Add Context::set_debug_on_hover and egui::trace!(ui)

CHANGELOG.md

@@ -17,6 +17,7 @@ NOTE: [`eframe`](eframe/CHANGELOG.md), [`egui_web`](egui_web/CHANGELOG.md) and [
 * Add support for [cint](https://crates.io/crates/cint) under `cint` feature.
 * Add features `extra_asserts` and `extra_debug_asserts` to enable additional checks.
 * `TextEdit` now supports edits on a generic buffer using `TextBuffer`.
+* Add `Context::set_debug_on_hover` and `egui::trace!(ui)`
 
 ### Changed 🔧
 * Plot: Changed `Curve` to `Line`.

egui/src/context.rs

@@ -726,6 +726,20 @@ impl Context {
             false
         }
     }
+
+    // ---------------------------------------------------------------------
+
+    /// Wether or not to debug widget layout on hover.
+    pub fn debug_on_hover(&self) -> bool {
+        self.memory().options.style.debug.debug_on_hover
+    }
+
+    /// Turn on/off wether or not to debug widget layout on hover.
+    pub fn set_debug_on_hover(&self, debug_on_hover: bool) {
+        let mut style = (*self.memory().options.style).clone();
+        style.debug.debug_on_hover = debug_on_hover;
+        self.set_style(style);
+    }
 }
 
 /// ## Animation
@@ -780,12 +794,14 @@ impl Context {
             .show(ui, |ui| {
                 let mut tessellation_options = self.memory().options.tessellation_options;
                 tessellation_options.ui(ui);
+                ui.vertical_centered(|ui| reset_button(ui, &mut tessellation_options));
                 self.memory().options.tessellation_options = tessellation_options;
             });
     }
 
     pub fn inspection_ui(&self, ui: &mut Ui) {
         use crate::containers::*;
+        crate::trace!(ui);
 
         ui.label(format!("Is using pointer: {}", self.is_using_pointer()))
             .on_hover_text(

egui/src/layout.rs

@@ -731,14 +731,13 @@ impl Layout {
 /// ## Debug stuff
 impl Layout {
     /// Shows where the next widget is going to be placed
-    pub(crate) fn debug_paint_cursor(
+    pub(crate) fn paint_text_at_cursor(
         &self,
+        painter: &crate::Painter,
         region: &Region,
         stroke: epaint::Stroke,
-        painter: &crate::Painter,
+        text: impl ToString,
     ) {
-        use epaint::*;
-
         let cursor = region.cursor;
         let next_pos = self.next_widget_position(region);
 
@@ -769,12 +768,6 @@ impl Layout {
             }
         }
 
-        painter.text(
+        painter.debug_text(next_pos, align, stroke.color, text);
-            next_pos,
-            align,
-            "cursor",
-            TextStyle::Monospace,
-            Color32::WHITE,
-        );
     }
 }

egui/src/lib.rs

@@ -416,6 +416,31 @@ macro_rules! github_link_file {
 
 // ----------------------------------------------------------------------------
 
+/// Show debug info on hover when [`Context::set_debug_on_hover`] has been turned on.
+///
+/// ```
+/// # let ui = &mut egui::Ui::__test();
+/// // Turn on tracing of widgets
+/// ui.ctx().set_debug_on_hover(true);
+///
+/// /// Show [`std::file`], [`std::line`] and argument on hover
+/// egui::trace!(ui, "MyWindow");
+///
+/// /// Show [`std::file`] and [`std::line`] on hover
+/// egui::trace!(ui);
+/// ```
+#[macro_export]
+macro_rules! trace {
+    ($ui:expr) => {{
+        $ui.trace_location(format!("{}:{}", file!(), line!()))
+    }};
+    ($ui:expr, $label:expr) => {{
+        $ui.trace_location(format!("{} - {}:{}", $label, file!(), line!()))
+    }};
+}
+
+// ----------------------------------------------------------------------------
+
 /// An assert that is only active when `egui` is compiled with the `egui_assert` feature
 /// or with the `debug_egui_assert` feature in debug builds.
 #[macro_export]

