wxWidget實作之圖片顯示

稍微碰了一下wxWidget，感覺它在設計menu或一些系統內建元件上比較方便，譬如說menu可以直接以文字定義快捷鍵，而無須另寫event；狀態列也可以直接對應元件操作而做出個別不同的輔助說明。

wxWidget編譯出來的是原生(Native)程式，不知道是不是因為這個緣故，使得它在繪圖上的設定幾乎與Windows API一樣難搞。雖然圖片已經更換，但畫面仍未改變，除非縮下再放大，或拖曳一個視窗在它前面晃過，才能顯示出來。實在不夠直覺，而我目前也還未想到方法可以徹底解決這個問題。麻煩，還是再回頭玩GTK+好了。



wxWidgetsApp.cpp：

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#include "wxWidgetsApp.h"
#include "wxWidgetsFrame.h"

IMPLEMENT_APP(wxWidgetsApp) 

 
   
// ============================================================================
// implementation 
// ============================================================================
wxWidgetsApp::wxWidgetsApp()
{
}

wxWidgetsApp::~wxWidgetsApp()
{
}

bool wxWidgetsApp::OnInit()
{
    
    wxInitAllImageHandlers() ; // 初始化所有的image handlers.


    wxImage image;
 wxWidgetsFrame *frame = new wxWidgetsFrame( wxBitmap(image), _("圖片顯示測試程式"),
                               wxPoint(50, 50), wxSize(400, 300));

 frame->Show(TRUE);
 SetTopWindow(frame);

 return TRUE;
}

wxWidgetsApp.h：

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#ifndef __WXWIDGETSAPP_H
#define __WXWIDGETSAPP_H

#include <wx/wx.h>

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

DECLARE_APP(wxWidgetsApp)

#endif //__WXWIDGETSAPP_H

wxWidgetsFrame.cpp：

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#include "wxWidgetsApp.h" 
#include "wxWidgetsFrame.h"  
 
  
// ----------------------------------------------------------------------------
// constants
// ----------------------------------------------------------------------------
 
enum 
{ 
 ID_MENU_QUIT = 1, 
 ID_MENU_ABOUT = 2,
 ID_MENU_OPEN = 3
};


IMPLEMENT_CLASS(wxWidgetsFrame, wxFrame)

BEGIN_EVENT_TABLE(wxWidgetsFrame, wxFrame)
 EVT_MENU(wxID_EXIT,  wxWidgetsFrame::OnQuit)
 EVT_MENU(wxID_ABOUT,  wxWidgetsFrame::OnAbout)
 EVT_MENU(wxID_OPEN,  wxWidgetsFrame::OnNewFrame)
 EVT_PAINT(wxWidgetsFrame::OnPaint)
END_EVENT_TABLE()

BEGIN_EVENT_TABLE(MyImageFrame, wxFrame)
    EVT_ERASE_BACKGROUND(MyImageFrame::OnEraseBackground)
    EVT_PAINT(MyImageFrame::OnPaint)
    EVT_LEFT_DCLICK(MyImageFrame::OnSave)
END_EVENT_TABLE()




// ----------------------------------------------------------------------------
// main frame
// ----------------------------------------------------------------------------
wxWidgetsFrame::wxWidgetsFrame(const wxBitmap& bitmap, const wxString& title, 
                               const wxPoint& pos, const wxSize& size)
: wxFrame((wxFrame *)NULL, wxID_ANY, title, pos, size )
{

 wxMenu *fileMenu = new wxMenu(_(""), wxMENU_TEAROFF);
 wxMenu *helpMenu = new wxMenu(_(""), wxMENU_TEAROFF);

    fileMenu->Append(wxID_OPEN, _("&開啟\tAlt-K"), _("開啟圖片"));
 fileMenu->Append(wxID_EXIT, _("&離開\tAlt-Y"), _("離開本程式"));
 helpMenu->Append(wxID_ABOUT, _("&關於\tAlt-Z"), _("關於本程式"));

 wxMenuBar *menuBar = new wxMenuBar();
 menuBar->Append(fileMenu, _("&檔案"));
 menuBar->Append(helpMenu, _("&幫助"));

