From 383ef94b4a38c8a03f05a0b52852a0eccc138da1 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emilernerfeldt@gmail.com>
Date: Wed, 9 Dec 2020 21:32:28 +0100
Subject: [PATCH] Label: correct y offset when sharing a row with another
 bigger widget

---
 egui/src/demos/widgets.rs | 24 +++++++++++++++---------
 egui/src/widgets/mod.rs   | 31 ++++++++++++++++++++-----------
 2 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/egui/src/demos/widgets.rs b/egui/src/demos/widgets.rs
index fb179db3..0a3be9d3 100644
--- a/egui/src/demos/widgets.rs
+++ b/egui/src/demos/widgets.rs
@@ -55,19 +55,25 @@ impl Widgets {
             ui.add(Label::new("and tooltips.")).on_hover_text(
                 "This is a multiline tooltip that demonstrates that you can easily add tooltips to any element.\nThis is the second line.\nThis is the third.",
             );
-            let tooltip_ui = |ui: &mut Ui| {
-                ui.heading("The name of the tooltip");
-                ui.horizontal(|ui| {
-                    ui.label("This tooltip was created with");
-                    ui.monospace(".on_hover_ui(...)");
-                });
-                let _ = ui.button("A button you can never press");
-            };
-            ui.label("Tooltips can be more than just simple text.").on_hover_ui(tooltip_ui);
+
+            ui.label("You can mix in other widgets into text, like this button:");
+            let _ = ui.button("button");
+
             ui.label("There is also (limited) non-ASCII support: Ευρηκα! τ = 2×π")
                 .on_hover_text("The current font supports only a few non-latin characters and Egui does not currently support right-to-left text.");
         });
 
+        let tooltip_ui = |ui: &mut Ui| {
+            ui.heading("The name of the tooltip");
+            ui.horizontal(|ui| {
+                ui.label("This tooltip was created with");
+                ui.monospace(".on_hover_ui(...)");
+            });
+            let _ = ui.button("A button you can never press");
+        };
+        ui.label("Tooltips can be more than just simple text.")
+            .on_hover_ui(tooltip_ui);
+
         ui.horizontal(|ui| {
             ui.radio_value(&mut self.radio, Enum::First, "First");
             ui.radio_value(&mut self.radio, Enum::Second, "Second");
diff --git a/egui/src/widgets/mod.rs b/egui/src/widgets/mod.rs
index c6383f29..fdd8f166 100644
--- a/egui/src/widgets/mod.rs
+++ b/egui/src/widgets/mod.rs
@@ -134,7 +134,7 @@ impl Widget for Label {
 
             let text_style = self.text_style_or_default(ui.style());
             let font = &ui.fonts()[text_style];
-            let galley = font.layout_multiline_with_indentation_and_max_width(
+            let mut galley = font.layout_multiline_with_indentation_and_max_width(
                 self.text.clone(),
                 first_row_indentation,
                 max_width,
@@ -142,21 +142,30 @@ impl Widget for Label {
 
             let pos = pos2(ui.min_rect().left(), ui.cursor().y);
 
-            let mut total_response = None;
+            assert!(!galley.rows.is_empty(), "Gallyes are never empty");
+            let rect = galley.rows[0].rect().translate(vec2(pos.x, pos.y));
+            ui.advance_cursor_after_rect(rect);
+            let mut total_response = ui.interact_hover(rect);
 
-            for row in &galley.rows {
-                let rect = row.rect().translate(vec2(pos.x, pos.y));
-                ui.advance_cursor_after_rect(rect);
-                let row_response = ui.interact_hover(rect);
-                if total_response.is_none() {
-                    total_response = Some(row_response);
-                } else {
-                    total_response = Some(total_response.unwrap().union(row_response));
+            let mut y_translation = 0.0;
+            if let Some(row) = galley.rows.get(1) {
+                // We could be sharing the first row with e.g. a button, that is higher than text.
+                // So we need to compensate for that:
+                if pos.y + row.y_min < ui.min_rect().bottom() {
+                    y_translation = ui.min_rect().bottom() - row.y_min - pos.y;
                 }
             }
 
+            for row in galley.rows.iter_mut().skip(1) {
+                row.y_min += y_translation;
+                row.y_max += y_translation;
+                let rect = row.rect().translate(vec2(pos.x, pos.y));
+                ui.advance_cursor_after_rect(rect);
+                total_response |= ui.interact_hover(rect);
+            }
+
             self.paint_galley(ui, pos, galley);
-            total_response.expect("Galley rows shouldn't be empty")
+            total_response
         } else {
             let galley = self.layout(ui);
             let rect = ui.allocate_space(galley.size);