Replace a special Color32::PLACEHOLDER with widget fallback color

crates/ecolor/src/color32.rs

@@ -7,6 +7,8 @@ use crate::{gamma_u8_from_linear_f32, linear_f32_from_gamma_u8, linear_f32_from_
 ///
 /// Internally this uses 0-255 gamma space `sRGBA` color with premultiplied alpha.
 /// Alpha channel is in linear space.
+///
+/// The special value of alpha=0 means the color is to be treated as an additive color.
 #[repr(C)]
 #[derive(Clone, Copy, Debug, Default, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
@@ -61,7 +63,16 @@ impl Color32 {
     pub const DEBUG_COLOR: Color32 = Color32::from_rgba_premultiplied(0, 200, 0, 128);
 
     /// An ugly color that is planned to be replaced before making it to the screen.
-    pub const TEMPORARY_COLOR: Color32 = Color32::from_rgb(64, 254, 0);
+    ///
+    /// This is an invalid color, in that it does not correspond to a valid multiplied color,
+    /// nor to an additive color.
+    ///
+    /// This is used as a special color key,
+    /// i.e. often taken to mean "no color".
+    pub const PLACEHOLDER: Color32 = Color32::from_rgba_premultiplied(64, 254, 0, 128);
+
+    #[deprecated = "Renmaed to PLACEHOLDER"]
+    pub const TEMPORARY_COLOR: Color32 = Self::PLACEHOLDER;
 
     #[inline]
     pub const fn from_rgb(r: u8, g: u8, b: u8) -> Self {

crates/egui/src/containers/collapsing_header.rs

@@ -495,22 +495,22 @@ impl CollapsingHeader {
         let text_pos = available.min + vec2(ui.spacing().indent, 0.0);
         let wrap_width = available.right() - text_pos.x;
         let wrap = Some(false);
-        let text = text.into_galley(ui, wrap, wrap_width, TextStyle::Button);
-        let text_max_x = text_pos.x + text.size().x;
+        let galley = text.into_galley(ui, wrap, wrap_width, TextStyle::Button);
+        let text_max_x = text_pos.x + galley.size().x;
 
         let mut desired_width = text_max_x + button_padding.x - available.left();
         if ui.visuals().collapsing_header_frame {
             desired_width = desired_width.max(available.width()); // fill full width
         }
 
-        let mut desired_size = vec2(desired_width, text.size().y + 2.0 * button_padding.y);
+        let mut desired_size = vec2(desired_width, galley.size().y + 2.0 * button_padding.y);
         desired_size = desired_size.at_least(ui.spacing().interact_size);
         let (_, rect) = ui.allocate_space(desired_size);
 
         let mut header_response = ui.interact(rect, id, Sense::click());
         let text_pos = pos2(
             text_pos.x,
-            header_response.rect.center().y - text.size().y / 2.0,
+            header_response.rect.center().y - galley.size().y / 2.0,
         );
 
         let mut state = CollapsingState::load_with_default_open(ui.ctx(), id, default_open);
@@ -525,7 +525,7 @@ impl CollapsingHeader {
         }
 
         header_response
-            .widget_info(|| WidgetInfo::labeled(WidgetType::CollapsingHeader, text.text()));
+            .widget_info(|| WidgetInfo::labeled(WidgetType::CollapsingHeader, galley.text()));
 
         let openness = state.openness(ui.ctx());
 
@@ -563,7 +563,7 @@ impl CollapsingHeader {
                 }
             }
 
-            text.paint_with_visuals(ui.painter(), text_pos, &visuals);
+            ui.painter().galley(text_pos, galley, visuals.text_color());
         }
 
         Prepared {

crates/egui/src/containers/combo_box.rs

@@ -327,7 +327,8 @@ fn combo_box_dyn<'c, R>(
             }
 
             let text_rect = Align2::LEFT_CENTER.align_size_within_rect(galley.size(), rect);
-            galley.paint_with_visuals(ui.painter(), text_rect.min, visuals);
+            ui.painter()
+                .galley(text_rect.min, galley, visuals.text_color());
         }
     });
 

crates/egui/src/containers/window.rs

@@ -1,7 +1,9 @@
 // WARNING: the code in here is horrible. It is a behemoth that needs breaking up into simpler parts.
 
