Previously, all keydown KeyEvents were accepted, causing parent widgets
not to receive them. With the addition of shortcut handling to keydown,
shortcuts were not called when the ImageEditor was focused.
This effectively creates a double-buffer for tools to use when modifying
the layer's bitmap (content or mask). Once the changes have been made
the tool reports to the layer that it has made changes along with a Rect
of the changed region. The layer will then merge the changes from the
scratch image to the real bitmap. This merge is done as follows: If a
given pixel is inside the selected region, the pixel from the scratch
bitmap is copied to the real bitmap. If the pixel is not inside the
selected region, the pixel from the real bitmap is copied to the scratch
bitmap.
As an optimization, when there is no selection active, the new method
for getting the scratch bitmap will return the real bitmap and no
merging will need to take place.
The Undo/Redo actions now tell you what kind of action will be
undone/redone. This is achieved by adding an "action text" field to the
ImageUndoCommand and having everyone who calls did_complete_action()
provide this text.
The non-AA outline ellipse was drawn outside the bounding rectangle
unlike all other ellipses. This commit now scales it to match the
size of the other ellipse drawing modes (AA, filled, etc).
This commit adds draw_ellipse() and moves the shared code
for circles and ellipses to draw_ellipse_part().
draw_ellipse_part() can draw an entire circle in one call using
8-way symmetry and an ellipse in two calls using 4-way symmetry.
This is in preparation to support masking of Layers. We now distinguish
between the "display_bitmap" which will be the whole Layer with every
effect applied and the "content_bitmap" which contains the actual
unmodified pixels in the Layer.
