added wxVScrolledWindow

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@20772 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/vscroll.cpp

@@ -0,0 +1,322 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        src/generic/vscroll.cpp
+// Purpose:     wxVScrolledWindow implementation
+// Author:      Vadim Zeitlin
+// Modified by:
+// Created:     30.05.03
+// RCS-ID:      $Id$
+// Copyright:   (c) 2003 Vadim Zeitlin <vadim@wxwindows.org>
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+// ============================================================================
+// declarations
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
+#include "wx/vscroll.h"
+
+// ----------------------------------------------------------------------------
+// event tables
+// ----------------------------------------------------------------------------
+
+BEGIN_EVENT_TABLE(wxVScrolledWindow, wxPanel)
+    EVT_SIZE(wxVScrolledWindow::OnSize)
+    EVT_SCROLLWIN(wxVScrolledWindow::OnScroll)
+END_EVENT_TABLE()
+
+
+// ============================================================================
+// implementation
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// initialization
+// ----------------------------------------------------------------------------
+
+void wxVScrolledWindow::Init()
+{
+    // we're initially empty
+    m_lineMax =
+    m_lineFirst = 0;
+
+    // this one should always be strictly positive
+    m_nVisible = 1;
+
+    m_heightTotal = 0;
+}
+
+// ----------------------------------------------------------------------------
+// various helpers
+// ----------------------------------------------------------------------------
+
+wxCoord wxVScrolledWindow::GetLinesHeight(size_t lineMin, size_t lineMax) const
+{
+    if ( lineMin == lineMax )
+        return 0;
+    else if ( lineMin > lineMax )
+        return -GetLinesHeight(lineMax, lineMin);
+    //else: lineMin < lineMax
+
+    // let the user code know that we're going to need all these lines
+    OnGetLinesHint(lineMin, lineMax);
+
+    // do sum up their heights
+    wxCoord height = 0;
+    for ( size_t line = lineMin; line < lineMax; line++ )
+    {
+        height += OnGetLineHeight(line);
+    }
+
+    return height;
+}
+
+size_t wxVScrolledWindow::FindFirstFromBottom(size_t lineLast)
+{
+    const wxCoord hWindow = GetClientSize().y;
+
+    // go upwards until we arrive at a line such that lineLast is not visible
+    // any more when it is shown
+    size_t lineFirst = lineLast;
+    wxCoord h = 0;
+    for ( ;; )
+    {
+        h += OnGetLineHeight(lineFirst);
+
+        if ( h > hWindow )
+        {
+            lineFirst++;
+
+            break;
+        }
+
+        if ( !lineFirst )
+            break;
+
+        lineFirst--;
+    }
+
+    return lineFirst;
+}
+
+void wxVScrolledWindow::UpdateScrollbar()
+{
+    // see how many lines can we fit on screen
+    const wxCoord hWindow = GetClientSize().y;
+
+    wxCoord h = 0;
+    size_t line;
+    for ( line = m_lineFirst; line < m_lineMax; line++ )
+    {
+        if ( h > hWindow )
+            break;
+
+        h += OnGetLineHeight(line);
+    }
+
+    m_nVisible = line - m_lineFirst;
+
+    int pageSize = m_nVisible;
+    if ( h > hWindow )
+    {
+        // last line is only partially visible, we still need the scrollbar and
+        // so we have to "fix" pageSize because if it is equal to m_lineMax the
+        // scrollbar is not shown at all under MSW
+        pageSize--;
+    }
+
+    // set the scrollbar parameters to reflect this
+    SetScrollbar(wxVERTICAL, m_lineFirst, pageSize, m_lineMax);
+}
+
+// ----------------------------------------------------------------------------
+// operations
+// ----------------------------------------------------------------------------
+
+void wxVScrolledWindow::SetLineCount(size_t count)
+{
+    // save the number of lines
+    m_lineMax = count;
+
+
+    // estimate the total height: it is impossible to call
+    // OnGetLineHeight() for every line because there may be too many of
+    // them, so we just make a guess using some lines in the beginning,
+    // some in the end and some in the middle
+    static const size_t NUM_LINES_TO_SAMPLE = 10;
+
+    if ( count < 3*NUM_LINES_TO_SAMPLE )
+    {
+        // in this case calculating exactly is faster and more correct than
+        // guessing
+        m_heightTotal = GetLinesHeight(0, m_lineMax);
+    }
+    else // too many lines to calculate exactly
+    {
+        // look at some lines in the beginning/middle/end
+        m_heightTotal =
+            GetLinesHeight(0, NUM_LINES_TO_SAMPLE) +
+                GetLinesHeight(count - NUM_LINES_TO_SAMPLE, count) +
+                    GetLinesHeight(count/2 - NUM_LINES_TO_SAMPLE/2,
+                                   count/2 + NUM_LINES_TO_SAMPLE/2);
+
+        // use the height of the lines we looked as the average
+        m_heightTotal = ((float)m_heightTotal / (3*NUM_LINES_TO_SAMPLE)) *
+                            m_lineMax;
+    }
+
+
+    // recalculate the scrollbars parameters
+    ScrollToLine(0);
+}
+
+// ----------------------------------------------------------------------------
+// scrolling
+// ----------------------------------------------------------------------------
+
+bool wxVScrolledWindow::ScrollToLine(size_t line)
+{
+    if ( !m_lineMax )
+    {
+        // we're empty, code below doesn't make sense in this case
+        return false;
+    }
+
+    // determine the real first line to scroll to: we shouldn't scroll beyond
+    // the end
+    size_t lineFirstLast = FindFirstFromBottom(m_lineMax - 1);
+    if ( line > lineFirstLast )
+        line = lineFirstLast;
+
+    // anything to do?
