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 EraseBgInPaint(bool erase) { m_eraseBgInPaint = erase; Refresh(); }
  64
  65 private:
  66     void OnPaint( wxPaintEvent &event );
  67     void OnChar( wxKeyEvent &event );
  68     void OnEraseBackground( wxEraseEvent &event );
  69
  70     void DoPaint(wxDC& dc);
  71
  72
  73     wxBitmap    m_bitmap;
  74     wxString    m_text;
  75
  76     // use wxMemoryDC in OnPaint()?
  77     bool m_useBuffer;
  78
  79     // erase background in OnPaint()?
  80     bool m_eraseBgInPaint;
  81
  82
  83     DECLARE_EVENT_TABLE()
  84 };
  85
  86 class MyFrame : public wxFrame
  87 {
  88 public:
  89     MyFrame();
  90
  91 private:
  92     void OnUseBuffer(wxCommandEvent& event);
  93     void OnEraseBgInPaint(wxCommandEvent& event);
  94     void OnChangeBgStyle(wxCommandEvent& event);
  95     void OnQuit(wxCommandEvent& event);
  96     void OnAbout(wxCommandEvent& event);
  97
  98     // we can only use double-buffering with wxBG_STYLE_PAINT
  99     void OnUpdateUIUseBuffer(wxUpdateUIEvent& event)
 100     {
 101         event.Enable( m_canvas->GetBackgroundStyle() == wxBG_STYLE_PAINT );
 102     }
 103
 104     void OnUpdateUIChangeBgStyle(wxUpdateUIEvent& event)
 105     {
 106         event.Enable( !m_canvas->UsesBuffer() );
 107     }
 108
 109     MyCanvas *m_canvas;
 110
 111     DECLARE_EVENT_TABLE()
 112 };
 113
 114
 115 // ----------------------------------------------------------------------------
 116 // constants
 117 // ----------------------------------------------------------------------------
 118
 119 enum
 120 {
 121     // menu items
 122     Erase_Menu_UseBuffer = 100,
 123     Erase_Menu_EraseBgInPaint,
 124     Erase_Menu_BgStyleErase,
 125     Erase_Menu_BgStyleSystem,
 126     Erase_Menu_BgStylePaint,
 127     Erase_Menu_Exit = wxID_EXIT,
 128     Erase_Menu_About = wxID_ABOUT
 129 };
 130
 131
 132 // ----------------------------------------------------------------------------
 133 // the application class
 134 // ----------------------------------------------------------------------------
 135
 136 IMPLEMENT_APP(MyApp)
 137
 138 bool MyApp::OnInit()
 139 {
 140     if ( !wxApp::OnInit() )
 141         return false;
 142
 143     MyFrame *frame = new MyFrame;
 144
 145     frame->Show(true);
 146
 147     return true;
 148 }
 149
 150 // ----------------------------------------------------------------------------
 151 // main frame
 152 // ----------------------------------------------------------------------------
 153
 154 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 155     EVT_MENU(Erase_Menu_UseBuffer, MyFrame::OnUseBuffer)
 156     EVT_MENU(Erase_Menu_EraseBgInPaint, MyFrame::OnEraseBgInPaint)
 157     EVT_MENU_RANGE(Erase_Menu_BgStyleErase, Erase_Menu_BgStylePaint,
 158                    MyFrame::OnChangeBgStyle)
 159
 160     EVT_MENU(Erase_Menu_Exit,  MyFrame::OnQuit)
 161     EVT_MENU(Erase_Menu_About, MyFrame::OnAbout)
 162
 163     EVT_UPDATE_UI(Erase_Menu_UseBuffer, MyFrame::OnUpdateUIUseBuffer)
 164     EVT_UPDATE_UI_RANGE(Erase_Menu_BgStyleErase, Erase_Menu_BgStylePaint,
