kdlogtextwidget.cpp

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/****************************************************************************
** Copyright (C) 2001-2010 Klaralvdalens Datakonsult AB.  All rights reserved.
**
** This file is part of the KD Tools library.
**
** Licensees holding valid commercial KD Tools licenses may use this file in
** accordance with the KD Tools Commercial License Agreement provided with
** the Software.
**
**
** This file may be distributed and/or modified under the terms of the
** GNU Lesser General Public License version 2 and version 3 as published by the
** Free Software Foundation and appearing in the file LICENSE.LGPL included.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
** Contact info@kdab.com if any conditions of this licensing are not
** clear to you.
**
**********************************************************************/

#include <config-kleopatra.h>

#include "kdlogtextwidget.h"

#include <QBasicTimer>
#include <QHash>
#include <QPainter>
#include <QPaintEvent>
#include <QScrollBar>

#include <cassert>
#include <algorithm>
#include <iterator>

class KDLogTextWidget::Private {
    friend class ::KDLogTextWidget;
    KDLogTextWidget * const q;
public:
    explicit Private( KDLogTextWidget * qq );
    ~Private();

    void updateCache() const;

    void triggerTimer() {
        if ( !timer.isActive() )
            timer.start( 500, q );
    }

    void addPendingLines();
    void enforceHistorySize();
    void updateScrollRanges();
    QPair<int,int> visibleLines( int top, int bottom ) {
        return qMakePair( qMax( 0, lineByYCoordinate( top ) ),
                          qMax( 0, 1 + lineByYCoordinate( bottom ) ) );
    }
    int lineByYCoordinate( int x ) const;

    QPoint scrollOffset() const;

    QRect lineRect( int idx ) const {
        assert( !cache.dirty );
        return QRect( 0, idx * cache.fontMetrics.lineSpacing, cache.dimensions.longestLineLength, cache.fontMetrics.lineSpacing-1 );
    }

    struct Style {
        QColor color;

        friend inline uint qHash( const Style & style ) {
            return qHash( style.color.rgba() );
        }
        bool operator==( const Style & other ) const { return this->color.rgba() == other.color.rgba(); }
        bool operator<( const Style & other ) const { return this->color.rgba() < other.color.rgba(); }
    };

    struct LineItem {
        QString text;
        unsigned int styleID;
    };

    unsigned int findOrAddStyle( const Style & style );

private:
    QHash<unsigned int, Style> styleByID;
    QHash<Style,unsigned int> idByStyle;

    QVector<LineItem> lines, pendingLines;

    unsigned int historySize;
    unsigned int minimumVisibleLines;
    unsigned int minimumVisibleColumns;

    bool alternatingRowColors;

    QBasicTimer timer;

    mutable struct Cache {
        enum { Dimensions = 1, FontMetrics = 2, All = FontMetrics|Dimensions };
        Cache() : dirty( All ) {}
        int dirty;

        struct {
            int lineSpacing;
            int ascent;
            int averageCharWidth;
            QVector<int> lineWidths;
        } fontMetrics;

        struct {
            int indexOfLongestLine;
            int longestLineLength;
        } dimensions;
    } cache;
};

KDLogTextWidget::KDLogTextWidget( QWidget * parent_ )
    : QAbstractScrollArea( parent_ ), d( new Private( this ) )
{

}

KDLogTextWidget::~KDLogTextWidget() {}


void KDLogTextWidget::setHistorySize( unsigned int hs ) {
    if ( hs == d->historySize )
        return;
    d->historySize = hs;
    d->enforceHistorySize();
    d->updateScrollRanges();
    viewport()->update();
}

unsigned int KDLogTextWidget::historySize() const {
    return d->historySize;
}

QString KDLogTextWidget::text() const {
    return lines().join( QLatin1String( "\n" ) );
}

void KDLogTextWidget::setLines( const QStringList & l ) {
    clear();
    Q_FOREACH( const QString & s, l )
        message( s );
}

