From 1a177f7ecd8bc1c526a056cb096bfeaf223c9a50 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Sat, 28 Aug 2021 10:28:50 +0200
Subject: [PATCH] Improve area introspection panel

---
 egui/src/context.rs | 35 +++++++++++++++++++++++++++--------
 egui/src/id.rs      |  3 ++-
 egui/src/layers.rs  | 21 +++++++++++++++++++++
 egui/src/memory.rs  |  7 +++++--
 4 files changed, 55 insertions(+), 11 deletions(-)

diff --git a/egui/src/context.rs b/egui/src/context.rs
index 472d34909..f96b3735a 100644
--- a/egui/src/context.rs
+++ b/egui/src/context.rs
@@ -722,6 +722,7 @@ impl Context {
         }
     }
 
+    /// Top-most layer at the given position.
     pub fn layer_id_at(&self, pos: Pos2) -> Option<LayerId> {
         let resize_grab_radius_side = self.style().interaction.resize_grab_radius_side;
         self.memory().layer_id_at(pos, resize_grab_radius_side)
@@ -823,7 +824,7 @@ impl Context {
         ))
         .on_hover_text("Is egui currently listening for text input?");
         ui.label(format!(
-            "keyboard focus widget: {}",
+            "Keyboard focus widget: {}",
             self.memory()
                 .interaction
                 .focus
@@ -833,6 +834,22 @@ impl Context {
                 .unwrap_or_default()
         ))
         .on_hover_text("Is egui currently listening for text input?");
+
+        let pointer_pos = self
+            .input()
+            .pointer
+            .hover_pos()
+            .map_or_else(String::new, |pos| format!("{:?}", pos));
+        ui.label(format!("Pointer pos: {}", pointer_pos));
+
+        let top_layer = self
+            .input()
+            .pointer
+            .hover_pos()
+            .and_then(|pos| self.layer_id_at(pos))
+            .map_or_else(String::new, |layer| layer.short_debug_format());
+        ui.label(format!("Top layer under mouse: {}", top_layer));
+
         ui.add_space(16.0);
 
         ui.label(format!(
@@ -864,7 +881,7 @@ impl Context {
 
         ui.horizontal(|ui| {
             ui.label(format!(
-                "{} areas (window positions)",
+                "{} areas (panels, windows, popups, …)",
                 self.memory().areas.count()
             ));
             if ui.button("Reset").clicked() {
@@ -872,18 +889,20 @@ impl Context {
             }
         });
         ui.indent("areas", |ui| {
+            ui.label("Visible areas, ordered back to front.");
+            ui.label("Hover to highlight");
             let layers_ids: Vec<LayerId> = self.memory().areas.order().to_vec();
             for layer_id in layers_ids {
                 let area = self.memory().areas.get(layer_id.id).cloned();
                 if let Some(area) = area {
                     let is_visible = self.memory().areas.is_visible(&layer_id);
+                    if !is_visible {
+                        continue;
+                    }
+                    let text = format!("{} - {:?}", layer_id.short_debug_format(), area.rect(),);
+                    // TODO: `Sense::hover_highlight()`
                     if ui
-                        .label(format!(
-                            "{:?} {:?} {}",
-                            layer_id.order,
-                            area.rect(),
-                            if is_visible { "" } else { "(INVISIBLE)" }
-                        ))
+                        .add(Label::new(text).monospace().sense(Sense::click()))
                         .hovered
                         && is_visible
                     {
diff --git a/egui/src/id.rs b/egui/src/id.rs
index 6a901992a..ce641fc6f 100644
--- a/egui/src/id.rs
+++ b/egui/src/id.rs
@@ -57,7 +57,8 @@ impl Id {
         Id(hasher.finish())
     }
 
-    pub(crate) fn short_debug_format(&self) -> String {
+    /// Short and readable summary
+    pub fn short_debug_format(&self) -> String {
         format!("{:04X}", self.0 as u16)
     }
 
diff --git a/egui/src/layers.rs b/egui/src/layers.rs
index f4b8bc879..7ba1ff662 100644
--- a/egui/src/layers.rs
+++ b/egui/src/layers.rs
@@ -48,6 +48,18 @@ impl Order {
             Self::Tooltip => false,
         }
     }
+
+    /// Short and readable summary
+    pub fn short_debug_format(&self) -> &'static str {
+        match self {
+            Self::Background => "backg",
+            Self::PanelResizeLine => "panel",
+            Self::Middle => "middl",
+            Self::Foreground => "foreg",
+            Self::Tooltip => "toolt",
+            Self::Debug => "debug",
+        }
+    }
 }
 
 /// An identifier for a paint layer.
@@ -82,6 +94,15 @@ impl LayerId {
     pub fn allow_interaction(&self) -> bool {
         self.order.allow_interaction()
     }
+
+    /// Short and readable summary
+    pub fn short_debug_format(&self) -> String {
+        format!(
+            "{} {}",
+            self.order.short_debug_format(),
+            self.id.short_debug_format()
+        )
+    }
 }
 
 /// A unique identifier of a specific [`Shape`] in a [`PaintList`].
diff --git a/egui/src/memory.rs b/egui/src/memory.rs
index 7aa0844b3..3bbbedb15 100644
--- a/egui/src/memory.rs
+++ b/egui/src/memory.rs
@@ -291,6 +291,7 @@ impl Memory {
         self.drag_value.end_frame(input);
     }
 
+    /// Top-most layer at the given position.
     pub fn layer_id_at(&self, pos: Pos2, resize_interact_radius_side: f32) -> Option<LayerId> {
         self.areas.layer_id_at(pos, resize_interact_radius_side)
     }
@@ -435,7 +436,7 @@ impl Memory {
 #[cfg_attr(feature = "persistence", serde(default))]
 pub struct Areas {
     areas: HashMap<Id, area::State>,
-    /// Top is last
+    /// Back-to-front. Top is last.
     order: Vec<LayerId>,
     visible_last_frame: HashSet<LayerId>,
     visible_current_frame: HashSet<LayerId>,
@@ -457,6 +458,7 @@ impl Areas {
         self.areas.get(&id)
     }
 
+    /// Back-to-front. Top is last.
     pub(crate) fn order(&self) -> &[LayerId] {
         &self.order
     }
@@ -469,11 +471,12 @@ impl Areas {
         }
     }
 
+    /// Top-most layer at the given position.
     pub fn layer_id_at(&self, pos: Pos2, resize_interact_radius_side: f32) -> Option<LayerId> {
         for layer in self.order.iter().rev() {
             if self.is_visible(layer) {
                 if let Some(state) = self.areas.get(&layer.id) {
-                    let mut rect = Rect::from_min_size(state.pos, state.size);
+                    let mut rect = state.rect();
                     if state.interactable {
                         // Allow us to resize by dragging just outside the window:
                         rect = rect.expand(resize_interact_radius_side);