Add demo of advanced TextEdit usage

egui_demo_lib/src/apps/demo/demo_app_windows.rs

@@ -28,6 +28,7 @@ impl Default for Demos {
             Box::new(super::plot_demo::PlotDemo::default()),
             Box::new(super::scrolling::Scrolling::default()),
             Box::new(super::sliders::Sliders::default()),
+            Box::new(super::text_edit::TextEdit::default()),
             Box::new(super::widget_gallery::WidgetGallery::default()),
             Box::new(super::window_options::WindowOptions::default()),
             Box::new(super::tests::WindowResizeTest::default()),

egui_demo_lib/src/apps/demo/mod.rs

@@ -21,6 +21,7 @@ pub mod plot_demo;
 pub mod scrolling;
 pub mod sliders;
 pub mod tests;
+pub mod text_edit;
 pub mod toggle_switch;
 pub mod widget_gallery;
 pub mod window_options;

egui_demo_lib/src/apps/demo/text_edit.rs

@@ -0,0 +1,83 @@
+/// Showcase [`TextEdit`].
+#[derive(PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+#[cfg_attr(feature = "serde", serde(default))]
+pub struct TextEdit {
+    pub text: String,
+}
+
+impl Default for TextEdit {
+    fn default() -> Self {
+        Self {
+            text: "Edit this text".to_owned(),
+        }
+    }
+}
+
+impl super::Demo for TextEdit {
+    fn name(&self) -> &'static str {
+        "🖹 TextEdit"
+    }
+
+    fn show(&mut self, ctx: &egui::CtxRef, open: &mut bool) {
+        egui::Window::new(self.name())
+            .open(open)
+            .resizable(false)
+            .show(ctx, |ui| {
+                use super::View as _;
+                self.ui(ui);
+            });
+    }
+}
+
+impl super::View for TextEdit {
+    fn ui(&mut self, ui: &mut egui::Ui) {
+        let Self { text } = self;
+
+        ui.horizontal(|ui| {
+            ui.spacing_mut().item_spacing.x = 0.0;
+            ui.label("Advanced usage of ");
+            ui.code("TextEdit");
+            ui.label(".");
+        });
+
+        let output = egui::TextEdit::multiline(text)
+            .hint_text("Type something!")
+            .show(ui);
+
+        ui.horizontal(|ui| {
+            ui.spacing_mut().item_spacing.x = 0.0;
+            ui.label("Selected text: ");
+            if let Some(text_cursor_range) = output.cursor_range {
+                use egui::TextBuffer as _;
+                let selected_chars = text_cursor_range.as_sorted_char_range();
+                let selected_text = text.char_range(selected_chars);
+                ui.code(selected_text);
+            }
+        });
+
+        let anything_selected = output
+            .cursor_range
+            .map_or(false, |cursor| !cursor.is_empty());
+
+        ui.add_enabled(
+            anything_selected,
+            egui::Label::new("Press ctrl+T to toggle the case of selected text (cmd+T on Mac)"),
+        );
+        if ui.input().modifiers.command_only() && ui.input().key_pressed(egui::Key::T) {
+            if let Some(text_cursor_range) = output.cursor_range {
+                use egui::TextBuffer as _;
+                let selected_chars = text_cursor_range.as_sorted_char_range();
+                let selected_text = text.char_range(selected_chars.clone());
+                let upper_case = selected_text.to_uppercase();
+                let new_text = if selected_text == upper_case {
+                    selected_text.to_lowercase()
+                } else {
+                    upper_case
+                };
+                text.delete_char_range(selected_chars.clone());
+                text.insert_text(&new_text, selected_chars.start);
+            }
+        }
+    }
+}