[wxWidgets]_[0基础]_[经常更新进度条程序]

场景:

1. 非常根据程序的进展需要处理业务，以更新进度条，进度条的目的是为了让用户知道业务流程的进度。一个进度条程序更友好，让用户知道在程序执行。不是没有反应。

2. 现在更新见过这两种方法的进展。事件（信号，队列）的发送让主线程依照发送的顺序来更新进度条，一种是设置一个全局整形变量，

通过执行定时器的方式来更新进度条。第一种不适合在更新频率比較高的地方，比方一秒钟发送了20个事件，这样会造成主线程忙于处理事件界面出现假死状态。

所以最好的办法就是使用第2种通过定时器更新进度条，设置一个合理的值，比方500毫秒这样既能看到更新的进度，也不会让主线程过于忙。

3. 这里用wxWidgets做样例。事实上mfc,wtl,cocoa都是一样的。

部分代码:

my_thread.cpp

#include "domain/my_thread.h"

#include "window/my_frame.h"

wxThread::ExitCode MyThread::Entry()

{

	Sleep(500);

	int i = 1;

	while (!TestDestroy() && i <= 100)

	{

		if(type_)

		{

			//第一种方法,发事件更新进度条,注意,不能直接更新进度条控件,由于非主线程不能更新控件

			wxCommandEvent* evt = new wxCommandEvent(wxEVT_COMMAND_MYTHREAD_UPDATE);

			evt->SetInt(i);

			wxQueueEvent(m_pHandler->GetEventHandler(), evt);

		}else

		{

			//另外一种方法,直接更新MyFrame里的Int成员变量,然会wxTimer会依据这个值自己主动更新进度条控件.

			m_pHandler->progress_value_ = i;

			Sleep(200);

		}

		++i;

	}

	//1.最后这个事实上还是必要的,告诉wxTimer能够结束了。总之就是通知界面工作任务已经完毕，你自己做该做的事。

	wxQueueEvent(m_pHandler->GetEventHandler(), new wxCommandEvent(wxEVT_COMMAND_MYTHREAD_COMPLETED));

	return (wxThread::ExitCode)0;

}

my_frame.cpp

#include "window/my_frame.h"

#include "wx/xrc/xmlres.h"

#include <iostream>

#include "domain/my_thread.h"

using namespace std;

BEGIN_EVENT_TABLE(MyFrame, wxFrame)

	EVT_COMMAND(wxID_ANY, wxEVT_COMMAND_MYTHREAD_UPDATE, MyFrame::OnThreadUpdate)

	EVT_COMMAND(wxID_ANY, wxEVT_COMMAND_MYTHREAD_COMPLETED,	MyFrame::OnThreadCompletion)

	EVT_TIMER(wxID_ANY,MyFrame::OnTimer)

END_EVENT_TABLE()

wxDEFINE_EVENT(wxEVT_COMMAND_MYTHREAD_COMPLETED, wxThreadEvent);

wxDEFINE_EVENT(wxEVT_COMMAND_MYTHREAD_UPDATE, wxThreadEvent);

void MyFrame::Init()

{

   gauge_ =  XRCCTRL(*this, "m_gauge1", wxGauge);

   event_update_button_ = XRCCTRL(*this, "m_button1", wxButton);

   event_update_button_->Bind(wxEVT_COMMAND_BUTTON_CLICKED,

        wxCommandEventHandler(MyFrame::OnEventUpdate), this, XRCID("m_button1"));

   timer_update_button_ = XRCCTRL(*this, "m_button3", wxButton);

   timer_update_button_->Bind(wxEVT_COMMAND_BUTTON_CLICKED,

        wxCommandEventHandler(MyFrame::OnTimerUpdate), this, XRCID("m_button3"));

   timer.SetOwner(this->GetEventHandler());

}

MyFrame::MyFrame(wxWindow* parent)

{

	progress_value_ = 0;

