# Objective
After the UI layout is computed when the coordinates are converted back
from physical coordinates to logical coordinates the `UiScale` is
ignored. This results in a confusing situation where we have two
different systems of logical coordinates.
Example:
```rust
use bevy::prelude::*;
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(Update, update)
.run();
}
fn setup(mut commands: Commands, mut ui_scale: ResMut<UiScale>) {
ui_scale.scale = 4.;
commands.spawn(Camera2dBundle::default());
commands.spawn(NodeBundle {
style: Style {
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
width: Val::Percent(100.),
..Default::default()
},
..Default::default()
})
.with_children(|builder| {
builder.spawn(NodeBundle {
style: Style {
width: Val::Px(100.),
height: Val::Px(100.),
..Default::default()
},
background_color: Color::MAROON.into(),
..Default::default()
}).with_children(|builder| {
builder.spawn(TextBundle::from_section("", TextStyle::default());
});
});
}
fn update(
mut text_query: Query<(&mut Text, &Parent)>,
node_query: Query<Ref<Node>>,
) {
for (mut text, parent) in text_query.iter_mut() {
let node = node_query.get(parent.get()).unwrap();
if node.is_changed() {
text.sections[0].value = format!("size: {}", node.size());
}
}
}
```
result:
We asked for a 100x100 UI node but the Node's size is multiplied by the
value of `UiScale` to give a logical size of 400x400.
## Solution
Divide the output physical coordinates by `UiScale` in
`ui_layout_system` and multiply the logical viewport size by `UiScale`
when creating the projection matrix for the UI's `ExtractedView` in
`extract_default_ui_camera_view`.
---
## Changelog
* The UI layout's physical coordinates are divided by both the window
scale factor and `UiScale` when converting them back to logical
coordinates. The logical size of Ui nodes now matches the values given
to their size constraints.
* Multiply the logical viewport size by `UiScale` before creating the
projection matrix for the UI's `ExtractedView` in
`extract_default_ui_camera_view`.
* In `ui_focus_system` the cursor position returned from `Window` is
divided by `UiScale`.
* Added a scale factor parameter to `Node::physical_size` and
`Node::physical_rect`.
* The example `viewport_debug` now uses a `UiScale` of 2. to ensure that
viewport coordinates are working correctly with a non-unit `UiScale`.
## Migration Guide
Physical UI coordinates are now divided by both the `UiScale` and the
window's scale factor to compute the logical sizes and positions of UI
nodes.
This ensures that UI Node size and position values, held by the `Node`
and `GlobalTransform` components, conform to the same logical coordinate
system as the style constraints from which they are derived,
irrespective of the current `scale_factor` and `UiScale`.
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
9655acebb6