path: root/src/declarative/graphicsitems/qdeclarativeimage.cpp

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#include "private/qdeclarativeimage_p.h"
#include "private/qdeclarativeimage_p_p.h"

#include <QKeyEvent>
#include <QPainter>

QT_BEGIN_NAMESPACE


/*!
    \qmlclass Image QDeclarativeImage
    \since 4.7
    \brief The Image element allows you to add bitmaps to a scene.
    \inherits Item

    An Image element displays a specified \l source image:

    \table
    \row
    \o \image declarative-qtlogo.png
    \o \qml
        import Qt 4.7

        Image { source: "qtlogo.png" }
    \endqml
    \endtable
    
    If a size is not specified explicitly, the Image element is sized to the loaded image.
    Image elements can be stretched and tiled using the \l fillMode property.

    If the image \l source is a network resource, the image is loaded asynchronous and the
    \l progress and \l status properties are updated appropriately.  Otherwise, if the image is
    available locally, it is loaded immediately and the user interface is blocked until loading is
    complete.  (This is typically the correct behavior for user interface elements.)
    For large local images, which do not need to be visible immediately, it may be preferable to
    enable \l asynchronous loading.  This loads the image in the background using a low priority thread.

    Images are cached and shared internally, so if several Image elements have the same source
    only one copy of the image will be loaded.

    \bold Note: Images are often the greatest user of memory in QML user interfaces.  It is recommended
    that images which do not form part of the user interface have their
    size bounded via the \l sourceSize property. This is especially important for content
    that is loaded from external sources or provided by the user.

    \sa {declarative/imageelements/image}{Image example}
*/

/*!
    \internal
    \class QDeclarativeImage Image
    \brief The QDeclarativeImage class provides an image item that you can add to a QDeclarativeView.

    Example:
    \qml
    Image { source: "pics/star.png" }
    \endqml

    A QDeclarativeImage object can be instantiated in QML using the tag \l Image.
*/

QDeclarativeImage::QDeclarativeImage(QDeclarativeItem *parent)
    : QDeclarativeImageBase(*(new QDeclarativeImagePrivate), parent)
{
}

QDeclarativeImage::QDeclarativeImage(QDeclarativeImagePrivate &dd, QDeclarativeItem *parent)
    : QDeclarativeImageBase(dd, parent)
{
}

QDeclarativeImage::~QDeclarativeImage()
{
}

/*!
    \qmlproperty QPixmap Image::pixmap

    This property holds the QPixmap image to display.

    This is useful for displaying images provided by a C++ implementation,
    for example, a model may provide a data role of type QPixmap.
*/

QPixmap QDeclarativeImage::pixmap() const
{
    Q_D(const QDeclarativeImage);
    return d->pix;
}

void QDeclarativeImage::setPixmap(const QPixmap &pix)
{
    Q_D(QDeclarativeImage);
    if (!d->url.isEmpty())
        return;
    d->setPixmap(pix);
}

void QDeclarativeImagePrivate::setPixmap(const QPixmap &pixmap)
{
    Q_Q(QDeclarativeImage);
    pix = pixmap;

    q->setImplicitWidth(pix.width());
    q->setImplicitHeight(pix.height());
    status = pix.isNull() ? QDeclarativeImageBase::Null : QDeclarativeImageBase::Ready;

    q->update();
    q->pixmapChange();
}

/*!
    \qmlproperty enumeration Image::fillMode

    Set this property to define what happens when the image set for the item is smaller
    than the size of the item.

    \list
    \o Image.Stretch - the image is scaled to fit
    \o Image.PreserveAspectFit - the image is scaled uniformly to fit without cropping
    \o Image.PreserveAspectCrop - the image is scaled uniformly to fill, cropping if necessary
    \o Image.Tile - the image is duplicated horizontally and vertically
    \o Image.TileVertically - the image is stretched horizontally and tiled vertically
    \o Image.TileHorizontally - the image is stretched vertically and tiled horizontally
    \endlist

    \table
    
    \row
    \o \image declarative-qtlogo-stretch.png
    \o Stretch (default)
    \qml
    Image {
        width: 130; height: 100
        smooth: true
        source: "qtlogo.png"
    }
    \endqml

    \row
    \o \image declarative-qtlogo-preserveaspectfit.png
    \o PreserveAspectFit
    \qml
    Image {
        width: 130; height: 100
        fillMode: Image.PreserveAspectFit
        smooth: true
        source: "qtlogo.png"
    }
    \endqml

    \row
    \o \image declarative-qtlogo-preserveaspectcrop.png
    \o PreserveAspectCrop
    \qml
    Image {
        width: 130; height: 100
        fillMode: Image.PreserveAspectCrop
        smooth: true
        source: "qtlogo.png"
    }
    \endqml