egui/src/memory.rs

@@ -83,6 +83,7 @@ pub struct Options {
     /// The default style for new `Ui`:s.
     #[cfg_attr(feature = "persistence", serde(skip))]
     pub(crate) style: std::sync::Arc<Style>,
+
     /// Controls the tessellator.
     pub(crate) tessellation_options: epaint::TessellationOptions,
 

egui/src/painter.rs

@@ -187,20 +187,31 @@ impl Painter {
     }
 
     pub fn error(&self, pos: Pos2, text: impl std::fmt::Display) -> Rect {
-        let galley = self.fonts().layout_multiline(
+        self.debug_text(pos, Align2::LEFT_TOP, Color32::RED, format!("🔥 {}", text))
-            TextStyle::Monospace,
+    }
-            format!("🔥 {}", text),
+
-            f32::INFINITY,
+    /// text with a background
-        );
+    #[allow(clippy::needless_pass_by_value)]
-        let rect = Rect::from_min_size(pos, galley.size);
+    pub fn debug_text(
+        &self,
+        pos: Pos2,
+        anchor: Align2,
+        color: Color32,
+        text: impl ToString,
+    ) -> Rect {
+        let galley = self
+            .fonts()
+            .layout_no_wrap(TextStyle::Monospace, text.to_string());
+        let rect = anchor.anchor_rect(Rect::from_min_size(pos, galley.size));
         let frame_rect = rect.expand(2.0);
         self.add(Shape::Rect {
             rect: frame_rect,
             corner_radius: 0.0,
             fill: Color32::from_black_alpha(240),
-            stroke: Stroke::new(1.0, Color32::RED),
+            // stroke: Stroke::new(1.0, color),
+            stroke: Default::default(),
         });
-        self.galley(rect.min, galley, Color32::RED);
+        self.galley(rect.min, galley, color);
         frame_rect
     }
 }

egui/src/placer.rs

@@ -248,15 +248,17 @@ impl Placer {
 }
 
 impl Placer {
-    pub(crate) fn debug_paint_cursor(&self, painter: &crate::Painter) {
+    pub(crate) fn debug_paint_cursor(&self, painter: &crate::Painter, text: impl ToString) {
-        let color = Color32::GREEN.linear_multiply(0.5);
+        let stroke = Stroke::new(1.0, Color32::DEBUG_COLOR);
-        let stroke = Stroke::new(2.0, color);
 
         if let Some(grid) = &self.grid {
-            painter.rect_stroke(grid.next_cell(self.cursor(), Vec2::splat(0.0)), 1.0, stroke)
+            let rect = grid.next_cell(self.cursor(), Vec2::splat(0.0));
+            painter.rect_stroke(rect, 1.0, stroke);
+            let align = Align2::CENTER_CENTER;
+            painter.debug_text(align.pos_in_rect(&rect), align, stroke.color, text);
         } else {
             self.layout
-                .debug_paint_cursor(&self.region, stroke, painter)
+                .paint_text_at_cursor(painter, &self.region, stroke, text)
         }
     }
 }

egui/src/style.rs

@@ -313,7 +313,7 @@ impl WidgetVisuals {
 #[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
 pub struct DebugOptions {
     /// However over widgets to see their rectangles
-    pub show_widgets: bool,
+    pub debug_on_hover: bool,
     /// Show which widgets make their parent wider
     pub show_expand_width: bool,
     /// Show which widgets make their parent higher
@@ -548,7 +548,7 @@ impl Style {
         ui.collapsing("📏 Spacing", |ui| spacing.ui(ui));
         ui.collapsing("☝ Interaction", |ui| interaction.ui(ui));
         ui.collapsing("🎨 Visuals", |ui| visuals.ui(ui));
-        ui.collapsing("⁉ Debug", |ui| debug.ui(ui));
+        ui.collapsing("🐛 Debug", |ui| debug.ui(ui));
 
