Tab identation for multiline text edit

build_demo_web.sh

@@ -32,4 +32,13 @@ wasm-bindgen "target/wasm32-unknown-unknown/$BUILD/$TARGET_NAME" \
 
 echo "Finished: docs/${CRATE_NAME}.wasm"
 
-open http://localhost:8888/index.html
+if [[ "$OSTYPE" == "linux-gnu"* ]]; then
+  # Linux, ex: Fedora
+  xdg-open http://localhost:8888/index.html
+elif [[ "$OSTYPE" == "msys" ]]; then
+  # Windows
+  start http://localhost:8888/index.html
+else
+  # Darmin aka MacOS or something else
+  open http://localhost:8888/index.html
+fi

egui/src/memory.rs

@@ -128,8 +128,12 @@ pub(crate) struct Focus {
     /// The last widget interested in focus.
     last_interested: Option<Id>,
 
+    /// Set at the beginning of the frame, set to `false` when "used".
+    is_focus_locked: bool,
+
     /// Set at the beginning of the frame, set to `false` when "used".
     pressed_tab: bool,
+
     /// Set at the beginning of the frame, set to `false` when "used".
     pressed_shift_tab: bool,
 }
@@ -186,6 +190,7 @@ impl Focus {
                 }
             ) {
                 self.id = None;
+                self.is_focus_locked = false;
                 break;
             }
 
@@ -195,10 +200,12 @@ impl Focus {
                 modifiers,
             } = event
             {
-                if modifiers.shift {
-                    self.pressed_shift_tab = true;
-                } else {
-                    self.pressed_tab = true;
+                if !self.is_focus_locked {
+                    if modifiers.shift {
+                        self.pressed_shift_tab = true;
+                    } else {
+                        self.pressed_tab = true;
+                    }
                 }
             }
         }
@@ -225,11 +232,11 @@ impl Focus {
             self.id = Some(id);
             self.give_to_next = false;
         } else if self.id == Some(id) {
-            if self.pressed_tab {
+            if self.pressed_tab && !self.is_focus_locked {
                 self.id = None;
                 self.give_to_next = true;
                 self.pressed_tab = false;
-            } else if self.pressed_shift_tab {
+            } else if self.pressed_shift_tab && !self.is_focus_locked {
                 self.id_next_frame = self.last_interested; // frame-delay so gained_focus works
                 self.pressed_shift_tab = false;
             }
@@ -287,14 +294,30 @@ impl Memory {
         self.interaction.focus.id == Some(id)
     }
 
+    pub(crate) fn lock_focus(&mut self, id: Id, b: bool) {
+        if self.had_focus_last_frame(id) && self.has_focus(id) {
+            self.interaction.focus.is_focus_locked = b;
+        }
+    }
+
+    pub(crate) fn has_lock_focus(&mut self, id: Id) -> bool {
+        if self.had_focus_last_frame(id) && self.has_focus(id) {
+            self.interaction.focus.is_focus_locked
+        } else {
+            false
+        }
+    }
+
     /// Give keyboard focus to a specific widget
     pub fn request_focus(&mut self, id: Id) {
         self.interaction.focus.id = Some(id);
+        self.interaction.focus.is_focus_locked = false;
     }
 
     pub fn surrender_focus(&mut self, id: Id) {
         if self.interaction.focus.id == Some(id) {
             self.interaction.focus.id = None;
+            self.interaction.focus.is_focus_locked = false;
         }
     }
 

egui/src/ui.rs

@@ -883,6 +883,25 @@ impl Ui {
         self.add(TextEdit::multiline(text))
     }
 
+    /// A `TextEdit` for code editing.
+    ///
+    /// Se also [`TextEdit::code_editor`].
+    pub fn code_editor(&mut self, text: &mut String) -> Response {
+        self.add(TextEdit::multiline(text).code_editor())
+    }
+
+    /// A `TextEdit` for code editing with configurable `Tab` management.
+    ///
+    /// Se also [`TextEdit::code_editor_with_config`].
+    pub fn code_editor_with_config(
+        &mut self,
+        text: &mut String,
+        tab_as_spaces: bool,
+        tab_moves_focus: bool,
+    ) -> Response {
+        self.add(TextEdit::multiline(text).code_editor_with_config(tab_as_spaces, tab_moves_focus))
+    }
+
     /// Usage: `if ui.button("Click me").clicked() { … }`
     ///
     /// Shortcut for `add(Button::new(text))`

egui/src/widgets/text_edit.rs

@@ -135,6 +135,8 @@ pub struct TextEdit<'t> {
     enabled: bool,
     desired_width: Option<f32>,
     desired_height_rows: usize,
+    tab_as_spaces: bool,
+    tab_moves_focus: bool,
 }
 impl<'t> TextEdit<'t> {
     pub fn cursor(ui: &Ui, id: Id) -> Option<CursorPair> {
@@ -165,6 +167,8 @@ impl<'t> TextEdit<'t> {
             enabled: true,
             desired_width: None,
             desired_height_rows: 1,
+            tab_as_spaces: false,
+            tab_moves_focus: true,
         }
     }
 
@@ -182,9 +186,71 @@ impl<'t> TextEdit<'t> {
             enabled: true,
             desired_width: None,
             desired_height_rows: 4,
+            tab_as_spaces: false,
+            tab_moves_focus: true,
         }
     }
 
