From 35b3c654c6ddef6771e6f1a1c3214c122702d936 Mon Sep 17 00:00:00 2001 From: dismine Date: Tue, 19 Aug 2014 15:46:52 +0300 Subject: [PATCH] New mechanizm zooming QGraphicsView using mouse wheel. --HG-- branch : develop --- src/app/widgets/vmaingraphicsview.cpp | 162 +++++++++++++++----------- src/app/widgets/vmaingraphicsview.h | 64 +++++++++- 2 files changed, 152 insertions(+), 74 deletions(-) diff --git a/src/app/widgets/vmaingraphicsview.cpp b/src/app/widgets/vmaingraphicsview.cpp index 04bc465d6..46ad814ac 100644 --- a/src/app/widgets/vmaingraphicsview.cpp +++ b/src/app/widgets/vmaingraphicsview.cpp @@ -34,100 +34,63 @@ #include #include "../tools/vabstracttool.h" +#include +#include + //--------------------------------------------------------------------------------------------------------------------- -/** - * @brief VMainGraphicsView constructor. - * @param parent parent object. - */ -VMainGraphicsView::VMainGraphicsView(QWidget *parent) - :QGraphicsView(parent), _numScheduledScalings(0) +GraphicsViewZoom::GraphicsViewZoom(QGraphicsView* view) + : QObject(view), _view(view), _numScheduledScalings(0) { - this->setResizeAnchor(QGraphicsView::AnchorUnderMouse); - this->setTransformationAnchor(QGraphicsView::AnchorUnderMouse); - this->setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform); - this->setInteractive(true); + _view->viewport()->installEventFilter(this); + _view->setMouseTracking(true); + _modifiers = Qt::ControlModifier; + _zoom_factor_base = 1.0015; } //--------------------------------------------------------------------------------------------------------------------- -/** - * @brief wheelEvent handle wheel events. - * @param event wheel event. - */ -//cppcheck-suppress unusedFunction -void VMainGraphicsView::wheelEvent(QWheelEvent *event) +void GraphicsViewZoom::gentle_zoom(double factor) { - int numSteps = event->delta() / 8 / 15; // see QWheelEvent documentation - - _numScheduledScalings += numSteps; - if (_numScheduledScalings * numSteps < 0) - { // if user moved the wheel in another direction, we reset - _numScheduledScalings = numSteps; // previously scheduled scalings - } - - QTimeLine *anim = new QTimeLine(300, this); - anim->setUpdateInterval(20); - - if (QApplication::keyboardModifiers() == Qt::ControlModifier) - {// If you press CTRL this code will be executed - connect(anim, &QTimeLine::valueChanged, this, &VMainGraphicsView::scalingTime); - } - else - { - connect(anim, &QTimeLine::valueChanged, this, &VMainGraphicsView::scrollingTime); - } - connect(anim, &QTimeLine::finished, this, &VMainGraphicsView::animFinished); - anim->start(); + _view->scale(factor, factor); + _view->centerOn(target_scene_pos); + QPointF delta_viewport_pos = target_viewport_pos - QPointF(_view->viewport()->width() / 2.0, + _view->viewport()->height() / 2.0); + QPointF viewport_center = _view->mapFromScene(target_scene_pos) - delta_viewport_pos; + _view->centerOn(_view->mapToScene(viewport_center.toPoint())); + emit zoomed(); } //--------------------------------------------------------------------------------------------------------------------- -/** - * @brief scalingTime call each time when need handle scaling. - * @param x value from 0.0 to 1.0 - */ -void VMainGraphicsView::scalingTime(qreal x) +void GraphicsViewZoom::set_modifiers(Qt::KeyboardModifiers modifiers) { - Q_UNUSED(x); - const QPointF p0scene = mapToScene(mapFromGlobal(QCursor::pos())); + _modifiers = modifiers; - qreal factor = 1.0 + static_cast(_numScheduledScalings) / 50.0; - scale(factor, factor); - - const QPointF p1mouse = mapFromScene(p0scene); - const QPointF move = p1mouse - this->mapFromGlobal(QCursor::pos()); // The move - horizontalScrollBar()->setValue(static_cast(move.x()) + horizontalScrollBar()->value()); - verticalScrollBar()->setValue(static_cast(move.y()) + verticalScrollBar()->value()); - - VAbstractTool::NewSceneRect(this->scene(), this); - - emit NewFactor(factor); } //--------------------------------------------------------------------------------------------------------------------- -/** - * @brief scrollingTime call each time when need handle scrolling. - * @param x value from 0.0 to 1.0 - */ -void VMainGraphicsView::scrollingTime(qreal x) +void GraphicsViewZoom::set_zoom_factor_base(double value) +{ + _zoom_factor_base = value; +} + +//--------------------------------------------------------------------------------------------------------------------- +void GraphicsViewZoom::scrollingTime(qreal x) { Q_UNUSED(x); qreal factor = 1.0; if (_numScheduledScalings < 0) { - verticalScrollBar()->setValue(qRound(verticalScrollBar()->value() + factor*3.5)); - emit NewFactor(factor); + factor = factor*2.8; } else { - verticalScrollBar()->setValue(qRound(verticalScrollBar()->value() - factor*3.5)); - emit NewFactor(factor); + factor = factor*-2.8; } + + _view->verticalScrollBar()->setValue(qRound(_view->verticalScrollBar()->value() + factor)); } //--------------------------------------------------------------------------------------------------------------------- -/** - * @brief animFinished - */ -void VMainGraphicsView::animFinished() +void GraphicsViewZoom::animFinished() { if (_numScheduledScalings > 0) { @@ -140,6 +103,69 @@ void VMainGraphicsView::animFinished() sender()->~QObject(); } +//--------------------------------------------------------------------------------------------------------------------- +bool GraphicsViewZoom::eventFilter(QObject *object, QEvent *event) +{ + if (event->type() == QEvent::MouseMove) + { + QMouseEvent* mouse_event = static_cast(event); + QPointF delta = target_viewport_pos - mouse_event->pos(); + if (qAbs(delta.x()) > 5 || qAbs(delta.y()) > 5) + { + target_viewport_pos = mouse_event->pos(); + target_scene_pos = _view->mapToScene(mouse_event->pos()); + } + } + else if (event->type() == QEvent::Wheel) + { + QWheelEvent* wheel_event = static_cast(event); + if (QApplication::keyboardModifiers() == _modifiers) + { + if (wheel_event->orientation() == Qt::Vertical) + { + double angle = wheel_event->angleDelta().y(); + double factor = qPow(_zoom_factor_base, angle); + gentle_zoom(factor); + return true; + } + } + else + { + int numSteps = wheel_event->delta() / 8 / 15; // see QWheelEvent documentation + + _numScheduledScalings += numSteps; + if (_numScheduledScalings * numSteps < 0) + { // if user moved the wheel in another direction, we reset + _numScheduledScalings = numSteps; // previously scheduled scalings + } + + QTimeLine *anim = new QTimeLine(300, this); + anim->setUpdateInterval(20); + connect(anim, &QTimeLine::valueChanged, this, &GraphicsViewZoom::scrollingTime); + connect(anim, &QTimeLine::finished, this, &GraphicsViewZoom::animFinished); + anim->start(); + return true; + } + } + Q_UNUSED(object) + return false; +} + +//--------------------------------------------------------------------------------------------------------------------- +/** + * @brief VMainGraphicsView constructor. + * @param parent parent object. + */ +VMainGraphicsView::VMainGraphicsView(QWidget *parent) + :QGraphicsView(parent), zoom(nullptr) +{ + zoom = new GraphicsViewZoom(this); + this->setResizeAnchor(QGraphicsView::AnchorUnderMouse); + this->setTransformationAnchor(QGraphicsView::AnchorUnderMouse); + this->setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform); + this->setInteractive(true); +} + //--------------------------------------------------------------------------------------------------------------------- void VMainGraphicsView::ZoomIn() { diff --git a/src/app/widgets/vmaingraphicsview.h b/src/app/widgets/vmaingraphicsview.h index 531fec782..e34baf781 100644 --- a/src/app/widgets/vmaingraphicsview.h +++ b/src/app/widgets/vmaingraphicsview.h @@ -29,8 +29,65 @@ #ifndef VMAINGRAPHICSVIEW_H #define VMAINGRAPHICSVIEW_H +#include #include +/*! + * This class adds ability to zoom QGraphicsView using mouse wheel. The point under cursor + * remains motionless while it's possible. + * + * Note that it becomes not possible when the scene's + * size is not large enough comparing to the viewport size. QGraphicsView centers the picture + * when it's smaller than the view. And QGraphicsView's scrolls boundaries don't allow to + * put any picture point at any viewport position. + * + * When the user starts scrolling, this class remembers original scene position and + * keeps it until scrolling is completed. It's better than getting original scene position at + * each scrolling step because that approach leads to position errors due to before-mentioned + * positioning restrictions. + * + * When zommed using scroll, this class emits zoomed() signal. + * + * Usage: + * + * new Graphics_view_zoom(view); + * + * The object will be deleted automatically when the view is deleted. + * + * You can set keyboard modifiers used for zooming using set_modified(). Zooming will be + * performed only on exact match of modifiers combination. The default modifier is Ctrl. + * + * You can change zoom velocity by calling set_zoom_factor_base(). + * Zoom coefficient is calculated as zoom_factor_base^angle_delta + * (see QWheelEvent::angleDelta). + * The default zoom factor base is 1.0015. + */ +class GraphicsViewZoom : public QObject +{ + Q_OBJECT +public: + GraphicsViewZoom(QGraphicsView* view); + void gentle_zoom(double factor); + void set_modifiers(Qt::KeyboardModifiers modifiers); + void set_zoom_factor_base(double value); +signals: + void zoomed(); +public slots: + void scrollingTime(qreal x); + void animFinished(); +private: + QGraphicsView* _view; + Qt::KeyboardModifiers _modifiers; + double _zoom_factor_base; + QPointF target_scene_pos; + QPointF target_viewport_pos; + + bool eventFilter(QObject* object, QEvent* event); +private: + /** @brief _numScheduledScalings keep number scheduled scalings. */ + qint32 _numScheduledScalings; +}; + /** * @brief The VMainGraphicsView class main scene view. */ @@ -53,20 +110,15 @@ signals: */ void MouseRelease(); public slots: - void scalingTime(qreal x); - void scrollingTime(qreal x); - void animFinished(); void ZoomIn(); void ZoomOut(); void ZoomOriginal(); void ZoomFitBest(); protected: - void wheelEvent ( QWheelEvent * event ); void mousePressEvent(QMouseEvent *mousePress); void mouseReleaseEvent(QMouseEvent *event); private: - /** @brief _numScheduledScalings keep number scheduled scalings. */ - qint32 _numScheduledScalings; + GraphicsViewZoom* zoom; }; #endif // VMAINGRAPHICSVIEW_H