WxWidgets learning notes (I): Interpretation of code:: blocks template project source code

One 、 development environment

• operating system ：Fedora 23
• Integrated development environment ：Code::Blocks 16.01
• G++ edition ：5.3.1
• GTK+ edition ：2.24.30（ Use command sudo dnf install gtk2 gtk2-devel gtk2-devel-docs install ）
• wxWidgets edition ：3.1.0（ After unpacking the source package, enter the top-level directory and enter ./configure、make、sudo make install Three orders ）

Two 、 newly build wxWidgets Formwork works

1、 Create a new one wxWidgets Formwork works ：

2、 Choose good wxWidgets Name the new project after version , And choose the path to save the project ：

3、 After entering the copyright information, select the type of template project ：

4、 Configure compiler ：

5、 To configure wxWidgets engineering , And complete the establishment of Formwork Engineering ：

3、 ... and 、 Interpretation of template project source code

1、 To make a wxWidgets The application runs , First, you should define a wxApp Subclasses of classes , And overload wxApp::OnInit function . because wxWidgets The application has no main function , Instead, it's in wxApp Member functions defined in class “wxApp::OnInit”, and wxApp Member functions in a class can use argc and argv Two command line arguments . Use wxApp Class needs to contain header files wx/app.h, from wxApp The subclass derived from class is in TemplateApp.h The document defines , This subclass also declares a virtual function that returns a Boolean value OnInit(), If the Boolean value is true, Indicates successful initialization .

/***************************************************************
 * Name:      TemplateApp.h
 * Purpose:   Defines Application Class
 * Author:    charmingsun ([email protected])
 * Created:   2016-06-08
 * Copyright: charmingsun (NULL)
 * License:
 **************************************************************/

#ifndef TEMPLATEAPP_H
#define TEMPLATEAPP_H

#include <wx/app.h>

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

#endif // TEMPLATEAPP_H

2、wxApp In subclass OnInit Function is defined in TemplateApp.cpp In file , So this file contains the header file TemplateApp.h.TemplateApp.cpp The file first uses IMPLEMENT_APP(TemplateApp) perhaps wxIMPLEMENT_APP(TemplateApp); Macro to dynamically create and start the above wxApp Instances of subclasses （ The macro must be followed by a semicolon ）.

Then the file defines wxApp A subclass OnInit function . Because in wxApp A subclass OnInit The function must contain a top-level wxFrame Class or wxDialog Class window , So the OnInit The first statement in the function defines a named frame Of TemplateFrame Class ,TemplateFrame Class is wxFrame Subclasses of classes , This subclass will be in TemplateMain.h The document defines , So the TemplateApp.cpp The file should contain TemplateMain.h This header file . This statement to frame The constructor of the instance passes two parameters , The first is long Type value 0, That is, the first parameter is empty NULL, The second parameter is _(“wxWidgets Application Template”) The return value of the function ,_() Macro and wxGetTranslation() Function equivalence , Will input const char * The string of type is converted to wxString String output of type .

The OnInit The second statement in the function explicitly calls TemplateFrame Class frame Example of Show() function , The Show() Function inherits TemplateFrame Class wxWindow The base class Show() function ,Show() The function should be called immediately after the window class is created , Make the window just created appear ,Show() The default input parameter of the function is true, This is the display window ,false Hide window for . In the end OnInit The last statement of the function returns true value , Indicates successful initialization .

* notes ： About this TemplateApp.cpp Description of the two precompiled instructions at the beginning of the file ： The first paragraph tells the compiler if the platform supports precompiled header files , It contains wx_pch.h This header file ; The second paragraph tells the compiler if Borland The company's C++ Builder Of IDE, It indicates that all header files contained before the precompiled instruction use precompiled header files to save compilation time .

/***************************************************************
 * Name:      TemplateApp.cpp
 * Purpose:   Code for Application Class
 * Author:    charmingsun ([email protected])
 * Created:   2016-06-08
 * Copyright: charmingsun (NULL)
 * License:
 **************************************************************/

#ifdef WX_PRECOMP
#include "wx_pch.h"
#endif

#ifdef __BORLANDC__
#pragma hdrstop
#endif //__BORLANDC__

#include "TemplateApp.h"
#include "TemplateMain.h"

IMPLEMENT_APP(TemplateApp);

bool TemplateApp::OnInit()
{
 TemplateFrame* frame = new TemplateFrame(0L, _("wxWidgets Application Template"));

 frame->Show();

 return true;
}

3、 The next in TemplateMain.h It's defined in the file wxFrame Subclasses of classes ——TemplateFrame class , May not include TemplateApp.h The header file .TemplateFrame Class first declares its constructor and destructor, two public member functions . Then the enumeration type is used to define idMenuQuit and idMenuAbout These two private member constants , These two constants are the identifiers of the menu items that generate the command , Will be in TemplateFrame The event table of the window class and the constructor are used .

