View: Implement pinch-zoom

The special handling of a moveMoveEvent without a preceeding
mousePressEvent is a workaround for an issue where you won't get
an emulated mousePressEvent for the primary touch after a multitouch
gesture where you release the primary touch before the secondary touch.

diff --git a/pv/view/view.cpp b/pv/view/view.cpp
index 392114c848aa2c01a3e598cc0372ae2d5681e504..1d55e14f7c91f20f55d09bffc1d4540d8819ddb6 100644 (file)
--- a/pv/view/view.cpp
+++ b/pv/view/view.cpp
@@ -469,6 +469,9 @@ bool View::viewportEvent(QEvent *e)
        case QEvent::MouseButtonDblClick:
        case QEvent::MouseMove:
        case QEvent::Wheel:
+       case QEvent::TouchBegin:
+       case QEvent::TouchUpdate:
+       case QEvent::TouchEnd:
                return false;
 
        default:

diff --git a/pv/view/viewport.cpp b/pv/view/viewport.cpp
index c5789630be883ed2bb45b3154576eafb4bad0a4b..9f60c1a82ad123897d93b4a6b3360045ffa074ea 100644 (file)
--- a/pv/view/viewport.cpp
+++ b/pv/view/viewport.cpp
@@ -38,8 +38,12 @@ namespace view {
 
 Viewport::Viewport(View &parent) :
        QWidget(&parent),
-        _view(parent)
+        _view(parent),
+       _mouse_down_valid(false),
+       _pinch_zoom_active(false)
 {
+       setAttribute(Qt::WA_AcceptTouchEvents, true);
+
        setMouseTracking(true);
        setAutoFillBackground(true);
        setBackgroundRole(QPalette::Base);
@@ -96,12 +100,43 @@ void Viewport::paintEvent(QPaintEvent*)
        p.end();
 }
 
+bool Viewport::event(QEvent *event)
+{
+       switch(event->type()) {
+       case QEvent::TouchBegin:
+       case QEvent::TouchUpdate:
+       case QEvent::TouchEnd:
+               if (touchEvent(static_cast<QTouchEvent *>(event)))
+                       return true;
+               break;
+
+       default:
+               break;
+       }
+
+       return QWidget::event(event);
+}
+
 void Viewport::mousePressEvent(QMouseEvent *event)
 {
        assert(event);
 
-       _mouse_down_point = event->pos();
-       _mouse_down_offset = _view.offset();
+       if (event->button() == Qt::LeftButton)
+       {
+               _mouse_down_point = event->pos();
+               _mouse_down_offset = _view.offset();
+               _mouse_down_valid = true;
+       }
+}
+
+void Viewport::mouseReleaseEvent(QMouseEvent *event)
+{
+       assert(event);
+
+       if (event->button() == Qt::LeftButton)
+       {
+               _mouse_down_valid = false;
+       }
 }
 
 void Viewport::mouseMoveEvent(QMouseEvent *event)
@@ -110,6 +145,12 @@ void Viewport::mouseMoveEvent(QMouseEvent *event)
 
        if (event->buttons() & Qt::LeftButton)
        {
+               if (! _mouse_down_valid) {
+                       _mouse_down_point = event->pos();
+                       _mouse_down_offset = _view.offset();
+                       _mouse_down_valid = true;
+               }
+
                _view.set_scale_offset(_view.scale(),
                        _mouse_down_offset +
                        (_mouse_down_point - event->pos()).x() *
@@ -142,6 +183,53 @@ void Viewport::wheelEvent(QWheelEvent *event)
        }
 }
 
+bool Viewport::touchEvent(QTouchEvent *event)
+{
+       QList<QTouchEvent::TouchPoint> touchPoints = event->touchPoints();
+
+       if (touchPoints.count() != 2) {
+               _pinch_zoom_active = false;
+               return false;
+       }
+
+       const QTouchEvent::TouchPoint &touchPoint0 = touchPoints.first();
+       const QTouchEvent::TouchPoint &touchPoint1 = touchPoints.last();
+
+       if (!_pinch_zoom_active ||
+           (event->touchPointStates() & Qt::TouchPointPressed)) {
+               _pinch_offset0 = _view.offset() + _view.scale() * touchPoint0.pos().x();
+               _pinch_offset1 = _view.offset() + _view.scale() * touchPoint1.pos().x();
+               _pinch_zoom_active = true;
+       }
+
+       double w = touchPoint1.pos().x() - touchPoint0.pos().x();
+       if (abs(w) >= 1.0) {
+               double scale = (_pinch_offset1 - _pinch_offset0) / w;
+               if (scale < 0)
+                       scale = -scale;
+               double offset = _pinch_offset0 - touchPoint0.pos().x() * scale;
+               if (scale > 0)
+                       _view.set_scale_offset(scale, offset);
+       }
+
+       if (event->touchPointStates() & Qt::TouchPointReleased) {
+               _pinch_zoom_active = false;
+
+               if (touchPoint0.state() & Qt::TouchPointReleased) {
+                       // Primary touch released
+                       _mouse_down_valid = false;
+               } else {
+                       // Update the mouse down fields so that continued
+                       // dragging with the primary touch will work correctly
+                       _mouse_down_point = touchPoint0.pos().toPoint();
+                       _mouse_down_offset = _view.offset();
+                       _mouse_down_valid = true;
+               }
+       }
+
+       return true;
+}
+
 void Viewport::on_signals_changed()
 {
        const vector< shared_ptr<Trace> > traces(_view.get_traces());

diff --git a/pv/view/viewport.h b/pv/view/viewport.h
index 0474b7eefe4dd7fde0752d28fd8ea417214f01c6..f7c8028754a1f27f1f7d93a2005d458fd9e991e1 100644 (file)
--- a/pv/view/viewport.h
+++ b/pv/view/viewport.h
@@ -23,6 +23,7 @@
 
 #include <QTimer>
 #include <QWidget>
+#include <QTouchEvent>
 
 class QPainter;
 class QPaintEvent;
@@ -46,10 +47,13 @@ protected:
        void paintEvent(QPaintEvent *event);
 
 private:
+       bool event(QEvent *event);
        void mousePressEvent(QMouseEvent *event);
+       void mouseReleaseEvent(QMouseEvent *event);
        void mouseMoveEvent(QMouseEvent *event);
        void mouseDoubleClickEvent(QMouseEvent * event);
        void wheelEvent(QWheelEvent *event);
+       bool touchEvent(QTouchEvent *e);
 
 private slots:
        void on_signals_changed();
@@ -60,6 +64,11 @@ private:
 
        QPoint _mouse_down_point;
        double _mouse_down_offset;
+       bool _mouse_down_valid;
+
+       double _pinch_offset0;
+       double _pinch_offset1;
+       bool _pinch_zoom_active;
 };
 
 } // namespace view