Add full-res image export functionality

[ameraner]

Problem
The current SIFT export image functionality basically takes a simple screenshot of what is currently shown in the image area, at the desktop resolution, and saves it to file.

Feature Request
A user request at the last Convection Working Group (9th CWG Recommendation 2), asks for the functionality of exporting what is in the image area (up to) the native full resolution of the data.

Additional Note
If possible, in addition to simple image formats, an export in GeoTiff including the projection information shall be selectable.

[djhoese]

What is expected to be visible in this final result? The overlay/boundaries? The polygons/probes from the SIFT UI? The colormap changes by the user? The easiest way to do this would be to get the extents of the current viewpoint and extract that portion of the data array out and put it in an image. The hard part is reproducing anything in the UI, especially the color stuff which are mostly GPU only as shaders.

I suppose if you drew to a fake buffer that was the appropriate size to make one specific layer be at full resolution (if there are multiple resolutions you'd have to pick one if you expected to draw more than one layer) that might work.

[ameraner]

I assume, in order of priority for implementation:

• the full-res image of the currently shown/active layers, with the currently respective selected and tuned colorbars
• on top of that the overlays (grid, coastlines), if active in the Layer Manager

I do not think that the polygons/probes would be necessary for the full-res output variant.