QSvgWidget: only start the animation timer when visible

Thanks to Gammaray, I noticed that a hidden (and rarely shown) QSvgWidget
whose purpose is to show a "searching..." animation was triggering a 33ms
QTimer for ever in the application. The slot simply calls update()
which doesn't do anything on a hidden widget, but waking up every 33ms
is still wasteful -- and noisy in gammaray's Events module.

[ChangeLog] Add animationEnabled property to QSvgRenderer,
and use it from QSvgWidget to stop animations when hidden.

Change-Id: I4ec63254b49a513688f8274cee49a1251b89a6cd
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

4 files changed, 61 insertions, 4 deletions

diff --git a/src/svg/qsvgrenderer.cpp b/src/svg/qsvgrenderer.cpp
index 31024cf..56c0b77 100644
--- a/src/svg/qsvgrenderer.cpp
+++ b/src/svg/qsvgrenderer.cpp
@@ -81,9 +81,9 @@ public:
         delete render;
     }
 
-    void startStopTimer()
+    void startOrStopTimer()
     {
-        if (render && render->animated() && fps > 0) {
+        if (animationEnabled && render && render->animated() && fps > 0) {
             ensureTimerCreated();
             timer->start(1000 / fps);
         } else if (timer) {
@@ -106,6 +106,7 @@ public:
     QTimer *timer;
     int fps;
     QSvg::FeatureSet featureSet;
+    bool animationEnabled = true;
 };
 
 /*!
@@ -219,6 +220,34 @@ bool QSvgRenderer::animated() const
 }
 
 /*!
+    \property QSvgRenderer::animationEnabled
+    \brief whether the animation should run, if the SVG is animated
+
+    Setting the property to false stops the animation timer.
+    Setting the property to false starts the animation timer,
+    provided that the SVG contains animated elements.
+
+    If the SVG is not animated, the property will have no effect.
+    Otherwise, the property defaults to true.
+
+    \sa animated()
+
+    \since 6.7
+*/
+bool QSvgRenderer::isAnimationEnabled() const
+{
+    Q_D(const QSvgRenderer);
+    return d->animationEnabled;
+}
+
+void QSvgRenderer::setAnimationEnabled(bool enable)
+{
+    Q_D(QSvgRenderer);
+    d->animationEnabled = enable;
+    d->startOrStopTimer();
+}
+
+/*!
     \property QSvgRenderer::framesPerSecond
     \brief the number of frames per second to be shown
 
@@ -240,7 +269,7 @@ void QSvgRenderer::setFramesPerSecond(int num)
         return;
     }
     d->fps = num;
-    d->startStopTimer();
+    d->startOrStopTimer();
 }
 
 /*!
@@ -363,7 +392,7 @@ static bool loadDocument(QSvgRenderer *const q,
         delete d->render;
         d->render = nullptr;
     }
-    d->startStopTimer();
+    d->startOrStopTimer();
 
     //force first update
     QSvgRendererPrivate::callRepaintNeeded(q);
diff --git a/src/svg/qsvgrenderer.h b/src/svg/qsvgrenderer.h
index 4bc2b25..7e898a4 100644
--- a/src/svg/qsvgrenderer.h
+++ b/src/svg/qsvgrenderer.h
@@ -29,6 +29,7 @@ class Q_SVG_EXPORT QSvgRenderer : public QObject
     Q_PROPERTY(int currentFrame READ currentFrame WRITE setCurrentFrame)
     Q_PROPERTY(Qt::AspectRatioMode aspectRatioMode READ aspectRatioMode WRITE setAspectRatioMode)
     Q_PROPERTY(QSvg::FeatureSet featureSet READ featureSet WRITE setFeatureSet)
+    Q_PROPERTY(bool animationEnabled READ isAnimationEnabled WRITE setAnimationEnabled)
 public:
     QSvgRenderer(QObject *parent = nullptr);
     QSvgRenderer(const QString &filename, QObject *parent = nullptr);
@@ -57,6 +58,8 @@ public:
     int currentFrame() const;
     void setCurrentFrame(int);
     int animationDuration() const;//in seconds
+    bool isAnimationEnabled() const;
+    void setAnimationEnabled(bool enable);
 
     QRectF boundsOnElement(const QString &id) const;
     bool elementExists(const QString &id) const;
diff --git a/src/svgwidgets/qsvgwidget.cpp b/src/svgwidgets/qsvgwidget.cpp
index 19b3a44..fc8d0a4 100644
--- a/src/svgwidgets/qsvgwidget.cpp
+++ b/src/svgwidgets/qsvgwidget.cpp
@@ -147,12 +147,32 @@ void QSvgWidget::paintEvent(QPaintEvent *)
 }
 
 /*!
+    \reimp
+*/
+void QSvgWidget::showEvent(QShowEvent *)
+{
+    Q_D(QSvgWidget);
+    d->renderer->setAnimationEnabled(true);
+}
+
+/*!
+    \reimp
+*/
+void QSvgWidget::hideEvent(QHideEvent *)
+{
+    Q_D(QSvgWidget);
+    d->renderer->setAnimationEnabled(false);
+}
+
+/*!
     Loads the contents of the specified SVG \a file and updates the widget.
 */
 void QSvgWidget::load(const QString &file)
 {
     Q_D(const QSvgWidget);
     d->renderer->load(file);
+    if (!isVisible())
+        d->renderer->setAnimationEnabled(false);
 }
 
 /*!
@@ -162,6 +182,8 @@ void QSvgWidget::load(const QByteArray &contents)
 {
     Q_D(const QSvgWidget);
     d->renderer->load(contents);
+    if (!isVisible())
+        d->renderer->setAnimationEnabled(false);
 }
 
 QT_END_NAMESPACE
diff --git a/src/svgwidgets/qsvgwidget.h b/src/svgwidgets/qsvgwidget.h
index a6e4bbf..cb17969 100644
--- a/src/svgwidgets/qsvgwidget.h
+++ b/src/svgwidgets/qsvgwidget.h
@@ -34,6 +34,9 @@ public Q_SLOTS:
     void load(const QByteArray &contents);
 protected:
     void paintEvent(QPaintEvent *event) override;
+    void showEvent(QShowEvent *event) override;
+    void hideEvent(QHideEvent *event) override;
+
 private:
     Q_DISABLE_COPY(QSvgWidget)
     Q_DECLARE_PRIVATE(QSvgWidget)