 165                         MyFrame::OnUpdateUIChangeBgStyle)
 166 END_EVENT_TABLE()
 167
 168 // frame constructor
 169 MyFrame::MyFrame()
 170        : wxFrame(NULL, wxID_ANY, "Erase sample",
 171                  wxPoint(50, 50), wxSize(450, 340))
 172 {
 173     SetIcon(wxICON(sample));
 174
 175     wxMenu *menuFile = new wxMenu("", wxMENU_TEAROFF);
 176     menuFile->AppendCheckItem(Erase_Menu_UseBuffer, "&Use memory DC\tCtrl-M");
 177     menuFile->AppendCheckItem(Erase_Menu_EraseBgInPaint,
 178                               "&Erase background in EVT_PAINT\tCtrl-R");
 179     menuFile->AppendSeparator();
 180     menuFile->AppendRadioItem(Erase_Menu_BgStyleErase,
 181                               "Use wxBG_STYLE_&ERASE\tCtrl-E");
 182     menuFile->AppendRadioItem(Erase_Menu_BgStyleSystem,
 183                               "Use wxBG_STYLE_&SYSTEM\tCtrl-S");
 184     menuFile->AppendRadioItem(Erase_Menu_BgStylePaint,
 185                               "Use wxBG_STYLE_&PAINT\tCtrl-P");
 186     menuFile->AppendSeparator();
 187     menuFile->Append(Erase_Menu_Exit, "E&xit\tAlt-X", "Quit this program");
 188
 189
 190     wxMenu *helpMenu = new wxMenu;
 191     helpMenu->Append(Erase_Menu_About, "&About...\tCtrl-A", "Show about dialog");
 192
 193     wxMenuBar *menuBar = new wxMenuBar();
 194     menuBar->Append(menuFile, "&File");
 195     menuBar->Append(helpMenu, "&Help");
 196
 197     SetMenuBar(menuBar);
 198
 199     m_canvas = new MyCanvas( this );
 200 }
 201
 202
 203 void MyFrame::OnUseBuffer(wxCommandEvent& event)
 204 {
 205     m_canvas->UseBuffer(event.IsChecked());
 206 }
 207
 208 void MyFrame::OnEraseBgInPaint(wxCommandEvent& event)
 209 {
 210     m_canvas->EraseBgInPaint(event.IsChecked());
 211 }
 212
 213 void MyFrame::OnChangeBgStyle(wxCommandEvent& event)
 214 {
 215     int style = wxBG_STYLE_ERASE + event.GetId() - Erase_Menu_BgStyleErase;
 216     m_canvas->SetBackgroundStyle(static_cast<wxBackgroundStyle>(style));
 217
 218     m_canvas->Refresh();
 219 }
 220
 221 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 222 {
 223     Close(true);
 224 }
 225
 226 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 227 {
 228     wxMessageBox
 229     (
 230         "This sample shows differences between different background styles "
 231         "and how you may draw custom background.\n"
 232         "\n"
 233         "(c) 1998 Robert Roebling\n"
 234         "(c) 2009 Vadim Zeitlin\n",
 235         "About Erase Sample",
 236         wxOK | wxICON_INFORMATION,
 237         this
 238     );
 239 }
 240
 241
 242 BEGIN_EVENT_TABLE(MyCanvas, wxScrolledWindow)
 243     EVT_PAINT(MyCanvas::OnPaint)
 244     EVT_CHAR(MyCanvas::OnChar)
 245     EVT_ERASE_BACKGROUND(MyCanvas::OnEraseBackground)
 246 END_EVENT_TABLE()
 247
 248 MyCanvas::MyCanvas(wxFrame *parent)
 249         : wxScrolledWindow(parent, wxID_ANY)
 250 {
 251     m_useBuffer = false;
 252     m_eraseBgInPaint = false;
 253
 254     SetScrollbars( 10, 10, 40, 100, 0, 0 );
 255
 256     m_bitmap = wxBitmap( wxICON(sample) );
 257
