Add debug-option to show a callstack to the widget under the mouse

.github/workflows/rust.yml

@@ -81,6 +81,9 @@ jobs:
       - name: Cranky
         run: cargo cranky --all-targets --all-features -- -D warnings
 
+      - name: Cranky release
+        run: cargo cranky --all-targets --all-features --release -- -D warnings
+
   # ---------------------------------------------------------------------------
 
   check_wasm:

crates/egui/Cargo.toml

@@ -25,6 +25,11 @@ default = ["default_fonts"]
 ## [`bytemuck`](https://docs.rs/bytemuck) enables you to cast [`epaint::Vertex`], [`emath::Vec2`] etc to `&[u8]`.
 bytemuck = ["epaint/bytemuck"]
 
+## Show a debug-ui on hover including the stacktrace to the hovered item.
+## This is very useful in finding the code that creates a part of the UI.
+## Does not work on web.
+callstack = ["dep:backtrace"]
+
 ## [`cint`](https://docs.rs/cint) enables interoperability with other color libraries.
 cint = ["epaint/cint"]
 
@@ -80,6 +85,8 @@ nohash-hasher = "0.2"
 ## accessibility APIs. Also requires support in the egui integration.
 accesskit = { version = "0.11", optional = true }
 
+backtrace = { version = "0.3", optional = true }
+
 ## Enable this when generating docs.
 document-features = { version = "0.2", optional = true }
 

crates/egui/src/callstack.rs

@@ -0,0 +1,186 @@
+#[derive(Clone)]
+struct Frame {
+    /// `_main` is usually as the deepest depth.
+    depth: usize,
+    name: String,
+    file_and_line: String,
+}
+
+/// Capture a callstack, skipping the frames that are not interesting.
+///
+/// In particular: slips everything before `egui::Context::run`,
+/// and skipping all frames in the `egui::` namespace.
+pub fn capture() -> String {
+    let mut frames = vec![];
+    let mut depth = 0;
+
+    backtrace::trace(|frame| {
+        // Resolve this instruction pointer to a symbol name
+        backtrace::resolve_frame(frame, |symbol| {
+            let mut file_and_line = symbol.filename().map(shorten_source_file_path);
+
+            if let Some(file_and_line) = &mut file_and_line {
+                if let Some(line_nr) = symbol.lineno() {
+                    file_and_line.push_str(&format!(":{line_nr}"));
+                }
+            }
+            let file_and_line = file_and_line.unwrap_or_default();
+
+            let name = symbol
+                .name()
+                .map(|name| name.to_string())
+                .unwrap_or_default();
+
+            frames.push(Frame {
+                depth,
+                name,
+                file_and_line,
+            });
+        });
+
+        depth += 1; // note: we can resolve multiple symbols on the same frame.
+
+        true // keep going to the next frame
+    });
+
+    if frames.is_empty() {
+        return Default::default();
+    }
+
+    // Inclusive:
+    let mut min_depth = 0;
+    let mut max_depth = frames.len() - 1;
+
+    for frame in &frames {
+        if frame.name.starts_with("egui::callstack::capture") {
+            min_depth = frame.depth + 1;
+        }
+        if frame.name.starts_with("egui::context::Context::run") {
+            max_depth = frame.depth;
+        }
+    }
+
+    // Remove frames that are uninteresting:
+    frames.retain(|frame| {
+        // Keep some special frames to give the user a sense of chronology:
+        if frame.name == "main"
+            || frame.name == "_main"
+            || frame.name.starts_with("egui::context::Context::run")
+            || frame.name.starts_with("eframe::run_native")
+        {
+            return true;
+        }
+
+        if frame.depth < min_depth || max_depth < frame.depth {
+            return false;
+        }
+
+        // Remove stuff that isn't user calls:
+        let skip_prefixes = [
+            // "backtrace::", // not needed, since we cut at at egui::callstack::capture
+            "egui::",
+            "<egui::",
+            "<F as egui::widgets::Widget>",
+            "egui_plot::",
+            "egui_extras::",
+            "core::ptr::drop_in_place<egui::ui::Ui>::",
+            "eframe::",
+            "core::ops::function::FnOnce::call_once",
+            "<alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once",
+        ];
+        for prefix in skip_prefixes {
+            if frame.name.starts_with(prefix) {
+                return false;
+            }
+        }
+        true
+    });
+
+    frames.reverse(); // main on top, i.e. chronological order. Same as Python.
+
+    let mut deepest_depth = 0;
+    let mut widest_file_line = 0;
+    for frame in &frames {
+        deepest_depth = frame.depth.max(deepest_depth);
+        widest_file_line = frame.file_and_line.len().max(widest_file_line);
+    }
+
+    let widest_depth = deepest_depth.to_string().len();
+
+    let mut formatted = String::new();
+
+    if !frames.is_empty() {
+        let mut last_depth = frames[0].depth;
+
+        for frame in &frames {
+            let Frame {
+                depth,
+                name,
+                file_and_line,
+            } = frame;
+
+            if frame.depth + 1 < last_depth || last_depth + 1 < frame.depth {
+                // Show that some frames were elided
+                formatted.push_str(&format!("{:widest_depth$}  …\n", ""));
+            }
+
+            formatted.push_str(&format!(
+                "{depth:widest_depth$}: {file_and_line:widest_file_line$}  {name}\n"
+            ));
+
+            last_depth = frame.depth;
+        }
+    }
+
+    formatted
+}
+
+/// Shorten a path to a Rust source file from a callstack.
+///
+/// Example input:
+/// * `/Users/emilk/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.24.1/src/runtime/runtime.rs`
+/// * `crates/rerun/src/main.rs`
+/// * `/rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/ops/function.rs`
+fn shorten_source_file_path(path: &std::path::Path) -> String {
+    // Look for `src` and strip everything up to it.
+
+    let components: Vec<_> = path.iter().map(|path| path.to_string_lossy()).collect();
+
+    let mut src_idx = None;
+    for (i, c) in components.iter().enumerate() {
+        if c == "src" {
+            src_idx = Some(i);
+        }
+    }
+
+    // Look for the last `src`:
+    if let Some(src_idx) = src_idx {
+        // Before `src` comes the name of the crate - let's include that:
+        let first_index = src_idx.saturating_sub(1);
+
+        let mut output = components[first_index].to_string();
+        for component in &components[first_index + 1..] {
+            output.push('/');
+            output.push_str(component);
+        }
+        output
+    } else {
+        // No `src` directory found - weird!
+        path.display().to_string()
+    }
+}
+
+#[test]
+fn test_shorten_path() {
+    for (before, after) in [
+        ("/Users/emilk/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.24.1/src/runtime/runtime.rs", "tokio-1.24.1/src/runtime/runtime.rs"),
+        ("crates/rerun/src/main.rs", "rerun/src/main.rs"),
+        ("/rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/ops/function.rs", "core/src/ops/function.rs"),
+        ("/weird/path/file.rs", "/weird/path/file.rs"),
+        ]
+        {
+        use std::str::FromStr as _;
+        let before = std::path::PathBuf::from_str(before).unwrap();
+        assert_eq!(shorten_source_file_path(&before), after);
+    }
+}

