qwt_graphic.cpp

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/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *****************************************************************************/

#include "qwt_graphic.h"
#include "qwt_painter_command.h"
#include "qwt_math.h"

#include <qvector.h>
#include <qpainter.h>
#include <qpaintengine.h>
#include <qimage.h>
#include <qpixmap.h>
#include <qpainterpath.h>

#if QT_VERSION >= 0x050000

#include <qguiapplication.h>

static inline qreal qwtDevicePixelRatio()
{
    return qGuiApp ? qGuiApp->devicePixelRatio() : 1.0;
}

#endif

static bool qwtHasScalablePen( const QPainter *painter )
{
    const QPen pen = painter->pen();

    bool scalablePen = false;

    if ( pen.style() != Qt::NoPen && pen.brush().style() != Qt::NoBrush )
    {
        scalablePen = !pen.isCosmetic();
#if QT_VERSION < 0x050000
        if ( !scalablePen && pen.widthF() == 0.0 )
        {
            const QPainter::RenderHints hints = painter->renderHints();
            if ( hints.testFlag( QPainter::NonCosmeticDefaultPen ) )
                scalablePen = true;
        }
#endif
    }

    return scalablePen;
}

static QRectF qwtStrokedPathRect(
    const QPainter *painter, const QPainterPath &path )
{
    QPainterPathStroker stroker;
    stroker.setWidth( painter->pen().widthF() );
    stroker.setCapStyle( painter->pen().capStyle() );
    stroker.setJoinStyle( painter->pen().joinStyle() );
    stroker.setMiterLimit( painter->pen().miterLimit() );

    QRectF rect;
    if ( qwtHasScalablePen( painter ) )
    {
        QPainterPath stroke = stroker.createStroke( path );
        rect = painter->transform().map( stroke ).boundingRect();
    }
    else
    {
        QPainterPath mappedPath = painter->transform().map( path );
        mappedPath = stroker.createStroke( mappedPath );

        rect = mappedPath.boundingRect();
    }

    return rect;
}

static inline void qwtExecCommand(
    QPainter *painter, const QwtPainterCommand &cmd,
    QwtGraphic::RenderHints renderHints,
    const QTransform &transform,
    const QTransform *initialTransform )
{
    switch( cmd.type() )
    {
        case QwtPainterCommand::Path:
        {
            bool doMap = false;

            if ( painter->transform().isScaling() )
            {
                bool isCosmetic = painter->pen().isCosmetic();
#if QT_VERSION < 0x050000
                if ( isCosmetic && painter->pen().widthF() == 0.0 )
                {
                    QPainter::RenderHints hints = painter->renderHints();
                    if ( hints.testFlag( QPainter::NonCosmeticDefaultPen ) )
                        isCosmetic = false;
                }
#endif

                if ( isCosmetic )
                {
                    // OpenGL2 seems to be buggy for cosmetic pens.
                    // It interpolates curves in too rough steps then

                    doMap = painter->paintEngine()->type() == QPaintEngine::OpenGL2;
                }
                else
                {
                    doMap = renderHints.testFlag( QwtGraphic::RenderPensUnscaled );
                }
            }

            if ( doMap )
            {
                const QTransform tr = painter->transform();

                painter->resetTransform();

                QPainterPath path = tr.map( *cmd.path() );
                if ( initialTransform )
                {
                    painter->setTransform( *initialTransform );
                    path = initialTransform->inverted().map( path );
                }

                painter->drawPath( path );

                painter->setTransform( tr );
            }
            else
            {
                painter->drawPath( *cmd.path() );
            }
            break;
        }
        case QwtPainterCommand::Pixmap:
        {
            const QwtPainterCommand::PixmapData *data = cmd.pixmapData();
            painter->drawPixmap( data->rect, data->pixmap, data->subRect );
            break;
        }
        case QwtPainterCommand::Image:
        {
            const QwtPainterCommand::ImageData *data = cmd.imageData();
            painter->drawImage( data->rect, data->image,
                data->subRect, data->flags );
            break;
        }
        case QwtPainterCommand::State:
        {
            const QwtPainterCommand::StateData *data = cmd.stateData();

