clicking on a panel without children should give it the focus (closes 215436)

[wxWidgets.git] / src / generic / vscroll.cpp

/////////////////////////////////////////////////////////////////////////////
// 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);
}