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