Snap behavior for shapes

[letsfindaway]

I'm using this issue to collect ideas and considerations for the snap behavior for shapes when creating, editing, moving or resizing shapes.

Create shapes

Note that we don't have any snap during creation with anything else but shapes. Before, the Line did snap. But this is now also a shape.

• After selecting a shape tool, the cursor turns into a cross. When the mouse is pressed, the shape is created at the nearest snap point.
• When then dragging the mouse, it snaps as the mouse is moved.
• For a polygon, each mouse click to create a new point snaps.

Edit shapes

When editing shapes, the behavior should be as follows:

• For rectangle and square, the right side and the bottom side snap, just as if resizing an image.
• For circle and ellipse as well as for a regular polygon, the bounding rectangle snaps.
• For a line, both end points snap.
• For a polygon, each point snaps.

Move shapes

If we move a shape by fetching it at the delegate frame, snapping already works. The same behavior should be implemented for moving the shape by dragging it directly.

Additionally the center of rectangle, square, ellipse, circle and regular polygon should snap. For this we have to add a new snap indicator, e.g. a triangle pointing upwards.

To help users with this it would also be a good idea to display a center mark while moving the item,

Resize shapes

The delegate of a shape does not offer resizing! So please see at "Edit shapes" for the behavior.