TextLayoutInfo::size should hold the drawn size of the text, and not a scaled value. (#7794)

# Objective

`TextLayoutInfo::size` isn't the drawn size of the text, but a scaled
value. This is fragile, counter-intuitive and makes it awkward to
retrieve the correct value.

## Solution

Multiply `TextLayoutInfo::size` by the reciprocal of the window's scale
factor after generating the text layout in `update_text2d_layout` and
`bevy_ui::widget::text_system`.

---

fixes: #7787

## Changelog

* Multiply `TextLayoutInfo::size` by the reciprocal of the scale factor
after text computation to reflect the actual size of the text as drawn.
* Reorder the operations in `extract_text2d_sprite` to apply the
alignment offset before the scale factor scaling.

## Migration Guide

The `size` value of `TextLayoutInfo` is stored in logical pixels and has
been renamed to `logical_size`. There is no longer any need to divide by
the window's scale factor to get the logical size.

crates/bevy_text/src/pipeline.rs

@@ -25,7 +25,7 @@ pub struct TextPipeline {
 #[derive(Component, Clone, Default, Debug)]
 pub struct TextLayoutInfo {
     pub glyphs: Vec<PositionedGlyph>,
-    pub size: Vec2,
+    pub logical_size: Vec2,
 }
 
 impl TextPipeline {
@@ -97,7 +97,10 @@ impl TextPipeline {
             y_axis_orientation,
         )?;
 
-        Ok(TextLayoutInfo { glyphs, size })
+        Ok(TextLayoutInfo {
+            glyphs,
+            logical_size: size,
+        })
     }
 }
 

crates/bevy_text/src/text2d.rs

@@ -36,6 +36,7 @@ use bevy_window::{PrimaryWindow, Window, WindowScaleFactorChanged};
 #[derive(Component, Copy, Clone, Debug, Reflect)]
 #[reflect(Component)]
 pub struct Text2dBounds {
+    /// The maximum width and height of text in logical pixels.
     pub size: Vec2,
 }
 
@@ -105,10 +106,10 @@ pub fn extract_text2d_sprite(
         }
 
         let text_anchor = -(anchor.as_vec() + 0.5);
-        let alignment_translation = text_layout_info.size * text_anchor;
+        let alignment_translation = text_layout_info.logical_size * text_anchor;
         let transform = *global_transform
-            * scaling
-            * GlobalTransform::from_translation(alignment_translation.extend(0.));
+            * GlobalTransform::from_translation(alignment_translation.extend(0.))
+            * scaling;
         let mut color = Color::WHITE;
         let mut current_section = usize::MAX;
         for PositionedGlyph {
@@ -172,6 +173,8 @@ pub fn update_text2d_layout(
         .map(|window| window.resolution.scale_factor())
         .unwrap_or(1.0);
 
+    let inverse_scale_factor = scale_factor.recip();
+
     for (entity, text, bounds, mut text_layout_info) in &mut text_query {
         if factor_changed || text.is_changed() || bounds.is_changed() || queue.remove(&entity) {
             let text_bounds = Vec2::new(
@@ -182,7 +185,6 @@ pub fn update_text2d_layout(
                 },
                 scale_value(bounds.size.y, scale_factor),
             );
-
             match text_pipeline.queue_text(
                 &fonts,
                 &text.sections,
@@ -205,7 +207,11 @@ pub fn update_text2d_layout(
                 Err(e @ TextError::FailedToAddGlyph(_)) => {
                     panic!("Fatal error when processing text: {e}.");
                 }
-                Ok(info) => *text_layout_info = info,
+                Ok(mut info) => {
+                    info.logical_size.x = scale_value(info.logical_size.x, inverse_scale_factor);
+                    info.logical_size.y = scale_value(info.logical_size.y, inverse_scale_factor);
+                    *text_layout_info = info;
+                }
             }
         }
     }

crates/bevy_ui/src/widget/text.rs

@@ -12,8 +12,8 @@ use bevy_reflect::{std_traits::ReflectDefault, Reflect};
 use bevy_render::texture::Image;
 use bevy_sprite::TextureAtlas;
 use bevy_text::{
-    BreakLineOn, Font, FontAtlasSets, FontAtlasWarning, Text, TextError, TextLayoutInfo,
-    TextMeasureInfo, TextPipeline, TextSettings, YAxisOrientation,
+    scale_value, BreakLineOn, Font, FontAtlasSets, FontAtlasWarning, Text, TextError,
+    TextLayoutInfo, TextMeasureInfo, TextPipeline, TextSettings, YAxisOrientation,
 };
 use bevy_window::{PrimaryWindow, Window};
 use taffy::style::AvailableSpace;
@@ -153,6 +153,7 @@ fn queue_text(
     textures: &mut Assets<Image>,
     text_settings: &TextSettings,
     scale_factor: f64,
+    inverse_scale_factor: f64,
     text: &Text,
     node: Ref<Node>,
     mut text_flags: Mut<TextFlags>,
@@ -189,7 +190,9 @@ fn queue_text(
             Err(e @ TextError::FailedToAddGlyph(_)) => {
                 panic!("Fatal error when processing text: {e}.");
             }
-            Ok(info) => {
+            Ok(mut info) => {
+                info.logical_size.x = scale_value(info.logical_size.x, inverse_scale_factor);
+                info.logical_size.y = scale_value(info.logical_size.y, inverse_scale_factor);
                 *text_layout_info = info;
                 text_flags.needs_recompute = false;
             }
@@ -226,7 +229,7 @@ pub fn text_system(
         .unwrap_or(1.);
 
     let scale_factor = ui_scale.0 * window_scale_factor;
-
+    let inverse_scale_factor = scale_factor.recip();
     if *last_scale_factor == scale_factor {
         // Scale factor unchanged, only recompute text for modified text nodes
         for (node, text, text_layout_info, text_flags) in text_query.iter_mut() {
@@ -240,6 +243,7 @@ pub fn text_system(
                     &mut textures,
                     &text_settings,
                     scale_factor,
+                    inverse_scale_factor,
                     text,
                     node,
                     text_flags,
@@ -261,6 +265,7 @@ pub fn text_system(
                 &mut textures,
                 &text_settings,
                 scale_factor,
+                inverse_scale_factor,
                 text,
                 node,
                 text_flags,