Ensure that we use the WrapMap where appropriate in DisplayMap

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

zed/src/editor/display_map.rs

@@ -156,7 +156,9 @@ impl DisplayMapSnapshot {
     }
 
     pub fn is_line_folded(&self, display_row: u32) -> bool {
-        self.folds_snapshot.is_line_folded(display_row)
+        let wrap_point = DisplayPoint::new(display_row, 0).0;
+        let row = self.wraps_snapshot.to_input_point(wrap_point).row();
+        self.folds_snapshot.is_line_folded(row)
     }
 
     pub fn text(&self) -> String {
@@ -191,11 +193,11 @@ impl DisplayMapSnapshot {
     }
 
     pub fn line_len(&self, row: u32) -> u32 {
-        self.tabs_snapshot.line_len(row)
+        self.wraps_snapshot.line_len(row)
     }
 
     pub fn longest_row(&self) -> u32 {
-        self.tabs_snapshot.longest_row()
+        self.wraps_snapshot.longest_row()
     }
 
     pub fn anchor_before(&self, point: DisplayPoint, bias: Bias) -> Anchor {

zed/src/editor/display_map/wrap_map.rs

@@ -164,6 +164,23 @@ impl Snapshot {
         self.to_output_point(self.input.max_point())
     }
 
+    pub fn line_len(&self, row: u32) -> u32 {
+        let mut len = 0;
+        for chunk in self.chunks_at(OutputPoint::new(row, 0)) {
+            if let Some(newline_ix) = chunk.find('\n') {
+                len += newline_ix;
+                break;
+            } else {
+                len += chunk.len();
+            }
+        }
+        len as u32
+    }
+
+    pub fn longest_row(&self) -> u32 {
+        self.transforms.summary().output.longest_row
+    }
+
     pub fn buffer_rows(&self, start_row: u32) -> BufferRows {
         let mut transforms = self.transforms.cursor::<OutputPoint, InputPoint>();
         transforms.seek(&OutputPoint::new(start_row, 0), Bias::Right, &());