    \row
    \o \image declarative-qtlogo-tile.png
    \o Tile
    \qml
    Image {
        width: 120; height: 120
        fillMode: Image.Tile
        source: "qtlogo.png"
    }
    \endqml

    \row
    \o \image declarative-qtlogo-tilevertically.png
    \o TileVertically
    \qml
    Image {
        width: 120; height: 120
        fillMode: Image.TileVertically
        source: "qtlogo.png"
    }
    \endqml

    \row
    \o \image declarative-qtlogo-tilehorizontally.png
    \o TileHorizontally
    \qml
    Image {
        width: 120; height: 120
        fillMode: Image.TileHorizontally
        source: "qtlogo.png"
    }
    \endqml

    \endtable
*/
QDeclarativeImage::FillMode QDeclarativeImage::fillMode() const
{
    Q_D(const QDeclarativeImage);
    return d->fillMode;
}

void QDeclarativeImage::setFillMode(FillMode mode)
{
    Q_D(QDeclarativeImage);
    if (d->fillMode == mode)
        return;
    d->fillMode = mode;
    update();
    updatePaintedGeometry();
    emit fillModeChanged();
}

qreal QDeclarativeImage::paintedWidth() const
{
    Q_D(const QDeclarativeImage);
    return d->paintedWidth;
}

qreal QDeclarativeImage::paintedHeight() const
{
    Q_D(const QDeclarativeImage);
    return d->paintedHeight;
}

/*!
    \qmlproperty enumeration Image::status

    This property holds the status of image loading.  It can be one of:
    \list
    \o Image.Null - no image has been set
    \o Image.Ready - the image has been loaded
    \o Image.Loading - the image is currently being loaded
    \o Image.Error - an error occurred while loading the image
    \endlist

    Use this status to provide an update or respond to the status change in some way.
    For example, you could:

    \e {Trigger a state change:}
    \qml 
        State { name: 'loaded'; when: image.status = Image.Ready }
    \endqml

    \e {Implement an \c onStatusChanged signal handler:}
    \qml 
        Image {
            id: image
            onStatusChanged: if (image.status == Image.Ready) console.log('Loaded')
        }
    \endqml

    \e {Bind to the status value:}
    \qml
        Text { text: image.status != Image.Ready ? 'Not Loaded' : 'Loaded' }
    \endqml

    \sa progress
*/

/*!
    \qmlproperty real Image::progress

    This property holds the progress of image loading, from 0.0 (nothing loaded)
    to 1.0 (finished).

    \sa status
*/

/*!
    \qmlproperty bool Image::smooth

    Set this property if you want the image to be smoothly filtered when scaled or
    transformed.  Smooth filtering gives better visual quality, but is slower.  If
    the image is displayed at its natural size, this property has no visual or
    performance effect.

    \note Generally scaling artifacts are only visible if the image is stationary on
    the screen.  A common pattern when animating an image is to disable smooth
    filtering at the beginning of the animation and reenable it at the conclusion.
*/

/*!
    \qmlproperty QSize Image::sourceSize

    This property holds the size of the loaded image, in pixels.

    This is used to control the storage used by a loaded image. Unlike
    the width and height properties, which scale the painting of the image, this property
    affects the number of pixels stored.

    If the image's actual size is larger than the sourceSize, the image is scaled down.
    If only one dimension of the size is set to greater than 0, the
    other dimension is set in proportion to preserve the source image's aspect ratio.
    (The \l fillMode is independent of this.)
   
    If the source is an instrinsically scalable image (eg. SVG), this property
    determines the size of the loaded image regardless of intrinsic size.
    Avoid changing this property dynamically; rendering an SVG is \e slow compared
    to an image.

    If the source is a non-scalable image (eg. JPEG), the loaded image will
    be no greater than this property specifies. For some formats (currently only JPEG),
    the whole image will never actually be loaded into memory.
 
    \note \e{Changing this property dynamically will lead to the image source being reloaded,
    potentially even from the network if it is not in the disk cache.}

    Here is an example that ensures the size of the image in memory is
    no larger than 1024x1024 pixels, regardless of the size of the Image element.

    \code
    Image {
       anchors.fill: parent
       source: "images/reallyBigImage.jpg"
       sourceSize.width: 1024
       sourceSize.height: 1024
    }
    \endcode

    The example below ensures the memory used by the image is no more than necessary 
    to display the image at the size of the Image element.
    Of course if the Image element is resized a costly reload will be required, so
    use this technique \e only when the Image size is fixed.

