src/generic/vscroll.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/generic/vscroll.cpp
   3 // Purpose:     wxVScrolledWindow implementation
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:     30.05.03
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 2003 Vadim Zeitlin <vadim@wxwindows.org>
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 // ============================================================================
  13 // declarations
  14 // ============================================================================
  15
  16 // ----------------------------------------------------------------------------
  17 // headers
  18 // ----------------------------------------------------------------------------
  19
  20 // For compilers that support precompilation, includes "wx.h".
  21 #include "wx/wxprec.h"
  22
  23 #ifdef __BORLANDC__
  24 #pragma hdrstop
  25 #endif
  26
  27 #include "wx/vscroll.h"
  28
  29 // ----------------------------------------------------------------------------
  30 // event tables
  31 // ----------------------------------------------------------------------------
  32
  33 BEGIN_EVENT_TABLE(wxVScrolledWindow, wxPanel)
  34     EVT_SIZE(wxVScrolledWindow::OnSize)
  35     EVT_SCROLLWIN(wxVScrolledWindow::OnScroll)
  36 #if wxUSE_MOUSEWHEEL
  37     EVT_MOUSEWHEEL(wxVScrolledWindow::OnMouseWheel)
  38 #endif
  39 END_EVENT_TABLE()
  40
  41
  42 // ============================================================================
  43 // implementation
  44 // ============================================================================
  45
  46 IMPLEMENT_ABSTRACT_CLASS(wxVScrolledWindow, wxPanel)
  47
  48 // ----------------------------------------------------------------------------
  49 // initialization
  50 // ----------------------------------------------------------------------------
  51
  52 void wxVScrolledWindow::Init()
  53 {
  54     // we're initially empty
  55     m_lineMax =
  56     m_lineFirst = 0;
  57
  58     // this one should always be strictly positive
  59     m_nVisible = 1;
  60
  61     m_heightTotal = 0;
  62
  63 #if wxUSE_MOUSEWHEEL
  64     m_sumWheelRotation = 0;
  65 #endif
  66 }
  67
  68 // ----------------------------------------------------------------------------
  69 // various helpers
  70 // ----------------------------------------------------------------------------
  71
  72 wxCoord wxVScrolledWindow::EstimateTotalHeight() const
  73 {
  74     // estimate the total height: it is impossible to call
  75     // OnGetLineHeight() for every line because there may be too many of
  76     // them, so we just make a guess using some lines in the beginning,
  77     // some in the end and some in the middle
  78     static const size_t NUM_LINES_TO_SAMPLE = 10;
  79
  80     wxCoord heightTotal;
  81     if ( m_lineMax < 3*NUM_LINES_TO_SAMPLE )
  82     {
  83         // in this case calculating exactly is faster and more correct than
  84         // guessing
  85         heightTotal = GetLinesHeight(0, m_lineMax);
  86     }
  87     else // too many lines to calculate exactly
  88     {
  89         // look at some lines in the beginning/middle/end
  90         heightTotal =
  91             GetLinesHeight(0, NUM_LINES_TO_SAMPLE) +
  92                 GetLinesHeight(m_lineMax - NUM_LINES_TO_SAMPLE, m_lineMax) +
  93                     GetLinesHeight(m_lineMax/2 - NUM_LINES_TO_SAMPLE/2,
  94                                    m_lineMax/2 + NUM_LINES_TO_SAMPLE/2);
  95
  96         // use the height of the lines we looked as the average
  97         heightTotal = (wxCoord)
  98                 (((float)heightTotal / (3*NUM_LINES_TO_SAMPLE)) * m_lineMax);
  99     }
 100
 101     return heightTotal;
 102 }
 103
 104 wxCoord wxVScrolledWindow::GetLinesHeight(size_t lineMin, size_t lineMax) const
 105 {
 106     if ( lineMin == lineMax )
 107         return 0;
 108     else if ( lineMin > lineMax )
 109         return -GetLinesHeight(lineMax, lineMin);
 110     //else: lineMin < lineMax
 111
 112     // let the user code know that we're going to need all these lines
 113     OnGetLinesHint(lineMin, lineMax);
 114
 115     // do sum up their heights
 116     wxCoord height = 0;
 117     for ( size_t line = lineMin; line < lineMax; line++ )
 118     {
 119         height += OnGetLineHeight(line);
 120     }
 121
 122     return height;
 123 }
 124
 125 size_t wxVScrolledWindow::FindFirstFromBottom(size_t lineLast, bool full)
 126 {
 127     const wxCoord hWindow = GetClientSize().y;
 128
 129     // go upwards until we arrive at a line such that lineLast is not visible
 130     // any more when it is shown
 131     size_t lineFirst = lineLast;
 132     wxCoord h = 0;
 133     for ( ;; )
 134     {
