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 #if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
  21 #pragma implementation "vscroll.h"
  22 #endif
  23
  24 // For compilers that support precompilation, includes "wx.h".
  25 #include "wx/wxprec.h"
  26
  27 #ifdef __BORLANDC__
  28 #pragma hdrstop
  29 #endif
  30
  31 #include "wx/vscroll.h"
  32
  33 // ----------------------------------------------------------------------------
  34 // event tables
  35 // ----------------------------------------------------------------------------
  36
  37 BEGIN_EVENT_TABLE(wxVScrolledWindow, wxPanel)
  38     EVT_SIZE(wxVScrolledWindow::OnSize)
  39     EVT_SCROLLWIN(wxVScrolledWindow::OnScroll)
  40 #if wxUSE_MOUSEWHEEL
  41     EVT_MOUSEWHEEL(wxVScrolledWindow::OnMouseWheel)
  42 #endif
  43 END_EVENT_TABLE()
  44
  45
  46 // ============================================================================
  47 // implementation
  48 // ============================================================================
  49
  50 IMPLEMENT_ABSTRACT_CLASS(wxVScrolledWindow, wxPanel)
  51
  52 // ----------------------------------------------------------------------------
  53 // initialization
  54 // ----------------------------------------------------------------------------
  55
  56 void wxVScrolledWindow::Init()
  57 {
  58     // we're initially empty
  59     m_lineMax =
  60     m_lineFirst = 0;
  61
  62     // this one should always be strictly positive
  63     m_nVisible = 1;
  64
  65     m_heightTotal = 0;
  66
  67 #if wxUSE_MOUSEWHEEL
  68     m_sumWheelRotation = 0;
  69 #endif
  70 }
  71
  72 // ----------------------------------------------------------------------------
  73 // various helpers
  74 // ----------------------------------------------------------------------------
  75
  76 wxCoord wxVScrolledWindow::EstimateTotalHeight() const
  77 {
  78     // estimate the total height: it is impossible to call
  79     // OnGetLineHeight() for every line because there may be too many of
  80     // them, so we just make a guess using some lines in the beginning,
  81     // some in the end and some in the middle
  82     static const size_t NUM_LINES_TO_SAMPLE = 10;
  83
  84     wxCoord heightTotal;
  85     if ( m_lineMax < 3*NUM_LINES_TO_SAMPLE )
  86     {
  87         // in this case calculating exactly is faster and more correct than
  88         // guessing
  89         heightTotal = GetLinesHeight(0, m_lineMax);
  90     }
  91     else // too many lines to calculate exactly
  92     {
  93         // look at some lines in the beginning/middle/end
  94         heightTotal =
  95             GetLinesHeight(0, NUM_LINES_TO_SAMPLE) +
  96                 GetLinesHeight(m_lineMax - NUM_LINES_TO_SAMPLE, m_lineMax) +
  97                     GetLinesHeight(m_lineMax/2 - NUM_LINES_TO_SAMPLE/2,
  98                                    m_lineMax/2 + NUM_LINES_TO_SAMPLE/2);
  99
 100         // use the height of the lines we looked as the average
 101         heightTotal = (wxCoord)
 102                 (((float)heightTotal / (3*NUM_LINES_TO_SAMPLE)) * m_lineMax);
 103     }
 104
 105     return heightTotal;
 106 }
 107
 108 wxCoord wxVScrolledWindow::GetLinesHeight(size_t lineMin, size_t lineMax) const
 109 {
 110     if ( lineMin == lineMax )
 111         return 0;
 112     else if ( lineMin > lineMax )
 113         return -GetLinesHeight(lineMax, lineMin);
 114     //else: lineMin < lineMax
 115
 116     // let the user code know that we're going to need all these lines
 117     OnGetLinesHint(lineMin, lineMax);
 118
 119     // do sum up their heights
 120     wxCoord height = 0;
 121     for ( size_t line = lineMin; line < lineMax; line++ )
 122     {
 123         height += OnGetLineHeight(line);
 124     }
 125
 126     return height;
 127 }
 128
 129 size_t wxVScrolledWindow::FindFirstFromBottom(size_t lineLast, bool full)
 130 {
 131     const wxCoord hWindow = GetClientSize().y;
 132
 133     // go upwards until we arrive at a line such that lineLast is not visible
 134     // any more when it is shown
 135     size_t lineFirst = lineLast;
 136     wxCoord h = 0;
 137     for ( ;; )
 138     {
 139         h += OnGetLineHeight(lineFirst);
 140
 141         if ( h > hWindow )
 142         {
 143             // for this line to be fully visible we need to go one line
 144             // down, but if it is enough for it to be only partly visible then
 145             // this line will do as well
