Add support for text truncation to egui::Style (#4556)

* Closes #4473

This PR introduce `Style::wrap_mode`, which adds support for text
truncation in addition to text wrapping. This PR also update some width
calculation of the ComboBox.

#### Core

- Add `egui::TextWrapMode` (pure enum with `Extend`, `Wrap`, `Truncate`)
- Add `Style::wrap_mode: Option<tTextWrapMode>`
- **DEPRECATED**: `Style::wrap`, use `Style::wrap_mode` instead.
- Add `Ui::wrap_mode()` to return the wrap mode to use in the current
ui. If specified in `Style`, return it. Otherwise, return
`TextWrapMode::Wrap` for vertical layout and wrapping horizontal layout,
and `TextWrapMode::Extend` otherwise.
- **DEPRECATED**: `Ui::wrap_text()`, use `Ui::wrap_mode` instead.

#### Widget

- Update the width calculation of the `ComboBox` button (_not_ its popup
menu).
- Now, `ComboBox::width()` (defaulting to `Spacing::combo_width`) is
always considered a minimum width and will extend the `Ui`, regardless
of the selected text width and wrap mode.
- Introduce `ComboBox::wrap_mode`, which overrides `Ui::wrap_mode` for
the selected text layout.
- Note: since `ComboBox` uses `ui.horizontal` internally, the default
wrap mode is always `TextWrapMode::Extend`, regardless of the caller's
`Ui`'s layout.
- The `ComboBox` button no longer extend to `ui.available_width()` with
wrapping is enabled.
- **BREAKING**: `ComboBox::wrap()` no longer has a `bool` argument and
is now a short-hand for `ComboBox::wrap_mode(TextWrapMode::Wrap)`.
- Added `ComboBox::truncate()` as short-hand for
`ComboBox::wrap_mode(TextWrapMode::Truncate)`.
- Update `Label`
  - Add `Label::wrap_mode()` to specify the text wrap mode.
- **BREAKING**: `Label::wrap()` no longer has a `bool` argument and is
now a short-hand for `Label::wrap_mode(TextWrapMode::Wrap)`.
- **BREAKING**: `Label::truncate()` no longer has a `bool` argument and
is now a short-hand for `Label::wrap_mode(TextWrapMode::Truncate)`.
- Update `Button`
  - Add `Button::wrap_mode()` to specify the text wrap mode.
- **BREAKING**: `Button::wrap()` no longer has a `bool` argument and is
now a short-hand for `Button::wrap_mode(TextWrapMode::Wrap)`.
- Added `Button::truncate()` as short-hand for
`Button::wrap_mode(TextWrapMode::Truncate)`.

#### Low-level

- **BREAKING**: `WidgetText::into_galley()` now takes an
`Option<TextWrapMode>` instead of a `Option<bool>` argument.
- **BREAKING**: `WidgetText::into_galley_impl(()` now takes a
`TextWrapping` argument instead of `wrap: bool` and `availalbe_width:
f32` arguments.

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/egui_demo_lib/src/demo/demo_app_windows.rs

@@ -335,7 +335,7 @@ fn file_menu_button(ui: &mut Ui) {
 
     ui.menu_button("File", |ui| {
         ui.set_min_width(220.0);
-        ui.style_mut().wrap = Some(false);
+        ui.style_mut().wrap_mode = Some(egui::TextWrapMode::Extend);
 
         // On the web the browser controls the zoom
         #[cfg(not(target_arch = "wasm32"))]

crates/egui_demo_lib/src/demo/frame_demo.rs

@@ -60,7 +60,7 @@ impl super::View for FrameDemo {
                     .rounding(ui.visuals().widgets.noninteractive.rounding)
                     .show(ui, |ui| {
                         self.frame.show(ui, |ui| {
-                            ui.style_mut().wrap = Some(false);
+                            ui.style_mut().wrap_mode = Some(egui::TextWrapMode::Extend);
                             ui.label(egui::RichText::new("Content").color(egui::Color32::WHITE));
                         });
                     });

