source: trunk/src/declarative/graphicsitems/qdeclarativepainteditem.cpp

/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtDeclarative module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

#include "private/qdeclarativepainteditem_p.h"
#include "private/qdeclarativepainteditem_p_p.h"

#include <QDebug>
#include <QPen>
#include <QEvent>
#include <QApplication>
#include <QGraphicsSceneMouseEvent>
#include <QPainter>
#include <QPaintEngine>
#include <qmath.h>

QT_BEGIN_NAMESPACE

/*!
    \class QDeclarativePaintedItem
    \brief The QDeclarativePaintedItem class is an abstract base class for QDeclarativeView items that want cached painting.
    \internal

    This is a convenience class for implementing items that cache their painting.
    The contents of the item are cached behind the scenes.
    The dirtyCache() function should be called if the contents change to
    ensure the cache is refreshed the next time painting occurs.

    To subclass QDeclarativePaintedItem, you must reimplement drawContents() to draw
    the contents of the item.
*/

/*!
    \fn void QDeclarativePaintedItem::drawContents(QPainter *painter, const QRect &rect)

    This function is called when the cache needs to be refreshed. When
    sub-classing QDeclarativePaintedItem this function should be implemented so as to
    paint the contents of the item using the given \a painter for the
    area of the contents specified by \a rect.
*/

/*!
    \property QDeclarativePaintedItem::contentsSize
    \brief The size of the contents

    The contents size is the size of the item in regards to how it is painted
    using the drawContents() function.  This is distinct from the size of the
    item in regards to height() and width().
*/

// XXX bug in WebKit - can call repaintRequested and other cache-changing functions from within render!
static int inpaint=0;
static int inpaint_clearcache=0;

extern Q_GUI_EXPORT bool qt_applefontsmoothing_enabled;

/*!
    Marks areas of the cache that intersect with the given \a rect as dirty and
    in need of being refreshed.

    \sa clearCache()
*/
void QDeclarativePaintedItem::dirtyCache(const QRect& rect)
{
    Q_D(QDeclarativePaintedItem);
    QRect srect(qCeil(rect.x()*d->contentsScale),
            qCeil(rect.y()*d->contentsScale),
            qCeil(rect.width()*d->contentsScale),
            qCeil(rect.height()*d->contentsScale));
    for (int i=0; i < d->imagecache.count(); ) {
        QDeclarativePaintedItemPrivate::ImageCacheItem *c = d->imagecache[i];
        QRect isect = (c->area & srect) | c->dirty;
        if (isect == c->area && !inpaint) {
            delete d->imagecache.takeAt(i);
        } else {
            c->dirty = isect;
            ++i;
        }
    }
}

/*!
    Marks the entirety of the contents cache as dirty.

    \sa dirtyCache()
*/
void QDeclarativePaintedItem::clearCache()
{
    if (inpaint) {
        inpaint_clearcache=1;
        return;
    }
    Q_D(QDeclarativePaintedItem);
    qDeleteAll(d->imagecache);
    d->imagecache.clear();
}

/*!
    Returns the size of the contents.

    \sa setContentsSize()
*/
QSize QDeclarativePaintedItem::contentsSize() const
{
    Q_D(const QDeclarativePaintedItem);
    return d->contentsSize;
}

/*!
    Sets the size of the contents to the given \a size.

