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 OnChar( wxKeyEvent &event );
  76     void OnEraseBackground( wxEraseEvent &event );
  77
  78     void DoPaint(wxDC& dc);
  79
  80     // Create an easily recognizable background bitmap.
  81     static wxBitmap GetBgBitmap()
  82     {
  83         static const int BMP_SIZE = 40;
  84
  85         wxBitmap bmp(BMP_SIZE, BMP_SIZE);
  86         wxMemoryDC dc(bmp);
  87         dc.SetBackground(*wxCYAN);
  88         dc.Clear();
  89
  90         dc.SetPen(*wxBLUE_PEN);
  91         dc.DrawLine(0, BMP_SIZE/2, BMP_SIZE/2, 0);
  92         dc.DrawLine(BMP_SIZE/2, 0, BMP_SIZE, BMP_SIZE/2);
  93         dc.DrawLine(BMP_SIZE, BMP_SIZE/2, BMP_SIZE/2, BMP_SIZE);
  94         dc.DrawLine(BMP_SIZE/2, BMP_SIZE, 0, BMP_SIZE/2);
  95
  96         return bmp;
  97     }
  98
  99     wxBitmap    m_bitmap;
 100     wxString    m_text;
 101
 102     // use wxMemoryDC in OnPaint()?
 103     bool m_useBuffer;
 104
 105     // use background bitmap?
 106     bool m_useBgBmp;
 107
 108     // erase background in OnPaint()?
 109     bool m_eraseBgInPaint;
 110
 111
 112     DECLARE_EVENT_TABLE()
 113 };
 114
 115 class MyFrame : public wxFrame
 116 {
 117 public:
 118     MyFrame();
 119
 120 private:
 121     void OnUseBuffer(wxCommandEvent& event);
 122     void OnUseBgBitmap(wxCommandEvent& event);
 123     void OnEraseBgInPaint(wxCommandEvent& event);
 124     void OnChangeBgStyle(wxCommandEvent& event);
 125     void OnQuit(wxCommandEvent& event);
 126     void OnAbout(wxCommandEvent& event);
 127
 128     // we can only use double-buffering with wxBG_STYLE_PAINT
 129     void OnUpdateUIUseBuffer(wxUpdateUIEvent& event)
 130     {
 131         event.Enable( m_canvas->GetBackgroundStyle() == wxBG_STYLE_PAINT );
 132     }
 133
 134     void OnUpdateUIChangeBgStyle(wxUpdateUIEvent& event)
 135     {
 136         event.Enable( !m_canvas->UsesBuffer() );
 137     }
 138
 139     MyCanvas *m_canvas;
 140
 141     DECLARE_EVENT_TABLE()
 142 };
 143
 144
 145 // ----------------------------------------------------------------------------
 146 // constants
 147 // ----------------------------------------------------------------------------
 148
 149 enum
 150 {
 151     // menu items
 152     Erase_Menu_UseBuffer = 100,
 153     Erase_Menu_UseBgBitmap,
 154     Erase_Menu_EraseBgInPaint,
 155     Erase_Menu_BgStyleErase,
 156     Erase_Menu_BgStyleSystem,
 157     Erase_Menu_BgStylePaint,
 158     Erase_Menu_Exit = wxID_EXIT,
 159     Erase_Menu_About = wxID_ABOUT
 160 };
 161
 162
 163 // ----------------------------------------------------------------------------
 164 // the application class
 165 // ----------------------------------------------------------------------------
 166
 167 IMPLEMENT_APP(MyApp)
 168
 169 bool MyApp::OnInit()
 170 {
 171     if ( !wxApp::OnInit() )
 172         return false;
 173
 174     MyFrame *frame = new MyFrame;
 175
 176     frame->Show(true);
 177
 178     return true;
 179 }
 180
 181 // ----------------------------------------------------------------------------
 182 // main frame
 183 // ----------------------------------------------------------------------------
 184
 185 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 186     EVT_MENU(Erase_Menu_UseBuffer, MyFrame::OnUseBuffer)
 187     EVT_MENU(Erase_Menu_UseBgBitmap, MyFrame::OnUseBgBitmap)
 188     EVT_MENU(Erase_Menu_EraseBgInPaint, MyFrame::OnEraseBgInPaint)
 189     EVT_MENU_RANGE(Erase_Menu_BgStyleErase, Erase_Menu_BgStylePaint,
 190                    MyFrame::OnChangeBgStyle)
 191
