Add demo of advanced TextEdit usage

egui/src/widgets/text_edit/builder.rs

@@ -44,6 +44,8 @@ use super::{CCursorRange, CursorRange, TextEditOutput, TextEditState};
 /// }
 /// ```
 ///
+/// ## Advanced usage
+/// See [`TextEdit::show`].
 #[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
 pub struct TextEdit<'t> {
     text: &'t mut dyn TextBuffer,
@@ -242,6 +244,20 @@ impl<'t> Widget for TextEdit<'t> {
 
 impl<'t> TextEdit<'t> {
     /// Show the [`TextEdit`], returning a rich [`TextEditOutput`].
+    ///
+    /// ```
+    /// # egui::__run_test_ui(|ui| {
+    /// # let mut my_string = String::new();
+    /// let output = egui::TextEdit::singleline(&mut my_string).show(ui);
+    /// 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 = my_string.char_range(selected_chars);
+    ///     ui.label("Selected text: ");
+    ///     ui.monospace(selected_text);
+    /// }
+    /// # });
+    /// ```
     pub fn show(self, ui: &mut Ui) -> TextEditOutput {
         let is_mutable = self.text.is_mutable();
         let frame = self.frame;
@@ -386,7 +402,8 @@ impl<'t> TextEdit<'t> {
             Sense::hover()
         };
         let mut response = ui.interact(rect, id, sense);
-        let painter = ui.painter_at(rect);
+        let text_clip_rect = rect;
+        let painter = ui.painter_at(text_clip_rect);
 
         if interactive {
             if let Some(pointer_pos) = ui.input().pointer.interact_pos() {
@@ -593,6 +610,8 @@ impl<'t> TextEdit<'t> {
         TextEditOutput {
             response,
             galley,
+            text_draw_pos,
+            text_clip_rect,
             state,
             cursor_range,
         }
@@ -806,7 +825,7 @@ fn paint_cursor_selection(
 
     // We paint the cursor selection on top of the text, so make it transparent:
     let color = ui.visuals().selection.bg_fill.linear_multiply(0.5);
-    let [min, max] = cursor_range.sorted();
+    let [min, max] = cursor_range.sorted_cursors();
     let min = min.rcursor;
     let max = max.rcursor;
 
@@ -875,7 +894,7 @@ fn paint_cursor_end(
 // ----------------------------------------------------------------------------
 
 fn selected_str<'s>(text: &'s dyn TextBuffer, cursor_range: &CursorRange) -> &'s str {
-    let [min, max] = cursor_range.sorted();
+    let [min, max] = cursor_range.sorted_cursors();
     text.char_range(min.ccursor.index..max.ccursor.index)
 }
 
@@ -886,7 +905,7 @@ fn insert_text(ccursor: &mut CCursor, text: &mut dyn TextBuffer, text_to_insert:
 // ----------------------------------------------------------------------------
 
 fn delete_selected(text: &mut dyn TextBuffer, cursor_range: &CursorRange) -> CCursor {
-    let [min, max] = cursor_range.sorted();
+    let [min, max] = cursor_range.sorted_cursors();
     delete_selected_ccursor_range(text, [min.ccursor, max.ccursor])
 }
 
@@ -927,7 +946,7 @@ fn delete_paragraph_before_cursor(
     galley: &Galley,
     cursor_range: &CursorRange,
 ) -> CCursor {
-    let [min, max] = cursor_range.sorted();
+    let [min, max] = cursor_range.sorted_cursors();
     let min = galley.from_pcursor(PCursor {
         paragraph: min.pcursor.paragraph,
         offset: 0,
@@ -945,7 +964,7 @@ fn delete_paragraph_after_cursor(
     galley: &Galley,
     cursor_range: &CursorRange,
 ) -> CCursor {
-    let [min, max] = cursor_range.sorted();
+    let [min, max] = cursor_range.sorted_cursors();
     let max = galley.from_pcursor(PCursor {
         paragraph: max.pcursor.paragraph,
         offset: usize::MAX, // end of paragraph
@@ -984,7 +1003,7 @@ fn on_key_press(
             };
             Some(CCursorRange::one(ccursor))
         }
-        Key::Delete if !(cfg!(target_os = "windows") && modifiers.shift) => {
+        Key::Delete if !modifiers.shift || !cfg!(target_os = "windows") => {
             let ccursor = if modifiers.mac_cmd {
                 delete_paragraph_after_cursor(text, galley, cursor_range)
             } else if let Some(cursor) = cursor_range.single() {
@@ -1031,9 +1050,9 @@ fn on_key_press(
 
         Key::ArrowLeft | Key::ArrowRight if modifiers.is_none() && !cursor_range.is_empty() => {
             if key == Key::ArrowLeft {
-                *cursor_range = CursorRange::one(cursor_range.sorted()[0]);
+                *cursor_range = CursorRange::one(cursor_range.sorted_cursors()[0]);
             } else {
-                *cursor_range = CursorRange::one(cursor_range.sorted()[1]);
+                *cursor_range = CursorRange::one(cursor_range.sorted_cursors()[1]);
             }
             None
         }

egui/src/widgets/text_edit/cursor_range.rs

@@ -37,6 +37,15 @@ impl CursorRange {
         }
     }
 
+    /// The range of selected character indices.
+    pub fn as_sorted_char_range(&self) -> std::ops::Range<usize> {
+        let [start, end] = self.sorted_cursors();
+        std::ops::Range {
+            start: start.ccursor.index,
+            end: end.ccursor.index,
+        }
+    }
+
     /// True if the selected range contains no characters.
     pub fn is_empty(&self) -> bool {
         self.primary.ccursor == self.secondary.ccursor
@@ -58,8 +67,19 @@ impl CursorRange {
         (p.index, p.prefer_next_row) <= (s.index, s.prefer_next_row)
     }
 
+    pub fn sorted(self) -> Self {
+        if self.is_sorted() {
+            self
+        } else {
+            Self {
+                primary: self.secondary,
+                secondary: self.primary,
+            }
+        }
+    }
+
     /// returns the two ends ordered
-    pub fn sorted(&self) -> [Cursor; 2] {
+    pub fn sorted_cursors(&self) -> [Cursor; 2] {
         if self.is_sorted() {
             [self.primary, self.secondary]
         } else {

egui/src/widgets/text_edit/output.rs

@@ -8,9 +8,17 @@ pub struct TextEditOutput {
     /// How the text was displayed.
     pub galley: Arc<crate::Galley>,
 
-    /// The state we stored after the run/
+    /// Where the text in [`Self::galley`] ended up on the screen.
+    pub text_draw_pos: crate::Pos2,
+
+    /// The text was clipped to this rectangle when painted.
+    pub text_clip_rect: crate::Rect,
+
+    /// The state we stored after the run.
     pub state: super::TextEditState,
 
     /// Where the text cursor is.
     pub cursor_range: Option<super::CursorRange>,
 }
+
+// TODO: add `output.paint` and `output.store` and split out that code from `TextEdit::show`.