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
Pick-to: 5.15
Change-Id: Ieb6d046168a2132659848a36ee0b694c580159b1
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 18 insertions, 6 deletions

diff --git a/examples/quick/imageelements/animatedsprite.qml b/examples/quick/imageelements/animatedsprite.qml
index cc5226882a..8666c2b9fc 100644
--- a/examples/quick/imageelements/animatedsprite.qml
+++ b/examples/quick/imageelements/animatedsprite.qml
@@ -70,19 +70,31 @@ Item {
     }
 //! [sprite]
 
+    Text {
+        text: "Left click to resume\nMiddle click to advance backward\nRight click to advance forward"
+        visible: sprite.paused
+    }
+
     MouseArea {
         anchors.fill: parent
-        acceptedButtons: Qt.LeftButton | Qt.RightButton
+        acceptedButtons: Qt.LeftButton | Qt.RightButton | Qt.MiddleButton
         onClicked: (mouse) => {
-            if (!sprite.running)
+            if (!sprite.running) {
                 sprite.start();
-            if (!sprite.paused)
+            } else if (!sprite.paused) {
                 sprite.pause();
-            if ( mouse.button == Qt.LeftButton ) {
-                sprite.advance(1);
             } else {
-                sprite.advance(-1);
+                if (mouse.button === Qt.LeftButton)
+                    sprite.resume();
+                else if (mouse.button === Qt.MiddleButton)
+                    sprite.advance(-1);
+                else if (mouse.button === Qt.RightButton)
+                    sprite.advance(1);
             }
         }
     }
+
+    Component.onCompleted: console.log("Press Space to toggle visibility. Click with mouse to pause/resume.")
+    focus: true
+    Keys.onSpacePressed: sprite.visible = !sprite.visible
 }