+use std::sync::Arc;
+
 use crate::collapsing_header::CollapsingState;
-use crate::{widget_text::WidgetTextGalley, *};
+use crate::*;
 use epaint::*;
 
 use super::*;
@@ -885,7 +887,7 @@ struct TitleBar {
     id: Id,
 
     /// Prepared text in the title
-    title_galley: WidgetTextGalley,
+    title_galley: Arc<Galley>,
 
     /// Size of the title bar in a collapsed state (if window is collapsible),
     /// which includes all necessary space for showing the expand button, the
@@ -984,11 +986,11 @@ impl TitleBar {
         let full_top_rect = Rect::from_x_y_ranges(self.rect.x_range(), self.min_rect.y_range());
         let text_pos =
             emath::align::center_size_in_rect(self.title_galley.size(), full_top_rect).left_top();
-        let text_pos = text_pos - self.title_galley.galley().rect.min.to_vec2();
+        let text_pos = text_pos - self.title_galley.rect.min.to_vec2();
         let text_pos = text_pos - 1.5 * Vec2::Y; // HACK: center on x-height of text (looks better)
-        self.title_galley.paint_with_fallback_color(
-            ui.painter(),
+        ui.painter().galley(
             text_pos,
+            self.title_galley.clone(),
             ui.visuals().text_color(),
         );
 

crates/egui/src/menu.rs

@@ -503,8 +503,8 @@ impl SubMenuButton {
             }
 
             let text_color = visuals.text_color();
-            text_galley.paint_with_fallback_color(ui.painter(), text_pos, text_color);
-            icon_galley.paint_with_fallback_color(ui.painter(), icon_pos, text_color);
+            ui.painter().galley(text_pos, text_galley, text_color);
+            ui.painter().galley(icon_pos, icon_galley, text_color);
         }
         response
     }

crates/egui/src/painter.rs

@@ -88,53 +88,53 @@ impl Painter {
 /// ## Accessors etc
 impl Painter {
     /// Get a reference to the parent [`Context`].
-    #[inline(always)]
+    #[inline]
     pub fn ctx(&self) -> &Context {
         &self.ctx
     }
 
     /// Read-only access to the shared [`Fonts`].
     ///
     /// See [`Context`] documentation for how locks work.
-    #[inline(always)]
+    #[inline]
     pub fn fonts<R>(&self, reader: impl FnOnce(&Fonts) -> R) -> R {
         self.ctx.fonts(reader)
     }
 
     /// Where we paint
-    #[inline(always)]
+    #[inline]
     pub fn layer_id(&self) -> LayerId {
         self.layer_id
     }
 
     /// Everything painted in this [`Painter`] will be clipped against this.
     /// This means nothing outside of this rectangle will be visible on screen.
-    #[inline(always)]
+    #[inline]
     pub fn clip_rect(&self) -> Rect {
         self.clip_rect
     }
 
     /// Everything painted in this [`Painter`] will be clipped against this.
     /// This means nothing outside of this rectangle will be visible on screen.
-    #[inline(always)]
+    #[inline]
     pub fn set_clip_rect(&mut self, clip_rect: Rect) {
         self.clip_rect = clip_rect;
     }
 
     /// Useful for pixel-perfect rendering.
-    #[inline(always)]
+    #[inline]
     pub fn round_to_pixel(&self, point: f32) -> f32 {
         self.ctx().round_to_pixel(point)
     }
 
     /// Useful for pixel-perfect rendering.
-    #[inline(always)]
+    #[inline]
     pub fn round_vec_to_pixels(&self, vec: Vec2) -> Vec2 {
         self.ctx().round_vec_to_pixels(vec)
     }
 