+    /// Registers if this widget will insert spaces instead of tab char
+    ///
+    /// ```rust, ignore
+    /// ui.add(egui::TextEdit::multiline(&mut self.multiline_text_input)
+    ///     .tab_as_spaces(true));
+    /// ```
+    pub fn tab_as_spaces(mut self, b: bool) -> Self {
+        self.tab_as_spaces = b;
+        self
+    }
+
+    /// When this is true, then pass focus to the next
+    /// widget.
+    ///
+    /// When this is false, then insert identation based on the value of
+    /// `tab_as_spaces` property.
+    ///
+    /// ```rust, ignore
+    /// ui.add(egui::TextEdit::multiline(&mut self.multiline_text_input)
+    ///     .tab_moves_focus(true));
+    /// ```
+    pub fn tab_moves_focus(mut self, b: bool) -> Self {
+        self.tab_moves_focus = b;
+        self
+    }
+
+    /// Build a `TextEdit` focused on code editing.
+    /// By default it comes with:
+    /// - monospaced font
+    /// - focus lock
+    /// - tab as spaces
+    ///
+    /// Shortcut for:
+    /// ```rust, ignore
+    /// egui::TextEdit::multiline(code_snippet)
+    ///     .text_style(TextStyle::Monospace)
+    ///     .tab_as_spaces(true)
+    ///     .tab_moves_focus(false);
+    /// ```
+    pub fn code_editor(self) -> Self {
+        self.text_style(TextStyle::Monospace)
+            .tab_as_spaces(true)
+            .tab_moves_focus(false)
+    }
+
+    /// Build a `TextEdit` focused on code editing with configurable `Tab` management.
+    ///
+    /// Shortcut for:
+    /// ```rust, ignore
+    /// egui::TextEdit::multiline(code_snippet)
+    ///     .code_editor()
+    ///     .tab_as_spaces(tab_as_spaces)
+    ///     .tab_moves_focus(tab_moves_focus);
+    /// ```
+    pub fn code_editor_with_config(self, tab_as_spaces: bool, tab_moves_focus: bool) -> Self {
+        self.code_editor()
+            .tab_as_spaces(tab_as_spaces)
+            .tab_moves_focus(tab_moves_focus)
+    }
+
     pub fn id(mut self, id: Id) -> Self {
         self.id = Some(id);
         self
@@ -297,6 +363,8 @@ impl<'t> TextEdit<'t> {
             enabled,
             desired_width,
             desired_height_rows,
+            tab_as_spaces,
+            tab_moves_focus,
         } = self;
 
         let text_style = text_style.unwrap_or_else(|| ui.style().body_text_style);
@@ -383,6 +451,8 @@ impl<'t> TextEdit<'t> {
         }
 
         if ui.memory().has_focus(id) && enabled {
+            ui.memory().lock_focus(id, !tab_moves_focus);
+
             let mut cursorp = state
                 .cursorp
                 .map(|cursorp| {
@@ -432,12 +502,34 @@ impl<'t> TextEdit<'t> {
                             && text_to_insert != "\r"
                         {
                             let mut ccursor = delete_selected(text, &cursorp);
+
                             insert_text(&mut ccursor, text, text_to_insert);
                             Some(CCursorPair::one(ccursor))
                         } else {
                             None
                         }
                     }
+                    Event::Key {
+                        key: Key::Tab,
+                        pressed: true,
+                        ..
+                    } => {
+                        if multiline {
+                            let mut ccursor = delete_selected(text, &cursorp);
+
+                            if ui.memory().has_lock_focus(id) {
+                                if tab_as_spaces {
+                                    insert_text(&mut ccursor, text, "    ");
+                                } else {
+                                    insert_text(&mut ccursor, text, "\t");
+                                }
+                            }
+
+                            Some(CCursorPair::one(ccursor))
+                        } else {
+                            None
+                        }
+                    }
                     Event::Key {
                         key: Key::Enter,
                         pressed: true,

egui_demo_lib/src/apps/demo/widgets.rs

@@ -23,7 +23,11 @@ pub struct Widgets {
     angle: f32,
     color: Color32,
     single_line_text_input: String,
+    tab_size: usize,
+    tab_as_spaces: bool,
+    tab_moves_focus: bool,
     multiline_text_input: String,
+    code_snippet: String,
 }
 
 impl Default for Widgets {
@@ -35,7 +39,22 @@ impl Default for Widgets {
             angle: std::f32::consts::TAU / 3.0,
             color: (Rgba::from_rgb(0.0, 1.0, 0.5) * 0.75).into(),
             single_line_text_input: "Hello World!".to_owned(),
-            multiline_text_input: "Text can both be so wide that it needs a line break, but you can also add manual line break by pressing enter, creating new paragraphs.\nThis is the start of the next paragraph.\n\nClick me to edit me!".to_owned(),
+
+            tab_size: 4,
+            tab_as_spaces: true,
+            tab_moves_focus: false,
+            multiline_text_input: r#"Text can both be so wide that it needs a line break, but you can also add manual line break by pressing enter, creating new paragraphs.
+This is the start of the next paragraph.
+
+Existing	tabs	are	kept	as	tabs.
+
+Click me to edit me!"#.to_owned(),
+            code_snippet: r#"
+// Use the configs above to play with the tab management
+fn main() {
+    println!("Hello world!");
+}
+"#.to_owned(),
         }
     }
 }
@@ -133,7 +152,26 @@ impl Widgets {
             }
         });
 
+        ui.separator();
+
         ui.label("Multiline text input:");
         ui.text_edit_multiline(&mut self.multiline_text_input);
+
+        ui.separator();
+
+        ui.horizontal(|ui| {
+            ui.label("Code editor:");
+
+            ui.separator();
+
+            ui.checkbox(&mut self.tab_as_spaces, "Tabs as spaces");
+            ui.checkbox(&mut self.tab_moves_focus, "Tabs moves focus");
+        });
+
+        ui.code_editor_with_config(
+            &mut self.code_snippet,
+            self.tab_as_spaces,
+            self.tab_moves_focus,
+        );
     }
 }