            if ( data->flags & QPaintEngine::DirtyPen )
                painter->setPen( data->pen );

            if ( data->flags & QPaintEngine::DirtyBrush )
                painter->setBrush( data->brush );

            if ( data->flags & QPaintEngine::DirtyBrushOrigin )
                painter->setBrushOrigin( data->brushOrigin );

            if ( data->flags & QPaintEngine::DirtyFont )
                painter->setFont( data->font );

            if ( data->flags & QPaintEngine::DirtyBackground )
            {
                painter->setBackgroundMode( data->backgroundMode );
                painter->setBackground( data->backgroundBrush );
            }

            if ( data->flags & QPaintEngine::DirtyTransform )
            {
                painter->setTransform( data->transform * transform );
            }

            if ( data->flags & QPaintEngine::DirtyClipEnabled )
                painter->setClipping( data->isClipEnabled );

            if ( data->flags & QPaintEngine::DirtyClipRegion )
            {
                painter->setClipRegion( data->clipRegion,
                    data->clipOperation );
            }

            if ( data->flags & QPaintEngine::DirtyClipPath )
            {
                painter->setClipPath( data->clipPath, data->clipOperation );
            }

            if ( data->flags & QPaintEngine::DirtyHints )
            {
                for ( int i = 0; i < 8; i++ )
                {
                    const QPainter::RenderHint hint = static_cast< QPainter::RenderHint >( 1 << i );
                    painter->setRenderHint( hint, data->renderHints.testFlag( hint ) );
                }
            }

            if ( data->flags & QPaintEngine::DirtyCompositionMode )
                painter->setCompositionMode( data->compositionMode );

            if ( data->flags & QPaintEngine::DirtyOpacity )
                painter->setOpacity( data->opacity );

            break;
        }
        default:
            break;
    }
}

class QwtGraphic::PathInfo
{
public:
    PathInfo():
        d_scalablePen( false )
    {
        // QVector needs a default constructor
    }

    PathInfo( const QRectF &pointRect,
            const QRectF &boundingRect, bool scalablePen ):
        d_pointRect( pointRect ),
        d_boundingRect( boundingRect ),
        d_scalablePen( scalablePen )
    {
    }

    inline QRectF scaledBoundingRect( qreal sx, qreal sy, bool scalePens ) const
    {
        if ( sx == 1.0 && sy == 1.0 )
            return d_boundingRect;

        QTransform transform;
        transform.scale( sx, sy );

        QRectF rect;
        if ( scalePens && d_scalablePen )
        {
            rect = transform.mapRect( d_boundingRect );
        }
        else
        {
            rect = transform.mapRect( d_pointRect );

            const qreal l = qAbs( d_pointRect.left() - d_boundingRect.left() );
            const qreal r = qAbs( d_pointRect.right() - d_boundingRect.right() );
            const qreal t = qAbs( d_pointRect.top() - d_boundingRect.top() );
            const qreal b = qAbs( d_pointRect.bottom() - d_boundingRect.bottom() );

            rect.adjust( -l, -t, r, b );
        }

        return rect;
    }

    inline double scaleFactorX( const QRectF& pathRect,
        const QRectF &targetRect, bool scalePens ) const
    {
        if ( pathRect.width() <= 0.0 )
            return 0.0;

        const QPointF p0 = d_pointRect.center();

        const qreal l = qAbs( pathRect.left() - p0.x() );
        const qreal r = qAbs( pathRect.right() - p0.x() );

        const double w = 2.0 * qwtMinF( l, r )
            * targetRect.width() / pathRect.width();

        double sx;
        if ( scalePens && d_scalablePen )
        {
            sx = w / d_boundingRect.width();
        }
        else
        {
            const qreal pw = qwtMaxF(
                qAbs( d_boundingRect.left() - d_pointRect.left() ),
                qAbs( d_boundingRect.right() - d_pointRect.right() ) );

            sx = ( w - 2 * pw ) / d_pointRect.width();
        }

        return sx;
    }

    inline double scaleFactorY( const QRectF& pathRect,
        const QRectF &targetRect, bool scalePens ) const
    {
        if ( pathRect.height() <= 0.0 )
            return 0.0;

