Fixes: NB#160502 Ability to disable physics

RevBy: Daniel d'Andrada
Details: This patch adds the posibility to disable the kinetic
scrolling of the physics engine. When this is done, the page
is scrollable but there is no sliding when the pointer is released.

1 files changed, 52 insertions, 5 deletions

diff --git a/src/corelib/widgets/mphysics2dpanning.cpp b/src/corelib/widgets/mphysics2dpanning.cpp
index 85f7eb3a..2f9ec2aa 100644
--- a/src/corelib/widgets/mphysics2dpanning.cpp
+++ b/src/corelib/widgets/mphysics2dpanning.cpp
@@ -28,6 +28,7 @@ static const int PanningTimelineInterval      =      20; /* in ms */
 static const int PositionNoiseDampingDelta    =       2; /* in px */
 
 MPhysics2DPanningPrivate::MPhysics2DPanningPrivate(MPhysics2DPanning *publicObject) :
+    enabled(true),
     range(QRectF(0.0, 0.0, 0.0, 0.0)),
     posX(0.0),
     posY(0.0),
@@ -143,6 +144,19 @@ MPhysics2DPanning::~MPhysics2DPanning()
     delete d_ptr;
 }
 
+bool MPhysics2DPanning::enabled() const
+{
+    return d_ptr->enabled;
+}
+
+void MPhysics2DPanning::setEnabled(bool enabled)
+{
+    Q_D(MPhysics2DPanning);
+
+    d->enabled = enabled;
+    if (d->enabled == false) stop();
+}
+
 Qt::Orientations MPhysics2DPanning::panDirection() const
 {
     return d_ptr->panDirection;
@@ -319,14 +333,43 @@ void MPhysics2DPanning::pointerMove(const QPointF &pos)
     Q_D(MPhysics2DPanning);
 
     // Tenses the pointer spring with the amount of movement of the pointer
-
     QPointF delta = pos - d->sceneLastPos;
 
     d->sceneLastPos = pos;
 
-    d->pointerSpringX += delta.x();
-    d->pointerSpringY += delta.y();
-    start();
+    if (d->enabled) {
+        d->pointerSpringX += delta.x();
+        d->pointerSpringY += delta.y();
+        start();
+    } else {
+
+        bool emitSignal = false;
+
+        if (d->panDirection.testFlag(Qt::Horizontal)) {
+
+            qreal prevPosX = d->posX;
+            d->posX -= delta.x();
+
+            if (d->posX < d->range.left()) d->posX = d->range.left();
+            if (d->posX > d->range.right()) d->posX = d->range.right();
+
+            if (prevPosX != d->posX) emitSignal = true;
+        }
+
+        if (d->panDirection.testFlag(Qt::Vertical)) {
+
+            qreal prevPosY = d->posY;
+            d->posY -= delta.y();
+
+            if (d->posY < d->range.top()) d->posY = d->range.top();
+            if (d->posY > d->range.bottom()) d->posY = d->range.bottom();
+
+            if (prevPosY != d->posY) emitSignal = true;
+        }
+
+        if (emitSignal) emit positionChanged(QPointF(d->posX, d->posY));
+    }
+
 }
 
 
@@ -335,8 +378,12 @@ void MPhysics2DPanning::pointerRelease()
     Q_D(MPhysics2DPanning);
 
     // Disables the pointer spring
-
     d->pointerPressed = false;
+
+    if (d->enabled == false) {
+        //The physics engine is not working, emitting panning stopped now.
+        emit panningStopped();
+    }
 }