    \sa contentsSize()
*/
void QDeclarativePaintedItem::setContentsSize(const QSize &size)
{
    Q_D(QDeclarativePaintedItem);
    if (d->contentsSize == size) return;
    prepareGeometryChange();
    d->contentsSize = size;
    clearCache();
    update();
    emit contentsSizeChanged();
}

qreal QDeclarativePaintedItem::contentsScale() const
{
    Q_D(const QDeclarativePaintedItem);
    return d->contentsScale;
}

void QDeclarativePaintedItem::setContentsScale(qreal scale)
{
    Q_D(QDeclarativePaintedItem);
    if (d->contentsScale == scale) return;
    d->contentsScale = scale;
    clearCache();
    update();
    emit contentsScaleChanged();
}


/*!
    Constructs a new QDeclarativePaintedItem with the given \a parent.
*/
QDeclarativePaintedItem::QDeclarativePaintedItem(QDeclarativeItem *parent)
  : QDeclarativeItem(*(new QDeclarativePaintedItemPrivate), parent)
{
}

/*!
    \internal
    Constructs a new QDeclarativePaintedItem with the given \a parent and
    initialized private data member \a dd.
*/
QDeclarativePaintedItem::QDeclarativePaintedItem(QDeclarativePaintedItemPrivate &dd, QDeclarativeItem *parent)
  : QDeclarativeItem(dd, parent)
{
}

/*!
    Destroys the image item.
*/
QDeclarativePaintedItem::~QDeclarativePaintedItem()
{
    clearCache();
}

void QDeclarativePaintedItem::geometryChanged(const QRectF &newGeometry,
                                              const QRectF &oldGeometry)
{
    if (newGeometry.width() != oldGeometry.width() ||
        newGeometry.height() != oldGeometry.height())
        clearCache();

    QDeclarativeItem::geometryChanged(newGeometry, oldGeometry);
}

QVariant QDeclarativePaintedItem::itemChange(GraphicsItemChange change,
                                             const QVariant &value)
{
    if (change == ItemVisibleHasChanged)
        clearCache();

    return QDeclarativeItem::itemChange(change, value);
}

void QDeclarativePaintedItem::setCacheFrozen(bool frozen)
{
    Q_D(QDeclarativePaintedItem);
    if (d->cachefrozen == frozen)
        return;
    d->cachefrozen = frozen;
    // XXX clear cache?
}

QRectF QDeclarativePaintedItem::boundingRect() const
{
    Q_D(const QDeclarativePaintedItem);
    qreal w = d->mWidth;
    QSizeF sz = d->contentsSize * d->contentsScale;
    if (w < sz.width())
        w = sz.width();
    qreal h = d->mHeight;
    if (h < sz.height())
        h = sz.height();
    return QRectF(0.0,0.0,w,h);
}

/*!
    \internal
*/
void QDeclarativePaintedItem::paint(QPainter *p, const QStyleOptionGraphicsItem *, QWidget *)
{
    Q_D(QDeclarativePaintedItem);
    const QRect content = boundingRect().toRect();
    if (content.width() <= 0 || content.height() <= 0)
        return;

    ++inpaint;

    const QTransform &x = p->deviceTransform();
    QTransform xinv = x.inverted();
    QRegion effectiveClip;
    QRegion sysClip = p->paintEngine()->systemClip();
    if (xinv.type() <= QTransform::TxScale && sysClip.numRects() < 5) {
        // simple transform, region gets no more complicated...
        effectiveClip = xinv.map(sysClip);
    } else {
        // do not make complicated regions...
        effectiveClip = xinv.mapRect(sysClip.boundingRect());
    }

    QRegion topaint = p->clipRegion();
    if (topaint.isEmpty()) {
        if (effectiveClip.isEmpty())
            topaint = QRect(0,0,p->device()->width(),p->device()->height());
        else
            topaint = effectiveClip;
    } else if (!effectiveClip.isEmpty()) {
        topaint &= effectiveClip;
    }

    topaint &= content;
    QRegion uncached(content);
    p->setRenderHints(QPainter::SmoothPixmapTransform, d->smooth);