QStringList KDLogTextWidget::lines() const {
    QStringList result;
    Q_FOREACH( const Private::LineItem & li, d->lines )
        result.push_back( li.text );
    Q_FOREACH( const Private::LineItem & li, d->pendingLines )
        result.push_back( li.text );
    return result;
}

void KDLogTextWidget::setMinimumVisibleLines( unsigned int num ) {
    if ( num == d->minimumVisibleLines )
        return;
    d->minimumVisibleLines = num;
    updateGeometry();
}

unsigned int KDLogTextWidget::minimumVisibleLines() const {
    return d->minimumVisibleLines;
}

void KDLogTextWidget::setMinimumVisibleColumns( unsigned int num ) {
    if ( num == d->minimumVisibleColumns )
        return;
    d->minimumVisibleColumns = num;
    updateGeometry();
}

unsigned int KDLogTextWidget::minimumVisibleColumns() const {
    return d->minimumVisibleColumns;
}

void KDLogTextWidget::setAlternatingRowColors( bool on ) {
    if ( on == d->alternatingRowColors )
        return;
    d->alternatingRowColors = on;
    update();
}

bool KDLogTextWidget::alternatingRowColors() const {
    return d->alternatingRowColors;
}

QSize KDLogTextWidget::minimumSizeHint() const {
    d->updateCache();
    const QSize base = QAbstractScrollArea::minimumSizeHint();
    const QSize view( d->minimumVisibleColumns * d->cache.fontMetrics.averageCharWidth,
                      d->minimumVisibleLines   * d->cache.fontMetrics.lineSpacing );
    const QSize scrollbars( verticalScrollBar() ? verticalScrollBar()->minimumSizeHint().width() : 0,
                            horizontalScrollBar() ? horizontalScrollBar()->minimumSizeHint().height() : 0 );
    return base + view + scrollbars;
}

QSize KDLogTextWidget::sizeHint() const {
    if ( d->minimumVisibleLines > 1 || d->minimumVisibleColumns > 1 )
        return minimumSizeHint();
    else
        return 2 * minimumSizeHint();
}

void KDLogTextWidget::clear() {
    d->timer.stop();
    d->lines.clear();
    d->pendingLines.clear();
    d->styleByID.clear();
    d->idByStyle.clear();
    d->cache.dirty = Private::Cache::All;
    viewport()->update();
}

void KDLogTextWidget::message( const QString & str, const QColor & color ) {
    const Private::Style s = { color };
    const Private::LineItem li = { str, d->findOrAddStyle( s ) };
    d->pendingLines.push_back( li );
    d->triggerTimer();
}

void KDLogTextWidget::message( const QString & str ) {
    const Private::LineItem li = { str, 0 };
    d->pendingLines.push_back( li );
    d->triggerTimer();
}

void KDLogTextWidget::paintEvent( QPaintEvent * e ) {

    d->updateCache();

    QPainter p( viewport() );

    p.translate( -d->scrollOffset() );

    const QRect visible = p.matrix().inverted().mapRect( e->rect() );

    const QPair<int,int> visibleLines
        = d->visibleLines( visible.top(), visible.bottom() );

    assert( visibleLines.first <= visibleLines.second );

    const Private::Style defaultStyle = { p.pen().color() };

    const Private::Cache & cache = d->cache;

    p.setPen( Qt::NoPen );

    p.setBrush( palette().base() );

    if ( d->alternatingRowColors ) {

        p.drawRect( visible );

#if 0 // leaves garbage
        for ( unsigned int i = visibleLines.first % 2 ? visibleLines.first+1 : visibleLines.first,   end = visibleLines.second ; i < end ; i+=2 )
            p.drawRect( d->lineRect( i ) );

        if ( visibleLines.second >= 0 ) {
            const int lastY = d->lineRect( visibleLines.second-1 ).y();
            if ( lastY < visible.bottom() )
                p.drawRect( 0, lastY+1, cache.dimensions.longestLineLength, visible.bottom() - lastY );
        }
#endif

        p.setBrush( palette().alternateBase() );
        for ( unsigned int i = visibleLines.first % 2 ? visibleLines.first   : visibleLines.first+1, end = visibleLines.second ; i < end ; i+=2 )
            p.drawRect( d->lineRect( i ) );

