⚠️ Frame now includes stroke width as part of padding

[emilk]

• Part of CSS-like Border #4019

Frame now includes the width of the stroke as part of its size. From the new docs:

Frame docs

The total (outer) size of a frame is content_size + inner_margin + 2*stroke.width + outer_margin.

Everything within the stroke is filled with the fill color (if any).

+-----------------^-------------------------------------- -+
|                 | outer_margin                           |
|    +------------v----^------------------------------+    |
|    |                 | stroke width                 |    |
|    |    +------------v---^---------------------+    |    |
|    |    |                | inner_margin        |    |    |
|    |    |    +-----------v----------------+    |    |    |
|    |    |    |             ^              |    |    |    |
|    |    |    |             |              |    |    |    |
|    |    |    |<------ content_size ------>|    |    |    |
|    |    |    |             |              |    |    |    |
|    |    |    |             v              |    |    |    |
|    |    |    +------- content_rect -------+    |    |    |
|    |    |                                      |    |    |
|    |    +-------------fill_rect ---------------+    |    |
|    |                                                |    |
|    +----------------- widget_rect ------------------+    |
|                                                          |
+---------------------- outer_rect ------------------------+

The four rectangles, from inside to outside, are:

• content_rect: the rectangle that is made available to the inner [Ui] or widget.
• fill_rect: the rectangle that is filled with the fill color (inside the stroke, if any).
• widget_rect: is the interactive part of the widget (what sense clicks etc).
• outer_rect: what is allocated in the outer [Ui], and is what is returned by [Response::rect].

Notes

This required rewriting a lot of the layout code for egui::Window, which was a massive pain. But now the window margin and stroke width is properly accounted for everywhere.

[github-actions]

Preview available at https://egui-pr-preview.github.io/pr/5575-emilkborder
Note that it might take a couple seconds for the update to show up after the preview_build workflow has completed.