Lock render method with mutex. Usefull e.g. for globe plugin which renders in threads

Author: mhugent

src/core/qgsmaprenderer.cpp

@@ -33,6 +33,7 @@
 
 #include <QDomDocument>
 #include <QDomNode>
+#include <QMutexLocker>
 #include <QPainter>
 #include <QListIterator>
 #include <QSettings>
@@ -214,6 +215,9 @@ void QgsMapRenderer::adjustExtentToSize()
 
 void QgsMapRenderer::render( QPainter* painter )
 {
+  //Lock render method for concurrent threads (e.g. from globe)
+  QMutexLocker renderLock( &mRenderMutex );
+
   //flag to see if the render context has changed
   //since the last time we rendered. If it hasnt changed we can
   //take some shortcuts with rendering

src/core/qgsmaprenderer.h

@@ -16,6 +16,7 @@
 #ifndef QGSMAPRENDER_H
 #define QGSMAPRENDER_H
 
+#include <QMutex>
 #include <QSize>
 #include <QStringList>
 #include <QVector>
@@ -318,6 +319,9 @@ class CORE_EXPORT QgsMapRenderer : public QObject
 
     //! Labeling engine (NULL by default)
     QgsLabelingEngineInterface* mLabelingEngine;
+
+    //! Locks rendering loop for concurrent draws
+    QMutex mRenderMutex;
 };
 
 #endif