        const QPointF p0 = d_pointRect.center();

        const qreal t = qAbs( pathRect.top() - p0.y() );
        const qreal b = qAbs( pathRect.bottom() - p0.y() );

        const qreal h = 2.0 * qwtMinF( t, b )
            * targetRect.height() / pathRect.height();

        double sy;
        if ( scalePens && d_scalablePen )
        {
            sy = h / d_boundingRect.height();
        }
        else
        {
            const qreal pw = qwtMaxF(
                qAbs( d_boundingRect.top() - d_pointRect.top() ),
                qAbs( d_boundingRect.bottom() - d_pointRect.bottom() ) );

            sy = ( h - 2 * pw ) / d_pointRect.height();
        }

        return sy;
    }

private:
    QRectF d_pointRect;
    QRectF d_boundingRect;
    bool d_scalablePen;
};

class QwtGraphic::PrivateData
{
public:
    PrivateData():
        boundingRect( 0.0, 0.0, -1.0, -1.0 ),
        pointRect( 0.0, 0.0, -1.0, -1.0 )
    {
    }

    QSizeF defaultSize;
    QVector< QwtPainterCommand > commands;
    QVector< QwtGraphic::PathInfo > pathInfos;

    QRectF boundingRect;
    QRectF pointRect;

    QwtGraphic::CommandTypes commandTypes;
    QwtGraphic::RenderHints renderHints;
};

QwtGraphic::QwtGraphic():
    QwtNullPaintDevice()
{
    setMode( QwtNullPaintDevice::PathMode );
    d_data = new PrivateData;
}

QwtGraphic::QwtGraphic( const QwtGraphic &other ):
    QwtNullPaintDevice()
{
    setMode( other.mode() );
    d_data = new PrivateData( *other.d_data );
}

QwtGraphic::~QwtGraphic()
{
    delete d_data;
}

QwtGraphic& QwtGraphic::operator=( const QwtGraphic &other )
{
    setMode( other.mode() );
    *d_data = *other.d_data;

    return *this;
}

void QwtGraphic::reset()
{
    d_data->commands.clear();
    d_data->pathInfos.clear();

    d_data->commandTypes = CommandTypes();

    d_data->boundingRect = QRectF( 0.0, 0.0, -1.0, -1.0 );
    d_data->pointRect = QRectF( 0.0, 0.0, -1.0, -1.0 );
    d_data->defaultSize = QSizeF();
}

bool QwtGraphic::isNull() const
{
    return d_data->commands.isEmpty();
}

bool QwtGraphic::isEmpty() const
{
    return d_data->boundingRect.isEmpty();
}

QwtGraphic::CommandTypes QwtGraphic::commandTypes() const
{
    return d_data->commandTypes;
}

void QwtGraphic::setRenderHint( RenderHint hint, bool on )
{
    if ( on )
        d_data->renderHints |= hint;
    else
        d_data->renderHints &= ~hint;
}

bool QwtGraphic::testRenderHint( RenderHint hint ) const
{
    return d_data->renderHints.testFlag( hint );
}

QwtGraphic::RenderHints QwtGraphic::renderHints() const
{
    return d_data->renderHints;
}

QRectF QwtGraphic::boundingRect() const
{
    if ( d_data->boundingRect.width() < 0 )
        return QRectF();

    return d_data->boundingRect;
}

QRectF QwtGraphic::controlPointRect() const
{
    if ( d_data->pointRect.width() < 0 )
        return QRectF();

    return d_data->pointRect;
}

QRectF QwtGraphic::scaledBoundingRect( qreal sx, qreal sy ) const
{
    if ( sx == 1.0 && sy == 1.0 )
        return d_data->boundingRect;

    const bool scalePens = !( d_data->renderHints & RenderPensUnscaled );

    QTransform transform;
    transform.scale( sx, sy );

