Resume AnimatedSprite playback when visibility changes

Amends f5e2783 that was made in 5.6 to avoid updating the AnimatedSprite
when not visible. The problem is, if the sprite was running, the
expectation is that becoming visible again resumes the playback.

It can be argued what the correct behavior is: do we expect the playback
to resume from the point when the sprite went invisible, or should it
take the time spent as invisible into account? This patch only corrects
the immediate problem and provides the former, i.e. playback will resume
from the point it had when becoming invisible.

The AnimatedSprite scene in the imageelements example is improved to be
able to test this. It can also exercise all the start/pause/resume/advance
functions now.

Fixes: QTBUG-63942
Change-Id: Ieb6d046168a2132659848a36ee0b694c580159b1
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
(cherry picked from commit af521a8df6caec41f626a4b3319601c20adff711)
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

2 files changed, 10 insertions, 0 deletions

diff --git a/src/quick/items/qquickanimatedsprite.cpp b/src/quick/items/qquickanimatedsprite.cpp
index b285fe56ed..f239f24367 100644
--- a/src/quick/items/qquickanimatedsprite.cpp
+++ b/src/quick/items/qquickanimatedsprite.cpp
@@ -502,6 +502,14 @@ void QQuickAnimatedSprite::maybeUpdate()
         update();
 }
 
+void QQuickAnimatedSprite::itemChange(ItemChange change, const ItemChangeData &value)
+{
+    Q_D(QQuickAnimatedSprite);
+    if (change == ItemVisibleHasChanged && d->m_running && !d->m_paused)
+        maybeUpdate();
+    QQuickItem::itemChange(change, value);
+}
+
 /*!
     \qmlmethod int QtQuick::AnimatedSprite::pause()
 
diff --git a/src/quick/items/qquickanimatedsprite_p.h b/src/quick/items/qquickanimatedsprite_p.h
index 546598a409..49fb6ddeea 100644
--- a/src/quick/items/qquickanimatedsprite_p.h
+++ b/src/quick/items/qquickanimatedsprite_p.h
@@ -183,6 +183,8 @@ protected Q_SLOTS:
 protected:
     void componentComplete() override;
     QSGNode *updatePaintNode(QSGNode *, UpdatePaintNodeData *) override;
+    void itemChange(ItemChange, const ItemChangeData &) override;
+
 private:
     void maybeUpdate();
     bool isCurrentFrameChangedConnected();