crates/egui/src/containers/resize.rs

@@ -314,6 +314,7 @@ impl Resize {
 
         state.store(ui.ctx(), id);
 
+        #[cfg(debug_assertions)]
         if ui.ctx().style().debug.show_resize {
             ui.ctx().debug_painter().debug_rect(
                 Rect::from_min_size(content_ui.min_rect().left_top(), state.desired_size),

crates/egui/src/context.rs

@@ -662,6 +662,7 @@ impl Context {
         // This solves the problem of overlapping widgets.
         // Whichever widget is added LAST (=on top) gets the input:
         if interact_rect.is_positive() && sense.interactive() {
+            #[cfg(debug_assertions)]
             if self.style().debug.show_interactive_widgets {
                 Self::layer_painter(self, LayerId::debug()).rect(
                     interact_rect,
@@ -670,6 +671,8 @@ impl Context {
                     Stroke::new(1.0, Color32::YELLOW.additive().linear_multiply(0.05)),
                 );
             }
+
+            #[cfg(debug_assertions)]
             let mut show_blocking_widget = None;
 
             self.write(|ctx| {
@@ -690,6 +693,7 @@ impl Context {
                                     // Another interactive widget is covering us at the pointer position,
                                     // so we aren't hovered.
 
+                                    #[cfg(debug_assertions)]
                                     if ctx.memory.options.style.debug.show_blocking_widget {
                                         // Store the rects to use them outside the write() call to
                                         // avoid deadlock
@@ -705,6 +709,7 @@ impl Context {
                 }
             });
 
+            #[cfg(debug_assertions)]
             if let Some((interact_rect, prev_rect)) = show_blocking_widget {
                 Self::layer_painter(self, LayerId::debug()).debug_rect(
                     interact_rect,
@@ -1528,15 +1533,15 @@ impl Context {
     // ---------------------------------------------------------------------
 
     /// Whether or not to debug widget layout on hover.
+    #[cfg(debug_assertions)]
     pub fn debug_on_hover(&self) -> bool {
         self.options(|opt| opt.style.debug.debug_on_hover)
     }
 