    QRectF rect = transform.mapRect( d_data->pointRect );

    for ( int i = 0; i < d_data->pathInfos.size(); i++ )
        rect |= d_data->pathInfos[i].scaledBoundingRect( sx, sy, scalePens );

    return rect;
}

QSize QwtGraphic::sizeMetrics() const
{
    const QSizeF sz = defaultSize();
    return QSize( qwtCeil( sz.width() ), qwtCeil( sz.height() ) );
}

void QwtGraphic::setDefaultSize( const QSizeF &size )
{
    const double w = qwtMaxF( 0.0, size.width() );
    const double h = qwtMaxF( 0.0, size.height() );

    d_data->defaultSize = QSizeF( w, h );
}

QSizeF QwtGraphic::defaultSize() const
{
    if ( !d_data->defaultSize.isEmpty() )
        return d_data->defaultSize;

    return boundingRect().size();
}

qreal QwtGraphic::heightForWidth( qreal width ) const
{
    const QSizeF sz = defaultSize();
    if ( sz.isEmpty() )
        return 0.0;

    return sz.height() * width / sz.width();
}

qreal QwtGraphic::widthForHeight( qreal height ) const
{
    const QSizeF sz = defaultSize();
    if ( sz.isEmpty() )
        return 0.0;

    return sz.width() * height / sz.height();
}

void QwtGraphic::render( QPainter *painter ) const
{
    renderGraphic( painter, NULL );
}

void QwtGraphic::renderGraphic( QPainter* painter, QTransform *initialTransform ) const
{
    if ( isNull() )
        return;

    const int numCommands = d_data->commands.size();
    const QwtPainterCommand *commands = d_data->commands.constData();

    const QTransform transform = painter->transform();

    painter->save();

    for ( int i = 0; i < numCommands; i++ )
    {
        qwtExecCommand( painter, commands[i],
            d_data->renderHints, transform, initialTransform );
    }

    painter->restore();
}

void QwtGraphic::render( QPainter *painter, const QSizeF &size,
    Qt::AspectRatioMode aspectRatioMode ) const
{
    const QRectF r( 0.0, 0.0, size.width(), size.height() );
    render( painter, r, aspectRatioMode );
}

void QwtGraphic::render( QPainter *painter, const QRectF &rect,
    Qt::AspectRatioMode aspectRatioMode ) const
{
    if ( isEmpty() || rect.isEmpty() )
        return;

    double sx = 1.0;
    double sy = 1.0;

    if ( d_data->pointRect.width() > 0.0 )
        sx = rect.width() / d_data->pointRect.width();

    if ( d_data->pointRect.height() > 0.0 )
        sy = rect.height() / d_data->pointRect.height();

    const bool scalePens = !d_data->renderHints.testFlag( RenderPensUnscaled );

    for ( int i = 0; i < d_data->pathInfos.size(); i++ )
    {
        const PathInfo &info = d_data->pathInfos[i];

        const double ssx = info.scaleFactorX(
            d_data->pointRect, rect, scalePens );

        if ( ssx > 0.0 )
            sx = qwtMinF( sx, ssx );

        const double ssy = info.scaleFactorY(
            d_data->pointRect, rect, scalePens );

        if ( ssy > 0.0 )
            sy = qwtMinF( sy, ssy );
    }

    if ( aspectRatioMode == Qt::KeepAspectRatio )
    {
        const qreal s = qwtMinF( sx, sy );
        sx = s;
        sy = s;
    }
    else if ( aspectRatioMode == Qt::KeepAspectRatioByExpanding )
    {
        const qreal s = qwtMaxF( sx, sy );
        sx = s;
        sy = s;
    }

    QTransform tr;
    tr.translate( rect.center().x() - 0.5 * sx * d_data->pointRect.width(),
        rect.center().y() - 0.5 * sy * d_data->pointRect.height() );
    tr.scale( sx, sy );
    tr.translate( -d_data->pointRect.x(), -d_data->pointRect.y() );

    const QTransform transform = painter->transform();

    painter->setTransform( tr, true );

    if ( !scalePens && transform.isScaling() )
    {
        // we don't want to scale pens according to sx/sy,
        // but we want to apply the scaling from the
        // painter transformation later

