Improve autoscrolling

- Start autoscrolling when doing a dragging
- Start autoscrolling with a small delay

diff --git a/src/kitemviews/kitemlistcontroller.cpp b/src/kitemviews/kitemlistcontroller.cpp
index 09c7d8d46487b8449af1d6b9f9805a18d44c7ff3..025249a34a4df329c9590a6b9bbcc83838c103ae 100644 (file)
--- a/src/kitemviews/kitemlistcontroller.cpp
+++ b/src/kitemviews/kitemlistcontroller.cpp
@@ -38,7 +38,6 @@
 
 KItemListController::KItemListController(QObject* parent) :
     QObject(parent),
-    m_dragging(false),
     m_selectionBehavior(NoSelection),
     m_model(0),
     m_view(0),
@@ -271,7 +270,6 @@ bool KItemListController::mousePressEvent(QGraphicsSceneMouseEvent* event, const
         return false;
     }
 
-    m_dragging = false;
     m_pressedMousePos = transform.map(event->pos());
     m_pressedIndex = m_view->itemAt(m_pressedMousePos);
 
@@ -362,13 +360,13 @@ bool KItemListController::mouseMoveEvent(QGraphicsSceneMouseEvent* event, const
 
     if (m_pressedIndex >= 0) {
         // Check whether a dragging should be started
-        if (!m_dragging && (event->buttons() & Qt::LeftButton)) {
+        if (event->buttons() & Qt::LeftButton) {
             const QPointF pos = transform.map(event->pos());
             const qreal minDragDiff = 4;
             const bool hasMinDragDiff = qAbs(pos.x() - m_pressedMousePos.x()) >= minDragDiff ||
                                         qAbs(pos.y() - m_pressedMousePos.y()) >= minDragDiff;
-            if (hasMinDragDiff && startDragging()) {
-                m_dragging = true;
+            if (hasMinDragDiff) {
+                startDragging();
             }
         }
     } else {
@@ -401,7 +399,7 @@ bool KItemListController::mouseReleaseEvent(QGraphicsSceneMouseEvent* event, con
     const bool shiftOrControlPressed = event->modifiers() & Qt::ShiftModifier ||
                                        event->modifiers() & Qt::ControlModifier;
 
-    bool clearSelection = !shiftOrControlPressed && !m_dragging && event->button() != Qt::RightButton;
+    bool clearSelection = !shiftOrControlPressed && event->button() != Qt::RightButton;
 
     KItemListRubberBand* rubberBand = m_view->rubberBand();
     if (rubberBand->isActive()) {
@@ -449,7 +447,6 @@ bool KItemListController::mouseReleaseEvent(QGraphicsSceneMouseEvent* event, con
         m_selectionManager->clearSelection();
     }
 
-    m_dragging = false;
     m_pressedMousePos = QPointF();
     m_pressedIndex = -1;
     return false;
@@ -494,8 +491,6 @@ bool KItemListController::dropEvent(QGraphicsSceneDragDropEvent* event, const QT
 {
     Q_UNUSED(event);
     Q_UNUSED(transform);
-
-    m_dragging = false;
     return false;
 }
 
@@ -737,16 +732,16 @@ void KItemListController::slotRubberBandChanged()
     }
 }
 
-bool KItemListController::startDragging()
+void KItemListController::startDragging()
 {
     if (!m_view || !m_model) {
-        return false;
+        return;
     }
 
     const QSet<int> selectedItems = m_selectionManager->selectedItems();
     QMimeData* data = m_model->createMimeData(selectedItems);
     if (!data) {
-        return false;
+        return;
     }
 
     // The created drag object will be owned and deleted
@@ -758,7 +753,6 @@ bool KItemListController::startDragging()
     drag->setPixmap(pixmap);
 
     drag->exec(Qt::MoveAction | Qt::CopyAction | Qt::LinkAction, Qt::IgnoreAction);
-    return true;
 }
 
 #include "kitemlistcontroller.moc"

diff --git a/src/kitemviews/kitemlistcontroller.h b/src/kitemviews/kitemlistcontroller.h
index 4ce5b804bd80db70c185617c0c86b76e0d410ee1..8ac2b554b14609d841eb272ac6175c613c4511cb 100644 (file)
--- a/src/kitemviews/kitemlistcontroller.h
+++ b/src/kitemviews/kitemlistcontroller.h
@@ -138,14 +138,11 @@ private slots:
 
 private:
     /**
-     * Creates a QDrag object to start a drag-operation.
-     * @return True if the QDrag object has been created. If false is returned
-     *         there is no implementation available for KItemModelBase::createMimeData().
+     * Creates a QDrag object and initiates a drag-operation.
      */
-    bool startDragging();
+    void startDragging();
 
 private:
-    bool m_dragging;
     SelectionBehavior m_selectionBehavior;
     KItemModelBase* m_model;
     KItemListView* m_view;

diff --git a/src/kitemviews/kitemlistview.cpp b/src/kitemviews/kitemlistview.cpp
index a35752a473ce3493c44e15cecfd9a0ddc32acff5..2a7b0e4cdd7b171efca6636b343246810d59a8b5 100644 (file)
--- a/src/kitemviews/kitemlistview.cpp
+++ b/src/kitemviews/kitemlistview.cpp
@@ -41,6 +41,15 @@
 #include <QStyleOptionRubberBand>
 #include <QTimer>
 
