UI text module refactor (#21630)

# Objective

The `measure_text_system` and `text_system` systems don't do anything
except iterate a query and then delegate to two other functions,
`create_text_measure` and `queue_text`, respectively. This doesn't serve
any purpose and just makes these systems harder to understand.

## Solution

Flatten the module by moving the code from `create_text_measure` and
`queue_text` into the systems and remove those functions.

Author: ickshonpe

crates/bevy_ui/src/widget/text.rs

@@ -12,7 +12,7 @@ use bevy_ecs::{
     query::With,
     reflect::ReflectComponent,
     system::{Query, Res, ResMut},
-    world::{Mut, Ref},
+    world::Ref,
 };
 use bevy_image::prelude::*;
 use bevy_math::Vec2;
@@ -223,55 +223,6 @@ impl Measure for TextMeasure {
     }
 }
 
-#[inline]
-fn create_text_measure<'a>(
-    entity: Entity,
-    fonts: &Assets<Font>,
-    scale_factor: f64,
-    spans: impl Iterator<Item = (Entity, usize, &'a str, &'a TextFont, Color, LineHeight)>,
-    block: Ref<TextLayout>,
-    text_pipeline: &mut TextPipeline,
-    mut content_size: Mut<ContentSize>,
-    mut text_flags: Mut<TextNodeFlags>,
-    mut computed: Mut<ComputedTextBlock>,
-    font_system: &mut CosmicFontSystem,
-) {
-    match text_pipeline.create_text_measure(
-        entity,
-        fonts,
-        spans,
-        scale_factor,
-        &block,
-        computed.as_mut(),
-        font_system,
-    ) {
-        Ok(measure) => {
-            if block.linebreak == LineBreak::NoWrap {
-                content_size.set(NodeMeasure::Fixed(FixedMeasure { size: measure.max }));
-            } else {
-                content_size.set(NodeMeasure::Text(TextMeasure { info: measure }));
-            }
-
-            // Text measure func created successfully, so set `TextNodeFlags` to schedule a recompute
-            text_flags.needs_measure_fn = false;
-            text_flags.needs_recompute = true;
-        }
-        Err(TextError::NoSuchFont) => {
-            // Try again next frame
-            text_flags.needs_measure_fn = true;
-        }
-        Err(
-            e @ (TextError::FailedToAddGlyph(_)
-            | TextError::FailedToGetGlyphImage(_)
-            | TextError::MissingAtlasLayout
-            | TextError::MissingAtlasTexture
-            | TextError::InconsistentAtlasState),
-        ) => {
-            panic!("Fatal error when processing text: {e}.");
-        }
-    };
-}
-
 /// Generates a new [`Measure`] for a text node on changes to its [`Text`] component.
 ///
 /// A `Measure` is used by the UI's layout algorithm to determine the appropriate amount of space
@@ -300,98 +251,61 @@ pub fn measure_text_system(
     mut text_pipeline: ResMut<TextPipeline>,
     mut font_system: ResMut<CosmicFontSystem>,
 ) {
-    for (entity, block, content_size, text_flags, computed, computed_target, computed_node) in
-        &mut text_query
+    for (
+        entity,
+        block,
+        mut content_size,
+        mut text_flags,
+        mut computed,
+        computed_target,
+        computed_node,
+    ) in &mut text_query
     {
         // Note: the ComputedTextBlock::needs_rerender bool is cleared in create_text_measure().
         // 1e-5 epsilon to ignore tiny scale factor float errors
-        if 1e-5
+        if !(1e-5
             < (computed_target.scale_factor() - computed_node.inverse_scale_factor.recip()).abs()
             || computed.needs_rerender()
             || text_flags.needs_measure_fn
-            || content_size.is_added()
+            || content_size.is_added())
         {
-            create_text_measure(
-                entity,
-                &fonts,
-                computed_target.scale_factor.into(),
-                text_reader.iter(entity),
-                block,
-                &mut text_pipeline,
-                content_size,
-                text_flags,
-                computed,
-                &mut font_system,
-            );
+            continue;
         }
-    }
-}
-
-#[inline]
-fn queue_text(
-    entity: Entity,
-    fonts: &Assets<Font>,
-    text_pipeline: &mut TextPipeline,
-    font_atlas_set: &mut FontAtlasSet,
-    texture_atlases: &mut Assets<TextureAtlasLayout>,
-    textures: &mut Assets<Image>,
-    scale_factor: f32,
-    inverse_scale_factor: f32,
-    block: &TextLayout,
-    node: Ref<ComputedNode>,
-    mut text_flags: Mut<TextNodeFlags>,
-    text_layout_info: Mut<TextLayoutInfo>,
-    computed: &mut ComputedTextBlock,
-    text_reader: &mut TextUiReader,
-    font_system: &mut CosmicFontSystem,
-    swash_cache: &mut SwashCache,
-) {
-    // Skip the text node if it is waiting for a new measure func
-    if text_flags.needs_measure_fn {
-        return;
-    }
 
