samples/erase/erase.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        samples/erase/erase.cpp
   3 // Purpose:     Erase wxWidgets sample
   4 // Author:      Robert Roebling, Vadim Zeitlin
   5 // Created:     04/01/98
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) 1998 Robert Roebling
   8 //              (c) 2009 Vadim Zeitlin
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 // ============================================================================
  13 // declarations
  14 // ============================================================================
  15
  16 // ----------------------------------------------------------------------------
  17 // headers
  18 // ----------------------------------------------------------------------------
  19
  20 // For compilers that support precompilation, includes "wx/wx.h".
  21 #include "wx/wxprec.h"
  22
  23 #ifdef __BORLANDC__
  24     #pragma hdrstop
  25 #endif
  26
  27 // for all others, include the necessary headers (this file is usually all you
  28 // need because it includes almost all "standard" wxWidgets headers)
  29 #ifndef WX_PRECOMP
  30     #include "wx/wx.h"
  31 #endif
  32
  33 #include "wx/dcbuffer.h"
  34
  35 // ----------------------------------------------------------------------------
  36 // resources
  37 // ----------------------------------------------------------------------------
  38
  39 // the application icon
  40 #if !defined(__WXMSW__) && !defined(__WXPM__)
  41     #include "../sample.xpm"
  42 #endif
  43
  44 // ----------------------------------------------------------------------------
  45 // private classes
  46 // ----------------------------------------------------------------------------
  47
  48 class MyApp : public wxApp
  49 {
  50 public:
  51     virtual bool OnInit();
  52 };
  53
  54
  55 class MyCanvas : public wxScrolledWindow
  56 {
  57 public:
  58     MyCanvas(wxFrame *parent);
  59
  60     void UseBuffer(bool useBuffer) { m_useBuffer = useBuffer; Refresh(); }
  61     bool UsesBuffer() const { return m_useBuffer; }
  62
  63     void UseBgBitmap(bool useBgBmp)
  64     {
  65         m_useBgBmp = useBgBmp;
  66         SetBackgroundBitmap(m_useBgBmp ? GetBgBitmap() : wxBitmap());
  67
  68         Refresh();
  69     }
  70
  71     void EraseBgInPaint(bool erase) { m_eraseBgInPaint = erase; Refresh(); }
  72
  73 private:
  74     void OnPaint( wxPaintEvent &event );
  75     void OnEraseBackground( wxEraseEvent &event );
  76
  77     void DoPaint(wxDC& dc);
  78
  79     // Create an easily recognizable background bitmap.
  80     static wxBitmap GetBgBitmap()
  81     {
  82         static const int BMP_SIZE = 40;
  83
  84         wxBitmap bmp(BMP_SIZE, BMP_SIZE);
  85         wxMemoryDC dc(bmp);
  86         dc.SetBackground(*wxCYAN);
  87         dc.Clear();
  88
  89         dc.SetPen(*wxBLUE_PEN);
  90         dc.DrawLine(0, BMP_SIZE/2, BMP_SIZE/2, 0);
  91         dc.DrawLine(BMP_SIZE/2, 0, BMP_SIZE, BMP_SIZE/2);
  92         dc.DrawLine(BMP_SIZE, BMP_SIZE/2, BMP_SIZE/2, BMP_SIZE);
  93         dc.DrawLine(BMP_SIZE/2, BMP_SIZE, 0, BMP_SIZE/2);
  94
  95         return bmp;
  96     }
  97
  98     wxBitmap    m_bitmap;
  99
 100     // use wxMemoryDC in OnPaint()?
 101     bool m_useBuffer;
 102
 103     // use background bitmap?
 104     bool m_useBgBmp;
 105
 106     // erase background in OnPaint()?
