fix some line wrapping state issues

7 files changed, 525 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5e3d691..123fd37 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## [Unreleased]
+
+## Fixed
+
+* Fixed some line wrapping state issues with `contents_diff`
+
 ## [0.13.0] - 2021-11-17
 
 ### Added
diff --git a/src/row.rs b/src/row.rs
index d828a73..cbd73ae 100644
--- a/src/row.rs
+++ b/src/row.rs
@@ -391,7 +391,14 @@ impl Row {
             crate::term::ClearRowForward::default().write_buf(contents);
         }
 
-        if prev.wrapped && !self.wrapped {
+        // if this row is going from wrapped to not wrapped, we need to erase
+        // and redraw the last character to break wrapping. if this row is
+        // wrapped, we need to redraw the last character without erasing it to
+        // position the cursor after the end of the line correctly so that
+        // drawing the next line can just start writing and be wrapped.
+        if (!self.wrapped && prev.wrapped)
+            || (self.wrapped && prev_pos.col < self.cols())
+        {
             let end_pos = if self
                 .get(self.cols() - 1)
                 .unwrap()
@@ -410,7 +417,9 @@ impl Row {
             crate::term::MoveFromTo::new(prev_pos, end_pos)
                 .write_buf(contents);
             prev_pos = end_pos;
-            crate::term::EraseChar::new(1).write_buf(contents);
+            if !self.wrapped {
+                crate::term::EraseChar::new(1).write_buf(contents);
+            }
             let end_cell = self.get(end_pos.col).unwrap();
             contents.extend(end_cell.contents().as_bytes());
             prev_pos.col += if end_cell.is_wide() { 2 } else { 1 };
diff --git a/tests/data/fixtures/il_dl.in b/tests/data/fixtures/il_dl.in
index db55d5e..f6ca5e0 100644
--- a/tests/data/fixtures/il_dl.in
+++ b/tests/data/fixtures/il_dl.in
@@ -16,3 +16,5 @@ b
 \x1b[L
 cd
 \x1bc\na\x1b[1;80Hb\x1b[M
+\x1bc\x1b[1;80Haaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\x1b[H
+\x1b[L
diff --git a/tests/data/fixtures/il_dl/19.json b/tests/data/fixtures/il_dl/19.json
new file mode 100644
index 0000000..2f22274
--- /dev/null
+++ b/tests/data/fixtures/il_dl/19.json
@@ -0,0 +1,252 @@
+{
+  "contents": "                                                                               aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+  "cells": {
+    "0,79": {
+      "contents": "a"
+    },
+    "1,0": {
+      "contents": "a"
+    },
+    "1,1": {
+      "contents": "a"
+    },
+    "1,10": {
+      "contents": "a"
+    },
+    "1,11": {
+      "contents": "a"
+    },
+    "1,12": {
+      "contents": "a"
+    },
+    "1,13": {
+      "contents": "a"
+    },
+    "1,14": {
+      "contents": "a"
+    },
+    "1,15": {
+      "contents": "a"
+    },
+    "1,16": {
+      "contents": "a"
+    },
+    "1,17": {
+      "contents": "a"
+    },
+    "1,18": {
+      "contents": "a"
+    },
+    "1,19": {
+      "contents": "a"
+    },
+    "1,2": {
+      "contents": "a"
+    },
+    "1,20": {
+      "contents": "a"
+    },
+    "1,21": {
+      "contents": "a"
+    },
+    "1,22": {
+      "contents": "a"
+    },
+    "1,23": {
+      "contents": "a"
+    },
+    "1,24": {
+      "contents": "a"
+    },
+    "1,25": {
+      "contents": "a"
+    },
+    "1,26": {
+      "contents": "a"
+    },
+    "1,27": {
+      "contents": "a"
+    },
+    "1,28": {
+      "contents": "a"
+    },
+    "1,29": {
+      "contents": "a"
+    },
+    "1,3": {
+      "contents": "a"
+    },
+    "1,30": {
+      "contents": "a"
+    },
+    "1,31": {
