ubuntu-touch-coreapps-reviewers team mailing list archive

[Stefano Verzegnassi <stefano92.100@xxxxxxxxx>]

Stefano Verzegnassi has proposed merging lp:~verzegnassi-stefano/ubuntu-docviewer-app/lo-use-timer-update-view into lp:~ubuntu-docviewer-dev/ubuntu-docviewer-app/lo-tiled-rendering.

Commit message:
[LOK-plugin] Use a QTimer to avoid multiple updates when contentX/contentY change

Requested reviews:
  Ubuntu Document Viewer Developers (ubuntu-docviewer-dev)

For more details, see:
https://code.launchpad.net/~verzegnassi-stefano/ubuntu-docviewer-app/lo-use-timer-update-view/+merge/264687

[LOK-plugin] Use a QTimer to avoid multiple updates when contentX/contentY change.

This avoids multiple calls of the updateVisibleRect() function, so that the Flickable can scroll smooth without the main thread being busy.

*** NOTES:
The interval of the timer is arbitrary, and we may need to change it as we'll have all the things in the right place (i.e. cache buffer and low-res page placeholder).

At the moment it is just set to 20ms, which seems to provide a good balance between the speed of Flickable's scrolling and the frequency of the updates of the view.
-- 
Your team Ubuntu Document Viewer Developers is requested to review the proposed merge of lp:~verzegnassi-stefano/ubuntu-docviewer-app/lo-use-timer-update-view into lp:~ubuntu-docviewer-dev/ubuntu-docviewer-app/lo-tiled-rendering.

=== modified file 'src/plugin/libreofficetoolkit-qml-plugin/loview.cpp'
--- src/plugin/libreofficetoolkit-qml-plugin/loview.cpp	2015-07-12 21:26:48 +0000
+++ src/plugin/libreofficetoolkit-qml-plugin/loview.cpp	2015-07-14 09:28:29 +0000
@@ -21,6 +21,7 @@
 
 #include <QPainter>
 #include <QImage>
+#include <QTimer>
 #include <QtCore/qmath.h>
 
 // TODO: Use a QQuickItem and implement painting through
@@ -34,26 +35,21 @@
     , m_document(nullptr)
     , m_zoomFactor(1.0)
     , m_visibleArea(0, 0, 0, 0)
+    , m_updateTimer(nullptr)
 {
-    Q_UNUSED(parent)
+    Q_UNUSED(parent)   
+    m_updateTimer = new QTimer();
 
-    // Connections for updating the canvas size.
     connect(this, SIGNAL(documentChanged()), this, SLOT(updateViewSize()));
     connect(this, SIGNAL(zoomFactorChanged()), this, SLOT(updateViewSize()));
-
     connect(this, SIGNAL(parentFlickableChanged()), this, SLOT(updateVisibleRect()));
+    connect(m_updateTimer, SIGNAL(timeout()), this, SLOT(updateVisibleRect()));
 }
 
 void LOView::paint(QPainter *painter)
 {
     // qDebug() << "Painting new tiles...";
 
-    // Clean area outside the visible one
-    painter->eraseRect(QRect(0, 0, m_visibleArea.right(), m_visibleArea.top()));  // TOP
-    painter->eraseRect(QRect(m_visibleArea.left(), m_visibleArea.bottom(), m_visibleArea.right(), this->height() - m_visibleArea.bottom()));    // BOTTOM
-    painter->eraseRect(QRect(0, m_visibleArea.top(), m_visibleArea.left(), m_visibleArea.height()));  // LEFT
-    painter->eraseRect(QRect(m_visibleArea.right(), m_visibleArea.top(), this->width() - m_visibleArea.right(), m_visibleArea.height()));  // RIGHT
-
     Q_FOREACH(TileItem* tile, m_tiles) {
         // if (!tile->painted) {
             painter->drawImage(tile->area, tile->texture);
@@ -83,8 +79,8 @@
     connect(m_parentFlickable, SIGNAL(widthChanged()), this, SLOT(updateVisibleRect()));
     connect(m_parentFlickable, SIGNAL(heightChanged()), this, SLOT(updateVisibleRect()));
 
-    connect(m_parentFlickable, SIGNAL(contentXChanged()), this, SLOT(updateVisibleRect()));
-    connect(m_parentFlickable, SIGNAL(contentYChanged()), this, SLOT(updateVisibleRect()));
+    connect(m_parentFlickable, SIGNAL(contentXChanged()), this, SLOT(queueVisibleRectUpdate()));
+    connect(m_parentFlickable, SIGNAL(contentYChanged()), this, SLOT(queueVisibleRectUpdate()));
 
     Q_EMIT parentFlickableChanged();
 }
@@ -212,9 +208,12 @@
 
     // TODO: Generate tiles in the cacheBuffer area
     // (currently called loadingArea).
+}
 
-    // Request a new paint.
-    this->update();
+void LOView::queueVisibleRectUpdate()
+{
+    if (!m_updateTimer->isActive())
+        m_updateTimer->start(20);
 }
 
 LOView::~LOView()

=== modified file 'src/plugin/libreofficetoolkit-qml-plugin/loview.h'
--- src/plugin/libreofficetoolkit-qml-plugin/loview.h	2015-07-04 16:00:33 +0000
+++ src/plugin/libreofficetoolkit-qml-plugin/loview.h	2015-07-14 09:28:29 +0000
@@ -24,6 +24,7 @@
 
 class LODocument;
 class TileItem;
+class QTimer;
 
 class LOView : public QQuickPaintedItem
 {
@@ -60,6 +61,7 @@
 private Q_SLOTS:
     void updateViewSize();
     void updateVisibleRect();
+    void queueVisibleRectUpdate();
 
 private:
     QQuickItem*             m_parentFlickable;
@@ -68,6 +70,8 @@
     qreal                   m_zoomFactor;
     QRect                   m_visibleArea;
 
+    QTimer*                 m_updateTimer;
+
     // TODO: Should we move tiles management in another class (e.g. TileBuffer)?
     QMap<int, TileItem*>    m_tiles;
 };