+namespace {
+    // Time in ms until reaching the autoscroll margin triggers
+    // an initial autoscrolling
+    const int InitialAutoScrollDelay = 700;
+
+    // Delay in ms for triggering the next autoscroll
+    const int RepeatingAutoScrollDelay = 1000 / 60;
+}
+
 KItemListView::KItemListView(QGraphicsWidget* parent) :
     QGraphicsWidget(parent),
     m_grouped(false),
@@ -64,6 +73,7 @@ KItemListView::KItemListView(QGraphicsWidget* parent) :
     m_skipAutoScrollForRubberBand(false),
     m_rubberBand(0),
     m_mousePos(),
+    m_autoScrollIncrement(0),
     m_autoScrollTimer(0)
 {
     setAcceptHoverEvents(true);
@@ -198,10 +208,9 @@ void KItemListView::setAutoScroll(bool enabled)
 {
     if (enabled && !m_autoScrollTimer) {
         m_autoScrollTimer = new QTimer(this);
-        m_autoScrollTimer->setInterval(1000 / 60); // 60 frames per second
         m_autoScrollTimer->setSingleShot(false);
         connect(m_autoScrollTimer, SIGNAL(timeout()), this, SLOT(triggerAutoScrolling()));
-        m_autoScrollTimer->start();
+        m_autoScrollTimer->start(InitialAutoScrollDelay);
     } else if (!enabled && m_autoScrollTimer) {
         delete m_autoScrollTimer;
         m_autoScrollTimer = 0;
@@ -482,17 +491,40 @@ void KItemListView::mousePressEvent(QGraphicsSceneMouseEvent* event)
 
 void KItemListView::mouseMoveEvent(QGraphicsSceneMouseEvent* event)
 {
-    m_mousePos = transform().map(event->pos());
     QGraphicsWidget::mouseMoveEvent(event);
 
+    m_mousePos = transform().map(event->pos());
     if (m_autoScrollTimer && !m_autoScrollTimer->isActive()) {
-        m_autoScrollTimer->start();
+        m_autoScrollTimer->start(InitialAutoScrollDelay);
     }
 }
 
 void KItemListView::dragEnterEvent(QGraphicsSceneDragDropEvent* event)
 {
     event->setAccepted(true);
+    setAutoScroll(true);
+}
+
+void KItemListView::dragMoveEvent(QGraphicsSceneDragDropEvent *event)
+{
+    QGraphicsWidget::dragMoveEvent(event);
+
+    m_mousePos = transform().map(event->pos());
+    if (m_autoScrollTimer && !m_autoScrollTimer->isActive()) {
+        m_autoScrollTimer->start(InitialAutoScrollDelay);
+    }
+}
+
+void KItemListView::dragLeaveEvent(QGraphicsSceneDragDropEvent *event)
+{
+    QGraphicsWidget::dragLeaveEvent(event);
+    setAutoScroll(false);
+}
+
+void KItemListView::dropEvent(QGraphicsSceneDragDropEvent* event)
+{
+    QGraphicsWidget::dropEvent(event);
+    setAutoScroll(false);
 }
 
 QList<KItemListWidget*> KItemListView::visibleItemListWidgets() const
@@ -816,8 +848,12 @@ void KItemListView::triggerAutoScrolling()
         visibleSize = size().width();
     }
 
-    const int inc = calculateAutoScrollingIncrement(pos, visibleSize);
-    if (inc == 0) {
+    if (m_autoScrollTimer->interval() == InitialAutoScrollDelay) {
+        m_autoScrollIncrement = 0;
+    }
+
+    m_autoScrollIncrement = calculateAutoScrollingIncrement(pos, visibleSize, m_autoScrollIncrement);
+    if (m_autoScrollIncrement == 0) {
         // The mouse position is not above an autoscroll margin (the autoscroll timer
         // will be restarted in mouseMoveEvent())
         m_autoScrollTimer->stop();
@@ -834,7 +870,7 @@ void KItemListView::triggerAutoScrolling()
         const qreal diff = (scrollOrientation() == Qt::Vertical)
                            ? m_rubberBand->endPosition().y() - m_rubberBand->startPosition().y()
                            : m_rubberBand->endPosition().x() - m_rubberBand->startPosition().x();
-        if (qAbs(diff) < minDiff || (inc < 0 && diff > 0) || (inc > 0 && diff < 0)) {
+        if (qAbs(diff) < minDiff || (m_autoScrollIncrement < 0 && diff > 0) || (m_autoScrollIncrement > 0 && diff < 0)) {
             // The rubberband direction is different from the scroll direction (e.g. the rubberband has
             // been moved up although the autoscroll direction might be down)
             m_autoScrollTimer->stop();
@@ -846,13 +882,11 @@ void KItemListView::triggerAutoScrolling()
     // the autoscrolling may not get skipped anymore until a new rubberband is created
     m_skipAutoScrollForRubberBand = false;
 
