Implement zooming to cursor

Zooming to cursor is now default operating mode of
the default input handler.

Task-number: QTRD-3263
Change-Id: I5699fc0ce7393059538972cd52f31f06d87e3d8d
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>

5 files changed, 160 insertions, 16 deletions

diff --git a/src/datavisualization/input/q3dinputhandler.cpp b/src/datavisualization/input/q3dinputhandler.cpp
index e6f3de24..0bed3cb9 100644
--- a/src/datavisualization/input/q3dinputhandler.cpp
+++ b/src/datavisualization/input/q3dinputhandler.cpp
@@ -18,13 +18,16 @@
 
 #include "datavisualizationglobal_p.h"
 #include "q3dinputhandler_p.h"
+#include "abstract3dcontroller_p.h"
 
 QT_BEGIN_NAMESPACE_DATAVISUALIZATION
 
-const int minZoomLevel         = 10;
-const int halfSizeZoomLevel    = 50;
-const int oneToOneZoomLevel    = 100;
-const int maxZoomLevel         = 500;
+const int minZoomLevel           = 10;
+const int halfSizeZoomLevel      = 50;
+const int oneToOneZoomLevel      = 100;
+const int maxZoomLevel           = 500;
+const int driftTowardCenterLevel = 175;
+const float wheelZoomDrift       = 0.1f;
 
 const int nearZoomRangeDivider = 12;
 const int midZoomRangeDivider  = 60;
@@ -84,6 +87,7 @@ const float rotationSpeed      = 100.0f;
  * \since QtDataVisualization 1.2
  *
  * This property specifies if this input handler allows graph rotation.
+ * Defaults to \c{true}.
  */
 
 /*!
@@ -91,6 +95,7 @@ const float rotationSpeed      = 100.0f;
  * \since QtDataVisualization 1.2
  *
  * This property specifies if this input handler allows graph zooming.
+ * Defaults to \c{true}.
  */
 
 /*!
@@ -98,6 +103,16 @@ const float rotationSpeed      = 100.0f;
  * \since QtDataVisualization 1.2
  *
  * This property specifies if this input handler allows selection from the graph.
+ * Defaults to \c{true}.
+ */
+
+/*!
+ * \qmlproperty bool InputHandler3D::zoomAtTargetEnabled
+ * \since QtDataVisualization 1.2
+ *
+ * This property specifies if zooming changes the camera target to the position of the input
+ * at the time of the zoom.
+ * Defaults to \c{true}.
  */
 
 /*!
@@ -236,7 +251,16 @@ void Q3DInputHandler::wheelEvent(QWheelEvent *event)
         else if (zoomLevel < minZoomLevel)
             zoomLevel = minZoomLevel;
 
-        scene()->activeCamera()->setZoomLevel(zoomLevel);
+        if (isZoomAtTargetEnabled()) {
+            scene()->setGraphPositionQuery(event->pos());
+            d_ptr->m_zoomAtTargetPending = true;
+            // If zoom at target is enabled, we don't want to zoom yet, as that causes
+            // jitter. Instead, we zoom next frame, when we apply the camera position.
+            d_ptr->m_requestedZoomLevel = zoomLevel;
+            d_ptr->m_driftMultiplier = wheelZoomDrift;
+        } else {
+            scene()->activeCamera()->setZoomLevel(zoomLevel);
+        }
     }
 }
 
@@ -245,6 +269,7 @@ void Q3DInputHandler::wheelEvent(QWheelEvent *event)
  * \since QtDataVisualization 1.2
  *
  * This property specifies if this input handler allows graph rotation.
+ * Defaults to \c{true}.
  */
 void Q3DInputHandler::setRotationEnabled(bool enable)
 {
@@ -264,6 +289,7 @@ bool Q3DInputHandler::isRotationEnabled() const
  * \since QtDataVisualization 1.2
  *
  * This property specifies if this input handler allows graph zooming.
+ * Defaults to \c{true}.
  */
 void Q3DInputHandler::setZoomEnabled(bool enable)
 {
@@ -283,6 +309,7 @@ bool Q3DInputHandler::isZoomEnabled() const
  * \since QtDataVisualization 1.2
  *
  * This property specifies if this input handler allows selection from the graph.
+ * Defaults to \c{true}.
  */
 void Q3DInputHandler::setSelectionEnabled(bool enable)
 {
@@ -297,17 +324,100 @@ bool Q3DInputHandler::isSelectionEnabled() const
     return d_ptr->m_selectionEnabled;
 }
 