    int cachesize=0;
    for (int i=0; i<d->imagecache.count(); ++i) {
        QRect area = d->imagecache[i]->area;
        if (topaint.contains(area)) {
            QRectF target(area.x(), area.y(), area.width(), area.height());
            if (!d->cachefrozen) {
                if (!d->imagecache[i]->dirty.isNull() && topaint.contains(d->imagecache[i]->dirty)) {
#ifdef Q_WS_MAC
                    bool oldSmooth = qt_applefontsmoothing_enabled;
                    qt_applefontsmoothing_enabled = false;
#endif
                    QPainter qp(&d->imagecache[i]->image);
#ifdef Q_WS_MAC
                    qt_applefontsmoothing_enabled = oldSmooth;
#endif
                    qp.setRenderHints(QPainter::HighQualityAntialiasing | QPainter::TextAntialiasing | QPainter::SmoothPixmapTransform, d->smoothCache);
                    qp.translate(-area.x(), -area.y());
                    qp.scale(d->contentsScale,d->contentsScale);
                    QRect clip = d->imagecache[i]->dirty;
                    QRect sclip(qFloor(clip.x()/d->contentsScale),
                            qFloor(clip.y()/d->contentsScale),
                            qCeil(clip.width()/d->contentsScale+clip.x()/d->contentsScale-qFloor(clip.x()/d->contentsScale)),
                            qCeil(clip.height()/d->contentsScale+clip.y()/d->contentsScale-qFloor(clip.y()/d->contentsScale)));
                    qp.setClipRect(sclip);
                    if (d->fillColor.isValid()){
                        if(d->fillColor.alpha() < 255){
                            // ### Might not work outside of raster paintengine
                            QPainter::CompositionMode prev = qp.compositionMode();
                            qp.setCompositionMode(QPainter::CompositionMode_Source);
                            qp.fillRect(sclip,d->fillColor);
                            qp.setCompositionMode(prev);
                        }else{
                            qp.fillRect(sclip,d->fillColor);
                        }
                    }
                    drawContents(&qp, sclip);
                    d->imagecache[i]->dirty = QRect();
                }
            }
            p->drawPixmap(target.toRect(), d->imagecache[i]->image);
            topaint -= area;
            d->imagecache[i]->age=0;
        } else {
            d->imagecache[i]->age++;
        }
        cachesize += area.width()*area.height();
        uncached -= area;
    }

    if (!topaint.isEmpty()) {
        if (!d->cachefrozen) {
            // Find a sensible larger area, otherwise will paint lots of tiny images.
            QRect biggerrect = topaint.boundingRect().adjusted(-64,-64,128,128);
            cachesize += biggerrect.width() * biggerrect.height();
            while (d->imagecache.count() && cachesize > d->max_imagecache_size) {
                int oldest=-1;
                int age=-1;
                for (int i=0; i<d->imagecache.count(); ++i) {
                    int a = d->imagecache[i]->age;
                    if (a > age) {
                        oldest = i;
                        age = a;
                    }
                }
                cachesize -= d->imagecache[oldest]->area.width()*d->imagecache[oldest]->area.height();
                uncached += d->imagecache[oldest]->area;
                delete d->imagecache.takeAt(oldest);
            }
            const QRegion bigger = QRegion(biggerrect) & uncached;
            const QVector<QRect> rects = bigger.rects();
            for (int i = 0; i < rects.count(); ++i) {
                const QRect &r = rects.at(i);
                QPixmap img(r.size());
                if (d->fillColor.isValid())
                    img.fill(d->fillColor);
                {
#ifdef Q_WS_MAC
                    bool oldSmooth = qt_applefontsmoothing_enabled;
                    qt_applefontsmoothing_enabled = false;
#endif
                    QPainter qp(&img);
#ifdef Q_WS_MAC
                    qt_applefontsmoothing_enabled = oldSmooth;
#endif
                    qp.setRenderHints(QPainter::HighQualityAntialiasing | QPainter::TextAntialiasing | QPainter::SmoothPixmapTransform, d->smoothCache);

