imagewidget.cpp Example File

gestures/imagegestures/imagewidget.cpp
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#include "imagewidget.h" #include <QtWidgets> Q_LOGGING_CATEGORY(lcExample, "qt.examples.imagegestures") ImageWidget::ImageWidget(QWidget *parent) : QWidget(parent), position(0), horizontalOffset(0), verticalOffset(0), rotationAngle(0), scaleFactor(1), currentStepScaleFactor(1) { setMinimumSize(QSize(100,100)); } void ImageWidget::grabGestures(const QList<Qt::GestureType> &gestures) { foreach (Qt::GestureType gesture, gestures) grabGesture(gesture); } bool ImageWidget::event(QEvent *event) { if (event->type() == QEvent::Gesture) return gestureEvent(static_cast<QGestureEvent*>(event)); return QWidget::event(event); } void ImageWidget::paintEvent(QPaintEvent*) { QPainter p(this); const qreal iw = currentImage.width(); const qreal ih = currentImage.height(); const qreal wh = height(); const qreal 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(); qCDebug(lcExample) << "reset on mouse double click"; } bool ImageWidget::gestureEvent(QGestureEvent *event) { qCDebug(lcExample) << "gestureEvent():" << 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; } 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(); qCDebug(lcExample) << "panTriggered():" << gesture; horizontalOffset += delta.x(); verticalOffset += delta.y(); update(); } void ImageWidget::pinchTriggered(QPinchGesture *gesture) { QPinchGesture::ChangeFlags changeFlags = gesture->changeFlags(); if (changeFlags & QPinchGesture::RotationAngleChanged) { qreal rotationDelta = gesture->rotationAngle() - gesture->lastRotationAngle(); rotationAngle += rotationDelta; qCDebug(lcExample) << "pinchTriggered(): rotate by" << rotationDelta << "->" << rotationAngle; } if (changeFlags & QPinchGesture::ScaleFactorChanged) { currentStepScaleFactor = gesture->totalScaleFactor(); qCDebug(lcExample) << "pinchTriggered(): zoom by" << gesture->scaleFactor() << "->" << currentStepScaleFactor; } if (gesture->state() == Qt::GestureFinished) { scaleFactor *= currentStepScaleFactor; currentStepScaleFactor = 1; } update(); } void ImageWidget::swipeTriggered(QSwipeGesture *gesture) { if (gesture->state() == Qt::GestureFinished) { if (gesture->horizontalDirection() == QSwipeGesture::Left || gesture->verticalDirection() == QSwipeGesture::Up) { qCDebug(lcExample) << "swipeTriggered(): swipe to previous"; goPrevImage(); } else { qCDebug(lcExample) << "swipeTriggered(): swipe to next"; goNextImage(); } update(); } } 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); reader.setAutoTransform(true); qCDebug(lcExample) << "loading" << QDir::toNativeSeparators(fileName) << position << '/' << files.size(); if (!reader.canRead()) { qCWarning(lcExample) << QDir::toNativeSeparators(fileName) << ": can't load image"; return QImage(); } QImage image; if (!reader.read(&image)) { qCWarning(lcExample) << QDir::toNativeSeparators(fileName) << ": corrupted image: " << reader.errorString(); return QImage(); } const QSize maximumSize(2000, 2000); // Reduce in case someone has large photo images. if (image.size().width() > maximumSize.width() || image.height() > maximumSize.height()) image = image.scaled(maximumSize, Qt::KeepAspectRatio, Qt::SmoothTransformation); 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 + QLatin1Char('/') + 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 + QLatin1Char('/') + files.at(position-1)); else prevImage = QImage(); } update(); } void ImageWidget::goToImage(int index) { if (files.isEmpty()) return; if (index < 0 || index >= files.size()) { qCWarning(lcExample) << "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 + QLatin1Char('/') + files.at(position-1)); else prevImage = QImage(); currentImage = loadImage(path + QLatin1Char('/') + files.at(position)); if (position+1 < files.size()) nextImage = loadImage(path + QLatin1Char('/') + files.at(position+1)); else nextImage = QImage(); update(); }