What does the extent mean when the map is rotated?

Question

QGIS 2.18.

I have put a map into print composer and rotated the map clockwise by 45 degrees by setting "Map rotation" to 45 (it's what the client wants!).

I'm struggling to get the region I want into the print composer.

What do the extents (X min, Y min, X max, and Y max) mean when the map has been rotated?

Or if that isn't a sensible question, how do I move the portion of the map that is shown in print composer? I need to move the map down and left in the rotated view (or equivalently move the window up and right).

Answer 1

Extent:

The extent values in composers map item are lower leftmost (X min, Y min) and upper rightmost (X max, Y max) coordinates that defines rectangle of desired map view.

The rotation of map item doesn't affect extent values. You only rotate the map item. In other words, you only visualise data in map item (rectangle) which is rotated, so the extent stay the same.

Move item content:

There is Move item content tool in composers toolbox panel. After activating this tool, you can drag and move and scroll to zoom map view (for finer zooming hold Ctrl), like in map canvas in main window.

You can also prepare your view in map canvas in main window and then in composer hit Set to map canvas extent button in the extent section of map item properties.