     /// Useful for pixel-perfect rendering.
-    #[inline(always)]
+    #[inline]
     pub fn round_pos_to_pixels(&self, pos: Pos2) -> Pos2 {
         self.ctx().round_pos_to_pixels(pos)
     }
@@ -236,7 +236,7 @@ impl Painter {
             0.0,
             Color32::from_black_alpha(150),
         ));
-        self.galley(rect.min, galley);
+        self.galley(rect.min, galley, color);
         frame_rect
     }
 }
@@ -379,14 +379,15 @@ impl Painter {
     ) -> Rect {
         let galley = self.layout_no_wrap(text.to_string(), font_id, text_color);
         let rect = anchor.anchor_rect(Rect::from_min_size(pos, galley.size()));
-        self.galley(rect.min, galley);
+        self.galley(rect.min, galley, text_color);
         rect
     }
 
     /// Will wrap text at the given width and line break at `\n`.
     ///
     /// Paint the results with [`Self::galley`].
-    #[inline(always)]
+    #[inline]
+    #[must_use]
     pub fn layout(
         &self,
         text: String,
@@ -400,7 +401,8 @@ impl Painter {
     /// Will line break at `\n`.
     ///
     /// Paint the results with [`Self::galley`].
-    #[inline(always)]
+    #[inline]
+    #[must_use]
     pub fn layout_no_wrap(
         &self,
         text: String,
@@ -414,23 +416,42 @@ impl Painter {
     ///
     /// You can create the [`Galley`] with [`Self::layout`].
     ///
-    /// If you want to change the color of the text, use [`Self::galley_with_color`].
-    #[inline(always)]
-    pub fn galley(&self, pos: Pos2, galley: Arc<Galley>) {
+    /// Any uncolored parts of the [`Galley`] (using [`Color32::PLACEHOLDER`]) will be replaced with the given color.
+    ///
+    /// Any non-placeholder color in the galley takes precedence over this fallback color.
+    #[inline]
+    pub fn galley(&self, pos: Pos2, galley: Arc<Galley>, fallback_color: Color32) {
         if !galley.is_empty() {
-            self.add(Shape::galley(pos, galley));
+            self.add(Shape::galley(pos, galley, fallback_color));
         }
     }
 
     /// Paint text that has already been laid out in a [`Galley`].
     ///
     /// You can create the [`Galley`] with [`Self::layout`].
     ///
-    /// The text color in the [`Galley`] will be replaced with the given color.
-    #[inline(always)]
+    /// All text color in the [`Galley`] will be replaced with the given color.
+    #[inline]
+    pub fn galley_with_override_text_color(
+        &self,
+        pos: Pos2,
+        galley: Arc<Galley>,
+        text_color: Color32,
+    ) {
+        if !galley.is_empty() {
+            self.add(Shape::galley_with_override_text_color(
+                pos, galley, text_color,
+            ));
+        }
+    }
+
+    #[deprecated = "Use `Painter::galley` or `Painter::galley_with_override_text_color` instead"]
+    #[inline]
     pub fn galley_with_color(&self, pos: Pos2, galley: Arc<Galley>, text_color: Color32) {
         if !galley.is_empty() {
-            self.add(Shape::galley_with_color(pos, galley, text_color));
+            self.add(Shape::galley_with_override_text_color(
+                pos, galley, text_color,
+            ));
         }
     }
 }

crates/egui/src/ui.rs

@@ -2269,7 +2269,8 @@ fn register_rect(ui: &Ui, rect: Rect) {
     if !callstack.is_empty() {
         let font_id = FontId::monospace(12.0);
         let text = format!("{callstack}\n\n(click to copy)");
-        let galley = painter.layout_no_wrap(text, font_id, Color32::WHITE);
+        let text_color = Color32::WHITE;
+        let galley = painter.layout_no_wrap(text, font_id, text_color);
 
         // Position the text either under or above:
         let screen_rect = ui.ctx().screen_rect();
@@ -2299,7 +2300,7 @@ fn register_rect(ui: &Ui, rect: Rect) {
         };
         let text_rect = Rect::from_min_size(text_pos, galley.size());
         painter.rect(text_rect, 0.0, text_bg_color, (1.0, text_rect_stroke_color));
-        painter.galley(text_pos, galley);
+        painter.galley(text_pos, galley, text_color);
 
         if ui.input(|i| i.pointer.any_click()) {
             ui.ctx().copy_text(callstack);