 146             if ( full )
 147             {
 148                 lineFirst++;
 149             }
 150
 151             break;
 152         }
 153
 154         if ( !lineFirst )
 155             break;
 156
 157         lineFirst--;
 158     }
 159
 160     return lineFirst;
 161 }
 162
 163 void wxVScrolledWindow::UpdateScrollbar()
 164 {
 165     // see how many lines can we fit on screen
 166     const wxCoord hWindow = GetClientSize().y;
 167
 168     wxCoord h = 0;
 169     size_t line;
 170     for ( line = m_lineFirst; line < m_lineMax; line++ )
 171     {
 172         if ( h > hWindow )
 173             break;
 174
 175         h += OnGetLineHeight(line);
 176     }
 177
 178     m_nVisible = line - m_lineFirst;
 179
 180     int pageSize = m_nVisible;
 181     if ( h > hWindow )
 182     {
 183         // last line is only partially visible, we still need the scrollbar and
 184         // so we have to "fix" pageSize because if it is equal to m_lineMax the
 185         // scrollbar is not shown at all under MSW
 186         pageSize--;
 187     }
 188
 189     // set the scrollbar parameters to reflect this
 190     SetScrollbar(wxVERTICAL, m_lineFirst, pageSize, m_lineMax);
 191 }
 192
 193 // ----------------------------------------------------------------------------
 194 // operations
 195 // ----------------------------------------------------------------------------
 196
 197 void wxVScrolledWindow::SetLineCount(size_t count)
 198 {
 199     // save the number of lines
 200     m_lineMax = count;
 201
 202     // and our estimate for their total height
 203     m_heightTotal = EstimateTotalHeight();
 204
 205     // recalculate the scrollbars parameters
 206     m_lineFirst = 1;    // make sure it is != 0
 207     ScrollToLine(0);
 208 }
 209
 210 void wxVScrolledWindow::RefreshLine(size_t line)
 211 {
 212     // is this line visible?
 213     if ( !IsVisible(line) )
 214     {
 215         // no, it is useless to do anything
 216         return;
 217     }
 218
 219     // calculate the rect occupied by this line on screen
 220     wxRect rect;
 221     rect.width = GetClientSize().x;
 222     rect.height = OnGetLineHeight(line);
 223     for ( size_t n = GetVisibleBegin(); n < line; n++ )
 224     {
 225         rect.y += OnGetLineHeight(n);
 226     }
 227
 228     // do refresh it
 229     RefreshRect(rect);
 230 }
 231
 232 void wxVScrolledWindow::RefreshLines(size_t from, size_t to)
 233 {
 234     wxASSERT_MSG( from <= to, _T("RefreshLines(): empty range") );
 235
 236     // clump the range to just the visible lines -- it is useless to refresh
 237     // the other ones
 238     if ( from < GetVisibleBegin() )
 239         from = GetVisibleBegin();
 240
 241     if ( to >= GetVisibleEnd() )
 242         to = GetVisibleEnd();
 243     else
 244         to++;
 245
 246     // calculate the rect occupied by these lines on screen
 247     wxRect rect;
 248     rect.width = GetClientSize().x;
 249     for ( size_t nBefore = GetVisibleBegin(); nBefore < from; nBefore++ )
 250     {
 251         rect.y += OnGetLineHeight(nBefore);
 252     }
 253
 254     for ( size_t nBetween = from; nBetween < to; nBetween++ )
 255     {
 256         rect.height += OnGetLineHeight(nBetween);
 257     }
 258
 259     // do refresh it
 260     RefreshRect(rect);
 261 }
 262
 263 void wxVScrolledWindow::RefreshAll()
 264 {
 265     UpdateScrollbar();
 266
 267     Refresh();
 268 }
 269
 270 int wxVScrolledWindow::HitTest(wxCoord WXUNUSED(x), wxCoord y) const
 271 {
 272     const size_t lineMax = GetVisibleEnd();
 273     for ( size_t line = GetVisibleBegin(); line < lineMax; line++ )
 274     {
 275         y -= OnGetLineHeight(line);
 276         if ( y < 0 )
 277             return line;
 278     }
 279
 280     return wxNOT_FOUND;
 281 }
 282
 283 // ----------------------------------------------------------------------------
 284 // scrolling
 285 // ----------------------------------------------------------------------------
 286
 287 bool wxVScrolledWindow::ScrollToLine(size_t line)
 288 {
 289     if ( !m_lineMax )
 290     {
 291         // we're empty, code below doesn't make sense in this case
 292         return false;
 293     }
 294
 295     // determine the real first line to scroll to: we shouldn't scroll beyond
 296     // the end
 297     size_t lineFirstLast = FindFirstFromBottom(m_lineMax - 1, true);
 298     if ( line > lineFirstLast )
 299         line = lineFirstLast;
 300
 301     // anything to do?