 192     EVT_MENU(Erase_Menu_Exit,  MyFrame::OnQuit)
 193     EVT_MENU(Erase_Menu_About, MyFrame::OnAbout)
 194
 195     EVT_UPDATE_UI(Erase_Menu_UseBuffer, MyFrame::OnUpdateUIUseBuffer)
 196     EVT_UPDATE_UI_RANGE(Erase_Menu_BgStyleErase, Erase_Menu_BgStylePaint,
 197                         MyFrame::OnUpdateUIChangeBgStyle)
 198 END_EVENT_TABLE()
 199
 200 // frame constructor
 201 MyFrame::MyFrame()
 202        : wxFrame(NULL, wxID_ANY, "Erase sample",
 203                  wxPoint(50, 50), wxSize(450, 340))
 204 {
 205     SetIcon(wxICON(sample));
 206
 207     wxMenu *menuFile = new wxMenu("", wxMENU_TEAROFF);
 208     menuFile->AppendCheckItem(Erase_Menu_UseBuffer, "&Use memory DC\tCtrl-M");
 209     menuFile->AppendCheckItem(Erase_Menu_UseBgBitmap,
 210                               "Use background &bitmap\tCtrl-B");
 211     menuFile->AppendCheckItem(Erase_Menu_EraseBgInPaint,
 212                               "&Erase background in EVT_PAINT\tCtrl-R");
 213     menuFile->AppendSeparator();
 214     menuFile->AppendRadioItem(Erase_Menu_BgStyleErase,
 215                               "Use wxBG_STYLE_&ERASE\tCtrl-E");
 216     menuFile->AppendRadioItem(Erase_Menu_BgStyleSystem,
 217                               "Use wxBG_STYLE_&SYSTEM\tCtrl-S");
 218     menuFile->AppendRadioItem(Erase_Menu_BgStylePaint,
 219                               "Use wxBG_STYLE_&PAINT\tCtrl-P");
 220     menuFile->AppendSeparator();
 221     menuFile->Append(Erase_Menu_Exit, "E&xit\tAlt-X", "Quit this program");
 222
 223
 224     wxMenu *helpMenu = new wxMenu;
 225     helpMenu->Append(Erase_Menu_About, "&About...\tCtrl-A", "Show about dialog");
 226
 227     wxMenuBar *menuBar = new wxMenuBar();
 228     menuBar->Append(menuFile, "&File");
 229     menuBar->Append(helpMenu, "&Help");
 230
 231     SetMenuBar(menuBar);
 232
 233     m_canvas = new MyCanvas( this );
 234 }
 235
 236
 237 void MyFrame::OnUseBuffer(wxCommandEvent& event)
 238 {
 239     m_canvas->UseBuffer(event.IsChecked());
 240 }
 241
 242 void MyFrame::OnUseBgBitmap(wxCommandEvent& event)
 243 {
 244     m_canvas->UseBgBitmap(event.IsChecked());
 245 }
 246
 247 void MyFrame::OnEraseBgInPaint(wxCommandEvent& event)
 248 {
 249     m_canvas->EraseBgInPaint(event.IsChecked());
 250 }
 251
 252 void MyFrame::OnChangeBgStyle(wxCommandEvent& event)
 253 {
 254     int style = wxBG_STYLE_ERASE + event.GetId() - Erase_Menu_BgStyleErase;
 255     m_canvas->SetBackgroundStyle(static_cast<wxBackgroundStyle>(style));
 256
 257     m_canvas->Refresh();
 258 }
 259
 260 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 261 {
 262     Close(true);
 263 }
 264
 265 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 266 {
 267     wxMessageBox
 268     (
 269         "This sample shows differences between different background styles "
 270         "and how you may draw custom background.\n"
 271         "\n"
 272         "(c) 1998 Robert Roebling\n"
 273         "(c) 2009 Vadim Zeitlin\n",
 274         "About Erase Sample",
 275         wxOK | wxICON_INFORMATION,
 276         this
 277     );
 278 }
 279
 280
 281 BEGIN_EVENT_TABLE(MyCanvas, wxScrolledWindow)
 282     EVT_PAINT(MyCanvas::OnPaint)
 283     EVT_CHAR(MyCanvas::OnChar)
 284     EVT_ERASE_BACKGROUND(MyCanvas::OnEraseBackground)
 285 END_EVENT_TABLE()
 286
 287 MyCanvas::MyCanvas(wxFrame *parent)
 288         : wxScrolledWindow(parent, wxID_ANY)
 289 {
 290     m_useBuffer = false;
 291     m_useBgBmp = false;
 292     m_eraseBgInPaint = false;
 293
 294     SetScrollbars( 10, 10, 40, 100, 0, 0 );
 295
