Support circular selection by choosing a point and dragging the mouse across the image. The callbacks and functions supported for rectangular selection should be also supported for circular selection.

(Circular region selection is a part of Paul O'Connor's visualization wish list and is a long promised feature.)

Copied from GitHub(XW 1/18/18)

This development includes,

• adding circular selection support for area selection.
• change select area icon on the tool bar from on/off button to a on/off button with dropdown selection at off state. The dropdown list supports the selection for 'rectangular selection', 'elliptical section' (circular area).
• add stats calculation for circular area selection on both rotated and non-rotated images.
• fix stats calculation for rectangular area selection on rotated image case.
• update 'select catalog' and 'filter catalog' functions for circular area selection.

Test:

• Do image selection:
  1. Click 'select area' icon (on 'off' state)  to get selection dropdown list,
  2. Select either 'rectangular selection' or 'elliptical selection' (this will move the 'select area' icon into 'on' state)  and draw a selected area by choosing a point over the image and dragging the mouse across the image.

          3. Click  'select  area' icon to move it back to 'off' state to remove the selected area.
          4. Select one of the extension buttons for 'crop', 'stats', 'zoom', or 'recenter' while either 'rectangular  selection' or 'elliptical selection' is selected.

• Repeat the steps by rotating the image first.

• Do catalog selection next:
  repeat the 'select area' steps done as image selection, and select one of the extension buttons for 'crop', 'stats', 'select mark data', 'filter', 'zoom' or 'recenter' while either 'rectangular selection' or 'elliptical selection' is selected.