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#include "imagewidget.h"

#include <QtGui>

//! [constructor]

ImageWidget::ImageWidget(QWidget *parent)

    : QWidget(parent),

    position(0),

    horizontalOffset(0),

    verticalOffset(0),

    rotationAngle(0),

    scaleFactor(1),

    currentStepScaleFactor(1)

{

    setMinimumSize(QSize(100,100));

//! [enable gestures]

    grabGesture(Qt::PanGesture);

    grabGesture(Qt::PinchGesture);

    grabGesture(Qt::SwipeGesture);

//! [enable gestures]

}

//! [constructor]

//! [event handler]

bool ImageWidget::event(QEvent *event)

{

    if (event->type() == QEvent::Gesture)

        return gestureEvent(static_cast<QGestureEvent*>(event));

    return QWidget::event(event);

}

//! [event handler]

void ImageWidget::paintEvent(QPaintEvent*)

{

    QPainter p(this);

    float iw = currentImage.width();

    float ih = currentImage.height();

    float wh = height();

    float ww = width();

    p.translate(ww/2, wh/2);

    p.translate(horizontalOffset, verticalOffset);

    p.rotate(rotationAngle);

    p.scale(currentStepScaleFactor * scaleFactor, currentStepScaleFactor * scaleFactor);

    p.translate(-iw/2, -ih/2);

    p.drawImage(0, 0, currentImage);

}

void ImageWidget::mouseDoubleClickEvent(QMouseEvent *)

{

    rotationAngle = 0;

    scaleFactor = 1;

    currentStepScaleFactor = 1;

    verticalOffset = 0;

    horizontalOffset = 0;

    update();

}

//! [gesture event handler]

bool ImageWidget::gestureEvent(QGestureEvent *event)

{

    if (QGesture *swipe = event->gesture(Qt::SwipeGesture))

        swipeTriggered(static_cast<QSwipeGesture *>(swipe));

    else if (QGesture *pan = event->gesture(Qt::PanGesture))

        panTriggered(static_cast<QPanGesture *>(pan));

    if (QGesture *pinch = event->gesture(Qt::PinchGesture))

        pinchTriggered(static_cast<QPinchGesture *>(pinch));

    return true;

}

//! [gesture event handler]

void ImageWidget::panTriggered(QPanGesture *gesture)

{

#ifndef QT_NO_CURSOR

    switch (gesture->state()) {

        case Qt::GestureStarted:

        case Qt::GestureUpdated:

            setCursor(Qt::SizeAllCursor);

            break;

        default:

            setCursor(Qt::ArrowCursor);

    }

#endif

    QPointF delta = gesture->delta();

    horizontalOffset += delta.x();

    verticalOffset += delta.y();

    update();

}

void ImageWidget::pinchTriggered(QPinchGesture *gesture)

{

    QPinchGesture::ChangeFlags changeFlags = gesture->changeFlags();

    if (changeFlags & QPinchGesture::RotationAngleChanged) {

        qreal value = gesture->property("rotationAngle").toReal();

        qreal lastValue = gesture->property("lastRotationAngle").toReal();

        rotationAngle += value - lastValue;

    }

    if (changeFlags & QPinchGesture::ScaleFactorChanged) {

        qreal value = gesture->property("scaleFactor").toReal();

        currentStepScaleFactor = value;

    }

    if (gesture->state() == Qt::GestureFinished) {

        scaleFactor *= currentStepScaleFactor;

        currentStepScaleFactor = 1;

    }

    update();

}

//! [swipe function]

void ImageWidget::swipeTriggered(QSwipeGesture *gesture)

{

    if (gesture->state() == Qt::GestureFinished) {

        if (gesture->horizontalDirection() == QSwipeGesture::Left

            || gesture->verticalDirection() == QSwipeGesture::Up)

            goPrevImage();

        else

            goNextImage();

        update();

    }

}

//! [swipe function]

void ImageWidget::resizeEvent(QResizeEvent*)

{

    update();

}

void ImageWidget::openDirectory(const QString &path)

{

    this->path = path;

    QDir dir(path);

    QStringList nameFilters;

    nameFilters << "*.jpg" << "*.png";

    files = dir.entryList(nameFilters, QDir::Files|QDir::Readable, QDir::Name);

    position = 0;

    goToImage(0);

    update();

}

QImage ImageWidget::loadImage(const QString &fileName)

{

    QImageReader reader(fileName);

    if (!reader.canRead()) {

        qDebug() << fileName << ": can't load image";

        return QImage();

    }

    QImage image;

    if (!reader.read(&image)) {

        qDebug() << fileName << ": corrupted image";

        return QImage();

    }

    return image;

}

void ImageWidget::goNextImage()

{

    if (files.isEmpty())

        return;

    if (position < files.size()-1) {

        ++position;

        prevImage = currentImage;

        currentImage = nextImage;

        if (position+1 < files.size())

            nextImage = loadImage(path+QLatin1String("/")+files.at(position+1));

        else

            nextImage = QImage();

    }

    update();

}

void ImageWidget::goPrevImage()

{

    if (files.isEmpty())

        return;

    if (position > 0) {

        --position;

        nextImage = currentImage;

        currentImage = prevImage;

        if (position > 0)

            prevImage = loadImage(path+QLatin1String("/")+files.at(position-1));

        else

            prevImage = QImage();

    }

    update();

}

void ImageWidget::goToImage(int index)

{

    if (files.isEmpty())

        return;

    if (index < 0 || index >= files.size()) {

        qDebug() << "goToImage: invalid index: " << index;

        return;

    }

    if (index == position+1) {

        goNextImage();

        return;

    }

    if (position > 0 && index == position-1) {

        goPrevImage();

        return;

    }

    position = index;

    if (index > 0)

        prevImage = loadImage(path+QLatin1String("/")+files.at(position-1));

    else

        prevImage = QImage();

    currentImage = loadImage(path+QLatin1String("/")+files.at(position));

    if (position+1 < files.size())

        nextImage = loadImage(path+QLatin1String("/")+files.at(position+1));

    else

        nextImage = QImage();

    update();

}