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 #ifndef WX_PRECOMP
  28     #include "wx/sizer.h"
  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::RemoveScrollbar()
 164 {
 165     m_lineFirst = 0;
 166     m_nVisible = m_lineMax;
 167     SetScrollbar(wxVERTICAL, 0, 0, 0);
 168 }
 169
 170 void wxVScrolledWindow::UpdateScrollbar()
 171 {
 172     // see how many lines can we fit on screen
 173     const wxCoord hWindow = GetClientSize().y;
 174
 175     wxCoord h = 0;
 176     size_t line;
 177     for ( line = m_lineFirst; line < m_lineMax; line++ )
 178     {
 179         if ( h > hWindow )
 180             break;
 181
 182         h += OnGetLineHeight(line);
 183     }
 184
 185     // if we still have remaining space below, maybe we can fit everything?
 186     if ( h < hWindow )
 187     {
 188         wxCoord hAll = h;
 189         for ( size_t lineFirst = m_lineFirst; lineFirst > 0; lineFirst-- )
 190         {
 191             hAll += OnGetLineHeight(m_lineFirst - 1);
 192             if ( hAll > hWindow )
 193                 break;
 194         }
 195
 196         if ( hAll < hWindow )
 197         {
 198             // we don't need scrollbar at all
 199             RemoveScrollbar();
 200             return;
 201         }
 202     }
 203
 204     m_nVisible = line - m_lineFirst;
 205
 206     int pageSize = m_nVisible;
 207     if ( h > hWindow )
 208     {
 209         // last line is only partially visible, we still need the scrollbar and
 210         // so we have to "fix" pageSize because if it is equal to m_lineMax the
 211         // scrollbar is not shown at all under MSW
 212         pageSize--;
 213     }
 214
 215     // set the scrollbar parameters to reflect this
 216     SetScrollbar(wxVERTICAL, m_lineFirst, pageSize, m_lineMax);
 217 }
 218
 219 // ----------------------------------------------------------------------------
 220 // operations
 221 // ----------------------------------------------------------------------------
 222
 223 void wxVScrolledWindow::SetLineCount(size_t count)
 224 {
 225     // save the number of lines
 226     m_lineMax = count;
 227
 228     // and our estimate for their total height
 229     m_heightTotal = EstimateTotalHeight();
 230
 231     // recalculate the scrollbars parameters
 232     if ( count )
 233     {
 234         m_lineFirst = 1;    // make sure it is != 0
 235         ScrollToLine(0);
 236     }
 237     else // no items
 238     {
 239         RemoveScrollbar();
 240     }
 241 }
 242
 243 void wxVScrolledWindow::RefreshLine(size_t line)
 244 {
 245     // is this line visible?
 246     if ( !IsVisible(line) )
 247     {
 248         // no, it is useless to do anything
 249         return;
 250     }
 251
 252     // calculate the rect occupied by this line on screen
 253     wxRect rect;
 254     rect.width = GetClientSize().x;
 255     rect.height = OnGetLineHeight(line);
 256     for ( size_t n = GetVisibleBegin(); n < line; n++ )
 257     {
 258         rect.y += OnGetLineHeight(n);
 259     }
 260
 261     // do refresh it
 262     RefreshRect(rect);
 263 }
 264
 265 void wxVScrolledWindow::RefreshLines(size_t from, size_t to)
 266 {
 267     wxASSERT_MSG( from <= to, _T("RefreshLines(): empty range") );
 268
 269     // clump the range to just the visible lines -- it is useless to refresh
 270     // the other ones
 271     if ( from < GetVisibleBegin() )
 272         from = GetVisibleBegin();
 273
 274     if ( to >= GetVisibleEnd() )
 275         to = GetVisibleEnd();
 276     else
 277         to++;
 278
 279     // calculate the rect occupied by these lines on screen
 280     wxRect rect;
 281     rect.width = GetClientSize().x;
 282     for ( size_t nBefore = GetVisibleBegin(); nBefore < from; nBefore++ )
 283     {
 284         rect.y += OnGetLineHeight(nBefore);
 285     }
 286
 287     for ( size_t nBetween = from; nBetween < to; nBetween++ )
 288     {
 289         rect.height += OnGetLineHeight(nBetween);
 290     }
 291
 292     // do refresh it
 293     RefreshRect(rect);
 294 }
 295
 296 void wxVScrolledWindow::RefreshAll()
 297 {
 298     UpdateScrollbar();
 299
 300     Refresh();
 301 }
 302
 303 bool wxVScrolledWindow::Layout()
 304 {
 305     if ( GetSizer() )
 306     {
 307         // adjust the sizer dimensions/position taking into account the
 308         // virtual size and scrolled position of the window.
 309
 310         int w, h;
 311         GetVirtualSize(&w, &h);
 312
 313         // x is always 0 so no variable needed
 314         int y = -GetLinesHeight(0, GetFirstVisibleLine());
 315
 316         GetSizer()->SetDimension(0, y, w, h);
 317         return true;
 318     }
 319
 320     // fall back to default for LayoutConstraints
 321     return wxPanel::Layout();
 322 }
 323
 324 int wxVScrolledWindow::HitTest(wxCoord WXUNUSED(x), wxCoord y) const
 325 {
 326     const size_t lineMax = GetVisibleEnd();
 327     for ( size_t line = GetVisibleBegin(); line < lineMax; line++ )
 328     {
 329         y -= OnGetLineHeight(line);
 330         if ( y < 0 )
 331             return line;
 332     }
 333
 334     return wxNOT_FOUND;
 335 }
 336
 337 // ----------------------------------------------------------------------------
 338 // scrolling
 339 // ----------------------------------------------------------------------------
 340
 341 bool wxVScrolledWindow::ScrollToLine(size_t line)
 342 {
 343     if ( !m_lineMax )
 344     {
 345         // we're empty, code below doesn't make sense in this case
 346         return false;
 347     }
 348
 349     // determine the real first line to scroll to: we shouldn't scroll beyond
 350     // the end
 351     size_t lineFirstLast = FindFirstFromBottom(m_lineMax - 1, true);
 352     if ( line > lineFirstLast )
 353         line = lineFirstLast;
 354
 355     // anything to do?