        QTransform initialTransform;
        initialTransform.scale( transform.m11(), transform.m22() );

        renderGraphic( painter, &initialTransform );
    }
    else
    {
        renderGraphic( painter, NULL );
    }

    painter->setTransform( transform );
}

void QwtGraphic::render( QPainter *painter,
    const QPointF &pos, Qt::Alignment alignment ) const
{
    QRectF r( pos, defaultSize() );

    if ( alignment & Qt::AlignLeft )
    {
        r.moveLeft( pos.x() );
    }
    else if ( alignment & Qt::AlignHCenter )
    {
        r.moveCenter( QPointF( pos.x(), r.center().y() ) );
    }
    else if ( alignment & Qt::AlignRight )
    {
        r.moveRight( pos.x() );
    }

    if ( alignment & Qt::AlignTop )
    {
        r.moveTop( pos.y() );
    }
    else if ( alignment & Qt::AlignVCenter )
    {
        r.moveCenter( QPointF( r.center().x(), pos.y() ) );
    }
    else if ( alignment & Qt::AlignBottom )
    {
        r.moveBottom( pos.y() );
    }

    render( painter, r );
}

QPixmap QwtGraphic::toPixmap( qreal devicePixelRatio ) const
{
    if ( isNull() )
        return QPixmap();

    const QSizeF sz = defaultSize();

    const int w = qwtCeil( sz.width() );
    const int h = qwtCeil( sz.height() );

    QPixmap pixmap( w, h );

#if QT_VERSION >= 0x050000
    if ( devicePixelRatio <= 0.0 )
        devicePixelRatio = qwtDevicePixelRatio();

    pixmap.setDevicePixelRatio( devicePixelRatio );
#else
    Q_UNUSED( devicePixelRatio )
#endif

    pixmap.fill( Qt::transparent );

    const QRectF r( 0.0, 0.0, sz.width(), sz.height() );

    QPainter painter( &pixmap );
    render( &painter, r, Qt::KeepAspectRatio );
    painter.end();

    return pixmap;
}

QPixmap QwtGraphic::toPixmap( const QSize &size,
    Qt::AspectRatioMode aspectRatioMode, qreal devicePixelRatio ) const
{
    QPixmap pixmap( size );

#if QT_VERSION >= 0x050000
    if ( devicePixelRatio <= 0.0 )
        devicePixelRatio = qwtDevicePixelRatio();

    pixmap.setDevicePixelRatio( devicePixelRatio );
#else
    Q_UNUSED( devicePixelRatio )
#endif
    pixmap.fill( Qt::transparent );

    const QRect r( 0, 0, size.width(), size.height() );

    QPainter painter( &pixmap );
    render( &painter, r, aspectRatioMode );
    painter.end();

    return pixmap;
}

QImage QwtGraphic::toImage( const QSize &size,
    Qt::AspectRatioMode aspectRatioMode, qreal devicePixelRatio  ) const
{
#if QT_VERSION >= 0x050000
    if ( devicePixelRatio <= 0.0 )
        devicePixelRatio = qwtDevicePixelRatio();

    QImage image( size * devicePixelRatio, QImage::Format_ARGB32_Premultiplied );
    image.setDevicePixelRatio( devicePixelRatio );
#else
    Q_UNUSED( devicePixelRatio )
    QImage image( size, QImage::Format_ARGB32_Premultiplied );
#endif

    image.fill( 0 );

    const QRect r( 0, 0, size.width(), size.height() );

    QPainter painter( &image );
    render( &painter, r, aspectRatioMode );
    painter.end();

    return image;
}

QImage QwtGraphic::toImage( qreal devicePixelRatio ) const
{
    if ( isNull() )
        return QImage();

    const QSizeF sz = defaultSize();

    int w = qwtCeil( sz.width() );
    int h = qwtCeil( sz.height() );

#if QT_VERSION >= 0x050000
    if ( devicePixelRatio <= 0.0 )
        devicePixelRatio = qwtDevicePixelRatio();

    w *= devicePixelRatio;
    h *= devicePixelRatio;

    QImage image( w, h, QImage::Format_ARGB32 );
    image.setDevicePixelRatio( devicePixelRatio );
#else
    Q_UNUSED( devicePixelRatio )
    QImage image( w, h, QImage::Format_ARGB32 );
#endif

    image.fill( 0 );

    const QRect r( 0, 0, sz.width(), sz.height() );

