viewer: use internal texture to allow viewer to control texture as part of its

context

More intuitive code flow and allows the user to undock the viewer (which
forcibly destroys and recreates the context) and the viewer will handle
creation of the new texture in said new context.

app/widget/viewer/viewer.cpp

@@ -83,7 +83,6 @@ ViewerWidget::ViewerWidget(QWidget *parent) :
 
   // Start background renderers
   video_renderer_ = new OpenGLBackend(this);
-  connect(video_renderer_, &VideoRenderBackend::CachedFrameReady, this, &ViewerWidget::RendererCachedFrame);
   connect(video_renderer_, &VideoRenderBackend::CachedTimeReady, this, &ViewerWidget::RendererCachedTime);
   connect(video_renderer_, &VideoRenderBackend::CachedTimeReady, ruler(), &TimeRuler::CacheTimeReady);
   connect(video_renderer_, &VideoRenderBackend::RangeInvalidated, ruler(), &TimeRuler::CacheInvalidatedRange);
@@ -215,17 +214,16 @@ VideoRenderBackend *ViewerWidget::video_renderer() const
   return video_renderer_;
 }
 
-void ViewerWidget::SetTexture(OpenGLTexturePtr tex)
-{
-  gl_widget_->SetTexture(tex);
-}
-
 void ViewerWidget::UpdateTextureFromNode(const rational& time)
 {
-  if (!GetConnectedNode()) {
-    SetTexture(nullptr);
+  if (!GetConnectedNode() || time >= GetConnectedNode()->Length()) {
+    gl_widget_->SetImage(QString());
   } else {
-    SetTexture(video_renderer_->GetCachedFrameAsTexture(time));
+    QString frame_fn = video_renderer_->GetCachedFrame(time);
+
+    if (!frame_fn.isEmpty()) {
+      gl_widget_->SetImage(frame_fn);
+    }
   }
 }
 
@@ -466,15 +464,6 @@ void ViewerWidget::PlaybackTimerUpdate()
   }
 }
 
-void ViewerWidget::RendererCachedFrame(const rational &time, QVariant value, qint64 job_time)
-{
-  if (GetTime() == time && job_time > frame_cache_job_time_) {
-    frame_cache_job_time_ = job_time;
-
-    SetTexture(value.value<OpenGLTexturePtr>());
-  }
-}
-
 void ViewerWidget::RendererCachedTime(const rational &time, qint64 job_time)
 {
   if (GetTime() == time && job_time > frame_cache_job_time_) {