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Add note about QgsMapCanvas::refresh() behavior
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wonder-sk committed Nov 15, 2014
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@@ -21,6 +21,10 @@ This page tries to maintain a list with incompatible changes that happened in pr
\subsection qgis_api_break_mtr Multi-threaded Rendering

<li>QgsMapCanvas::refresh() only schedules a map refresh (in near feature) and returns immediately - before it would do the drawing immediately
and return when the map is redrawn. A call to refresh() will have no effect if there is already a scheduled pending refresh.
When map canvas does actual rendering, it will first emit renderStarting() signal, once done it will emit mapCanvasRefreshed().
The client code doing refresh() in order to later save map image should be updated to use new QgsMapRendererJob API which is better suited for such task.
<li>QgsPluginLayer::draw() is now run in a background thread. It is recommended to implement newly added QgsPluginLayer::createMapRenderer()
method instead of using QgsPluginLayer::draw().

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