I have been working on a plugin which essentially doing the same as "GPS information" live tracking but with capability of displaying two GPS streams. I am comparing streams and doing some other calculations on the run.
I am trying to find a way to play with rendering options. If you guys can recall there is a render check box at the bottom of QGIS, which can be used to disable rendering, I want a similar control from plugin but in my case I want to render the complete Layer Extent (not visible extent) before disabling the rendering option.
I have set "Scale dependent visibility" on my layers and everytime I zoom in or out, I need to refresh the canvas to cater for new Layers which might appear or disappear at different zoom level. The issue is I want to disable rendering inside a particular zoom range after having rendered the whole layer extent. So what I need is a way to render to complete layer extent? How can I do that?. If I don't have rendering to layer extent, my canvas looks like this when GPS moves out of rendered image: To stop/start rendering I am using:
I have tried following to get full extent of the layer:
ms = self.canvas.mapSettings() extent_of_layers = ms.fullExtent() ms.setExtent(extent_of_layers)
Haven't made any progress after above. any pointers will be helpfull.
Reply to First comment I may not be accustomed to terms used here..sorry for that.. In short I want to know if its possible to take a snap shot/render a complete layers extent so that when my path/poniters move on the canvas, it will always have some background available for it, to have an idea where GPSs are on the map. Also to add, I am currently handling it by calling canvas.refresh() whenever pointer/path moves outside the visible canvas But it cause white flashes which is not easy on the eye especially zoomed in. So I was thinking of rendering everything on Layers (even outside the visible canvas) at particular zoom levels and disable rendering otherwise, so that even when marker moves away from current extent there always some background available.