    } else {

        p.drawRect( visible );

    }

    // ### unused optimization: paint lines by styles to minimise pen changes.
    for ( unsigned int i = visibleLines.first, end = visibleLines.second ; i != end ; ++i ) {
        const Private::LineItem & li = d->lines[i];
        assert( !li.styleID || d->styleByID.contains( li.styleID ) );
        const Private::Style & st = li.styleID ? d->styleByID[li.styleID] : defaultStyle ;

        p.setPen( st.color );
        p.drawText( 0, i * cache.fontMetrics.lineSpacing + cache.fontMetrics.ascent, li.text );
    }

}

void KDLogTextWidget::timerEvent( QTimerEvent * e ) {
    if ( e->timerId() == d->timer.timerId() ) {
        d->addPendingLines();
        d->timer.stop();
    } else {
        QAbstractScrollArea::timerEvent( e );
    }
}

void KDLogTextWidget::changeEvent( QEvent * e ) {
    QAbstractScrollArea::changeEvent( e );
    d->cache.dirty |= Private::Cache::FontMetrics;
}

void KDLogTextWidget::resizeEvent( QResizeEvent * ) {
    d->updateScrollRanges();
}

KDLogTextWidget::Private::Private( KDLogTextWidget * qq )
    : q( qq ),
      styleByID(),
      idByStyle(),
      lines(),
      pendingLines(),
      historySize( 0xFFFFFFFF ),
      minimumVisibleLines( 1 ),
      minimumVisibleColumns( 1 ),
      alternatingRowColors( false ),
      timer(),
      cache()
{
    // PENDING(marc) find all the magic flags we need here...
    QWidget * const vp = qq->viewport();
    vp->setBackgroundRole( QPalette::Base );
    vp->setAttribute( Qt::WA_StaticContents );
    vp->setAttribute( Qt::WA_NoSystemBackground );
#ifndef QT_NO_CURSOR
    vp->setCursor(Qt::IBeamCursor);
#endif
}

KDLogTextWidget::Private::~Private() {}


void KDLogTextWidget::Private::updateCache() const {

    if ( cache.dirty >= Cache::FontMetrics ) {
        const QFontMetrics & fm = q->fontMetrics();
        cache.fontMetrics.lineSpacing = fm.lineSpacing();
        cache.fontMetrics.ascent = fm.ascent();
        cache.fontMetrics.averageCharWidth = fm.averageCharWidth();

        QVector<int> & lw = cache.fontMetrics.lineWidths;
        lw.clear();
        lw.reserve( lines.size() );
        Q_FOREACH( const LineItem & li, lines )
            lw.push_back( fm.width( li.text ) );
    }

    if ( cache.dirty >= Cache::Dimensions ) {
        const QVector<int> & lw = cache.fontMetrics.lineWidths;
        const QVector<int>::const_iterator it =
            std::max_element( lw.begin(), lw.end() );
        if ( it == lw.end() ) {
            cache.dimensions.indexOfLongestLine = -1;
            cache.dimensions.longestLineLength = 0;
        } else {
            cache.dimensions.indexOfLongestLine = it - lw.begin();
            cache.dimensions.longestLineLength = *it;
        }
    }

    cache.dirty = false;
}

unsigned int KDLogTextWidget::Private::findOrAddStyle( const Style & s ) {
    if ( idByStyle.contains( s ) ) {
        const unsigned int id = idByStyle[s];
        assert( styleByID.contains( id ) );
        assert( styleByID[id] == s );
        return id;
    } else {
        static unsigned int nextID = 0; // remember, 0 is reserved
        const unsigned int id = ++nextID;
        idByStyle.insert( s, id );
        styleByID.insert( id, s );
        return id;
    }
}

void KDLogTextWidget::Private::enforceHistorySize() {
    const size_t numLimes = lines.size();
    if ( numLimes <= historySize )
        return;
    const int remove = numLimes - historySize ;
    lines.erase( lines.begin(), lines.begin() + remove );