 135         h += OnGetLineHeight(lineFirst);
 136
 137         if ( h > hWindow )
 138         {
 139             // for this line to be fully visible we need to go one line
 140             // down, but if it is enough for it to be only partly visible then
 141             // this line will do as well
 142             if ( full )
 143             {
 144                 lineFirst++;
 145             }
 146
 147             break;
 148         }
 149
 150         if ( !lineFirst )
 151             break;
 152
 153         lineFirst--;
 154     }
 155
 156     return lineFirst;
 157 }
 158
 159 void wxVScrolledWindow::UpdateScrollbar()
 160 {
 161     // see how many lines can we fit on screen
 162     const wxCoord hWindow = GetClientSize().y;
 163
 164     wxCoord h = 0;
 165     size_t line;
 166     for ( line = m_lineFirst; line < m_lineMax; line++ )
 167     {
 168         if ( h > hWindow )
 169             break;
 170
 171         h += OnGetLineHeight(line);
 172     }
 173
 174     m_nVisible = line - m_lineFirst;
 175
 176     int pageSize = m_nVisible;
 177     if ( h > hWindow )
 178     {
 179         // last line is only partially visible, we still need the scrollbar and
 180         // so we have to "fix" pageSize because if it is equal to m_lineMax the
 181         // scrollbar is not shown at all under MSW
 182         pageSize--;
 183     }
 184
 185     // set the scrollbar parameters to reflect this
 186     SetScrollbar(wxVERTICAL, m_lineFirst, pageSize, m_lineMax);
 187 }
 188
 189 // ----------------------------------------------------------------------------
 190 // operations
 191 // ----------------------------------------------------------------------------
 192
 193 void wxVScrolledWindow::SetLineCount(size_t count)
 194 {
 195     // save the number of lines
 196     m_lineMax = count;
 197
 198     // and our estimate for their total height
 199     m_heightTotal = EstimateTotalHeight();
 200
 201     // recalculate the scrollbars parameters
 202     m_lineFirst = 1;    // make sure it is != 0
 203     ScrollToLine(0);
 204 }
 205
 206 void wxVScrolledWindow::RefreshLine(size_t line)
 207 {
 208     // is this line visible?
 209     if ( !IsVisible(line) )
 210     {
 211         // no, it is useless to do anything
 212         return;
 213     }
 214
 215     // calculate the rect occupied by this line on screen
 216     wxRect rect;
 217     rect.width = GetClientSize().x;
 218     rect.height = OnGetLineHeight(line);
 219     for ( size_t n = GetVisibleBegin(); n < line; n++ )
 220     {
 221         rect.y += OnGetLineHeight(n);
 222     }
 223
 224     // do refresh it
 225     RefreshRect(rect);
 226 }
 227
 228 void wxVScrolledWindow::RefreshLines(size_t from, size_t to)
 229 {
 230     wxASSERT_MSG( from <= to, _T("RefreshLines(): empty range") );
 231
 232     // clump the range to just the visible lines -- it is useless to refresh
 233     // the other ones
 234     if ( from < GetVisibleBegin() )
 235         from = GetVisibleBegin();
 236
 237     if ( to >= GetVisibleEnd() )
 238         to = GetVisibleEnd();
 239     else
 240         to++;
 241
 242     // calculate the rect occupied by these lines on screen
 243     wxRect rect;
 244     rect.width = GetClientSize().x;
 245     for ( size_t nBefore = GetVisibleBegin(); nBefore < from; nBefore++ )
 246     {
 247         rect.y += OnGetLineHeight(nBefore);
 248     }
 249
 250     for ( size_t nBetween = from; nBetween < to; nBetween++ )
 251     {
 252         rect.height += OnGetLineHeight(nBetween);
 253     }
 254
 255     // do refresh it
 256     RefreshRect(rect);
 257 }
 258
 259 void wxVScrolledWindow::RefreshAll()
 260 {
 261     UpdateScrollbar();
 262
 263     Refresh();
 264 }
 265
 266 int wxVScrolledWindow::HitTest(wxCoord WXUNUSED(x), wxCoord y) const
 267 {
 268     const size_t lineMax = GetVisibleEnd();
 269     for ( size_t line = GetVisibleBegin(); line < lineMax; line++ )
 270     {
 271         y -= OnGetLineHeight(line);
 272         if ( y < 0 )
 273             return line;
 274     }
 275
 276     return wxNOT_FOUND;
 277 }
 278
 279 // ----------------------------------------------------------------------------
 280 // scrolling
 281 // ----------------------------------------------------------------------------
 282
 283 bool wxVScrolledWindow::ScrollToLine(size_t line)
 284 {
 285     if ( !m_lineMax )
 286     {
 287         // we're empty, code below doesn't make sense in this case
 288         return false;
 289     }
 290
 291     // determine the real first line to scroll to: we shouldn't scroll beyond
 292     // the end
 293     size_t lineFirstLast = FindFirstFromBottom(m_lineMax - 1, true);
 294     if ( line > lineFirstLast )
 295         line = lineFirstLast;
 296
 297     // anything to do?