-    let physical_node_size = if block.linebreak == LineBreak::NoWrap {
-        // With `NoWrap` set, no constraints are placed on the width of the text.
-        TextBounds::UNBOUNDED
-    } else {
-        // `scale_factor` is already multiplied by `UiScale`
-        TextBounds::new(node.unrounded_size.x, node.unrounded_size.y)
-    };
+        match text_pipeline.create_text_measure(
+            entity,
+            fonts.as_ref(),
+            text_reader.iter(entity),
+            computed_target.scale_factor.into(),
+            &block,
+            computed.as_mut(),
+            &mut font_system,
+        ) {
+            Ok(measure) => {
+                if block.linebreak == LineBreak::NoWrap {
+                    content_size.set(NodeMeasure::Fixed(FixedMeasure { size: measure.max }));
+                } else {
+                    content_size.set(NodeMeasure::Text(TextMeasure { info: measure }));
+                }
 
-    let text_layout_info = text_layout_info.into_inner();
-    match text_pipeline.queue_text(
-        text_layout_info,
-        fonts,
-        text_reader.iter(entity),
-        scale_factor.into(),
-        block,
-        physical_node_size,
-        font_atlas_set,
-        texture_atlases,
-        textures,
-        computed,
-        font_system,
-        swash_cache,
-    ) {
-        Err(TextError::NoSuchFont) => {
-            // There was an error processing the text layout, try again next frame
-            text_flags.needs_recompute = true;
-        }
-        Err(
-            e @ (TextError::FailedToAddGlyph(_)
-            | TextError::FailedToGetGlyphImage(_)
-            | TextError::MissingAtlasLayout
-            | TextError::MissingAtlasTexture
-            | TextError::InconsistentAtlasState),
-        ) => {
-            panic!("Fatal error when processing text: {e}.");
-        }
-        Ok(()) => {
-            text_layout_info.scale_factor = scale_factor;
-            text_layout_info.size *= inverse_scale_factor;
-            text_flags.needs_recompute = false;
-        }
+                // Text measure func created successfully, so set `TextNodeFlags` to schedule a recompute
+                text_flags.needs_measure_fn = false;
+                text_flags.needs_recompute = true;
+            }
+            Err(TextError::NoSuchFont) => {
+                // Try again next frame
+                text_flags.needs_measure_fn = true;
+            }
+            Err(
+                e @ (TextError::FailedToAddGlyph(_)
+                | TextError::FailedToGetGlyphImage(_)
+                | TextError::MissingAtlasLayout
+                | TextError::MissingAtlasTexture
+                | TextError::InconsistentAtlasState),
+            ) => {
+                panic!("Fatal error when processing text: {e}.");
+            }
+        };
     }
 }
 
@@ -421,26 +335,57 @@ pub fn text_system(
     mut font_system: ResMut<CosmicFontSystem>,
     mut swash_cache: ResMut<SwashCache>,
 ) {
-    for (entity, node, block, text_layout_info, text_flags, mut computed) in &mut text_query {
-        if node.is_changed() || text_flags.needs_recompute {
-            queue_text(
-                entity,
-                &fonts,
-                &mut text_pipeline,
-                &mut font_atlas_set,
-                &mut texture_atlases,
-                &mut textures,
-                node.inverse_scale_factor.recip(),
-                node.inverse_scale_factor,
-                block,
-                node,
-                text_flags,
-                text_layout_info,
-                computed.as_mut(),
-                &mut text_reader,
-                &mut font_system,
-                &mut swash_cache,
-            );
+    for (entity, node, block, text_layout_info, mut text_flags, mut computed) in &mut text_query {
+        // Skip the text node if it is waiting for a new measure func
+        if text_flags.needs_measure_fn {
+            continue;
+        }
+
+        if !(node.is_changed() || text_flags.needs_recompute) {
+            continue;
+        }
+
+        let physical_node_size = if block.linebreak == LineBreak::NoWrap {
+            // With `NoWrap` set, no constraints are placed on the width of the text.
+            TextBounds::UNBOUNDED
+        } else {
+            // `scale_factor` is already multiplied by `UiScale`
+            TextBounds::new(node.unrounded_size.x, node.unrounded_size.y)
+        };
+
+        let text_layout_info = text_layout_info.into_inner();
+        match text_pipeline.queue_text(
+            text_layout_info,
+            &fonts,
+            text_reader.iter(entity),
+            node.inverse_scale_factor.recip() as f64,
+            block,
+            physical_node_size,
+            &mut font_atlas_set,
+            &mut texture_atlases,
+            &mut textures,
+            &mut computed,
+            &mut font_system,
+            &mut swash_cache,
+        ) {
+            Err(TextError::NoSuchFont) => {
+                // There was an error processing the text layout, try again next frame
+                text_flags.needs_recompute = true;
+            }
+            Err(
+                e @ (TextError::FailedToAddGlyph(_)
+                | TextError::FailedToGetGlyphImage(_)
+                | TextError::MissingAtlasLayout
+                | TextError::MissingAtlasTexture
+                | TextError::InconsistentAtlasState),
+            ) => {
+                panic!("Fatal error when processing text: {e}.");
+            }
+            Ok(()) => {
+                text_layout_info.scale_factor = node.inverse_scale_factor.recip();
+                text_layout_info.size *= node.inverse_scale_factor;
+                text_flags.needs_recompute = false;
+            }
         }
     }
 }