Implement TextArea::important_area

src/views/linear_layout.rs

@@ -597,16 +597,28 @@ impl View for LinearLayout {
     }
 
     fn important_area(&self, _: Vec2) -> Rect {
+        if self.children.is_empty() {
+            // Return dummy area if we are empty.
+            return Rect::from((0, 0));
+        }
+
+        // Pick the focused item, with its offset
+        let item = {
             let mut iterator = ChildIterator::new(
                 self.children.iter(),
                 self.orientation,
                 usize::max_value(),
             );
-        let item = iterator.nth(self.focus).unwrap();
+            iterator.nth(self.focus).unwrap()
+        };
 
-        let rect = item.child.view.important_area(item.child.size);
+        // Make a vector offset from the scalar value
         let offset = self.orientation.make_vec(item.offset, 0);
 
+        // And ask the child its own area.
+        let rect = item.child.view.important_area(item.child.size);
+
+        // Add `offset` to the rect.
         rect + offset
     }
 }

src/views/text_area.rs

@@ -1,6 +1,7 @@
 use {Printer, With, XY};
 use direction::Direction;
 use event::{Event, EventResult, Key, MouseButton, MouseEvent};
+use rect::Rect;
 use std::cmp::min;
 use theme::{ColorStyle, Effect};
 use unicode_segmentation::UnicodeSegmentation;
@@ -133,6 +134,10 @@ impl TextArea {
         self.row_at(self.cursor)
     }
 
+    fn selected_col(&self) -> usize {
+        self.col_at(self.cursor)
+    }
+
     fn page_up(&mut self) {
         for _ in 0..5 {
             self.move_up();
@@ -593,4 +598,24 @@ impl View for TextArea {
         self.last_size = size;
         self.compute_rows(size);
     }
+
+    fn important_area(&self, _: Vec2) -> Rect {
+        // The important area is a single character
+        let char_width = if self.cursor >= self.content.len() {
+            // If we're are the end of the content, it'll be a space
+            1
+        } else {
+            // Otherwise it's the selected grapheme
+            self.content[self.cursor..]
+                .graphemes(true)
+                .next()
+                .unwrap()
+                .width()
+        };
+
+        Rect::from_size(
+            (self.selected_col(), self.selected_row()),
+            (char_width, 1),
+        )
+    }
 }