a9515cd02f
The swipe handler is simple, and also doesn't currently work on every platform. But the pinch handler is the one that needs explanation, because the difference between incremental and absolute values of the rotation and scale properties is tricky. Change-Id: Ie3c7f4941d4a17734c9a920a8dd978f86fb03c4b Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com> Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
289 lines
8.6 KiB
C++
289 lines
8.6 KiB
C++
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/****************************************************************************
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**
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** Copyright (C) 2015 The Qt Company Ltd.
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** Contact: http://www.qt.io/licensing/
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**
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** This file is part of the examples of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:BSD$
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** You may use this file under the terms of the BSD license as follows:
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**
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** "Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are
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** met:
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in
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** the documentation and/or other materials provided with the
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** distribution.
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** * Neither the name of The Qt Company Ltd nor the names of its
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** contributors may be used to endorse or promote products derived
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** from this software without specific prior written permission.
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**
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**
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "imagewidget.h"
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#include <QtWidgets>
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Q_LOGGING_CATEGORY(lcExample, "qt.examples.imagegestures")
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//! [constructor]
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ImageWidget::ImageWidget(QWidget *parent)
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: QWidget(parent),
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position(0),
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horizontalOffset(0),
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verticalOffset(0),
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rotationAngle(0),
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scaleFactor(1),
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currentStepScaleFactor(1)
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{
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setMinimumSize(QSize(100,100));
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}
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//! [constructor]
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void ImageWidget::grabGestures(const QList<Qt::GestureType> &gestures)
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{
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//! [enable gestures]
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foreach (Qt::GestureType gesture, gestures)
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grabGesture(gesture);
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//! [enable gestures]
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}
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//! [event handler]
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bool ImageWidget::event(QEvent *event)
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{
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if (event->type() == QEvent::Gesture)
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return gestureEvent(static_cast<QGestureEvent*>(event));
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return QWidget::event(event);
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}
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//! [event handler]
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//! [paint method]
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void ImageWidget::paintEvent(QPaintEvent*)
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{
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QPainter p(this);
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const qreal iw = currentImage.width();
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const qreal ih = currentImage.height();
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const qreal wh = height();
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const qreal ww = width();
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p.translate(ww/2, wh/2);
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p.translate(horizontalOffset, verticalOffset);
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p.rotate(rotationAngle);
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p.scale(currentStepScaleFactor * scaleFactor, currentStepScaleFactor * scaleFactor);
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p.translate(-iw/2, -ih/2);
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p.drawImage(0, 0, currentImage);
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}
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//! [paint method]
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void ImageWidget::mouseDoubleClickEvent(QMouseEvent *)
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{
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rotationAngle = 0;
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scaleFactor = 1;
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currentStepScaleFactor = 1;
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verticalOffset = 0;
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horizontalOffset = 0;
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update();
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qCDebug(lcExample) << "reset on mouse double click";
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}
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//! [gesture event handler]
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bool ImageWidget::gestureEvent(QGestureEvent *event)
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{
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qCDebug(lcExample) << "gestureEvent():" << event;
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if (QGesture *swipe = event->gesture(Qt::SwipeGesture))
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swipeTriggered(static_cast<QSwipeGesture *>(swipe));
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else if (QGesture *pan = event->gesture(Qt::PanGesture))
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panTriggered(static_cast<QPanGesture *>(pan));
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if (QGesture *pinch = event->gesture(Qt::PinchGesture))
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pinchTriggered(static_cast<QPinchGesture *>(pinch));
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return true;
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}
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//! [gesture event handler]
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void ImageWidget::panTriggered(QPanGesture *gesture)
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{
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#ifndef QT_NO_CURSOR
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switch (gesture->state()) {
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case Qt::GestureStarted:
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case Qt::GestureUpdated:
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setCursor(Qt::SizeAllCursor);
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break;
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default:
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setCursor(Qt::ArrowCursor);
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}
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#endif
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QPointF delta = gesture->delta();
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qCDebug(lcExample) << "panTriggered():" << gesture;
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horizontalOffset += delta.x();
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verticalOffset += delta.y();
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update();
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}
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//! [pinch function]
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void ImageWidget::pinchTriggered(QPinchGesture *gesture)
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{
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QPinchGesture::ChangeFlags changeFlags = gesture->changeFlags();
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if (changeFlags & QPinchGesture::RotationAngleChanged) {
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qreal rotationDelta = gesture->rotationAngle() - gesture->lastRotationAngle();
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rotationAngle += rotationDelta;