+/*!
+ * \property Q3DInputHandler::zoomAtTargetEnabled
+ * \since QtDataVisualization 1.2
+ *
+ * This property specifies if zooming should change the camera target so that the zoomed point
+ * of the graph stays at the same location after the zoom.
+ * Defaults to \c{true}.
+ */
+void Q3DInputHandler::setZoomAtTargetEnabled(bool enable)
+{
+    if (d_ptr->m_zoomAtTargetEnabled != enable) {
+        d_ptr->m_zoomAtTargetEnabled = enable;
+        emit zoomAtTargetEnabledChanged(enable);
+    }
+}
+
+bool Q3DInputHandler::isZoomAtTargetEnabled() const
+{
+    return d_ptr->m_zoomAtTargetEnabled;
+}
+
 Q3DInputHandlerPrivate::Q3DInputHandlerPrivate(Q3DInputHandler *q)
     : q_ptr(q),
       m_inputState(QAbstract3DInputHandlerPrivate::InputStateNone),
       m_rotationEnabled(true),
       m_zoomEnabled(true),
-      m_selectionEnabled(true)
+      m_selectionEnabled(true),
+      m_zoomAtTargetEnabled(true),
+      m_zoomAtTargetPending(false),
+      m_controller(0),
+      m_requestedZoomLevel(0.0f),
+      m_driftMultiplier(0.0f)
 {
+    QObject::connect(q, &QAbstract3DInputHandler::sceneChanged,
+                     this, &Q3DInputHandlerPrivate::handleSceneChange);
 }
 
 Q3DInputHandlerPrivate::~Q3DInputHandlerPrivate()
 {
 }
 
+void Q3DInputHandlerPrivate::handleSceneChange(Q3DScene *scene)
+{
+    if (scene) {
+        if (m_controller) {
+            QObject::disconnect(m_controller, &Abstract3DController::queriedGraphPositionChanged,
+                                this, &Q3DInputHandlerPrivate::handleQueriedGraphPositionChange);
+        }
+
+        m_controller = qobject_cast<Abstract3DController *>(scene->parent());
+
+        if (m_controller) {
+            QObject::connect(m_controller, &Abstract3DController::queriedGraphPositionChanged,
+                             this, &Q3DInputHandlerPrivate::handleQueriedGraphPositionChange);
+        }
+    }
+}
+
+void Q3DInputHandlerPrivate::handleQueriedGraphPositionChange()
+{
+    if (m_zoomAtTargetPending) {
+        // Check if the zoom point is on graph
+        QVector3D newTarget = m_controller->queriedGraphPosition();
+        float currentZoom = m_requestedZoomLevel;
+        float previousZoom = q_ptr->scene()->activeCamera()->zoomLevel();
+        q_ptr->scene()->activeCamera()->setZoomLevel(currentZoom);
+        float diffAdj = 0.0f;
+
+        // If zooming in/out outside the graph, or zooming out after certain point,
+        // move towards the center.
+        if ((qAbs(newTarget.x()) > 1.0f
+             || qAbs(newTarget.y()) > 1.0f
+             || qAbs(newTarget.z()) > 1.0f)
+                || (previousZoom > currentZoom && currentZoom <= driftTowardCenterLevel)) {
+            newTarget = zeroVector;
+            // Add some extra correction so that we actually reach the center eventually
+            diffAdj = m_driftMultiplier;
+            if (previousZoom > currentZoom)
+                diffAdj *= 2.0f; // Correct towards center little more when zooming out
+        }
+
+        float zoomFraction = 1.0f - (previousZoom / currentZoom);
+
+        // Adjust camera towards the zoom point, attempting to keep the cursor at same graph point
+        QVector3D oldTarget = q_ptr->scene()->activeCamera()->target();
+        QVector3D origDiff = newTarget - oldTarget;
+        QVector3D diff = origDiff * zoomFraction + (origDiff.normalized() * diffAdj);
+        if (diff.length() > origDiff.length())
+            diff = origDiff;
+        q_ptr->scene()->activeCamera()->setTarget(oldTarget + diff);
+
+        if (q_ptr->scene()->selectionQueryPosition() == Q3DScene::invalidSelectionPoint())
+            m_zoomAtTargetPending = false;
+    }
+}
+
 QT_END_NAMESPACE_DATAVISUALIZATION
diff --git a/src/datavisualization/input/q3dinputhandler.h b/src/datavisualization/input/q3dinputhandler.h
index 9afeb945..5423b4ea 100644
--- a/src/datavisualization/input/q3dinputhandler.h
+++ b/src/datavisualization/input/q3dinputhandler.h
@@ -31,6 +31,7 @@ class QT_DATAVISUALIZATION_EXPORT Q3DInputHandler : public QAbstract3DInputHandl
     Q_PROPERTY(bool rotationEnabled READ isRotationEnabled WRITE setRotationEnabled NOTIFY rotationEnabledChanged)
     Q_PROPERTY(bool zoomEnabled READ isZoomEnabled WRITE setZoomEnabled NOTIFY zoomEnabledChanged)
     Q_PROPERTY(bool selectionEnabled READ isSelectionEnabled WRITE setSelectionEnabled NOTIFY selectionEnabledChanged)
+    Q_PROPERTY(bool zoomAtTargetEnabled READ isZoomAtTargetEnabled WRITE setZoomAtTargetEnabled NOTIFY zoomAtTargetEnabledChanged)
 