 107     bool m_eraseBgInPaint;
 108
 109
 110     DECLARE_EVENT_TABLE()
 111 };
 112
 113 class MyFrame : public wxFrame
 114 {
 115 public:
 116     MyFrame();
 117
 118 private:
 119     void OnUseBuffer(wxCommandEvent& event);
 120     void OnUseBgBitmap(wxCommandEvent& event);
 121     void OnEraseBgInPaint(wxCommandEvent& event);
 122     void OnChangeBgStyle(wxCommandEvent& event);
 123     void OnQuit(wxCommandEvent& event);
 124     void OnAbout(wxCommandEvent& event);
 125
 126     // we can only use double-buffering with wxBG_STYLE_PAINT
 127     void OnUpdateUIUseBuffer(wxUpdateUIEvent& event)
 128     {
 129         event.Enable( m_canvas->GetBackgroundStyle() == wxBG_STYLE_PAINT );
 130     }
 131
 132     void OnUpdateUIChangeBgStyle(wxUpdateUIEvent& event)
 133     {
 134         event.Enable( !m_canvas->UsesBuffer() );
 135     }
 136
 137     MyCanvas *m_canvas;
 138
 139     DECLARE_EVENT_TABLE()
 140 };
 141
 142
 143 // ----------------------------------------------------------------------------
 144 // constants
 145 // ----------------------------------------------------------------------------
 146
 147 enum
 148 {
 149     // menu items
 150     Erase_Menu_UseBuffer = 100,
 151     Erase_Menu_UseBgBitmap,
 152     Erase_Menu_EraseBgInPaint,
 153     Erase_Menu_BgStyleErase,
 154     Erase_Menu_BgStyleSystem,
 155     Erase_Menu_BgStylePaint,
 156     Erase_Menu_Exit = wxID_EXIT,
 157     Erase_Menu_About = wxID_ABOUT
 158 };
 159
 160
 161 // ----------------------------------------------------------------------------
 162 // the application class
 163 // ----------------------------------------------------------------------------
 164
 165 IMPLEMENT_APP(MyApp)
 166
 167 bool MyApp::OnInit()
 168 {
 169     if ( !wxApp::OnInit() )
 170         return false;
 171
 172     MyFrame *frame = new MyFrame;
 173
 174     frame->Show(true);
 175
 176     return true;
 177 }
 178
 179 // ----------------------------------------------------------------------------
 180 // main frame
 181 // ----------------------------------------------------------------------------
 182
 183 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 184     EVT_MENU(Erase_Menu_UseBuffer, MyFrame::OnUseBuffer)
 185     EVT_MENU(Erase_Menu_UseBgBitmap, MyFrame::OnUseBgBitmap)
 186     EVT_MENU(Erase_Menu_EraseBgInPaint, MyFrame::OnEraseBgInPaint)
 187     EVT_MENU_RANGE(Erase_Menu_BgStyleErase, Erase_Menu_BgStylePaint,
 188                    MyFrame::OnChangeBgStyle)
 189
 190     EVT_MENU(Erase_Menu_Exit,  MyFrame::OnQuit)
 191     EVT_MENU(Erase_Menu_About, MyFrame::OnAbout)
 192
 193     EVT_UPDATE_UI(Erase_Menu_UseBuffer, MyFrame::OnUpdateUIUseBuffer)
 194     EVT_UPDATE_UI_RANGE(Erase_Menu_BgStyleErase, Erase_Menu_BgStylePaint,
 195                         MyFrame::OnUpdateUIChangeBgStyle)
 196 END_EVENT_TABLE()
 197
 198 // frame constructor
 199 MyFrame::MyFrame()
 200        : wxFrame(NULL, wxID_ANY, "Erase sample",
 201                  wxPoint(50, 50), wxSize(450, 340))
 202 {
 203     SetIcon(wxICON(sample));
 204
 205     wxMenu *menuFile = new wxMenu("", wxMENU_TEAROFF);
 206     menuFile->AppendCheckItem(Erase_Menu_UseBuffer, "&Use memory DC\tCtrl-M");
 207     menuFile->AppendCheckItem(Erase_Menu_UseBgBitmap,
 208                               "Use background &bitmap\tCtrl-B");
 209     menuFile->AppendCheckItem(Erase_Menu_EraseBgInPaint,
 210                               "&Erase background in EVT_PAINT\tCtrl-R");
 211     menuFile->AppendSeparator();
 212     menuFile->AppendRadioItem(Erase_Menu_BgStyleErase,
 213                               "Use wxBG_STYLE_&ERASE\tCtrl-E");
 214     menuFile->AppendRadioItem(Erase_Menu_BgStyleSystem,
 215                               "Use wxBG_STYLE_&SYSTEM\tCtrl-S");
 216     menuFile->AppendRadioItem(Erase_Menu_BgStylePaint,
 217                               "Use wxBG_STYLE_&PAINT\tCtrl-P");
 218     menuFile->AppendSeparator();
 219     menuFile->Append(Erase_Menu_Exit, "E&xit\tAlt-X", "Quit this program");
 220
 221
 222     wxMenu *helpMenu = new wxMenu;
 223     helpMenu->Append(Erase_Menu_About, "&About...\tCtrl-A", "Show about dialog");
 224
 225     wxMenuBar *menuBar = new wxMenuBar();
 226     menuBar->Append(menuFile, "&File");
 227     menuBar->Append(helpMenu, "&Help");