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qCDebug(lcExample) << "pinchTriggered(): rotate by" <<
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rotationDelta << "->" << rotationAngle;
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}
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if (changeFlags & QPinchGesture::ScaleFactorChanged) {
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currentStepScaleFactor = gesture->totalScaleFactor();
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qCDebug(lcExample) << "pinchTriggered(): zoom by" <<
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gesture->scaleFactor() << "->" << currentStepScaleFactor;
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}
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if (gesture->state() == Qt::GestureFinished) {
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scaleFactor *= currentStepScaleFactor;
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currentStepScaleFactor = 1;
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}
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update();
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}
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//! [pinch function]
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//! [swipe function]
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void ImageWidget::swipeTriggered(QSwipeGesture *gesture)
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{
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if (gesture->state() == Qt::GestureFinished) {
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if (gesture->horizontalDirection() == QSwipeGesture::Left
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|| gesture->verticalDirection() == QSwipeGesture::Up) {
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qCDebug(lcExample) << "swipeTriggered(): swipe to previous";
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goPrevImage();
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} else {
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qCDebug(lcExample) << "swipeTriggered(): swipe to next";
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goNextImage();
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}
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update();
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}
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}
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//! [swipe function]
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void ImageWidget::resizeEvent(QResizeEvent*)
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{
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update();
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}
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void ImageWidget::openDirectory(const QString &path)
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{
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this->path = path;
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QDir dir(path);
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QStringList nameFilters;
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nameFilters << "*.jpg" << "*.png";
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files = dir.entryList(nameFilters, QDir::Files|QDir::Readable, QDir::Name);
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position = 0;
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goToImage(0);
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update();
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}
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QImage ImageWidget::loadImage(const QString &fileName)
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{
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qDebug() << position << files << fileName;
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QImageReader reader(fileName);
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qCDebug(lcExample) << "loading" << QDir::toNativeSeparators(fileName) << position << '/' << files.size();
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if (!reader.canRead()) {
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qCWarning(lcExample) << QDir::toNativeSeparators(fileName) << ": can't load image";
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return QImage();
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}
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QImage image;
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if (!reader.read(&image)) {
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qCWarning(lcExample) << QDir::toNativeSeparators(fileName) << ": corrupted image: " << reader.errorString();
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return QImage();
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}
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const QSize maximumSize(2000, 2000); // Reduce in case someone has large photo images.
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if (image.size().width() > maximumSize.width() || image.height() > maximumSize.height())
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image = image.scaled(maximumSize, Qt::KeepAspectRatio, Qt::SmoothTransformation);
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return image;
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}
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void ImageWidget::goNextImage()
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{
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if (files.isEmpty())
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return;
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if (position < files.size()-1) {
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++position;
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prevImage = currentImage;
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currentImage = nextImage;
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if (position+1 < files.size())
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nextImage = loadImage(path+QLatin1String("/")+files.at(position+1));
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else
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nextImage = QImage();
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}
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update();
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}
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void ImageWidget::goPrevImage()
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{
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if (files.isEmpty())
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return;
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if (position > 0) {
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--position;
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nextImage = currentImage;
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currentImage = prevImage;
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if (position > 0)
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prevImage = loadImage(path+QLatin1String("/")+files.at(position-1));
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else
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prevImage = QImage();
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}
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update();
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}
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void ImageWidget::goToImage(int index)
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{
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if (files.isEmpty())
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return;
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if (index < 0 || index >= files.size()) {
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qCWarning(lcExample) << "goToImage: invalid index: " << index;
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return;
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}
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if (index == position+1) {
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goNextImage();
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return;
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}
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if (position > 0 && index == position-1) {
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goPrevImage();
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return;
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}
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position = index;
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if (index > 0)
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prevImage = loadImage(path+QLatin1String("/")+files.at(position-1));
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else
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prevImage = QImage();
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currentImage = loadImage(path+QLatin1String("/")+files.at(position));
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if (position+1 < files.size())
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nextImage = loadImage(path+QLatin1String("/")+files.at(position+1));
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else
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nextImage = QImage();
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update();
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}
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