         ui.vertical_centered(|ui| reset_button(ui, self));
     }
@@ -746,13 +746,13 @@ impl Visuals {
 impl DebugOptions {
     pub fn ui(&mut self, ui: &mut crate::Ui) {
         let Self {
-            show_widgets: debug_widgets,
+            debug_on_hover,
             show_expand_width: debug_expand_width,
             show_expand_height: debug_expand_height,
             show_resize: debug_resize,
         } = self;
 
-        ui.checkbox(debug_widgets, "Show widget bounds on hover");
+        ui.checkbox(debug_on_hover, "Show debug info on hover");
         ui.checkbox(
             debug_expand_width,
             "Show which widgets make their parent wider",

egui/src/ui.rs

@@ -601,10 +601,10 @@ impl Ui {
 
         let rect = self.allocate_space_impl(desired_size);
 
-        if self.style().debug.show_widgets && self.rect_contains_pointer(rect) {
+        if self.style().debug.debug_on_hover && self.rect_contains_pointer(rect) {
             let painter = self.ctx().debug_painter();
             painter.rect_stroke(rect, 4.0, (1.0, Color32::LIGHT_BLUE));
-            self.placer.debug_paint_cursor(&painter);
+            self.placer.debug_paint_cursor(&painter, "next");
         }
 
         let debug_expand_width = self.style().debug.show_expand_width;
@@ -666,10 +666,10 @@ impl Ui {
         let item_spacing = self.spacing().item_spacing;
         self.placer.advance_after_rects(rect, rect, item_spacing);
 
-        if self.style().debug.show_widgets && self.rect_contains_pointer(rect) {
+        if self.style().debug.debug_on_hover && self.rect_contains_pointer(rect) {
             let painter = self.ctx().debug_painter();
             painter.rect_stroke(rect, 4.0, (1.0, Color32::LIGHT_BLUE));
-            self.placer.debug_paint_cursor(&painter);
+            self.placer.debug_paint_cursor(&painter, "next");
         }
 
         let id = Id::new(self.next_auto_id_source);
@@ -735,11 +735,11 @@ impl Ui {
         self.placer
             .advance_after_rects(final_child_rect, final_child_rect, item_spacing);
 
-        if self.style().debug.show_widgets && self.rect_contains_pointer(final_child_rect) {
+        if self.style().debug.debug_on_hover && self.rect_contains_pointer(final_child_rect) {
             let painter = self.ctx().debug_painter();
             painter.rect_stroke(frame_rect, 4.0, (1.0, Color32::LIGHT_BLUE));
             painter.rect_stroke(final_child_rect, 4.0, (1.0, Color32::LIGHT_BLUE));
-            self.placer.debug_paint_cursor(&painter);
+            self.placer.debug_paint_cursor(&painter, "next");
         }
 
         let response = self.interact(final_child_rect, child_ui.id, Sense::hover());
@@ -1523,10 +1523,10 @@ impl Ui {
         let item_spacing = self.spacing().item_spacing;
         self.placer.advance_after_rects(rect, rect, item_spacing);
 
-        if self.style().debug.show_widgets && self.rect_contains_pointer(rect) {
+        if self.style().debug.debug_on_hover && self.rect_contains_pointer(rect) {
             let painter = self.ctx().debug_painter();
             painter.rect_stroke(rect, 4.0, (1.0, Color32::LIGHT_BLUE));
-            self.placer.debug_paint_cursor(&painter);
+            self.placer.debug_paint_cursor(&painter, "next");
         }
 