 298     if ( line == m_lineFirst )
 299     {
 300         // no
 301         return false;
 302     }
 303
 304
 305     // remember the currently shown lines for the refresh code below
 306     size_t lineFirstOld = GetVisibleBegin(),
 307            lineLastOld = GetVisibleEnd();
 308
 309     m_lineFirst = line;
 310
 311
 312     // the size of scrollbar thumb could have changed
 313     UpdateScrollbar();
 314
 315
 316     // finally refresh the display -- but only redraw as few lines as possible
 317     // to avoid flicker
 318     if ( GetVisibleBegin() >= lineLastOld ||
 319             GetVisibleEnd() <= lineFirstOld )
 320     {
 321         // the simplest case: we don't have any old lines left, just redraw
 322         // everything
 323         Refresh();
 324     }
 325     else // overlap between the lines we showed before and should show now
 326     {
 327         ScrollWindow(0, GetLinesHeight(GetVisibleBegin(), lineFirstOld));
 328     }
 329
 330     return true;
 331 }
 332
 333 bool wxVScrolledWindow::ScrollLines(int lines)
 334 {
 335     lines += m_lineFirst;
 336     if ( lines < 0 )
 337         lines = 0;
 338
 339     return ScrollToLine(lines);
 340 }
 341
 342 bool wxVScrolledWindow::ScrollPages(int pages)
 343 {
 344     bool didSomething = false;
 345
 346     while ( pages )
 347     {
 348         int line;
 349         if ( pages > 0 )
 350         {
 351             line = GetVisibleEnd();
 352             if ( line )
 353                 line--;
 354             pages--;
 355         }
 356         else // pages < 0
 357         {
 358             line = FindFirstFromBottom(GetVisibleBegin());
 359             pages++;
 360         }
 361
 362         didSomething = ScrollToLine(line);
 363     }
 364
 365     return didSomething;
 366 }
 367
 368 // ----------------------------------------------------------------------------
 369 // event handling
 370 // ----------------------------------------------------------------------------
 371
 372 void wxVScrolledWindow::OnSize(wxSizeEvent& event)
 373 {
 374     UpdateScrollbar();
 375
 376     event.Skip();
 377 }
 378
 379 void wxVScrolledWindow::OnScroll(wxScrollWinEvent& event)
 380 {
 381     size_t lineFirstNew;
 382
 383     const wxEventType evtType = event.GetEventType();
 384
 385     if ( evtType == wxEVT_SCROLLWIN_TOP )
 386     {
 387         lineFirstNew = 0;
 388     }
 389     else if ( evtType == wxEVT_SCROLLWIN_BOTTOM )
 390     {
 391         lineFirstNew = m_lineMax;
 392     }
 393     else if ( evtType == wxEVT_SCROLLWIN_LINEUP )
 394     {
 395         lineFirstNew = m_lineFirst ? m_lineFirst - 1 : 0;
 396     }
 397     else if ( evtType == wxEVT_SCROLLWIN_LINEDOWN )
 398     {
 399         lineFirstNew = m_lineFirst + 1;
 400     }
 401     else if ( evtType == wxEVT_SCROLLWIN_PAGEUP )
 402     {
 403         lineFirstNew = FindFirstFromBottom(m_lineFirst);
 404     }
 405     else if ( evtType == wxEVT_SCROLLWIN_PAGEDOWN )
 406     {
 407         lineFirstNew = GetVisibleEnd();
 408         if ( lineFirstNew )
 409             lineFirstNew--;
 410     }
 411     else if ( evtType == wxEVT_SCROLLWIN_THUMBRELEASE )
 412     {
 413         lineFirstNew = event.GetPosition();
 414     }
 415     else if ( evtType == wxEVT_SCROLLWIN_THUMBTRACK )
 416     {
 417         lineFirstNew = event.GetPosition();
 418     }
 419
 420     else // unknown scroll event?
 421     {
 422         wxFAIL_MSG( _T("unknown scroll event type?") );
 423         return;
 424     }
 425
 426     ScrollToLine(lineFirstNew);
 427
 428 #ifdef __WXMAC__
 429     Update();
 430 #endif // __WXMAC__
 431 }
 432
 433 #if wxUSE_MOUSEWHEEL
 434
 435 void wxVScrolledWindow::OnMouseWheel(wxMouseEvent& event)
 436 {
 437     m_sumWheelRotation += event.GetWheelRotation();
 438     int delta = event.GetWheelDelta();
 439
 440     // how much to scroll this time
 441     int units_to_scroll = -(m_sumWheelRotation/delta);
 442     if ( !units_to_scroll )
 443         return;
 444
 445     m_sumWheelRotation += units_to_scroll*delta;
 446
 447     if ( !event.IsPageScroll() )
 448         ScrollLines( units_to_scroll*event.GetLinesPerAction() );
 449     else
 450         // scroll pages instead of lines
 451         ScrollPages( units_to_scroll );
 452 }
 453
 454 #endif