    // can't quickly update the dimensions if the fontMetrics aren't uptodate.
    if ( cache.dirty & Cache::FontMetrics ) {
        cache.dirty |= Cache::Dimensions;
        return;
    }

    QVector<int> & lw = cache.fontMetrics.lineWidths;

    assert( lw.size() > remove );
    lw.erase( lw.begin(), lw.begin() + remove );

    if ( cache.dirty & Cache::Dimensions )
        return;

    if ( cache.dimensions.indexOfLongestLine >= remove )
        cache.dimensions.indexOfLongestLine -= remove;
    else
        cache.dirty |= Cache::Dimensions;
}

static void set_scrollbar_properties( QScrollBar & sb, int document, int viewport, int singleStep, Qt::Orientation o ) {
    const int min = 0;
    const int max = std::max( 0, document - viewport );
    const int value = sb.value();
    const bool wasAtEnd = value == sb.maximum();
    sb.setRange( min, max );
    sb.setPageStep( viewport );
    sb.setSingleStep( singleStep );
    sb.setValue( o == Qt::Vertical && wasAtEnd ? sb.maximum() : value );
}

void KDLogTextWidget::Private::updateScrollRanges() {

    updateCache();

    if ( QScrollBar * const sb = q->verticalScrollBar() ) {
        const int document = lines.size() * cache.fontMetrics.lineSpacing ;
        const int viewport = q->viewport()->height();
        const int singleStep = cache.fontMetrics.lineSpacing;
        set_scrollbar_properties( *sb, document, viewport, singleStep, Qt::Vertical );
    }

    if ( QScrollBar * const sb = q->horizontalScrollBar() ) {
        const int document = cache.dimensions.longestLineLength;
        const int viewport = q->viewport()->width();
        const int singleStep = cache.fontMetrics.lineSpacing; // rather randomly chosen
        set_scrollbar_properties( *sb, document, viewport, singleStep, Qt::Horizontal );
    }
}

void KDLogTextWidget::Private::addPendingLines() {
    if ( pendingLines.empty() )
        return;

    const unsigned int oldNumLines = lines.size();

    lines += pendingLines;

    // if the cache isn't dirty, we can quickly update it without
    // invalidation:

    if ( !cache.dirty ) {

        // update fontMetrics:
        const QFontMetrics & fm = q->fontMetrics();
        QVector<int> plw;
        plw.reserve( pendingLines.size() );
        Q_FOREACH( const LineItem & li, pendingLines )
            plw.push_back( fm.width( li.text ) );

        // update dimensions:
        const QVector<int>::const_iterator it =
            std::max_element( plw.constBegin(), plw.constEnd() );
        if ( *it >= cache.dimensions.longestLineLength ) {
            cache.dimensions.longestLineLength = *it;
            cache.dimensions.indexOfLongestLine = oldNumLines + ( it - plw.constBegin() );
        }
    }

    pendingLines.clear();

    enforceHistorySize();
    updateScrollRanges();
    q->viewport()->update();
}

int KDLogTextWidget::Private::lineByYCoordinate( int y ) const {
    updateCache();
    if ( cache.fontMetrics.lineSpacing == 0 )
        return -1;
    const int raw = y / cache.fontMetrics.lineSpacing ;
    if ( raw < 0 )
        return -1;
    if ( raw >= lines.size() )
        return lines.size() - 1;
    return raw;
}

static int get_scrollbar_offset( const QScrollBar * sb ) {
    return sb ? sb->value() : 0 ;
}

QPoint KDLogTextWidget::Private::scrollOffset() const {
    return QPoint( get_scrollbar_offset( q->horizontalScrollBar() ),
                   get_scrollbar_offset( q->verticalScrollBar() ) );
}