         InnerResponse::new(inner, self.interact(rect, child_ui.id, Sense::hover()))
@@ -1628,6 +1628,16 @@ impl Ui {
 impl Ui {
     /// Shows where the next widget is going to be placed
     pub fn debug_paint_cursor(&self) {
-        self.placer.debug_paint_cursor(&self.painter);
+        self.placer.debug_paint_cursor(&self.painter, "next");
+    }
+
+    /// Shows the given text where the next widget is to be placed
+    /// if when [`Context::set_debug_on_hover`] has been turned on and the mouse is hovering the Ui.
+    pub fn trace_location(&self, text: impl ToString) {
+        let rect = self.max_rect_finite();
+        if self.style().debug.debug_on_hover && self.rect_contains_pointer(rect) {
+            self.placer
+                .debug_paint_cursor(&self.ctx().debug_painter(), text);
+        }
     }
 }

egui_demo_lib/src/apps/demo/demo_app_windows.rs

@@ -156,6 +156,7 @@ impl DemoWindows {
             .min_width(150.0)
             .default_width(190.0)
             .show(ctx, |ui| {
+                egui::trace!(ui);
                 ui.vertical_centered(|ui| {
                     ui.heading("✒ egui demos");
                 });
@@ -296,6 +297,7 @@ impl EguiWindows {
 }
 
 fn show_menu_bar(ui: &mut Ui) {
+    trace!(ui);
     use egui::*;
 
     menu::bar(ui, |ui| {

egui_demo_lib/src/wrap_app.rs

@@ -75,6 +75,7 @@ impl epi::App for WrapApp {
         }
 
         egui::TopBottomPanel::top("wrap_app_top_bar").show(ctx, |ui| {
+            egui::trace!(ui);
             self.bar_contents(ui, frame);
         });
 
@@ -262,6 +263,7 @@ impl BackendPanel {
     }
 
     fn ui(&mut self, ui: &mut egui::Ui, frame: &mut epi::Frame<'_>) {
+        egui::trace!(ui);
         ui.vertical_centered(|ui| {
             ui.heading("💻 Backend");
         });
@@ -327,9 +329,20 @@ impl BackendPanel {
             }
         }
 
-        let mut screen_reader = ui.ctx().memory().options.screen_reader;
+        {
-        ui.checkbox(&mut screen_reader, "Screen reader").on_hover_text("Experimental feature: checking this will turn on the screen reader on supported platforms");
+            let mut debug_on_hover = ui.ctx().debug_on_hover();
-        ui.ctx().memory().options.screen_reader = screen_reader;
+            ui.checkbox(&mut debug_on_hover, "🐛 Debug on hover")
+                .on_hover_text("Show structure of the ui when you hover with the mouse");
+            ui.ctx().set_debug_on_hover(debug_on_hover);
+        }
+
+        ui.separator();
+
+        {
+            let mut screen_reader = ui.ctx().memory().options.screen_reader;
+            ui.checkbox(&mut screen_reader, "Screen reader").on_hover_text("Experimental feature: checking this will turn on the screen reader on supported platforms");
+            ui.ctx().memory().options.screen_reader = screen_reader;
+        }
 
         ui.collapsing("Output events", |ui| {
             ui.set_max_width(450.0);

epaint/src/color.rs

@@ -49,6 +49,8 @@ impl Color32 {
     pub const LIGHT_BLUE: Color32 = Color32::from_rgb(140, 160, 255);
     pub const GOLD: Color32 = Color32::from_rgb(255, 215, 0);
 
+    pub const DEBUG_COLOR: Color32 = Color32::from_rgba_premultiplied(0, 200, 0, 128);
+
     #[inline(always)]
     pub const fn from_rgb(r: u8, g: u8, b: u8) -> Self {
         Self([r, g, b, 255])

epaint/src/tessellator.rs

@@ -229,7 +229,7 @@ pub enum PathType {
 use self::PathType::{Closed, Open};
 
 /// Tessellation quality options
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 #[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
 #[cfg_attr(feature = "persistence", serde(default))]
 pub struct TessellationOptions {