 public:
     explicit Q3DInputHandler(QObject *parent = 0);
@@ -42,6 +43,8 @@ public:
     bool isZoomEnabled() const;
     void setSelectionEnabled(bool enable);
     bool isSelectionEnabled() const;
+    void setZoomAtTargetEnabled(bool enable);
+    bool isZoomAtTargetEnabled() const;
 
     // Input event listeners
     virtual void mousePressEvent(QMouseEvent *event, const QPoint &mousePos);
@@ -53,6 +56,7 @@ signals:
     void rotationEnabledChanged(bool enable);
     void zoomEnabledChanged(bool enable);
     void selectionEnabledChanged(bool enable);
+    void zoomAtTargetEnabledChanged(bool enable);
 
 private:
     Q_DISABLE_COPY(Q3DInputHandler)
diff --git a/src/datavisualization/input/q3dinputhandler_p.h b/src/datavisualization/input/q3dinputhandler_p.h
index a3ed8c9c..79b1c8dd 100644
--- a/src/datavisualization/input/q3dinputhandler_p.h
+++ b/src/datavisualization/input/q3dinputhandler_p.h
@@ -34,19 +34,34 @@
 
 QT_BEGIN_NAMESPACE_DATAVISUALIZATION
 
-class Q3DInputHandlerPrivate
+class Abstract3DController;
+
+class Q3DInputHandlerPrivate : public QObject
 {
+    Q_OBJECT
 public:
     Q3DInputHandlerPrivate(Q3DInputHandler *q);
     ~Q3DInputHandlerPrivate();
 
-protected:
+public slots:
+    void handleSceneChange(Q3DScene *scene);
+    void handleQueriedGraphPositionChange();
+
+private:
     Q3DInputHandler *q_ptr;
+protected:
     QAbstract3DInputHandlerPrivate::InputState m_inputState;
 
     bool m_rotationEnabled;
     bool m_zoomEnabled;
     bool m_selectionEnabled;
+    bool m_zoomAtTargetEnabled;
+    bool m_zoomAtTargetPending;
+
+    Abstract3DController *m_controller; // Not owned
+
+    float m_requestedZoomLevel;
+    float m_driftMultiplier;
 
     friend class Q3DInputHandler;
 };
diff --git a/src/datavisualization/input/qtouch3dinputhandler.cpp b/src/datavisualization/input/qtouch3dinputhandler.cpp
index 5d62922b..b811548b 100644
--- a/src/datavisualization/input/qtouch3dinputhandler.cpp
+++ b/src/datavisualization/input/qtouch3dinputhandler.cpp
@@ -33,6 +33,7 @@ const int tapAndHoldTime = 250;
 const float rotationSpeed = 200.0f;
 const int minZoomLevel = 10;
 const int maxZoomLevel = 500;
+const float touchZoomDrift = 0.02f;
 