    \code
    Image {
       anchors.fill: parent
       source: "images/reallyBigImage.jpg"
       sourceSize.width: width
       sourceSize.height: height
    }
    \endcode
*/

void QDeclarativeImage::updatePaintedGeometry()
{
    Q_D(QDeclarativeImage);

    if (d->fillMode == PreserveAspectFit) {
        if (!d->pix.width() || !d->pix.height())
            return;
        qreal widthScale = width() / qreal(d->pix.width());
        qreal heightScale = height() / qreal(d->pix.height());
        if (widthScale <= heightScale) {
            d->paintedWidth = width();
            d->paintedHeight = widthScale * qreal(d->pix.height());
        } else if(heightScale < widthScale) {
            d->paintedWidth = heightScale * qreal(d->pix.width());
            d->paintedHeight = height();
        }
        if (widthValid() && !heightValid()) {
            setImplicitHeight(d->paintedHeight);
        }
        if (heightValid() && !widthValid()) {
            setImplicitWidth(d->paintedWidth);
        }
    } else {
        d->paintedWidth = width();
        d->paintedHeight = height();
    }
    emit paintedGeometryChanged();
}

void QDeclarativeImage::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    QDeclarativeImageBase::geometryChanged(newGeometry, oldGeometry);
    updatePaintedGeometry();
}

/*!
    \qmlproperty url Image::source

    Image can handle any image format supported by Qt, loaded from any URL scheme supported by Qt.

    The URL may be absolute, or relative to the URL of the component.
*/

/*!
    \qmlproperty bool Image::asynchronous

    Specifies that images on the local filesystem should be loaded
    asynchronously in a separate thread.  The default value is
    false, causing the user interface thread to block while the
    image is loaded.  Setting \a asynchronous to true is useful where
    maintaining a responsive user interface is more desireable
    than having images immediately visible.

    Note that this property is only valid for images read from the
    local filesystem.  Images loaded via a network resource (e.g. HTTP)
    are always loaded asynchonously.
*/

void QDeclarativeImage::paint(QPainter *p, const QStyleOptionGraphicsItem *, QWidget *)
{
    Q_D(QDeclarativeImage);
    if (d->pix.isNull())
        return;

    bool oldAA = p->testRenderHint(QPainter::Antialiasing);
    bool oldSmooth = p->testRenderHint(QPainter::SmoothPixmapTransform);
    if (d->smooth)
        p->setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform, d->smooth);

    if (width() != d->pix.width() || height() != d->pix.height()) {
        if (d->fillMode >= Tile) {
            if (d->fillMode == Tile) {
                p->drawTiledPixmap(QRectF(0,0,width(),height()), d->pix);
            } else {
                qreal widthScale = width() / qreal(d->pix.width());
                qreal heightScale = height() / qreal(d->pix.height());

                QTransform scale;
                if (d->fillMode == TileVertically) {
                    scale.scale(widthScale, 1.0);
                    QTransform old = p->transform();
                    p->setWorldTransform(scale * old);
                    p->drawTiledPixmap(QRectF(0,0,d->pix.width(),height()), d->pix);
                    p->setWorldTransform(old);
                } else {
                    scale.scale(1.0, heightScale);
                    QTransform old = p->transform();
                    p->setWorldTransform(scale * old);
                    p->drawTiledPixmap(QRectF(0,0,width(),d->pix.height()), d->pix);
                    p->setWorldTransform(old);
                }
            }
        } else {
            qreal widthScale = width() / qreal(d->pix.width());
            qreal heightScale = height() / qreal(d->pix.height());

            QTransform scale;

            if (d->fillMode == PreserveAspectFit) {
                if (widthScale <= heightScale) {
                    heightScale = widthScale;
                    scale.translate(0, (height() - heightScale * d->pix.height()) / 2);
                } else if(heightScale < widthScale) {
                    widthScale = heightScale;
                    scale.translate((width() - widthScale * d->pix.width()) / 2, 0);
                }
            } else if (d->fillMode == PreserveAspectCrop) {
                if (widthScale < heightScale) {
                    widthScale = heightScale;
                    scale.translate((width() - widthScale * d->pix.width()) / 2, 0);
                } else if(heightScale < widthScale) {
                    heightScale = widthScale;
                    scale.translate(0, (height() - heightScale * d->pix.height()) / 2);
                }
            }
            if (clip()) {
                p->save();
                p->setClipRect(boundingRect(), Qt::IntersectClip);
            }
            scale.scale(widthScale, heightScale);
            QTransform old = p->transform();
            p->setWorldTransform(scale * old);
            p->drawPixmap(0, 0, d->pix);
            p->setWorldTransform(old);
            if (clip()) {
                p->restore();
            }
        }
    } else {
        p->drawPixmap(0, 0, d->pix);
    }

    if (d->smooth) {
        p->setRenderHint(QPainter::Antialiasing, oldAA);
        p->setRenderHint(QPainter::SmoothPixmapTransform, oldSmooth);
    }
}

void QDeclarativeImage::pixmapChange()
{
    updatePaintedGeometry();
    emit pixmapChanged();
}

QT_END_NAMESPACE