 302     if ( line == m_lineFirst )
 303     {
 304         // no
 305         return false;
 306     }
 307
 308
 309     // remember the currently shown lines for the refresh code below
 310     size_t lineFirstOld = GetVisibleBegin(),
 311            lineLastOld = GetVisibleEnd();
 312
 313     m_lineFirst = line;
 314
 315
 316     // the size of scrollbar thumb could have changed
 317     UpdateScrollbar();
 318
 319
 320     // finally refresh the display -- but only redraw as few lines as possible
 321     // to avoid flicker
 322     if ( GetVisibleBegin() >= lineLastOld ||
 323             GetVisibleEnd() <= lineFirstOld )
 324     {
 325         // the simplest case: we don't have any old lines left, just redraw
 326         // everything
 327         Refresh();
 328     }
 329     else // overlap between the lines we showed before and should show now
 330     {
 331         ScrollWindow(0, GetLinesHeight(GetVisibleBegin(), lineFirstOld));
 332     }
 333
 334     return true;
 335 }
 336
 337 bool wxVScrolledWindow::ScrollLines(int lines)
 338 {
 339     lines += m_lineFirst;
 340     if ( lines < 0 )
 341         lines = 0;
 342
 343     return ScrollToLine(lines);
 344 }
 345
 346 bool wxVScrolledWindow::ScrollPages(int pages)
 347 {
 348     bool didSomething = false;
 349
 350     while ( pages )
 351     {
 352         int line;
 353         if ( pages > 0 )
 354         {
 355             line = GetVisibleEnd();
 356             if ( line )
 357                 line--;
 358             pages--;
 359         }
 360         else // pages < 0
 361         {
 362             line = FindFirstFromBottom(GetVisibleBegin());
 363             pages++;
 364         }
 365
 366         didSomething = ScrollToLine(line);
 367     }
 368
 369     return didSomething;
 370 }
 371
 372 // ----------------------------------------------------------------------------
 373 // event handling
 374 // ----------------------------------------------------------------------------
 375
 376 void wxVScrolledWindow::OnSize(wxSizeEvent& event)
 377 {
 378     UpdateScrollbar();
 379
 380     event.Skip();
 381 }
 382
 383 void wxVScrolledWindow::OnScroll(wxScrollWinEvent& event)
 384 {
 385     size_t lineFirstNew;
 386
 387     const wxEventType evtType = event.GetEventType();
 388
 389     if ( evtType == wxEVT_SCROLLWIN_TOP )
 390     {
 391         lineFirstNew = 0;
 392     }
 393     else if ( evtType == wxEVT_SCROLLWIN_BOTTOM )
 394     {
 395         lineFirstNew = m_lineMax;
 396     }
 397     else if ( evtType == wxEVT_SCROLLWIN_LINEUP )
 398     {
 399         lineFirstNew = m_lineFirst ? m_lineFirst - 1 : 0;
 400     }
 401     else if ( evtType == wxEVT_SCROLLWIN_LINEDOWN )
 402     {
 403         lineFirstNew = m_lineFirst + 1;
 404     }
 405     else if ( evtType == wxEVT_SCROLLWIN_PAGEUP )
 406     {
 407         lineFirstNew = FindFirstFromBottom(m_lineFirst);
 408     }
 409     else if ( evtType == wxEVT_SCROLLWIN_PAGEDOWN )
 410     {
 411         lineFirstNew = GetVisibleEnd();
 412         if ( lineFirstNew )
 413             lineFirstNew--;
 414     }
 415     else if ( evtType == wxEVT_SCROLLWIN_THUMBRELEASE )
 416     {
 417         lineFirstNew = event.GetPosition();
 418     }
 419     else if ( evtType == wxEVT_SCROLLWIN_THUMBTRACK )
 420     {
 421         lineFirstNew = event.GetPosition();
 422     }
 423
 424     else // unknown scroll event?
 425     {
 426         wxFAIL_MSG( _T("unknown scroll event type?") );
 427         return;
 428     }
 429
 430     ScrollToLine(lineFirstNew);
 431
 432 #ifdef __WXMAC__
 433     Update();
 434 #endif // __WXMAC__
 435 }
 436
 437 #if wxUSE_MOUSEWHEEL
 438
 439 void wxVScrolledWindow::OnMouseWheel(wxMouseEvent& event)
 440 {
 441     m_sumWheelRotation += event.GetWheelRotation();
 442     int delta = event.GetWheelDelta();
 443
 444     // how much to scroll this time
 445     int units_to_scroll = -(m_sumWheelRotation/delta);
 446     if ( !units_to_scroll )
 447         return;
 448
 449     m_sumWheelRotation += units_to_scroll*delta;
 450
 451     if ( !event.IsPageScroll() )
 452         ScrollLines( units_to_scroll*event.GetLinesPerAction() );
 453     else
 454         // scroll pages instead of lines
 455         ScrollPages( units_to_scroll );
 456 }
 457
 458 #endif