}

MyFrame::~MyFrame()

{

}

void MyFrame::OnThreadUpdate(wxCommandEvent& evt)

{

	cout << "OnThreadUpdate" << endl;

	gauge_->SetValue(evt.GetInt());

}

void MyFrame::OnThreadCompletion(wxCommandEvent&)

{

	cout << "OnThreadCompletion" << endl;

	if(!type_)

	{

		timer.Stop();

		gauge_->SetValue(progress_value_);

	}

	timer_update_button_->Enable();

	event_update_button_->Enable();

}

void MyFrame::OnTimer(wxTimerEvent&)

{

	cout << "OnTimer" << endl;

	gauge_->SetValue(progress_value_);

}

void MyFrame::DoTask(bool type)

{

	timer_update_button_->Enable(false);

	event_update_button_->Enable(false);

    MyThread *m_pThread = new MyThread(type,this);

	if ( m_pThread->Run() != wxTHREAD_NO_ERROR )

	{

		cout << "Can't create the thread!: " << type << endl;

		delete m_pThread;

		m_pThread = NULL;

	}

}

void MyFrame::OnTimerUpdate(wxCommandEvent& evt)

{

	cout << "OnTimerUpdate" << endl;

	gauge_->SetValue(0);

	progress_value_ = 0;

	type_ = false;

	timer.Start(500);

	DoTask(type_);

}

void MyFrame::OnEventUpdate(wxCommandEvent& evt)

{

    cout << "OnEventUpdate" << endl;

	gauge_->SetValue(0);

	progress_value_ = 0;

	type_ = true;

	DoTask(type_);

}

gui.cpp

#include "wx/wxprec.h"

#ifndef WX_PRECOMP

    #include "wx/wx.h"

#endif

#include "wx/xrc/xmlres.h"

#include <assert.h>

#include <iostream>

#include <stdio.h>

#include <io.h>

#include <fcntl.h>

#include "wx/listctrl.h"

#include "wx/grid.h"

#include "wx/event.h"

#include "window/my_frame.h"

using namespace std;

static void OpenConsole()

{

	AllocConsole();

	HANDLE   handle   =   GetStdHandle(STD_OUTPUT_HANDLE);

	int   hCrt   =   _open_osfhandle((long)handle,_O_TEXT);

	FILE   *   hf   =   _fdopen(   hCrt,   "w"   );

	*stdout   =   *hf;

}

static wxString GetAppRunDirectory()

{

    wxString directory(wxTheApp->argv[0]);

    directory.Replace(wxT("\\"), wxT("/"));

    wxString str = directory.BeforeLast('/');

    if(str.IsEmpty())

    {

      return wxT(".");

    }

    return directory.BeforeLast('/');

}

static wxString GetInstallDirectory()

{

	wxString directory = GetAppRunDirectory();

#ifdef __QXWIN32__

    return directory.BeforeLast('/');

#else

    return directory;

#endif

}

class MyApp : public wxApp

{

public:

    virtual bool OnInit();

    virtual int OnExit();

};

IMPLEMENT_APP(MyApp)

// 'Main program' equivalent: the program execution "starts" here

bool MyApp::OnInit()

{

  if (!wxApp::OnInit())

  {

	return false;

  }

  OpenConsole();

  wxInitAllImageHandlers();

  wxXmlResource::Get()->InitAllHandlers();

  wxString ui_dir = GetInstallDirectory()+wxT("/Themes");

  wxXmlResource::Get()->LoadAllFiles(ui_dir);

  MyFrame *frame = new MyFrame(NULL);

  bool loaded = wxXmlResource::Get()->LoadFrame(frame, NULL, "MyFrame1");

  assert(loaded);

  frame->Init();

  frame->Show(true);

  return true;

}

int MyApp::OnExit()

{

	return 0;

}

截图:

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完整代代码下载：

http://download.csdn.net/detail/infoworld/8105011