And then it defines a name called OnClose Event handler for , This function inputs a wxCloseEvent Event classes , This class contains some information about closing windows and session events . And then it defines a name called OnQuit And a man named OnAbout Event handler for , Both functions enter a wxCommandEvent Event classes , This class contains some information about command Events . The information returned by these event handling functions is passed by input parameters , And it is usually not called by external classes , So the return value is empty , And it is usually declared as a private member function . Event handler functions are usually in the form of OnSomething(); Format naming , But there is no rule that it must be named according to this format .

Last , stay TemplateFrame A named... Is inserted at the end of the class DECLARE_EVENT_TABLE() The macro （ This macro is equivalent to wxDECLARE_EVENT_TABLE(); macro ）, This macro declares a static event table for this class to handle events . This macro can be placed anywhere in the class that handles the event , But it is customary to put it at the end of the class . Because this macro will change the access type internally , So it's safest to put it at the end of the class . The class that handles the event must be by wxEvtHandler Class derived from , and wxWindow Class is from wxEvtHandler Class , So anything by wxWindow Class can receive and process events , such as wxFrame Classes and wxDialog class .

/***************************************************************
 * Name:      TemplateMain.h
 * Purpose:   Defines Application Frame
 * Author:    charmingsun ([email protected])
 * Created:   2016-06-08
 * Copyright: charmingsun (NULL)
 * License:
 **************************************************************/

#ifndef TEMPLATEMAIN_H
#define TEMPLATEMAIN_H

#ifndef WX_PRECOMP
 #include <wx/wx.h>
#endif

#include "TemplateApp.h"

class TemplateFrame: public wxFrame
{
 public:
 TemplateFrame(wxFrame *frame, const wxString& title);
 ~TemplateFrame();
 private:
 enum
 {
    
 idMenuQuit = 1000,
 idMenuAbout
 };
 void OnClose(wxCloseEvent& event);
 void OnQuit(wxCommandEvent& event);
 void OnAbout(wxCommandEvent& event);
 DECLARE_EVENT_TABLE()
};

#endif // TEMPLATEMAIN_H

4、TemplateMain.cpp The document defines TemplateFrame Event table and event handler function in class . The file first defines a file named wxbuildinfo Help functions for , This function is used for TemplateFrame Class and a constructor named OnAbout Event handler for . The wxbuildinfo The function inputs a file named wxbuildinfoformat The value of the enumeration type , If the input is short_f, Then the function takes wxString Type return wxWidgets Version number of , If the input is long_f, Then the function takes wxString Type return wxWidgets Version number of 、 The operating system and platform are used Unicode Code or ANSI code .

Then the file defines TemplateFrame Class , The event table tells wxWidgets How the event is mapped to the function responsible for handling the event . The event table consists of wxBEGIN_EVENT_TABLE() and wxEND_EVENT_TABLE() These two macros and the relationship between them EVT_xxx Macro composition .wxBEGIN_EVENT_TABLE(theClass,baseClass) The first parameter of the macro is the class that needs to capture events , The second parameter is the base class of the class that needs to capture events ,wxEND_EVENT_TABLE() Macro has no arguments ,EVT_xxx The macro redirects the event to the member function in the parameter .EVT_CLOSE(TemplateFrame::OnClose) Macro belongs to wxCloseEvent class , This macro will command events wxEVT_CLOSE_WINDOW Event redirected to TemplateFrame Class OnClose Member functions .EVT_MENU(id, func) Macro belongs to wxCommandEvent class , The first parameter is to generate wxEVT_MENU The identifier of the menu item of the command , The second parameter is processing wxEVT_MENU Member function of command .

Then the file defines TemplateFrame Class constructor , The two parameters in the total parameter table of the constructor will be passed to TemplateFrame Class's base class constructor wxFrame::wxFrame(wxWindow * parent , wxWindowID id , const wxString & title , const wxPoint & pos = wxDefaultPosition , const wxSize & size = wxDefaultSize , long style = wxDEFAULT_FRAME_STYLE , const wxString & name = wxFrameNameStr),wxFrame The first parameter of the class is the parent class of the window , The second parameter is the identifier of the window （ The default value is -1）, The third parameter is the title of the window .