 /*!
  * \class QTouch3DInputHandler
@@ -113,7 +114,8 @@ void QTouch3DInputHandler::touchEvent(QTouchEvent *event)
     if (!scene()->isSlicingActive() && points.count() == 2) {
         d_ptr->m_holdTimer->stop();
         QPointF distance = points.at(0).pos() - points.at(1).pos();
-        d_ptr->handlePinchZoom(distance.manhattanLength());
+        QPoint midPoint = ((points.at(0).pos() + points.at(1).pos()) / 2.0).toPoint();
+        d_ptr->handlePinchZoom(distance.manhattanLength(), midPoint);
     } else if (points.count() == 1) {
         QPointF pointerPos = points.at(0).pos();
         if (event->type() == QEvent::TouchBegin) {
@@ -165,7 +167,8 @@ void QTouch3DInputHandler::touchEvent(QTouchEvent *event)
 }
 
 QTouch3DInputHandlerPrivate::QTouch3DInputHandlerPrivate(QTouch3DInputHandler *q)
-    : q_ptr(q),
+    : Q3DInputHandlerPrivate(q),
+      q_ptr(q),
       m_holdTimer(0),
       m_inputState(QAbstract3DInputHandlerPrivate::InputStateNone)
 {
@@ -181,7 +184,7 @@ QTouch3DInputHandlerPrivate::~QTouch3DInputHandlerPrivate()
     delete m_holdTimer;
 }
 
-void QTouch3DInputHandlerPrivate::handlePinchZoom(float distance)
+void QTouch3DInputHandlerPrivate::handlePinchZoom(float distance, const QPoint &pos)
 {
     if (q_ptr->isZoomEnabled()) {
         int newDistance = distance;
@@ -200,7 +203,18 @@ void QTouch3DInputHandlerPrivate::handlePinchZoom(float distance)
             zoomLevel = maxZoomLevel;
         else if (zoomLevel < minZoomLevel)
             zoomLevel = minZoomLevel;
-        camera->setZoomLevel(zoomLevel);
+
+        if (q_ptr->isZoomAtTargetEnabled()) {
+            q_ptr->scene()->setGraphPositionQuery(pos);
+            m_zoomAtTargetPending = true;
+            // If zoom at target is enabled, we don't want to zoom yet, as that causes
+            // jitter. Instead, we zoom next frame, when we apply the camera position.
+            m_requestedZoomLevel = zoomLevel;
+            m_driftMultiplier = touchZoomDrift;
+        } else {
+            camera->setZoomLevel(zoomLevel);
+        }
+
         q_ptr->setPrevDistance(newDistance);
     }
 }
diff --git a/src/datavisualization/input/qtouch3dinputhandler_p.h b/src/datavisualization/input/qtouch3dinputhandler_p.h
index 613b5f28..b01904ca 100644
--- a/src/datavisualization/input/qtouch3dinputhandler_p.h
+++ b/src/datavisualization/input/qtouch3dinputhandler_p.h
@@ -19,7 +19,7 @@
 #ifndef QTOUCH3DINPUTHANDLER_P_H
 #define QTOUCH3DINPUTHANDLER_P_H
 
-#include "qabstract3dinputhandler_p.h"
+#include "q3dinputhandler_p.h"
 #include "qtouch3dinputhandler.h"
 
 class QTimer;
@@ -28,7 +28,7 @@ QT_BEGIN_NAMESPACE_DATAVISUALIZATION
 
 class QAbstract3DInputHandler;
 
-class QTouch3DInputHandlerPrivate : public QObject
+class QTouch3DInputHandlerPrivate : public Q3DInputHandlerPrivate
 {
     Q_OBJECT
 
@@ -36,13 +36,14 @@ public:
     QTouch3DInputHandlerPrivate(QTouch3DInputHandler *q);
     ~QTouch3DInputHandlerPrivate();
 
-    void handlePinchZoom(float distance);
+    void handlePinchZoom(float distance, const QPoint &pos);
     void handleTapAndHold();
     void handleSelection(const QPointF &position);
     void handleRotation(const QPointF &position);
 
-public:
+private:
     QTouch3DInputHandler *q_ptr;
+public:
     QTimer *m_holdTimer;
     QAbstract3DInputHandlerPrivate::InputState m_inputState;
     QPointF m_startHoldPos;