Export regions

[mrtripie]

An export region would allow you to export only a rectangular region of the whole canvas. This would be represented by a box that is drawn over the canvas similar to guides. This could be useful as an alternative to #779 to allow the user to have part of their canvas outside of what would be exported.

• A possible option would be to allow whatever is not inside an export region to be covered by a semi-transparent overlay (wouldn't be needed for a first version though)

• Another possibility would be to have multiple export regions, with names assigned to each one. This would allow for both to be exported at once, with the region's name appended/prepended to the export names.
  • For example exporting art.png with two export regions may actually export:
    • art_region1.png
    • art_region2.png
  • Region names could be another optional overlay

• Adding/editing the regions could work one of 2 ways:
  • A dedicated toolbar tool
  • A panel similar to the one for reference images

[dphaldes]

small addition: along with export the selected area, I would also like if I could extract selection into a new tab/project