Add const version of QgsRenderContext::painter

python/core/auto_generated/qgsrendercontext.sip.in

@@ -109,6 +109,7 @@ Returns the destination QPainter for the render operation.
 .. seealso:: :py:func:`setPainter`
 %End
 
+
     QPainter *maskPainter( int id = 0 );
 %Docstring
 Returns a mask QPainter for the render operation.

src/core/qgsrendercontext.h

@@ -170,6 +170,16 @@ class CORE_EXPORT QgsRenderContext
     */
     QPainter *painter() {return mPainter;}
 
+#ifndef SIP_RUN
+
+    /**
+     * Returns the const destination QPainter for the render operation.
+     * \see setPainter()
+    * \since QGIS 3.12
+    */
+    const QPainter *painter() const { return mPainter; }
+#endif
+
     /**
      * Returns a mask QPainter for the render operation.
      * Multiple mask painters can be defined, each with a unique identifier.