+      "contents": "a"
+    },
+    "1,32": {
+      "contents": "a"
+    },
+    "1,33": {
+      "contents": "a"
+    },
+    "1,34": {
+      "contents": "a"
+    },
+    "1,35": {
+      "contents": "a"
+    },
+    "1,36": {
+      "contents": "a"
+    },
+    "1,37": {
+      "contents": "a"
+    },
+    "1,38": {
+      "contents": "a"
+    },
+    "1,39": {
+      "contents": "a"
+    },
+    "1,4": {
+      "contents": "a"
+    },
+    "1,40": {
+      "contents": "a"
+    },
+    "1,41": {
+      "contents": "a"
+    },
+    "1,42": {
+      "contents": "a"
+    },
+    "1,43": {
+      "contents": "a"
+    },
+    "1,44": {
+      "contents": "a"
+    },
+    "1,45": {
+      "contents": "a"
+    },
+    "1,46": {
+      "contents": "a"
+    },
+    "1,47": {
+      "contents": "a"
+    },
+    "1,48": {
+      "contents": "a"
+    },
+    "1,49": {
+      "contents": "a"
+    },
+    "1,5": {
+      "contents": "a"
+    },
+    "1,50": {
+      "contents": "a"
+    },
+    "1,51": {
+      "contents": "a"
+    },
+    "1,52": {
+      "contents": "a"
+    },
+    "1,53": {
+      "contents": "a"
+    },
+    "1,54": {
+      "contents": "a"
+    },
+    "1,55": {
+      "contents": "a"
+    },
+    "1,56": {
+      "contents": "a"
+    },
+    "1,57": {
+      "contents": "a"
+    },
+    "1,58": {
+      "contents": "a"
+    },
+    "1,59": {
+      "contents": "a"
+    },
+    "1,6": {
+      "contents": "a"
+    },
+    "1,60": {
+      "contents": "a"
+    },
+    "1,61": {
+      "contents": "a"
+    },
+    "1,62": {
+      "contents": "a"
+    },
+    "1,63": {
+      "contents": "a"
+    },
+    "1,64": {
+      "contents": "a"
+    },
+    "1,65": {
+      "contents": "a"
+    },
+    "1,66": {
+      "contents": "a"
+    },
+    "1,67": {
+      "contents": "a"
+    },
+    "1,68": {
+      "contents": "a"
+    },
+    "1,69": {
+      "contents": "a"
+    },
+    "1,7": {
+      "contents": "a"
+    },
+    "1,70": {
+      "contents": "a"
+    },
+    "1,71": {
+      "contents": "a"
+    },
+    "1,72": {
+      "contents": "a"
+    },
+    "1,73": {
+      "contents": "a"
+    },
+    "1,74": {
+      "contents": "a"
+    },
+    "1,75": {
+      "contents": "a"
+    },
+    "1,76": {
+      "contents": "a"
+    },
+    "1,77": {
+      "contents": "a"
+    },
+    "1,78": {
+      "contents": "a"
+    },
+    "1,79": {
+      "contents": "a"
+    },
+    "1,8": {
+      "contents": "a"
+    },
+    "1,9": {
+      "contents": "a"
+    }
+  },
+  "cursor_position": [
+    0,
+    0
+  ]
+}
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/19.typescript b/tests/data/fixtures/il_dl/19.typescript
new file mode 100644
index 0000000..bdb7b92
--- /dev/null
+++ b/tests/data/fixtures/il_dl/19.typescript
@@ -0,0 +1 @@
+caaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/20.json b/tests/data/fixtures/il_dl/20.json
new file mode 100644
index 0000000..04b7166
--- /dev/null
+++ b/tests/data/fixtures/il_dl/20.json
@@ -0,0 +1,252 @@
+{
+  "contents": "\n                                                                               aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+  "cells": {
+    "1,79": {
+      "contents": "a"
+    },
+    "2,0": {
+      "contents": "a"
+    },
+    "2,1": {
+      "contents": "a"
+    },
+    "2,10": {
+      "contents": "a"
+    },
+    "2,11": {
+      "contents": "a"
+    },
+    "2,12": {
+      "contents": "a"
+    },
+    "2,13": {
+      "contents": "a"
+    },
+    "2,14": {
+      "contents": "a"
+    },
+    "2,15": {
+      "contents": "a"
+    },
+    "2,16": {
