I got annoyed by all the slightly different variations of "collect
snapshot results and unwrap them at the end of test" I've written, so I
added a struct to make this nice and simple.
One controversial thing: It panics when dropped. I wanted to ensure
people cannot forget to unwrap the results at the end, and this was the
best thing I could come up with. I don't think this is possible via
clippy lint or something like that.
* [x] I have followed the instructions in the PR template
## Defining what `Rounding` is
This PR defines what `Rounding` means: it is the corner radius of
underlying `RectShape` rectangle. If you use `StrokeKind::Inside`, this
means the rounding is of the outer part of the stroke. Conversely, if
you use `StrokeKind::Outside`, the stroke is outside the rounded
rectangle, so the stroke has an inner radius or `rounding`, and an outer
radius that is larger by `stroke.width`.
This definitions is the same as Figma uses.
## Improving general shape rendering
The rendering of filled shapes (rectangles, circles, paths, bezier) has
been rewritten. Instead of first painting the fill with the stroke on
top, we now paint them as one single mesh with shared vertices at the
border. This has several benefits:
* Less work (faster and with fewer vertices produced)
* No overdraw (nicer rendering of translucent shapes)
* Correct blending of stroke and fill
The logic for rendering thin strokes has also been improved, so that the
width of a stroke of `StrokeKind::Outside` never affects the filled area
(this used to be wrong for thin strokes).
## Improving of rectangle rendering
Rectangles also has specific improvements in how thin rectangles are
painted.
The handling of "Blur width" is also a lot better, and now works for
rectangles with strokes.
There also used to be bugs with specific combinations of corner radius
and stroke width, that are now fixed.
## But why?
With the new `egui::Scene` we end up with a lot of zoomed out shapes,
with sub-pixel strokes. These need to look good! One thing led to
another, and then I became obsessive 😅
## Tessellation Test
In order to investigate the rendering, I created a Tessellation Test in
the `egui_demo_lib`.
[Try it
here](https://egui-pr-preview.github.io/pr/5669-emilkimprove-tessellator)
This is a breaking change, requiring users to think about wether the
stroke is inside/centered/outside the rect.
When in doubt, add `egui::StrokeKind::Inside` to the function call.
Previously, `Harness::run` just called `Harness::step` 3 times. If that
wasn't enough, tests would often call run multiple times so all
animations would finish properly.
Also, I introduced `HarnessBuilder::with_step_dt` to customize with how
big of a dt each frame is called. I set the default to 1.0 / 6.0 (~6fps)
so we don't waste cpu in tests waiting on animations.
`HarnessBuilder::max_steps` allows us to control how many steps
`Harness::run` should run before panicing.
The default is 6, so we run for up to 1.0 logical seconds (six frames at
6 fps), which should be enough to finish most animations.
Turns out a lot of snapshots where rendered before fully shown and had a
light opacity, those are now fixed.
* [x] I have followed the instructions in the PR template
* Part of https://github.com/emilk/egui/issues/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).
```text
+-----------------^-------------------------------------- -+
| | 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.
Emil Ernerfeldt
lucasmerlin