frame = new MyFrame(NULL, wxT("wxWidgets"));    //为新窗口分配空间，设定标题

    frame->Show();

    return wxOK;
}

/***************************************************************
 * Name:      MyFrame.h
 * Purpose:   Defines Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#ifndef WXTESTMAIN_H
#define WXTESTMAIN_H

#include <wx/frame.h>

class MyFrame : public wxFrame
{
    public:
        //Constructor
        MyFrame(wxWindow * parent, const wxString & title);
        //Destructor
        ~MyFrame() {};

        //Event handlers
        void OnAbout    (wxCommandEvent & event);
        void OnQuit     (wxCommandEvent & event);
        void OnMotion   (wxMouseEvent   & event);
        void OnPaint    (wxPaintEvent   & event);

    private:
        DECLARE_EVENT_TABLE();
};

#endif // WXTESTMAIN_H

/***************************************************************
 * Name:      MyFrame.cpp
 * Purpose:   Code for Application Frame
 * Author:    PingGe (414236069@qq.com)
 * Created:   2013-10-14
 * Copyright: PingGe (http://www.cnblogs.com/pingge/)
 * License:
 **************************************************************/

#include "MyFrame.h"

//(*InternalHeaders(wxTestDialog)
#include "wx/wx.h"
#include "wx/dcbuffer.h"
#include "MyApp.h"
//*)


BEGIN_EVENT_TABLE(MyFrame,wxFrame)
    //(*EventTable(wxTestDialog)
    EVT_MENU    (wxID_ABOUT, MyFrame::OnAbout)
    EVT_MENU    (wxID_EXIT,  MyFrame::OnQuit)
    EVT_MOTION  (            MyFrame::OnMotion)
    EVT_PAINT   (            MyFrame::OnPaint)
    //*)
END_EVENT_TABLE()


#include "wx.xpm"
MyFrame::MyFrame(wxWindow * parent, const wxString & title)
       : wxFrame(NULL, wxID_ANY, title)
{
    SetIcon(wxIcon(wx_xpm));

    wxMenu * fileMenu = new wxMenu;             //定义两个菜单项
    wxMenu * helpMenu = new wxMenu;

    //增加菜单项（标识、文本、帮助字符）
    helpMenu->Append(wxID_ABOUT, wxT("&About...	F2"),   wxT("Show about dialog"));
    fileMenu->Append(wxID_EXIT,  wxT("&Exit...	Alt-X"), wxT("Quit this programe"));

    wxMenuBar * menuBar = new wxMenuBar();      //定义菜单条
    menuBar->Append(fileMenu, wxT("&File"));
    menuBar->Append(helpMenu, wxT("&Help"));

    SetMenuBar(menuBar);

    CreateStatusBar(2);                         //创建两个状态栏，并写上字符串
    SetStatusText(wxT("welcome to wxWidgets!"));
}

void MyFrame::OnAbout(wxCommandEvent & event)
{
    wxString msg;
    msg.Printf(wxT("hello and welcome to %s"), wxVERSION_STRING);   //消息的字符串

    //消息框：（消息内容、标题、窗口类型、父窗口）
    wxMessageBox(msg, wxT("About Minimal"), wxOK | wxICON_INFORMATION, this);
}

void MyFrame::OnQuit(wxCommandEvent & event)
{
    Close();
}

void MyFrame::OnMotion(wxMouseEvent & event)
{
    if(event.Dragging())    //鼠标拖动时为真
    {
        wxClientDC dc(this);    //创建一个指向当前窗口的设备指针dc
        wxPen pen(*wxRED, 1);   //创建画笔，颜色：红色，宽度：1
        dc.SetPen(pen);
        dc.DrawPoint(event.GetPosition());
        dc.SetPen(wxNullPen);
    }
}

void MyFrame::OnPaint(wxPaintEvent & event)
{
    wxBufferedPaintDC mydc(this);
    mydc.SetPen(*wxBLACK_PEN);
    mydc.SetBrush(*wxRED_BRUSH);

    wxSize sz = GetClientSize();    //获取窗口大小

    wxCoord w = 100, h = 50;        //要绘制的矩形大小

    int x = wxMax(0, sz.x / 2) - w / 2;     //将矩形放置在窗口的正中间，但不为负
    int y = wxMax(0, sz.y / 2) - h / 2;

    wxRect rectToDraw(x, y, w, h);

    if(IsExposed(rectToDraw))       //只有在需要的时候才重新画以便提高效率
    {
        mydc.DrawRectangle(rectToDraw);
    }
    /*
    窗口最大化后出现两个矩形，原因是窗口变大时原先部分没有刷新，
    只把新增部分刷新出来；
    */
}