    QPainter painter( &image );
    render( &painter, r, Qt::KeepAspectRatio );
    painter.end();

    return image;
}

void QwtGraphic::drawPath( const QPainterPath &path )
{
    const QPainter *painter = paintEngine()->painter();
    if ( painter == NULL )
        return;

    d_data->commands += QwtPainterCommand( path );
    d_data->commandTypes |= QwtGraphic::VectorData;

    if ( !path.isEmpty() )
    {
        const QPainterPath scaledPath = painter->transform().map( path );

        QRectF pointRect = scaledPath.boundingRect();
        QRectF boundingRect = pointRect;

        if ( painter->pen().style() != Qt::NoPen
            && painter->pen().brush().style() != Qt::NoBrush )
        {
            boundingRect = qwtStrokedPathRect( painter, path );
        }

        updateControlPointRect( pointRect );
        updateBoundingRect( boundingRect );

        d_data->pathInfos += PathInfo( pointRect,
            boundingRect, qwtHasScalablePen( painter ) );
    }
}

void QwtGraphic::drawPixmap( const QRectF &rect,
    const QPixmap &pixmap, const QRectF &subRect )
{
    const QPainter *painter = paintEngine()->painter();
    if ( painter == NULL )
        return;

    d_data->commands += QwtPainterCommand( rect, pixmap, subRect );
    d_data->commandTypes |= QwtGraphic::RasterData;

    const QRectF r = painter->transform().mapRect( rect );
    updateControlPointRect( r );
    updateBoundingRect( r );
}

void QwtGraphic::drawImage( const QRectF &rect, const QImage &image,
    const QRectF &subRect, Qt::ImageConversionFlags flags )
{
    const QPainter *painter = paintEngine()->painter();
    if ( painter == NULL )
        return;

    d_data->commands += QwtPainterCommand( rect, image, subRect, flags );
    d_data->commandTypes |= QwtGraphic::RasterData;

    const QRectF r = painter->transform().mapRect( rect );

    updateControlPointRect( r );
    updateBoundingRect( r );
}

void QwtGraphic::updateState( const QPaintEngineState &state )
{
    d_data->commands += QwtPainterCommand( state );

    if ( state.state() & QPaintEngine::DirtyTransform )
    {
        if ( !( d_data->commandTypes & QwtGraphic::Transformation ) )
        {
            /*
                QTransform::isScaling() returns true for all type
                of transformations beside simple translations
                even if it is f.e a rotation
             */
            if ( state.transform().isScaling() )
                d_data->commandTypes |= QwtGraphic::Transformation;
        }
    }
}

void QwtGraphic::updateBoundingRect( const QRectF &rect )
{
    QRectF br = rect;

    const QPainter *painter = paintEngine()->painter();
    if ( painter && painter->hasClipping() )
    {
        QRectF cr = painter->clipRegion().boundingRect();
        cr = painter->transform().mapRect( cr );

        br &= cr;
    }

    if ( d_data->boundingRect.width() < 0 )
        d_data->boundingRect = br;
    else
        d_data->boundingRect |= br;
}

void QwtGraphic::updateControlPointRect( const QRectF &rect )
{
    if ( d_data->pointRect.width() < 0.0 )
        d_data->pointRect = rect;
    else
        d_data->pointRect |= rect;
}

const QVector< QwtPainterCommand > &QwtGraphic::commands() const
{
    return d_data->commands;
}

void QwtGraphic::setCommands( const QVector< QwtPainterCommand > &commands )
{
    reset();

    const int numCommands = commands.size();
    if ( numCommands <= 0 )
        return;

    // to calculate a proper bounding rectangle we don't simply copy
    // the commands.

    const QwtPainterCommand *cmds = commands.constData();

    const QTransform noTransform;
    const RenderHints noRenderHints;

    QPainter painter( this );
    for ( int i = 0; i < numCommands; i++ )
        qwtExecCommand( &painter, cmds[i], noRenderHints, noTransform, NULL );

    painter.end();
}