-    setOffset(offset() + inc);
+    setOffset(offset() + m_autoScrollIncrement);
 
-    if (!m_autoScrollTimer->isActive()) {
-       // Trigger the autoscroll timer which will periodically call
-       // triggerAutoScrolling()
-       m_autoScrollTimer->start();
-    }
+   // Trigger the autoscroll timer which will periodically call
+   // triggerAutoScrolling()
+   m_autoScrollTimer->start(RepeatingAutoScrollDelay);
 }
 
 void KItemListView::setController(KItemListController* controller)
@@ -1261,7 +1295,7 @@ void KItemListView::updateWidgetProperties(KItemListWidget* widget, int index)
     widget->setData(m_model->data(index));
 }
 
-int KItemListView::calculateAutoScrollingIncrement(int pos, int size)
+int KItemListView::calculateAutoScrollingIncrement(int pos, int range, int oldInc)
 {
     int inc = 0;
 
@@ -1270,16 +1304,18 @@ int KItemListView::calculateAutoScrollingIncrement(int pos, int size)
     const int speedLimiter = 96;
     const int autoScrollBorder = 64;
 
+    // Limit the increment that is allowed to be added in comparison to 'oldInc'.
+    // This assures that the autoscrolling speed grows gradually.
+    const int incLimiter = 1;
+
     if (pos < autoScrollBorder) {
         inc = -minSpeed + qAbs(pos - autoScrollBorder) * (pos - autoScrollBorder) / speedLimiter;
-        if (inc < -maxSpeed) {
-            inc = -maxSpeed;
-        }
-    } else if (pos > size - autoScrollBorder) {
-        inc = minSpeed + qAbs(pos - size + autoScrollBorder) * (pos - size + autoScrollBorder) / speedLimiter;
-        if (inc > maxSpeed) {
-            inc = maxSpeed;
-        }
+        inc = qMax(inc, -maxSpeed);
+        inc = qMax(inc, oldInc - incLimiter);
+    } else if (pos > range - autoScrollBorder) {
+        inc = minSpeed + qAbs(pos - range + autoScrollBorder) * (pos - range + autoScrollBorder) / speedLimiter;
+        inc = qMin(inc, maxSpeed);
+        inc = qMin(inc, oldInc + incLimiter);
     }
 
     return inc;

diff --git a/src/kitemviews/kitemlistview.h b/src/kitemviews/kitemlistview.h
index 9977e3639f8f3a3cedb807c1cb7888aa146d76f2..55a5c334428a9cb81d7fe6ce09533b7535c032c9 100644 (file)
--- a/src/kitemviews/kitemlistview.h
+++ b/src/kitemviews/kitemlistview.h
@@ -200,6 +200,9 @@ protected:
     virtual void mousePressEvent(QGraphicsSceneMouseEvent* event);
     virtual void mouseMoveEvent(QGraphicsSceneMouseEvent* event);
     virtual void dragEnterEvent(QGraphicsSceneDragDropEvent* event);
+    virtual void dragMoveEvent(QGraphicsSceneDragDropEvent* event);
+    virtual void dragLeaveEvent(QGraphicsSceneDragDropEvent* event);
+    virtual void dropEvent(QGraphicsSceneDragDropEvent* event);
 
     QList<KItemListWidget*> visibleItemListWidgets() const;
 
@@ -290,12 +293,16 @@ private:
     void updateWidgetProperties(KItemListWidget* widget, int index);
 
     /**
-     * Helper function for triggerAutoScrolling(). Returns the scroll increment
-     * that should be added to the offset() based on the available size \a size
-     * and the current mouse position \a pos. As soon as \a pos is inside
-     * the autoscroll-margin a value != 0 will be returned.
+     * Helper function for triggerAutoScrolling().
+     * @param pos    Logical position of the mouse relative to the range.
+     * @param range  Range of the visible area.
+     * @param oldInc Previous increment. Is used to assure that the increment
+     *               increases only gradually.
+     * @return Scroll increment that should be added to the offset().
+     *         As soon as \a pos is inside the autoscroll-margin a
+     *         value != 0 will be returned.
      */
-    static int calculateAutoScrollingIncrement(int pos, int size);
+    static int calculateAutoScrollingIncrement(int pos, int range, int oldInc);
 
 private:
     bool m_grouped;
@@ -326,6 +333,7 @@ private:
     KItemListRubberBand* m_rubberBand;
 
     QPointF m_mousePos;
+    int m_autoScrollIncrement;
     QTimer* m_autoScrollTimer;
 
     friend class KItemListController;