 258     new wxStaticBitmap( this, wxID_ANY, m_bitmap, wxPoint(80,20) );
 259
 260     SetFocusIgnoringChildren();
 261     SetBackgroundColour(*wxBLUE);
 262 }
 263
 264 void MyCanvas::OnChar( wxKeyEvent &event )
 265 {
 266 #if wxUSE_UNICODE
 267     if (event.m_uniChar)
 268     {
 269         m_text += event.m_uniChar;
 270         Refresh();
 271         return;
 272     }
 273 #endif
 274
 275     // some test cases
 276     switch (event.m_keyCode)
 277     {
 278         case WXK_UP: m_text += wxT( "<UP>" ); break;
 279         case WXK_LEFT: m_text += wxT( "<LEFT>" ); break;
 280         case WXK_RIGHT: m_text += wxT( "<RIGHT>" ); break;
 281         case WXK_DOWN: m_text += wxT( "<DOWN>" ); break;
 282         case WXK_RETURN: m_text += wxT( "<ENTER>" ); break;
 283         default: m_text += (wxChar)event.m_keyCode; break;
 284     }
 285 }
 286
 287 void MyCanvas::DoPaint(wxDC& dc)
 288 {
 289     if ( m_eraseBgInPaint )
 290     {
 291         dc.SetBackground(*wxLIGHT_GREY);
 292         dc.Clear();
 293
 294         dc.DrawText("Background erased in OnPaint", 65, 110);
 295     }
 296     else if ( GetBackgroundStyle() == wxBG_STYLE_PAINT )
 297     {
 298         dc.SetTextForeground(*wxRED);
 299         dc.DrawText("You must enable erasing background in OnPaint to avoid "
 300                     "display corruption", 65, 110);
 301     }
 302
 303     dc.SetBrush( *wxBLACK_BRUSH );
 304     dc.DrawRectangle( 10,10,60,50 );
 305
 306     dc.DrawBitmap( m_bitmap, 20, 20, true );
 307
 308     dc.SetTextForeground(*wxWHITE);
 309     dc.DrawText("This text is drawn from OnPaint", 65, 65);
 310
 311     wxString tmp;
 312     tmp.Printf("Hit any key to display more text: %s", m_text);
 313
 314     int w,h;
 315     dc.GetTextExtent( tmp, &w, &h );
 316     dc.DrawRectangle( 65, 85, w, h );
 317     dc.DrawText( tmp, 65, 85 );
 318 }
 319
 320 void MyCanvas::OnPaint( wxPaintEvent &WXUNUSED(event) )
 321 {
 322     if ( m_useBuffer )
 323     {
 324         wxAutoBufferedPaintDC dc(this);
 325         PrepareDC(dc);
 326
 327         DoPaint(dc);
 328     }
 329     else
 330     {
 331         wxPaintDC dc(this);
 332         PrepareDC(dc);
 333
 334         DoPaint(dc);
 335     }
 336 }
 337
 338 void MyCanvas::OnEraseBackground( wxEraseEvent& event )
 339 {
 340     wxASSERT_MSG
 341     (
 342         GetBackgroundStyle() == wxBG_STYLE_ERASE,
 343         "shouldn't be called unless background style is \"erase\""
 344     );
 345
 346     wxDC& dc = *event.GetDC();
 347     dc.SetPen(*wxGREEN_PEN);
 348
 349     PrepareDC( dc );
 350
 351     // clear any junk currently displayed
 352     dc.Clear();
 353
 354     const wxSize size = GetClientSize();
 355     for ( int x = 0; x < size.x; x += 15 )
 356     {
 357         dc.DrawLine(x, 0, x, size.y);
 358     }
 359
 360     for ( int y = 0; y < size.y; y += 15 )
 361     {
 362         dc.DrawLine(0, y, size.x, y);
 363     }
 364
 365     dc.SetTextForeground(*wxRED);
 366     dc.SetBackgroundMode(wxSOLID);
 367     dc.DrawText("This text is drawn from OnEraseBackground", 60, 160);
 368 }
 369