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 #include "wx/vscroll.h"
  21
  22 // ----------------------------------------------------------------------------
  23 // event tables
  24 // ----------------------------------------------------------------------------
  25
  26 BEGIN_EVENT_TABLE(wxVScrolledWindow, wxPanel)
  27     EVT_SIZE(wxVScrolledWindow::OnSize)
  28     EVT_SCROLLWIN(wxVScrolledWindow::OnScroll)
  29 END_EVENT_TABLE()
  30
  31
  32 // ============================================================================
  33 // implementation
  34 // ============================================================================
  35
  36 // ----------------------------------------------------------------------------
  37 // initialization
  38 // ----------------------------------------------------------------------------
  39
  40 void wxVScrolledWindow::Init()
  41 {
  42     // we're initially empty
  43     m_lineMax =
  44     m_lineFirst = 0;
  45
  46     // this one should always be strictly positive
  47     m_nVisible = 1;
  48
  49     m_heightTotal = 0;
  50 }
  51
  52 // ----------------------------------------------------------------------------
  53 // various helpers
  54 // ----------------------------------------------------------------------------
  55
  56 wxCoord wxVScrolledWindow::GetLinesHeight(size_t lineMin, size_t lineMax) const
  57 {
  58     if ( lineMin == lineMax )
  59         return 0;
  60     else if ( lineMin > lineMax )
  61         return -GetLinesHeight(lineMax, lineMin);
  62     //else: lineMin < lineMax
  63
  64     // let the user code know that we're going to need all these lines
  65     OnGetLinesHint(lineMin, lineMax);
  66
  67     // do sum up their heights
  68     wxCoord height = 0;
  69     for ( size_t line = lineMin; line < lineMax; line++ )
  70     {
  71         height += OnGetLineHeight(line);
  72     }
  73
  74     return height;
  75 }
  76
  77 size_t wxVScrolledWindow::FindFirstFromBottom(size_t lineLast)
  78 {
  79     const wxCoord hWindow = GetClientSize().y;
  80
  81     // go upwards until we arrive at a line such that lineLast is not visible
  82     // any more when it is shown
  83     size_t lineFirst = lineLast;
  84     wxCoord h = 0;
  85     for ( ;; )
  86     {
  87         h += OnGetLineHeight(lineFirst);
  88
  89         if ( h > hWindow )
  90         {
  91             lineFirst++;
  92
  93             break;
  94         }
  95
  96         if ( !lineFirst )
  97             break;
  98
  99         lineFirst--;
 100     }
 101
 102     return lineFirst;
 103 }
 104
 105 void wxVScrolledWindow::UpdateScrollbar()
 106 {
 107     // see how many lines can we fit on screen
 108     const wxCoord hWindow = GetClientSize().y;
 109
 110     wxCoord h = 0;
 111     size_t line;
 112     for ( line = m_lineFirst; line < m_lineMax; line++ )
 113     {
 114         if ( h > hWindow )
 115             break;
 116
 117         h += OnGetLineHeight(line);
 118     }
 119
 120     m_nVisible = line - m_lineFirst;
 121
 122     int pageSize = m_nVisible;
 123     if ( h > hWindow )
 124     {
 125         // last line is only partially visible, we still need the scrollbar and
 126         // so we have to "fix" pageSize because if it is equal to m_lineMax the
 127         // scrollbar is not shown at all under MSW
 128         pageSize--;
 129     }
 130
 131     // set the scrollbar parameters to reflect this
 132     SetScrollbar(wxVERTICAL, m_lineFirst, pageSize, m_lineMax);
 133 }
 134
 135 // ----------------------------------------------------------------------------
 136 // operations
 137 // ----------------------------------------------------------------------------
 138
 139 void wxVScrolledWindow::SetLineCount(size_t count)
 140 {
 141     // save the number of lines
 142     m_lineMax = count;
 143
 144
 145     // estimate the total height: it is impossible to call
 146     // OnGetLineHeight() for every line because there may be too many of
 147     // them, so we just make a guess using some lines in the beginning,
 148     // some in the end and some in the middle
 149     static const size_t NUM_LINES_TO_SAMPLE = 10;
 150
 151     if ( count < 3*NUM_LINES_TO_SAMPLE )
 152     {
 153         // in this case calculating exactly is faster and more correct than
 154         // guessing
 155         m_heightTotal = GetLinesHeight(0, m_lineMax);
 156     }
 157     else // too many lines to calculate exactly
 158     {
 159         // look at some lines in the beginning/middle/end
 160         m_heightTotal =
 161             GetLinesHeight(0, NUM_LINES_TO_SAMPLE) +
 162                 GetLinesHeight(count - NUM_LINES_TO_SAMPLE, count) +
 163                     GetLinesHeight(count/2 - NUM_LINES_TO_SAMPLE/2,
 164                                    count/2 + NUM_LINES_TO_SAMPLE/2);
 165
 166         // use the height of the lines we looked as the average
 167         m_heightTotal = ((float)m_heightTotal / (3*NUM_LINES_TO_SAMPLE)) *
 168                             m_lineMax;
 169     }
 170
 171
 172     // recalculate the scrollbars parameters
 173     ScrollToLine(0);
 174 }
 175
 176 // ----------------------------------------------------------------------------
 177 // scrolling
 178 // ----------------------------------------------------------------------------
 179
 180 bool wxVScrolledWindow::ScrollToLine(size_t line)
 181 {
 182     if ( !m_lineMax )
 183     {
 184         // we're empty, code below doesn't make sense in this case
 185         return false;
 186     }
 187
 188     // determine the real first line to scroll to: we shouldn't scroll beyond
 189     // the end
 190     size_t lineFirstLast = FindFirstFromBottom(m_lineMax - 1);
 191     if ( line > lineFirstLast )
 192         line = lineFirstLast;
 193
 194     // anything to do?
