Merge pull request #1036 from mitchellh/resize

terminal: resize to less rows with empty lines should trim lines

src/terminal/Screen.zig

@@ -2485,11 +2485,14 @@ pub fn resizeWithoutReflow(self: *Screen, rows: usize, cols: usize) !void {
         // because we aren't going to trim.
         if (self.rows == rows) break :blank 0;
 
-        // If there is history, blank line counting is disabled and
-        // we generate scrollback. Why? Terminal.app does it, seems... fine.
-        if (self.history > 0) break :blank 0;
+        const blank = self.trailingBlankLines();
 
-        break :blank self.trailingBlankLines();
+        // If we are shrinking the number of rows, we don't want to trim
+        // off more blank rows than the number we're shrinking because it
+        // creates a jarring screen move experience.
+        if (self.rows > rows) break :blank @min(blank, self.rows - rows);
+
+        break :blank blank;
     };
 
     // Make a copy so we can access the old indexes.
@@ -5764,6 +5767,31 @@ test "Screen: resize (no reflow) less rows with scrollback" {
     }
 }
 
+// https://github.com/mitchellh/ghostty/issues/1030
+test "Screen: resize (no reflow) less rows with empty trailing" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var s = try init(alloc, 3, 5, 5);
+    defer s.deinit();
+    const str = "1\n2\n3\n4\n5\n6\n7\n8";
+    try s.testWriteString(str);
+    try s.scroll(.{ .clear = {} });
+    s.cursor.x = 0;
+    s.cursor.y = 0;
+    try s.testWriteString("A\nB");
+
+    const cursor = s.cursor;
+    try s.resizeWithoutReflow(2, 5);
+    try testing.expectEqual(cursor, s.cursor);
+
+    {
+        const contents = try s.testString(alloc, .viewport);
+        defer alloc.free(contents);
+        try testing.expectEqualStrings("A\nB", contents);
+    }
+}
+
 test "Screen: resize (no reflow) empty screen" {
     const testing = std.testing;
     const alloc = testing.allocator;