 228
 229     SetMenuBar(menuBar);
 230
 231     m_canvas = new MyCanvas( this );
 232 }
 233
 234
 235 void MyFrame::OnUseBuffer(wxCommandEvent& event)
 236 {
 237     m_canvas->UseBuffer(event.IsChecked());
 238 }
 239
 240 void MyFrame::OnUseBgBitmap(wxCommandEvent& event)
 241 {
 242     m_canvas->UseBgBitmap(event.IsChecked());
 243 }
 244
 245 void MyFrame::OnEraseBgInPaint(wxCommandEvent& event)
 246 {
 247     m_canvas->EraseBgInPaint(event.IsChecked());
 248 }
 249
 250 void MyFrame::OnChangeBgStyle(wxCommandEvent& event)
 251 {
 252     int style = wxBG_STYLE_ERASE + event.GetId() - Erase_Menu_BgStyleErase;
 253     m_canvas->SetBackgroundStyle(static_cast<wxBackgroundStyle>(style));
 254
 255     m_canvas->Refresh();
 256 }
 257
 258 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 259 {
 260     Close(true);
 261 }
 262
 263 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 264 {
 265     wxMessageBox
 266     (
 267         "This sample shows differences between different background styles "
 268         "and how you may draw custom background.\n"
 269         "\n"
 270         "(c) 1998 Robert Roebling\n"
 271         "(c) 2009 Vadim Zeitlin\n",
 272         "About Erase Sample",
 273         wxOK | wxICON_INFORMATION,
 274         this
 275     );
 276 }
 277
 278
 279 BEGIN_EVENT_TABLE(MyCanvas, wxScrolledWindow)
 280     EVT_PAINT(MyCanvas::OnPaint)
 281     EVT_ERASE_BACKGROUND(MyCanvas::OnEraseBackground)
 282 END_EVENT_TABLE()
 283
 284 MyCanvas::MyCanvas(wxFrame *parent)
 285         : wxScrolledWindow(parent, wxID_ANY)
 286 {
 287     m_useBuffer = false;
 288     m_useBgBmp = false;
 289     m_eraseBgInPaint = false;
 290
 291     SetScrollbars( 10, 10, 40, 100, 0, 0 );
 292
 293     m_bitmap = wxBitmap( wxICON(sample) );
 294
 295     new wxStaticBitmap( this, wxID_ANY, m_bitmap, wxPoint(80,20) );
 296
 297     new wxStaticText(this, wxID_ANY,
 298                      "Left bitmap is a wxStaticBitmap,\n"
 299                      "right one drawn directly",
 300                      wxPoint(150, 20));
 301
 302     SetFocusIgnoringChildren();
 303     SetBackgroundColour(*wxCYAN);
 304 }
 305
 306 void MyCanvas::DoPaint(wxDC& dc)
 307 {
 308     if ( m_eraseBgInPaint )
 309     {
 310         dc.SetBackground(*wxLIGHT_GREY);
 311         dc.Clear();
 312
 313         dc.DrawText("Background erased in OnPaint", 65, 110);
 314     }
 315     else if ( GetBackgroundStyle() == wxBG_STYLE_PAINT )
 316     {
 317         dc.SetTextForeground(*wxRED);
 318         dc.DrawText("You must enable erasing background in OnPaint to avoid "
 319                     "display corruption", 65, 110);
 320     }
 321
 322     dc.DrawBitmap( m_bitmap, 20, 20, true );
 323
 324     dc.SetTextForeground(*wxRED);
 325     dc.DrawText("This text is drawn from OnPaint", 65, 65);
 326 }
 327
 328 void MyCanvas::OnPaint( wxPaintEvent &WXUNUSED(event) )
 329 {
 330     if ( m_useBuffer )
 331     {
 332         wxAutoBufferedPaintDC dc(this);
 333         PrepareDC(dc);
 334
 335         DoPaint(dc);
 336     }
 337     else
 338     {
 339         wxPaintDC dc(this);
 340         PrepareDC(dc);
 341
 342         DoPaint(dc);
 343     }
 344 }
 345
 346 void MyCanvas::OnEraseBackground( wxEraseEvent& event )
 347 {
 348     // We must not erase the background ourselves if we asked wxPanel to erase
 349     // it using a background bitmap.
 350     if ( m_useBgBmp )
 351     {
 352         event.Skip();
 353         return;
 354     }
 355
 356     wxASSERT_MSG
 357     (
 358         GetBackgroundStyle() == wxBG_STYLE_ERASE,
 359         "shouldn't be called unless background style is \"erase\""
 360     );
 361
 362     wxDC& dc = *event.GetDC();
 363     dc.SetPen(*wxGREEN_PEN);
 364
 365     PrepareDC( dc );
 366
 367     // clear any junk currently displayed
 368     dc.Clear();
 369
 370     const wxSize size = GetClientSize();
 371     for ( int x = 0; x < size.x; x += 15 )
 372     {
 373         dc.DrawLine(x, 0, x, size.y);
 374     }
 375
 376     for ( int y = 0; y < size.y; y += 15 )
 377     {
 378         dc.DrawLine(0, y, size.x, y);
 379     }
 380
 381     dc.SetTextForeground(*wxRED);
 382     dc.SetBackgroundMode(wxSOLID);
 383     dc.DrawText("This text is drawn from OnEraseBackground", 60, 160);
 384 }
 385