2 files changed, 45 insertions, 25 deletions

diff --git a/alacritty_terminal/src/grid/mod.rs b/alacritty_terminal/src/grid/mod.rs
index febdff69..34d989db 100644
--- a/alacritty_terminal/src/grid/mod.rs
+++ b/alacritty_terminal/src/grid/mod.rs
@@ -145,24 +145,21 @@ impl<T: GridCell + PartialEq + Copy> Grid<T> {
         Grid { raw, cols, lines, display_offset: 0, selection: None, max_scroll_limit: scrollback }
     }
 
-    pub fn buffer_to_visible(&self, point: impl Into<Point<usize>>) -> Option<Point<usize>> {
-        let mut point = point.into();
-
-        if point.line < self.display_offset || point.line >= self.display_offset + self.lines.0 {
-            return None;
+    /// Clamp a buffer point to the visible region.
+    pub fn clamp_buffer_to_visible(&self, point: Point<usize>) -> Point {
+        if point.line < self.display_offset {
+            Point::new(self.lines - 1, self.cols - 1)
+        } else if point.line >= self.display_offset + self.lines.0 {
+            Point::new(Line(0), Column(0))
+        } else {
+            // Since edgecases are handled, conversion is identical as visible to buffer
+            self.visible_to_buffer(point.into()).into()
         }
-
-        point.line = self.lines.0 + self.display_offset - point.line - 1;
-
-        Some(point)
     }
 
+    /// Convert viewport relative point to global buffer indexing.
     pub fn visible_to_buffer(&self, point: Point) -> Point<usize> {
-        Point { line: self.visible_line_to_buffer(point.line), col: point.col }
-    }
-
-    fn visible_line_to_buffer(&self, line: Line) -> usize {
-        self.line_to_offset(line) + self.display_offset
+        Point { line: self.lines.0 + self.display_offset - point.line.0 - 1, col: point.col }
     }
 
     /// Update the size of the scrollback history
@@ -453,17 +450,6 @@ impl<T: GridCell + PartialEq + Copy> Grid<T> {
         self.lines = target;
     }
 
-    /// Convert a Line index (active region) to a buffer offset
-    ///
-    /// # Panics
-    ///
-    /// This method will panic if `Line` is larger than the grid dimensions
-    pub fn line_to_offset(&self, line: Line) -> usize {
-        assert!(line < self.num_lines());
-
-        *(self.num_lines() - line - 1)
-    }
-
     #[inline]
     pub fn scroll_down(&mut self, region: &Range<Line>, positions: Line, template: &T) {
         let num_lines = self.num_lines().0;
diff --git a/alacritty_terminal/src/grid/tests.rs b/alacritty_terminal/src/grid/tests.rs
index e4fdad5c..e8f4fb8d 100644
--- a/alacritty_terminal/src/grid/tests.rs
+++ b/alacritty_terminal/src/grid/tests.rs
@@ -37,6 +37,40 @@ impl GridCell for usize {
     }
 }
 
+#[test]
+fn grid_clamp_buffer_point() {
+    let mut grid = Grid::new(Line(10), Column(10), 1_000, 0);
+    grid.display_offset = 5;
+
+    let point = grid.clamp_buffer_to_visible(Point::new(10, Column(3)));
+    assert_eq!(point, Point::new(Line(4), Column(3)));
+
+    let point = grid.clamp_buffer_to_visible(Point::new(15, Column(3)));
+    assert_eq!(point, Point::new(Line(0), Column(0)));
+
+    let point = grid.clamp_buffer_to_visible(Point::new(4, Column(3)));
+    assert_eq!(point, Point::new(Line(9), Column(9)));
+
+    grid.display_offset = 0;
+
+    let point = grid.clamp_buffer_to_visible(Point::new(4, Column(3)));
+    assert_eq!(point, Point::new(Line(5), Column(3)));
+}
+
+#[test]
+fn visible_to_buffer() {
+    let mut grid = Grid::new(Line(10), Column(10), 1_000, 0);
+    grid.display_offset = 5;
+
+    let point = grid.visible_to_buffer(Point::new(Line(4), Column(3)));
+    assert_eq!(point, Point::new(10, Column(3)));
+
+    grid.display_offset = 0;
+
+    let point = grid.visible_to_buffer(Point::new(Line(5), Column(3)));
+    assert_eq!(point, Point::new(4, Column(3)));
+}
+
 // Scroll up moves lines upwards
 #[test]
 fn scroll_up() {