 356     if ( line == m_lineFirst )
 357     {
 358         // no
 359         return false;
 360     }
 361
 362
 363     // remember the currently shown lines for the refresh code below
 364     size_t lineFirstOld = GetVisibleBegin(),
 365            lineLastOld = GetVisibleEnd();
 366
 367     m_lineFirst = line;
 368
 369
 370     // the size of scrollbar thumb could have changed
 371     UpdateScrollbar();
 372
 373
 374     // finally refresh the display -- but only redraw as few lines as possible
 375     // to avoid flicker
 376     if ( GetVisibleBegin() >= lineLastOld ||
 377             GetVisibleEnd() <= lineFirstOld )
 378     {
 379         // the simplest case: we don't have any old lines left, just redraw
 380         // everything
 381         Refresh();
 382     }
 383     else // overlap between the lines we showed before and should show now
 384     {
 385         ScrollWindow(0, GetLinesHeight(GetVisibleBegin(), lineFirstOld));
 386     }
 387
 388     return true;
 389 }
 390
 391 bool wxVScrolledWindow::ScrollLines(int lines)
 392 {
 393     lines += m_lineFirst;
 394     if ( lines < 0 )
 395         lines = 0;
 396
 397     return ScrollToLine(lines);
 398 }
 399
 400 bool wxVScrolledWindow::ScrollPages(int pages)
 401 {
 402     bool didSomething = false;
 403
 404     while ( pages )
 405     {
 406         int line;
 407         if ( pages > 0 )
 408         {
 409             line = GetVisibleEnd();
 410             if ( line )
 411                 line--;
 412             pages--;
 413         }
 414         else // pages < 0
 415         {
 416             line = FindFirstFromBottom(GetVisibleBegin());
 417             pages++;
 418         }
 419
 420         didSomething = ScrollToLine(line);
 421     }
 422
 423     return didSomething;
 424 }
 425
 426 // ----------------------------------------------------------------------------
 427 // event handling
 428 // ----------------------------------------------------------------------------
 429
 430 void wxVScrolledWindow::OnSize(wxSizeEvent& event)
 431 {
 432     UpdateScrollbar();
 433
 434     event.Skip();
 435 }
 436
 437 void wxVScrolledWindow::OnScroll(wxScrollWinEvent& event)
 438 {
 439     size_t lineFirstNew;
 440
 441     const wxEventType evtType = event.GetEventType();
 442
 443     if ( evtType == wxEVT_SCROLLWIN_TOP )
 444     {
 445         lineFirstNew = 0;
 446     }
 447     else if ( evtType == wxEVT_SCROLLWIN_BOTTOM )
 448     {
 449         lineFirstNew = m_lineMax;
 450     }
 451     else if ( evtType == wxEVT_SCROLLWIN_LINEUP )
 452     {
 453         lineFirstNew = m_lineFirst ? m_lineFirst - 1 : 0;
 454     }
 455     else if ( evtType == wxEVT_SCROLLWIN_LINEDOWN )
 456     {
 457         lineFirstNew = m_lineFirst + 1;
 458     }
 459     else if ( evtType == wxEVT_SCROLLWIN_PAGEUP )
 460     {
 461         lineFirstNew = FindFirstFromBottom(m_lineFirst);
 462     }
 463     else if ( evtType == wxEVT_SCROLLWIN_PAGEDOWN )
 464     {
 465         lineFirstNew = GetVisibleEnd();
 466         if ( lineFirstNew )
 467             lineFirstNew--;
 468     }
 469     else if ( evtType == wxEVT_SCROLLWIN_THUMBRELEASE )
 470     {
 471         lineFirstNew = event.GetPosition();
 472     }
 473     else if ( evtType == wxEVT_SCROLLWIN_THUMBTRACK )
 474     {
 475         lineFirstNew = event.GetPosition();
 476     }
 477
 478     else // unknown scroll event?
 479     {
 480         wxFAIL_MSG( _T("unknown scroll event type?") );
 481         return;
 482     }
 483
 484     ScrollToLine(lineFirstNew);
 485
 486 #ifdef __WXMAC__
 487     Update();
 488 #endif // __WXMAC__
 489 }
 490
 491 #if wxUSE_MOUSEWHEEL
 492
 493 void wxVScrolledWindow::OnMouseWheel(wxMouseEvent& event)
 494 {
 495     m_sumWheelRotation += event.GetWheelRotation();
 496     int delta = event.GetWheelDelta();
 497
 498     // how much to scroll this time
 499     int units_to_scroll = -(m_sumWheelRotation/delta);
 500     if ( !units_to_scroll )
 501         return;
 502
 503     m_sumWheelRotation += units_to_scroll*delta;
 504
 505     if ( !event.IsPageScroll() )
 506         ScrollLines( units_to_scroll*event.GetLinesPerAction() );
 507     else
 508         // scroll pages instead of lines
 509         ScrollPages( units_to_scroll );
 510 }
 511
 512 #endif // wxUSE_MOUSEWHEEL
 513