     /// Turn on/off whether or not to debug widget layout on hover.
+    #[cfg(debug_assertions)]
     pub fn set_debug_on_hover(&self, debug_on_hover: bool) {
-        let mut style = self.options(|opt| (*opt.style).clone());
-        style.debug.debug_on_hover = debug_on_hover;
-        self.set_style(style);
+        self.style_mut(|style| style.debug.debug_on_hover = debug_on_hover);
     }
 }
 
@@ -1619,7 +1624,6 @@ impl Context {
     /// Show the state of egui, including its input and output.
     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(

crates/egui/src/data/input.rs

@@ -455,6 +455,11 @@ impl Modifiers {
         !self.is_none()
     }
 
+    #[inline]
+    pub fn all(&self) -> bool {
+        self.alt && self.ctrl && self.shift && self.command
+    }
+
     /// Is shift the only pressed button?
     #[inline]
     pub fn shift_only(&self) -> bool {

crates/egui/src/frame_state.rs

@@ -54,6 +54,9 @@ pub(crate) struct FrameState {
 
     /// Highlight these widgets the next frame. Write to this.
     pub(crate) highlight_next_frame: IdSet,
+
+    #[cfg(debug_assertions)]
+    pub(crate) has_debug_viewed_this_frame: bool,
 }
 
 impl Default for FrameState {
@@ -70,6 +73,9 @@ impl Default for FrameState {
             accesskit_state: None,
             highlight_this_frame: Default::default(),
             highlight_next_frame: Default::default(),
+
+            #[cfg(debug_assertions)]
+            has_debug_viewed_this_frame: false,
         }
     }
 }
@@ -89,6 +95,9 @@ impl FrameState {
             accesskit_state,
             highlight_this_frame,
             highlight_next_frame,
+
+            #[cfg(debug_assertions)]
+            has_debug_viewed_this_frame,
         } = self;
 
         used_ids.clear();
@@ -99,6 +108,11 @@ impl FrameState {
         *scroll_delta = input.scroll_delta;
         *scroll_target = [None, None];
 
+        #[cfg(debug_assertions)]
+        {
+            *has_debug_viewed_this_frame = false;
+        }
+
         #[cfg(feature = "accesskit")]
         {
             *accesskit_state = None;

crates/egui/src/grid.rs

@@ -187,24 +187,27 @@ impl GridLayout {
     }
 
     pub(crate) fn advance(&mut self, cursor: &mut Rect, _frame_rect: Rect, widget_rect: Rect) {
-        let debug_expand_width = self.style.debug.show_expand_width;
-        let debug_expand_height = self.style.debug.show_expand_height;
-        if debug_expand_width || debug_expand_height {
-            let rect = widget_rect;
-            let too_wide = rect.width() > self.prev_col_width(self.col);
-            let too_high = rect.height() > self.prev_row_height(self.row);
-
-            if (debug_expand_width && too_wide) || (debug_expand_height && too_high) {
-                let painter = self.ctx.debug_painter();
-                painter.rect_stroke(rect, 0.0, (1.0, Color32::LIGHT_BLUE));
-
-                let stroke = Stroke::new(2.5, Color32::from_rgb(200, 0, 0));
-                let paint_line_seg = |a, b| painter.line_segment([a, b], stroke);
-
-                if debug_expand_width && too_wide {
-                    paint_line_seg(rect.left_top(), rect.left_bottom());
-                    paint_line_seg(rect.left_center(), rect.right_center());
-                    paint_line_seg(rect.right_top(), rect.right_bottom());
+        #[cfg(debug_assertions)]
+        {
+            let debug_expand_width = self.style.debug.show_expand_width;
+            let debug_expand_height = self.style.debug.show_expand_height;
+            if debug_expand_width || debug_expand_height {
+                let rect = widget_rect;
+                let too_wide = rect.width() > self.prev_col_width(self.col);
+                let too_high = rect.height() > self.prev_row_height(self.row);
+
+                if (debug_expand_width && too_wide) || (debug_expand_height && too_high) {
+                    let painter = self.ctx.debug_painter();
+                    painter.rect_stroke(rect, 0.0, (1.0, Color32::LIGHT_BLUE));
+
+                    let stroke = Stroke::new(2.5, Color32::from_rgb(200, 0, 0));
+                    let paint_line_seg = |a, b| painter.line_segment([a, b], stroke);
+
+                    if debug_expand_width && too_wide {
+                        paint_line_seg(rect.left_top(), rect.left_bottom());
+                        paint_line_seg(rect.left_center(), rect.right_center());
+                        paint_line_seg(rect.right_top(), rect.right_bottom());
+                    }
                 }
             }
         }