IASS: Correct Buffering of last Slide

There is a mechanism to pre-fetch the next slide, but
at the last slide that just gets not reset/refreshed.
Thus the last slide *is* the buffered slide.
When making changes and refreshing the SlideShow display
for the last slide this pe-fetched one is just used, so
the slide content gets not re-created and thus not
updated.
I added needed code to do that now when reacing the last
slide to make that work.

Change-Id: Ie57e6917e0996d5fce46021aeb933064c47dd90f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/166011
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@me.com>

2 files changed, 20 insertions, 0 deletions

diff --git a/sd/source/ui/slideshow/slideshowimpl.cxx b/sd/source/ui/slideshow/slideshowimpl.cxx
index 339b54382adc..d20b2c750709 100644
--- a/sd/source/ui/slideshow/slideshowimpl.cxx
+++ b/sd/source/ui/slideshow/slideshowimpl.cxx
@@ -500,6 +500,18 @@ void AnimationSlideController::displayCurrentSlide( const Reference< XSlideShow
                 Any(aValue),
                 PropertyState_DIRECT_VALUE);
     }
+    else if (-1 == nNextSlideNumber)
+    {
+        // IASS: next slide does not exist, thus current slide is the last one.
+        // we need to signal to stop Prefetch since else SlideShowImpl *keeps* the
+        // last slide buffered and will just re-use it when asked to update, thus
+        // updates will not work.
+        aProperties.emplace_back( "Prefetch" ,
+                -1,
+                Any(false),
+                PropertyState_DIRECT_VALUE);
+    }
+
     if (bSkipAllMainSequenceEffects)
     {
         // Add one property that prevents the slide transition from being
diff --git a/slideshow/source/engine/slideshowimpl.cxx b/slideshow/source/engine/slideshowimpl.cxx
index 5e0dbbb8074e..121416327191 100644
--- a/slideshow/source/engine/slideshowimpl.cxx
+++ b/slideshow/source/engine/slideshowimpl.cxx
@@ -1041,6 +1041,14 @@ public:
                 seq[0] >>= mpSlideShowImpl->mxPrefetchSlide;
                 seq[1] >>= mpSlideShowImpl->mxPrefetchAnimationNode;
             }
+            else // rProperty.Value might be tested to 'bool' and 'false'
+            {
+                // IASS: There is no 'next' slide (last one is displayed),
+                // so end/flush Prefetch since that might still hold the
+                // last slide what would prevent updating/re-creating it
+                mpSlideShowImpl->mxPrefetchSlide.clear();
+                mpSlideShowImpl->mpPrefetchSlide.reset();
+            }
         }
         else if ( rProperty.Name == "SkipAllMainSequenceEffects" )
         {