crates/egui_demo_lib/src/demo/layout_test.rs

@@ -176,7 +176,7 @@ impl LayoutTest {
 }
 
 fn demo_ui(ui: &mut Ui) {
-    ui.add(egui::Label::new("Wrapping text followed by example widgets:").wrap(true));
+    ui.add(egui::Label::new("Wrapping text followed by example widgets:").wrap());
     let mut dummy = false;
     ui.checkbox(&mut dummy, "checkbox");
     ui.radio_value(&mut dummy, false, "radio");

crates/egui_demo_lib/src/demo/misc_demo_window.rs

@@ -223,7 +223,7 @@ fn label_ui(ui: &mut egui::Ui) {
         egui::Label::new(
             "Labels containing long text can be set to elide the text that doesn't fit on a single line using `Label::elide`. When hovered, the label will show the full text.",
         )
-        .truncate(true),
+        .truncate(),
     );
 }
 

crates/egui_demo_lib/src/demo/pan_zoom.rs

@@ -1,4 +1,5 @@
 use egui::emath::TSTransform;
+use egui::TextWrapMode;
 
 #[derive(Clone, Default, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
@@ -122,7 +123,7 @@ impl super::View for PanZoom {
                         .stroke(ui.ctx().style().visuals.window_stroke)
                         .fill(ui.style().visuals.panel_fill)
                         .show(ui, |ui| {
-                            ui.style_mut().wrap = Some(false);
+                            ui.style_mut().wrap_mode = Some(TextWrapMode::Extend);
                             callback(ui, self)
                         });
                 })

crates/egui_demo_lib/src/demo/plot_demo.rs

@@ -200,7 +200,7 @@ impl LineDemo {
             });
 
             ui.vertical(|ui| {
-                ui.style_mut().wrap = Some(false);
+                ui.style_mut().wrap_mode = Some(TextWrapMode::Extend);
                 ui.checkbox(animate, "Animate");
                 ui.checkbox(square, "Square view")
                     .on_hover_text("Always keep the viewport square.");

crates/egui_demo_lib/src/demo/scrolling.rs

@@ -82,7 +82,7 @@ impl super::View for Scrolling {
             }
             ScrollDemo::Bidirectional => {
                 egui::ScrollArea::both().show(ui, |ui| {
-                    ui.style_mut().wrap = Some(false);
+                    ui.style_mut().wrap_mode = Some(TextWrapMode::Extend);
                     for _ in 0..100 {
                         ui.label(crate::LOREM_IPSUM);
                     }

crates/egui_demo_lib/src/demo/table_demo.rs

@@ -1,4 +1,4 @@
-use egui::TextStyle;
+use egui::{TextStyle, TextWrapMode};
 
 #[derive(PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
@@ -196,7 +196,7 @@ impl TableDemo {
                                 ui.label(long_text(row_index));
                             });
                             row.col(|ui| {
-                                ui.style_mut().wrap = Some(false);
+                                ui.style_mut().wrap_mode = Some(egui::TextWrapMode::Extend);
                                 if is_thick {
                                     ui.heading("Extra thick row");
                                 } else {
@@ -227,7 +227,8 @@ impl TableDemo {
                         });
                         row.col(|ui| {
                             ui.add(
-                                egui::Label::new("Thousands of rows of even height").wrap(false),
+                                egui::Label::new("Thousands of rows of even height")
+                                    .wrap_mode(TextWrapMode::Extend),
                             );
                         });
 
@@ -253,7 +254,7 @@ impl TableDemo {
                             ui.label(long_text(row_index));
                         });
                         row.col(|ui| {
-                            ui.style_mut().wrap = Some(false);
+                            ui.style_mut().wrap_mode = Some(egui::TextWrapMode::Extend);
                             if thick_row(row_index) {
                                 ui.heading("Extra thick row");
                             } else {

crates/egui_demo_lib/src/demo/widget_gallery.rs

@@ -172,7 +172,7 @@ impl WidgetGallery {
         egui::ComboBox::from_label("Take your pick")
             .selected_text(format!("{radio:?}"))
             .show_ui(ui, |ui| {
-                ui.style_mut().wrap = Some(false);
+                ui.style_mut().wrap_mode = Some(egui::TextWrapMode::Extend);
                 ui.set_min_width(60.0);
                 ui.selectable_value(radio, Enum::First, "First");
                 ui.selectable_value(radio, Enum::Second, "Second");