 195     if ( line == m_lineFirst )
 196     {
 197         // no
 198         return false;
 199     }
 200
 201
 202     // remember the currently shown lines for the refresh code below
 203     size_t lineFirstOld = GetFirstVisibleLine(),
 204            lineLastOld = GetLastVisibleLine();
 205
 206     m_lineFirst = line;
 207
 208
 209     // the size of scrollbar thumb could have changed
 210     UpdateScrollbar();
 211
 212
 213     // finally refresh the display -- but only redraw as few lines as possible
 214     // to avoid flicker
 215     if ( GetFirstVisibleLine() > lineLastOld ||
 216             GetLastVisibleLine() < lineFirstOld )
 217     {
 218         // the simplest case: we don't have any old lines left, just redraw
 219         // everything
 220         Refresh();
 221     }
 222     else // overlap between the lines we showed before and should show now
 223     {
 224         ScrollWindow(0, GetLinesHeight(GetFirstVisibleLine(), lineFirstOld));
 225     }
 226
 227     return true;
 228 }
 229
 230 bool wxVScrolledWindow::ScrollLines(int lines)
 231 {
 232     lines += m_lineFirst;
 233     if ( lines < 0 )
 234         lines = 0;
 235
 236     return ScrollToLine(lines);
 237 }
 238
 239 bool wxVScrolledWindow::ScrollPages(int pages)
 240 {
 241     bool didSomething = false;
 242
 243     while ( pages )
 244     {
 245         int line;
 246         if ( pages > 0 )
 247         {
 248             line = GetLastVisibleLine();
 249             pages--;
 250         }
 251         else // pages < 0
 252         {
 253             line = FindFirstFromBottom(GetFirstVisibleLine());
 254             pages++;
 255         }
 256
 257         didSomething = ScrollToLine(line);
 258     }
 259
 260     return didSomething;
 261 }
 262
 263 // ----------------------------------------------------------------------------
 264 // event handling
 265 // ----------------------------------------------------------------------------
 266
 267 void wxVScrolledWindow::OnSize(wxSizeEvent& event)
 268 {
 269     UpdateScrollbar();
 270
 271     event.Skip();
 272 }
 273
 274 void wxVScrolledWindow::OnScroll(wxScrollWinEvent& event)
 275 {
 276     size_t lineFirstNew;
 277
 278     const wxEventType evtType = event.GetEventType();
 279     if ( evtType == wxEVT_SCROLLWIN_TOP )
 280     {
 281         lineFirstNew = 0;
 282     }
 283     else if ( evtType == wxEVT_SCROLLWIN_BOTTOM )
 284     {
 285         lineFirstNew = m_lineMax;
 286     }
 287     else if ( evtType == wxEVT_SCROLLWIN_LINEUP )
 288     {
 289         lineFirstNew = m_lineFirst ? m_lineFirst - 1 : 0;
 290     }
 291     else if ( evtType == wxEVT_SCROLLWIN_LINEDOWN )
 292     {
 293         lineFirstNew = m_lineFirst + 1;
 294     }
 295     else if ( evtType == wxEVT_SCROLLWIN_PAGEUP )
 296     {
 297         lineFirstNew = FindFirstFromBottom(m_lineFirst);
 298     }
 299     else if ( evtType == wxEVT_SCROLLWIN_PAGEDOWN )
 300     {
 301         lineFirstNew = GetLastVisibleLine();
 302     }
 303     else // unknown scroll event?
 304     {
 305         if ( evtType == wxEVT_SCROLLWIN_THUMBRELEASE )
 306         {
 307             lineFirstNew = event.GetPosition();
 308         }
 309         else
 310         {
 311             wxASSERT_MSG( evtType == wxEVT_SCROLLWIN_THUMBTRACK,
 312                             _T("unknown scroll event type?") );
 313
 314             // don't do anything, otherwise dragging the thumb around would
 315             // be too slow
 316             return;
 317         }
 318     }
 319
 320     ScrollToLine(lineFirstNew);
 321 }
 322