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     m_lineFirst = 1;    // make sure it is != 0
 174     ScrollToLine(0);
 175 }
 176
 177 void wxVScrolledWindow::RefreshLine(size_t line)
 178 {
 179     // is this line visible?
 180     if ( !IsVisible(line) )
 181     {
 182         // no, it is useless to do anything
 183         return;
 184     }
 185
 186     // calculate the rect occupied by this line on screen
 187     wxRect rect;
 188     rect.width = GetClientSize().x;
 189     rect.height = OnGetLineHeight(line);
 190     for ( size_t n = GetFirstVisibleLine(); n < line; n++ )
 191     {
 192         rect.y += OnGetLineHeight(n);
 193     }
 194
 195     // do refresh it
 196     RefreshRect(rect);
 197 }
 198
 199 int wxVScrolledWindow::HitTest(wxCoord WXUNUSED(x), wxCoord y) const
 200 {
 201     const size_t lineMax = GetLastVisibleLine();
 202     for ( size_t line = GetFirstVisibleLine(); line <= lineMax; line++ )
 203     {
 204         y -= OnGetLineHeight(line);
 205         if ( y < 0 )
 206             return line;
 207     }
 208
 209     return wxNOT_FOUND;
 210 }
 211
 212 // ----------------------------------------------------------------------------
 213 // scrolling
 214 // ----------------------------------------------------------------------------
 215
 216 bool wxVScrolledWindow::ScrollToLine(size_t line)
 217 {
 218     if ( !m_lineMax )
 219     {
 220         // we're empty, code below doesn't make sense in this case
 221         return false;
 222     }
 223
 224     // determine the real first line to scroll to: we shouldn't scroll beyond
 225     // the end
 226     size_t lineFirstLast = FindFirstFromBottom(m_lineMax - 1);
 227     if ( line > lineFirstLast )
 228         line = lineFirstLast;
 229
 230     // anything to do?
 231     if ( line == m_lineFirst )
 232     {
 233         // no
 234         return false;
 235     }
 236
 237
 238     // remember the currently shown lines for the refresh code below
 239     size_t lineFirstOld = GetFirstVisibleLine(),
 240            lineLastOld = GetLastVisibleLine();
 241
 242     m_lineFirst = line;
 243
 244
 245     // the size of scrollbar thumb could have changed
 246     UpdateScrollbar();
 247
 248
 249     // finally refresh the display -- but only redraw as few lines as possible
 250     // to avoid flicker
 251     if ( GetFirstVisibleLine() > lineLastOld ||
 252             GetLastVisibleLine() < lineFirstOld )
 253     {
 254         // the simplest case: we don't have any old lines left, just redraw
 255         // everything
 256         Refresh();
 257     }
 258     else // overlap between the lines we showed before and should show now
 259     {
 260         ScrollWindow(0, GetLinesHeight(GetFirstVisibleLine(), lineFirstOld));
 261     }
 262
 263     return true;
 264 }
 265
 266 bool wxVScrolledWindow::ScrollLines(int lines)
 267 {
 268     lines += m_lineFirst;
 269     if ( lines < 0 )
 270         lines = 0;
 271
 272     return ScrollToLine(lines);
 273 }
 274
 275 bool wxVScrolledWindow::ScrollPages(int pages)
 276 {
 277     bool didSomething = false;
 278
 279     while ( pages )
 280     {
 281         int line;
 282         if ( pages > 0 )
 283         {
 284             line = GetLastVisibleLine();
 285             pages--;
 286         }
 287         else // pages < 0
 288         {
 289             line = FindFirstFromBottom(GetFirstVisibleLine());
 290             pages++;
 291         }
 292
 293         didSomething = ScrollToLine(line);
 294     }
 295
 296     return didSomething;
 297 }
 298
 299 // ----------------------------------------------------------------------------
 300 // event handling
 301 // ----------------------------------------------------------------------------
 302
 303 void wxVScrolledWindow::OnSize(wxSizeEvent& event)
 304 {
 305     UpdateScrollbar();
 306
 307     event.Skip();
 308 }
 309
 310 void wxVScrolledWindow::OnScroll(wxScrollWinEvent& event)
 311 {
 312     size_t lineFirstNew;
 313
 314     const wxEventType evtType = event.GetEventType();
 315     if ( evtType == wxEVT_SCROLLWIN_TOP )
 316     {
 317         lineFirstNew = 0;
 318     }
 319     else if ( evtType == wxEVT_SCROLLWIN_BOTTOM )
 320     {
 321         lineFirstNew = m_lineMax;
 322     }
 323     else if ( evtType == wxEVT_SCROLLWIN_LINEUP )
 324     {
 325         lineFirstNew = m_lineFirst ? m_lineFirst - 1 : 0;
 326     }
 327     else if ( evtType == wxEVT_SCROLLWIN_LINEDOWN )
 328     {
 329         lineFirstNew = m_lineFirst + 1;
 330     }
 331     else if ( evtType == wxEVT_SCROLLWIN_PAGEUP )
 332     {
 333         lineFirstNew = FindFirstFromBottom(m_lineFirst);
 334     }
 335     else if ( evtType == wxEVT_SCROLLWIN_PAGEDOWN )
 336     {
 337         lineFirstNew = GetLastVisibleLine();
 338     }
 339     else // unknown scroll event?
 340     {
 341         if ( evtType == wxEVT_SCROLLWIN_THUMBRELEASE )
 342         {
 343             lineFirstNew = event.GetPosition();
 344         }
 345         else
 346         {
 347             wxASSERT_MSG( evtType == wxEVT_SCROLLWIN_THUMBTRACK,
 348                             _T("unknown scroll event type?") );
 349
 350             // don't do anything, otherwise dragging the thumb around would
 351             // be too slow
 352             return;
 353         }
 354     }
 355
 356     ScrollToLine(lineFirstNew);
 357 }
 358