+      "contents": "a"
+    },
+    "2,17": {
+      "contents": "a"
+    },
+    "2,18": {
+      "contents": "a"
+    },
+    "2,19": {
+      "contents": "a"
+    },
+    "2,2": {
+      "contents": "a"
+    },
+    "2,20": {
+      "contents": "a"
+    },
+    "2,21": {
+      "contents": "a"
+    },
+    "2,22": {
+      "contents": "a"
+    },
+    "2,23": {
+      "contents": "a"
+    },
+    "2,24": {
+      "contents": "a"
+    },
+    "2,25": {
+      "contents": "a"
+    },
+    "2,26": {
+      "contents": "a"
+    },
+    "2,27": {
+      "contents": "a"
+    },
+    "2,28": {
+      "contents": "a"
+    },
+    "2,29": {
+      "contents": "a"
+    },
+    "2,3": {
+      "contents": "a"
+    },
+    "2,30": {
+      "contents": "a"
+    },
+    "2,31": {
+      "contents": "a"
+    },
+    "2,32": {
+      "contents": "a"
+    },
+    "2,33": {
+      "contents": "a"
+    },
+    "2,34": {
+      "contents": "a"
+    },
+    "2,35": {
+      "contents": "a"
+    },
+    "2,36": {
+      "contents": "a"
+    },
+    "2,37": {
+      "contents": "a"
+    },
+    "2,38": {
+      "contents": "a"
+    },
+    "2,39": {
+      "contents": "a"
+    },
+    "2,4": {
+      "contents": "a"
+    },
+    "2,40": {
+      "contents": "a"
+    },
+    "2,41": {
+      "contents": "a"
+    },
+    "2,42": {
+      "contents": "a"
+    },
+    "2,43": {
+      "contents": "a"
+    },
+    "2,44": {
+      "contents": "a"
+    },
+    "2,45": {
+      "contents": "a"
+    },
+    "2,46": {
+      "contents": "a"
+    },
+    "2,47": {
+      "contents": "a"
+    },
+    "2,48": {
+      "contents": "a"
+    },
+    "2,49": {
+      "contents": "a"
+    },
+    "2,5": {
+      "contents": "a"
+    },
+    "2,50": {
+      "contents": "a"
+    },
+    "2,51": {
+      "contents": "a"
+    },
+    "2,52": {
+      "contents": "a"
+    },
+    "2,53": {
+      "contents": "a"
+    },
+    "2,54": {
+      "contents": "a"
+    },
+    "2,55": {
+      "contents": "a"
+    },
+    "2,56": {
+      "contents": "a"
+    },
+    "2,57": {
+      "contents": "a"
+    },
+    "2,58": {
+      "contents": "a"
+    },
+    "2,59": {
+      "contents": "a"
+    },
+    "2,6": {
+      "contents": "a"
+    },
+    "2,60": {
+      "contents": "a"
+    },
+    "2,61": {
+      "contents": "a"
+    },
+    "2,62": {
+      "contents": "a"
+    },
+    "2,63": {
+      "contents": "a"
+    },
+    "2,64": {
+      "contents": "a"
+    },
+    "2,65": {
+      "contents": "a"
+    },
+    "2,66": {
+      "contents": "a"
+    },
+    "2,67": {
+      "contents": "a"
+    },
+    "2,68": {
+      "contents": "a"
+    },
+    "2,69": {
+      "contents": "a"
+    },
+    "2,7": {
+      "contents": "a"
+    },
+    "2,70": {
+      "contents": "a"
+    },
+    "2,71": {
+      "contents": "a"
+    },
+    "2,72": {
+      "contents": "a"
+    },
+    "2,73": {
+      "contents": "a"
+    },
+    "2,74": {
+      "contents": "a"
+    },
+    "2,75": {
+      "contents": "a"
+    },
+    "2,76": {
+      "contents": "a"
+    },
+    "2,77": {
+      "contents": "a"
+    },
+    "2,78": {
+      "contents": "a"
+    },
+    "2,79": {
+      "contents": "a"
+    },
+    "2,8": {
+      "contents": "a"
+    },
+    "2,9": {
+      "contents": "a"
+    }
+  },
+  "cursor_position": [
+    0,
+    0
+  ]
+}
\ No newline at end of file
diff --git a/tests/data/fixtures/il_dl/20.typescript b/tests/data/fixtures/il_dl/20.typescript
new file mode 100644
index 0000000..a330c08
--- /dev/null
+++ b/tests/data/fixtures/il_dl/20.typescript
@@ -0,0 +1 @@
+
\ No newline at end of file