                    qp.translate(-r.x(),-r.y());
                    qp.scale(d->contentsScale,d->contentsScale);
                    QRect sclip(qFloor(r.x()/d->contentsScale),
                            qFloor(r.y()/d->contentsScale),
                            qCeil(r.width()/d->contentsScale+r.x()/d->contentsScale-qFloor(r.x()/d->contentsScale)),
                            qCeil(r.height()/d->contentsScale+r.y()/d->contentsScale-qFloor(r.y()/d->contentsScale)));
                    drawContents(&qp, sclip);
                }
                QDeclarativePaintedItemPrivate::ImageCacheItem *newitem = new QDeclarativePaintedItemPrivate::ImageCacheItem;
                newitem->area = r;
                newitem->image = img;
                d->imagecache.append(newitem);
                p->drawPixmap(r, newitem->image);
            }
        } else {
            const QVector<QRect> rects = uncached.rects();
            for (int i = 0; i < rects.count(); ++i)
                p->fillRect(rects.at(i), Qt::lightGray);
        }
    }

    if (inpaint_clearcache) {
        clearCache();
        inpaint_clearcache = 0;
    }

    --inpaint;
}

/*!
  \qmlproperty int PaintedItem::pixelCacheSize

  This property holds the maximum number of pixels of image cache to
  allow. The default is 0.1 megapixels. The cache will not be larger
  than the (unscaled) size of the WebView.
*/
/*!
  \property QDeclarativePaintedItem::pixelCacheSize

  The maximum number of pixels of image cache to allow. The default
  is 0.1 megapixels. The cache will not be larger than the (unscaled)
  size of the QDeclarativePaintedItem.
*/
int QDeclarativePaintedItem::pixelCacheSize() const
{
    Q_D(const QDeclarativePaintedItem);
    return d->max_imagecache_size;
}

void QDeclarativePaintedItem::setPixelCacheSize(int pixels)
{
    Q_D(QDeclarativePaintedItem);
    if (pixels < d->max_imagecache_size) {
        int cachesize=0;
        for (int i=0; i<d->imagecache.count(); ++i) {
            QRect area = d->imagecache[i]->area;
            cachesize += area.width()*area.height();
        }
        while (d->imagecache.count() && cachesize > pixels) {
            int oldest=-1;
            int age=-1;
            for (int i=0; i<d->imagecache.count(); ++i) {
                int a = d->imagecache[i]->age;
                if (a > age) {
                    oldest = i;
                    age = a;
                }
            }
            cachesize -= d->imagecache[oldest]->area.width()*d->imagecache[oldest]->area.height();
            delete d->imagecache.takeAt(oldest);
        }
    }
    d->max_imagecache_size = pixels;
}



/*!
    \property QDeclarativePaintedItem::fillColor

    The color to be used to fill the item prior to calling drawContents().
    By default, this is Qt::transparent.

    Performance improvements can be achieved if subclasses call this with either an
    invalid color (QColor()), or an appropriate solid color.
*/
void QDeclarativePaintedItem::setFillColor(const QColor& c)
{
    Q_D(QDeclarativePaintedItem);
    if (d->fillColor == c)
        return;
    d->fillColor = c;
    emit fillColorChanged();
    update();
}

QColor QDeclarativePaintedItem::fillColor() const
{
    Q_D(const QDeclarativePaintedItem);
    return d->fillColor;
}

/*!
    \qmlproperty bool PaintedItem::smoothCache

    Controls whether the cached tiles of which the item is composed are
    rendered smoothly when they are generated.

    This is in addition toe Item::smooth, which controls the smooth painting of
    the already-painted cached tiles under transformation.
*/
bool QDeclarativePaintedItem::smoothCache() const
{
    Q_D(const QDeclarativePaintedItem);
    return d->smoothCache;
}

void QDeclarativePaintedItem::setSmoothCache(bool on)
{
    Q_D(QDeclarativePaintedItem);
    if (d->smoothCache != on) {
        d->smoothCache = on;
        clearCache();
    }
}


QT_END_NAMESPACE