 296     m_bitmap = wxBitmap( wxICON(sample) );
 297
 298     new wxStaticBitmap( this, wxID_ANY, m_bitmap, wxPoint(80,20) );
 299
 300     new wxStaticText(this, wxID_ANY,
 301                      "Left bitmap is a wxStaticBitmap,\n"
 302                      "right one drawn directly",
 303                      wxPoint(150, 20));
 304
 305     SetFocusIgnoringChildren();
 306     SetBackgroundColour(*wxCYAN);
 307 }
 308
 309 void MyCanvas::OnChar( wxKeyEvent &event )
 310 {
 311 #if wxUSE_UNICODE
 312     if (event.m_uniChar)
 313     {
 314         m_text += event.m_uniChar;
 315         Refresh();
 316         return;
 317     }
 318 #endif
 319
 320     // some test cases
 321     switch (event.m_keyCode)
 322     {
 323         case WXK_UP: m_text += wxT( "<UP>" ); break;
 324         case WXK_LEFT: m_text += wxT( "<LEFT>" ); break;
 325         case WXK_RIGHT: m_text += wxT( "<RIGHT>" ); break;
 326         case WXK_DOWN: m_text += wxT( "<DOWN>" ); break;
 327         case WXK_RETURN: m_text += wxT( "<ENTER>" ); break;
 328         default: m_text += (wxChar)event.m_keyCode; break;
 329     }
 330 }
 331
 332 void MyCanvas::DoPaint(wxDC& dc)
 333 {
 334     if ( m_eraseBgInPaint )
 335     {
 336         dc.SetBackground(*wxLIGHT_GREY);
 337         dc.Clear();
 338
 339         dc.DrawText("Background erased in OnPaint", 65, 110);
 340     }
 341     else if ( GetBackgroundStyle() == wxBG_STYLE_PAINT )
 342     {
 343         dc.SetTextForeground(*wxRED);
 344         dc.DrawText("You must enable erasing background in OnPaint to avoid "
 345                     "display corruption", 65, 110);
 346     }
 347
 348     dc.SetBrush( *wxBLACK_BRUSH );
 349     dc.DrawRectangle( 10,10,60,50 );
 350
 351     dc.DrawBitmap( m_bitmap, 20, 20, true );
 352
 353     dc.SetTextForeground(*wxRED);
 354     dc.DrawText("This text is drawn from OnPaint", 65, 65);
 355
 356     wxString tmp;
 357     tmp.Printf("Hit any key to display more text: %s", m_text);
 358
 359     int w,h;
 360     dc.GetTextExtent( tmp, &w, &h );
 361     dc.DrawRectangle( 65, 85, w, h );
 362     dc.DrawText( tmp, 65, 85 );
 363 }
 364
 365 void MyCanvas::OnPaint( wxPaintEvent &WXUNUSED(event) )
 366 {
 367     if ( m_useBuffer )
 368     {
 369         wxAutoBufferedPaintDC dc(this);
 370         PrepareDC(dc);
 371
 372         DoPaint(dc);
 373     }
 374     else
 375     {
 376         wxPaintDC dc(this);
 377         PrepareDC(dc);
 378
 379         DoPaint(dc);
 380     }
 381 }
 382
 383 void MyCanvas::OnEraseBackground( wxEraseEvent& event )
 384 {
 385     // We must not erase the background ourselves if we asked wxPanel to erase
 386     // it using a background bitmap.
 387     if ( m_useBgBmp )
 388     {
 389         event.Skip();
 390         return;
 391     }
 392
 393     wxASSERT_MSG
 394     (
 395         GetBackgroundStyle() == wxBG_STYLE_ERASE,
 396         "shouldn't be called unless background style is \"erase\""
 397     );
 398
 399     wxDC& dc = *event.GetDC();
 400     dc.SetPen(*wxGREEN_PEN);
 401
 402     PrepareDC( dc );
 403
 404     // clear any junk currently displayed
 405     dc.Clear();
 406
 407     const wxSize size = GetClientSize();
 408     for ( int x = 0; x < size.x; x += 15 )
 409     {
 410         dc.DrawLine(x, 0, x, size.y);
 411     }
 412
 413     for ( int y = 0; y < size.y; y += 15 )
 414     {
 415         dc.DrawLine(0, y, size.x, y);
 416     }
 417
 418     dc.SetTextForeground(*wxRED);
 419     dc.SetBackgroundMode(wxSOLID);
 420     dc.DrawText("This text is drawn from OnEraseBackground", 60, 160);
 421 }
 422