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

    Displays the image from the specified \l source.  If a size is not specified explicitly,
    the Image element will be sized to the loaded image.

    If the source resolves to a network resource, the image will be loaded asynchronously,
    updating the \l progress and \l status properties appropriately.

    Images which are available locally
    will be loaded immediately, blocking the user interface.  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 will load 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 UIs.  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.

    The Image element supports untransformed, stretched and tiled images.

    For an explanation of stretching and tiling, see the fillMode property description.

    Examples:
    \table
    \row
    \o \image declarative-qtlogo1.png
    \o Untransformed
    \qml
    Image { source: "pics/qtlogo.png" }
    \endqml
    \row
    \o \image declarative-qtlogo2.png
    \o fillMode: Stretch (default)
    \qml
    Image {
        width: 160
        height: 160
        source: "pics/qtlogo.png"
    }
    \endqml
    \row
    \o \image declarative-qtlogo3.png
    \o fillMode: Tile
    \qml
    Image {
        fillMode: Image.Tile
        width: 160; height: 160
        source: "pics/qtlogo.png"
    }
    \endqml
    \row
    \o \image declarative-qtlogo6.png
    \o fillMode: TileVertically
    \qml
    Image {
        fillMode: Image.TileVertically
        width: 160; height: 160
        source: "pics/qtlogo.png"
    }
    \endqml
    \row
    \o \image declarative-qtlogo5.png
    \o fillMode: TileHorizontally
    \qml
    Image {
        fillMode: Image.TileHorizontally
        width: 160; height: 160
        source: "pics/qtlogo.png"
    }
    \endqml
    \endtable
*/

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

    \image declarative-image_fillMode.gif
*/
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 Null - no image has been set
    \o Ready - the image has been loaded
    \o Loading - the image is currently being loaded
    \o Error - an error occurred while loading the image
    \endlist

    Note that a change in the status property does not cause anything to happen
    (although it reflects what has happened with the image internally). If you wish
    to react to the change in status you need to do it yourself, for example in one
    of the following ways:
    \list
    \o Create a state, so that a state change occurs, e.g.
    \qml State { name: 'loaded'; when: image.status = Image.Ready } \endqml
    \o Do something inside the onStatusChanged signal handler, e.g.
    \qml Image { id: image; onStatusChanged: if (image.status == Image.Ready) console.log('Loaded') } \endqml
    \o Bind to the status variable somewhere, e.g.
    \qml Text { text: if (image.status != Image.Ready) { 'Not Loaded' } else { 'Loaded' } } \endqml
    \endlist

    \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 properties is the size of the loaded image, in pixels.

    If you set this property explicitly, you can to control the storage
    used by a loaded image. The image will be scaled down if its intrinsic size
    is greater than this value.

    If only one dimension of the size is set (and the other left at 0), the
    unset dimension will be set in proportion to the set dimension to preserve
    the source image aspect ratio. The fillMode is independent of this.

    Unlike setting the width and height properties, which merely scale the painting
    of the image, this property affects the number of pixels stored.

    \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.}

    If the source is an instrinsically scalable image (eg. SVG), this property
    determines the size of the loaded image regardless of intrinsic size. You should
    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.

    The example below will ensure that 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 will ensure that 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