implemented base for thumbnail display

app/node/traverser.cpp

@@ -443,17 +443,14 @@ void NodeTraverser::ResolveJobs(NodeValue &val, const TimeRange &range)
         VideoParams render_params = GetCacheVideoParams();
         VideoParams job_params = job.video_params();
 
-        // HACK/FIXME: Override old cached probe data that contains an invalid divider. Might be
-        //             good in the future to version the probe data so we can automatically
-        //             ignore older stuff.
-        job_params.set_divider(render_params.divider());
-
-        // See if we can make this divider larger (i.e. if the footage is smaller)
-        while (job_params.divider() > 1
-               && VideoParams::GetScaledDimension(job_params.width(), job_params.divider()-1) < render_params.effective_width()
-               && VideoParams::GetScaledDimension(job_params.height(), job_params.divider()-1) < render_params.effective_height()) {
-          job_params.set_divider(job_params.divider() - 1);
+        if (render_params.divider() > 1) {
+          // Use a divider appropriate for this target resolution
+          job_params.set_divider(VideoParams::GetDividerForTargetResolution(job_params.width(), job_params.height(), render_params.effective_width(), render_params.effective_height()));
+        } else {
+          // Render everything at full res
+          job_params.set_divider(1);
         }
+
         job.set_video_params(job_params);
 
         if (footage_time.isNaN()) {