+    if ( line == m_lineFirst )
+    {
+        // no
+        return false;
+    }
+
+
+    // remember the currently shown lines for the refresh code below
+    size_t lineFirstOld = GetFirstVisibleLine(),
+           lineLastOld = GetLastVisibleLine();
+
+    m_lineFirst = line;
+
+
+    // the size of scrollbar thumb could have changed
+    UpdateScrollbar();
+
+
+    // finally refresh the display -- but only redraw as few lines as possible
+    // to avoid flicker
+    if ( GetFirstVisibleLine() > lineLastOld ||
+            GetLastVisibleLine() < lineFirstOld )
+    {
+        // the simplest case: we don't have any old lines left, just redraw
+        // everything
+        Refresh();
+    }
+    else // overlap between the lines we showed before and should show now
+    {
+        ScrollWindow(0, GetLinesHeight(GetFirstVisibleLine(), lineFirstOld));
+    }
+
+    return true;
+}
+
+bool wxVScrolledWindow::ScrollLines(int lines)
+{
+    lines += m_lineFirst;
+    if ( lines < 0 )
+        lines = 0;
+
+    return ScrollToLine(lines);
+}
+
+bool wxVScrolledWindow::ScrollPages(int pages)
+{
+    bool didSomething = false;
+
+    while ( pages )
+    {
+        int line;
+        if ( pages > 0 )
+        {
+            line = GetLastVisibleLine();
+            pages--;
+        }
+        else // pages < 0
+        {
+            line = FindFirstFromBottom(GetFirstVisibleLine());
+            pages++;
+        }
+
+        didSomething = ScrollToLine(line);
+    }
+
+    return didSomething;
+}
+
+// ----------------------------------------------------------------------------
+// event handling
+// ----------------------------------------------------------------------------
+
+void wxVScrolledWindow::OnSize(wxSizeEvent& event)
+{
+    UpdateScrollbar();
+
+    event.Skip();
+}
+
+void wxVScrolledWindow::OnScroll(wxScrollWinEvent& event)
+{
+    size_t lineFirstNew;
+
+    const wxEventType evtType = event.GetEventType();
+    if ( evtType == wxEVT_SCROLLWIN_TOP )
+    {
+        lineFirstNew = 0;
+    }
+    else if ( evtType == wxEVT_SCROLLWIN_BOTTOM )
+    {
+        lineFirstNew = m_lineMax;
+    }
+    else if ( evtType == wxEVT_SCROLLWIN_LINEUP )
+    {
+        lineFirstNew = m_lineFirst ? m_lineFirst - 1 : 0;
+    }
+    else if ( evtType == wxEVT_SCROLLWIN_LINEDOWN )
+    {
+        lineFirstNew = m_lineFirst + 1;
+    }
+    else if ( evtType == wxEVT_SCROLLWIN_PAGEUP )
+    {
+        lineFirstNew = FindFirstFromBottom(m_lineFirst);
+    }
+    else if ( evtType == wxEVT_SCROLLWIN_PAGEDOWN )
+    {
+        lineFirstNew = GetLastVisibleLine();
+    }
+    else // unknown scroll event?
+    {
+        if ( evtType == wxEVT_SCROLLWIN_THUMBRELEASE )
+        {
+            lineFirstNew = event.GetPosition();
+        }
+        else
+        {
+            wxASSERT_MSG( evtType == wxEVT_SCROLLWIN_THUMBTRACK,
+                            _T("unknown scroll event type?") );
+
+            // don't do anything, otherwise dragging the thumb around would
+            // be too slow
+            return;
+        }
+    }
+
+    ScrollToLine(lineFirstNew);
+}
+