The TemplateFrame The first precompiled instruction in the constructor of the class contains code that creates a menu bar . Click on the class name to read wxMenu class and wxMenuBar class Online reference manual for , Please understand the source code according to the reference manual . among _T() The macro will enter const char * The string of type is converted to Unicode Encoded string output , For details, please click the name to read the online reference manual of the macro . among SetMenuBar(mbar); Statement called wxFrame Class SetMenuBar() function , This function tells wxWidgets The frame displays the menu bar passed in by the parameter .

The TemplateFrame The code contained in the second precompiled instruction in the constructor of the class creates a status bar . among CreateStatusBar(2); Statement creates a status bar with two partitions ,SetStatusText(_(“Hello Code::Blocks user!”),0); Statement sets the text in the first section of the status bar and redraws the status bar ,SetStatusText(wxbuildinfo(short_f), 1); Statement sets the text in the second section of the status bar and redraws the status bar . For more information, please click on the class name to read wxFrame class Online reference manual for .

Finally, the file defines TemplateFrame Destructor of class 、OnClose Event handler 、OnQuit Event handling functions and OnAbout Event handler . Use virtual bool wxWindow::Destroy() Function to log out of the window safely . Use wxMessageBox(msg, _(“Welcome to…”)); Statement to create a statement titled “Welcome to…” The content is “wxWidgets 3.1.0-Linux-Unicode build” The dialog . of wxMessageBox function For more information, please click on the function name to read the online reference manual .

/*************************************************************** * Name: TemplateMain.cpp * Purpose: Code for Application Frame * Author: charmingsun ([email protected]) * Created: 2016-06-08 * Copyright: charmingsun (NULL) * License: **************************************************************/

#ifdef WX_PRECOMP
#include "wx_pch.h"
#endif

#ifdef __BORLANDC__
#pragma hdrstop
#endif //__BORLANDC__

#include "TemplateMain.h"

//helper functions
enum wxbuildinfoformat {
    short_f, long_f };

wxString wxbuildinfo(wxbuildinfoformat format)
{
    wxString wxbuild(wxVERSION_STRING);

    if (format == long_f )
    {
#if defined(__WXMSW__)
        wxbuild << _T("-Windows");
#elif defined(__WXMAC__)
        wxbuild << _T("-Mac");
#elif defined(__UNIX__)
        wxbuild << _T("-Linux");
#endif

#if wxUSE_UNICODE
        wxbuild << _T("-Unicode build");
#else
        wxbuild << _T("-ANSI build");
#endif // wxUSE_UNICODE
    }

    return wxbuild;
}

BEGIN_EVENT_TABLE(TemplateFrame, wxFrame)
    EVT_CLOSE(TemplateFrame::OnClose)
    EVT_MENU(idMenuQuit, TemplateFrame::OnQuit)
    EVT_MENU(idMenuAbout, TemplateFrame::OnAbout)
END_EVENT_TABLE()

TemplateFrame::TemplateFrame(wxFrame *frame, const wxString& title)
    : wxFrame(frame, -1, title)
{
#if wxUSE_MENUS
    // create a menu bar
    wxMenuBar* mbar = new wxMenuBar();
    wxMenu* fileMenu = new wxMenu(_T(""));
    fileMenu->Append(idMenuQuit, _("&Quit\tAlt-F4"), _("Quit the application"));
    mbar->Append(fileMenu, _("&File"));

    wxMenu* helpMenu = new wxMenu(_T(""));
    helpMenu->Append(idMenuAbout, _("&About\tF1"), _("Show info about this application"));
    mbar->Append(helpMenu, _("&Help"));

    SetMenuBar(mbar);
#endif // wxUSE_MENUS

#if wxUSE_STATUSBAR
    // create a status bar with some information about the used wxWidgets version
    CreateStatusBar(2);
    SetStatusText(_("Hello Code::Blocks user!"),0);
    SetStatusText(wxbuildinfo(short_f), 1);
#endif // wxUSE_STATUSBAR

}

TemplateFrame::~TemplateFrame()
{
}

void TemplateFrame::OnClose(wxCloseEvent &event)
{
    Destroy();
}

void TemplateFrame::OnQuit(wxCommandEvent &event)
{
    Destroy();
}

void TemplateFrame::OnAbout(wxCommandEvent &event)
{
    wxString msg = wxbuildinfo(long_f);
    wxMessageBox(msg, _("Welcome to..."));
}

Four 、 Further study

wxWidgets: Hello World Example
wxWidgets: A Quick Guide to Writing Applications
wxWidgets: Programming Guides
wxWidgets tutorial