paysages : Preview rendering is balanced when two previews are visible.

git-svn-id: https://subversion.assembla.com/svn/thunderk/paysages@366 b1fd45b6-86a6-48da-8261-f70d1f35bdcc

TODO

@@ -28,7 +28,6 @@ Technology Preview 2 :
 - Fix "RGB parameters out of range" (and segfault) on preview while moving render params fast in render tab.
    => May need to change the updateData system.
    => Previews need to be paused while updating data.
-- When there are two previews in the same view, balance rendering between the two.
 - Lock some previews together (eg: terrain height and colored preview).
 - Find a new licence.
 

gui_qt/basepreview.cpp

@@ -25,6 +25,11 @@ public:
         _alive = true;
     }
     
+    inline BasePreview* preview()
+    {
+        return _preview;
+    }
+    
     inline bool isOnFront()
     {
         return _preview->isVisible() && _preview->window()->isActiveWindow();
@@ -132,6 +137,7 @@ PreviewDrawingManager::PreviewDrawingManager()
     {
         _thread_count = 1;
     }
+    _lastRendered = NULL;
 }
 
 void PreviewDrawingManager::startThreads()
@@ -236,12 +242,24 @@ void PreviewDrawingManager::performOneThreadJob()
     _lock.lock();
     if (!_updateQueue.isEmpty())
     {
-        chunk = _updateQueue.takeFirst();
+        for (int i = _updateQueue.size(); i > 0; i--)
+        {
+            chunk = _updateQueue.takeFirst();
+            if (chunk && i > 1 && chunk->preview() == _lastRendered)
+            {
+                _updateQueue.append(chunk);
+            }
+            else
+            {
+                break;
+            }
+        }
     }
     _lock.unlock();
 
     if (chunk)
     {
+        _lastRendered = chunk->preview();
         chunk->render();
     }        
 }

gui_qt/basepreview.h

@@ -136,6 +136,7 @@ private:
     QVector<PreviewDrawingThread*> _threads;
     QVector<PreviewChunk*> _chunks;
     QList<PreviewChunk*> _updateQueue;
+    BasePreview* _lastRendered;
     QMutex _lock;
 };