Make really sure to wait for previews after zoom changes

Relying on the fact that the timer is not active anymore does not
guarantee that the previews at the correct zoom are ready because
the regeneration process may take several seconds and during this
time the zoom factor may be changed again. So, we need an additional
guard for assuring that everything has settled down.

diff --git a/src/graphics/PreviewLoader.cpp b/src/graphics/PreviewLoader.cpp
index ea8e3ce11be12dfc5c1a028a09a9ba3f295ed334..7a969763fb804e6ba4d86840c29f2884ad036496 100644 (file)
--- a/src/graphics/PreviewLoader.cpp
+++ b/src/graphics/PreviewLoader.cpp
@@ -254,6 +254,8 @@ private:
        mutable int font_scaling_factor_;
        ///
        QTimer * delay_refresh_;
+       ///
+       bool finished_generating_;
 
        /// We don't own this
        static lyx::Converter const * pconverter_;
@@ -402,7 +404,7 @@ namespace lyx {
 namespace graphics {
 
 PreviewLoader::Impl::Impl(PreviewLoader & p, Buffer const & b)
-       : parent_(p), buffer_(b)
+       : parent_(p), buffer_(b), finished_generating_(true)
 {
        font_scaling_factor_ = int(buffer_.fontScalingFactor());
        if (!pconverter_)
@@ -437,8 +439,8 @@ PreviewLoader::Impl::preview(string const & latex_snippet) const
                // has not been changed for about 1 second.
                delay_refresh_->start(1000);
        }
-       // Don't try to access the cache until we are finished.
-       if (delay_refresh_->isActive())
+       // Don't try to access the cache until we are done.
+       if (delay_refresh_->isActive() || !finished_generating_)
                return 0;
        Cache::const_iterator it = cache_.find(latex_snippet);
        return (it == cache_.end()) ? 0 : it->second.get();
@@ -452,6 +454,7 @@ void PreviewLoader::Impl::refreshPreviews()
        Cache::const_iterator cend = cache_.end();
        while (cit != cend)
                parent_.remove((cit++)->first);
+       finished_generating_ = false;
        buffer_.updatePreviews();
 }
 
@@ -788,6 +791,7 @@ void PreviewLoader::Impl::finishedGenerating(pid_t pid, int retval)
        for (; nit != nend; ++nit) {
                imageReady(*nit->get());
        }
+       finished_generating_ = true;
 }