 SetMenuBar(menuBar);
 CreateStatusBar(2);
 SetStatusText(_("狀態列"));
 
 wxImage image;

}

wxWidgetsFrame::~wxWidgetsFrame()
{
}

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

void wxWidgetsFrame::OnAbout(wxCommandEvent& event)
{
 wxString msg;
 msg.Printf(_( "Hello and welcome to %s" ),
            wxVERSION_STRING);
 wxMessageBox(msg, _( "About" ),
              wxOK | wxICON_INFORMATION, this);
} 

  

void wxWidgetsFrame::OnNewFrame( wxCommandEvent &WXUNUSED(event) )
{
    wxString filename = wxFileSelector(_("Select image file"));
    if ( !filename )
        return; 
 
    wxImage image;
    if ( !image.LoadFile(filename) )
    {
        wxLogError(_T("Couldn't load image from '%s'."), filename.c_str());

        return;
    } 
     
    (new MyImageFrame(this, wxBitmap(image), filename))->Show(); // 另開圖片顯示視窗 

    m_bitmap = wxBitmap(image); // 儲存讀入的圖片資料    
    
    SetClientSize(m_bitmap.GetWidth(), m_bitmap.GetHeight()); // 隨圖片大小改變視窗大小 
    
}

void wxWidgetsFrame::OnPaint(wxPaintEvent& WXUNUSED(event))
{
         
    wxPaintDC dc( this );
        
    //dc.SetBackground(*wxGREY_BRUSH);
    //dc.Clear() ;
        
    dc.DrawBitmap( m_bitmap, 0, 0, false /* use mask */ ); // 繪出圖片 
}


// ----------------------------------------------------------------------------
// image frame
// ----------------------------------------------------------------------------
 
MyImageFrame::MyImageFrame(wxFrame *parent, const wxBitmap& bitmap, wxString filename)
: wxFrame(parent, wxID_ANY, _(filename),
                  wxDefaultPosition, wxDefaultSize,
                  wxCAPTION | wxSYSTEM_MENU | wxCLOSE_BOX),
                  m_bitmap(bitmap)
{ 
    SetClientSize(bitmap.GetWidth(), bitmap.GetHeight()); // 隨圖片大小變更視窗大小 
}


void MyImageFrame::OnEraseBackground(wxEraseEvent& WXUNUSED(event))
{
    // do nothing here to be able to see how transparent images are shown
}

void MyImageFrame::OnPaint(wxPaintEvent& WXUNUSED(event))
{
    wxPaintDC dc( this );
    dc.DrawBitmap( m_bitmap, 0, 0, true /* use mask */ );
}

void MyImageFrame::OnSave(wxMouseEvent& WXUNUSED(event))
{
}

wxWidgetsFrame.h：

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#ifndef __WXWIDGETSFRAME_H
#define __WXWIDGETSFRAME_H

#include <wx/wx.h>
#include <wx/wxprec.h>
#include <wx/brush.h>
#include <wx/image.h>
#include <wx/file.h>


class wxWidgetsFrame : public wxFrame
{
public:
 wxWidgetsFrame(const wxBitmap& bitmap, const wxString& title, 
                   const wxPoint& pos, const wxSize& size);
 virtual ~wxWidgetsFrame();

 void OnQuit(wxCommandEvent& event);
 void OnAbout(wxCommandEvent& event);
 void OnNewFrame(wxCommandEvent& event);
 void OnPaint(wxPaintEvent& WXUNUSED(event));
 
 wxBitmap m_bitmap ;

private:
 DECLARE_CLASS(wxWidgetsFrame)

 DECLARE_EVENT_TABLE()
};


class MyImageFrame : public wxFrame
{
public: 
    MyImageFrame(wxFrame *parent, const wxBitmap& bitmap, wxString filename);

    void OnEraseBackground(wxEraseEvent& WXUNUSED(event));
    void OnPaint(wxPaintEvent& WXUNUSED(event));
    void OnSave(wxMouseEvent& WXUNUSED(event));

private:
    wxBitmap m_bitmap;

    DECLARE_EVENT_TABLE()
};


#endif //__WXWIDGETSFRAME_H