d-r: add new rendering mode

added: DIRTYREGION_SOLVER_FILL_VIEWPORT_ON_CHANGE
This solver (mode 3) always marks the entire screen as dirty. The difference
between this and mode 0 is that it stops rendering when there are no dirty
regions left.

This should be a safe default as it does not require preserved backbuffers,
though to be safe we will need to stop flipping when we haven't rendered.

xbmc/guilib/DirtyRegionSolvers.cpp

@@ -39,6 +39,12 @@ void CFillViewportAlwaysRegionSolver::Solve(const CDirtyRegionList &input, CDirt
   output.push_back(unifiedRegion);
 }
 
+void CFillViewportOnChangeRegionSolver::Solve(const CDirtyRegionList &input, CDirtyRegionList &output)
+{
+  if (input.size() > 0)
+    output.assign(1,g_graphicsContext.GetViewWindow());
+}
+
 CGreedyDirtyRegionSolver::CGreedyDirtyRegionSolver()
 {
   m_costNewRegion = 10.0f;

xbmc/guilib/DirtyRegionSolvers.h

@@ -34,6 +34,12 @@ class CFillViewportAlwaysRegionSolver : public IDirtyRegionSolver
   virtual void Solve(const CDirtyRegionList &input, CDirtyRegionList &output);
 };
 
+class CFillViewportOnChangeRegionSolver : public IDirtyRegionSolver
+{
+public:
+  virtual void Solve(const CDirtyRegionList &input, CDirtyRegionList &output);
+};
+
 class CGreedyDirtyRegionSolver : public IDirtyRegionSolver
 {
 public:

xbmc/guilib/DirtyRegionTracker.cpp

@@ -41,14 +41,18 @@ void CDirtyRegionTracker::SelectAlgorithm()
 
   switch (g_advancedSettings.m_guiAlgorithmDirtyRegions)
   {
-    case DIRTYREGION_SOLVER_UNION:
-      m_solver = new CUnionDirtyRegionSolver();
-      CLog::Log(LOGDEBUG, "guilib: Union as algorithm for solving rendering passes");
+    case DIRTYREGION_SOLVER_FILL_VIEWPORT_ON_CHANGE:
+      CLog::Log(LOGDEBUG, "guilib: Fill viewport on change for solving rendering passes");
+      m_solver = new CFillViewportOnChangeRegionSolver();
       break;
     case DIRTYREGION_SOLVER_COST_REDUCTION:
       CLog::Log(LOGDEBUG, "guilib: Cost reduction as algorithm for solving rendering passes");
       m_solver = new CGreedyDirtyRegionSolver();
       break;
+    case DIRTYREGION_SOLVER_UNION:
+      m_solver = new CUnionDirtyRegionSolver();
+      CLog::Log(LOGDEBUG, "guilib: Union as algorithm for solving rendering passes");
+      break;
     case DIRTYREGION_SOLVER_FILL_VIEWPORT_ALWAYS:
     default:
       CLog::Log(LOGDEBUG, "guilib: Fill viewport always for solving rendering passes");

xbmc/guilib/GUIWindowManager.cpp

@@ -554,6 +554,14 @@ bool CGUIWindowManager::Render()
     RenderPass();
     hasRendered = true;
   }
+  else if (g_advancedSettings.m_guiAlgorithmDirtyRegions == DIRTYREGION_SOLVER_FILL_VIEWPORT_ON_CHANGE)
+  {
+    if (dirtyRegions.size() > 0)
+    {
+      RenderPass();
+      hasRendered = true;
+    }
+  }
   else
   {
     for (CDirtyRegionList::const_iterator i = dirtyRegions.begin(); i != dirtyRegions.end(); i++)

xbmc/guilib/IDirtyRegionSolver.h

@@ -25,6 +25,7 @@
 #define DIRTYREGION_SOLVER_FILL_VIEWPORT_ALWAYS 0
 #define DIRTYREGION_SOLVER_UNION 1
 #define DIRTYREGION_SOLVER_COST_REDUCTION 2
+#define DIRTYREGION_SOLVER_FILL_VIEWPORT_ON_CHANGE 3
 
 class IDirtyRegionSolver
 {