terminal/new: resize more cols ignores trailing empty cells

src/terminal/Screen.zig

@@ -6711,6 +6711,7 @@ test "Screen: resize more cols with reflow that fits full width" {
     try testing.expectEqual(@as(usize, 0), s.cursor.y);
 }
 
+// X
 test "Screen: resize more cols with reflow that ends in newline" {
     const testing = std.testing;
     const alloc = testing.allocator;

src/terminal/new/PageList.zig

@@ -533,6 +533,20 @@ const ReflowCursor = struct {
         self.x = x;
         self.y = y;
     }
+
+    fn countTrailingEmptyCells(self: *const ReflowCursor) usize {
+        // If the row is wrapped, all empty cells are meaningful.
+        if (self.page_row.wrap) return 0;
+
+        const cells: [*]pagepkg.Cell = @ptrCast(self.page_cell);
+        const len: usize = self.page.size.cols - self.x;
+        for (0..len) |i| {
+            const rev_i = len - i - 1;
+            if (!cells[rev_i].isEmpty()) return i;
+        }
+
+        return len;
+    }
 };
 
 /// Reflow the given page into the new capacity. The new capacity can have
@@ -590,9 +604,24 @@ fn reflowPage(
             }
 
             src_cursor.cursorAbsolute(0, @intCast(src_y));
-            for (src_cursor.x..src_cursor.page.size.cols) |src_x| {
+
+            // Trim trailing empty cells if the row is not wrapped. If the
+            // row is wrapped then we don't trim trailing empty cells because
+            // the empty cells can be meaningful.
+            const trailing_empty = src_cursor.countTrailingEmptyCells();
+            const cols_len = src_cursor.page.size.cols - trailing_empty;
+
+            for (src_cursor.x..cols_len) |src_x| {
                 assert(src_cursor.x == src_x);
 
+                // std.log.warn("src_y={} src_x={} dst_y={} dst_x={} cp={u}", .{
+                //     src_cursor.y,
+                //     src_cursor.x,
+                //     dst_cursor.y,
+                //     dst_cursor.x,
+                //     src_cursor.page_cell.content.codepoint,
+                // });
+
                 if (dst_cursor.pending_wrap) {
                     dst_cursor.page_row.wrap = true;
                     dst_cursor.cursorScroll();
@@ -2940,7 +2969,7 @@ test "PageList resize reflow more cols cursor in wrapped row that isn't unwrappe
             rac.row.wrap_continuation = true;
         }
         for (0..s.cols) |x| {
-            const rac = page.getRowAndCell(x, 1);
+            const rac = page.getRowAndCell(x, 2);
             rac.cell.* = .{
                 .content_tag = .codepoint,
                 .content = .{ .codepoint = @intCast(x) },

src/terminal/new/Screen.zig

@@ -2304,3 +2304,48 @@ test "Screen: resize more cols with reflow that fits full width" {
     try testing.expectEqual(@as(usize, 5), s.cursor.x);
     try testing.expectEqual(@as(usize, 0), s.cursor.y);
 }
+
+test "Screen: resize more cols with reflow that ends in newline" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var s = try init(alloc, 6, 3, 0);
+    defer s.deinit();
+    const str = "1ABCD2EFGH\n3IJKL";
+    try s.testWriteString(str);
+
+    // Verify we soft wrapped
+    {
+        const contents = try s.dumpStringAlloc(alloc, .{ .viewport = .{} });
+        defer alloc.free(contents);
+        const expected = "1ABCD2\nEFGH\n3IJKL";
+        try testing.expectEqualStrings(expected, contents);
+    }
+
+    // Let's put our cursor on the last row
+    s.cursorAbsolute(0, 2);
+    {
+        const list_cell = s.pages.getCell(.{ .active = .{
+            .x = s.cursor.x,
+            .y = s.cursor.y,
+        } }).?;
+        try testing.expectEqual(@as(u21, '3'), list_cell.cell.content.codepoint);
+    }
+
+    // Resize and verify we undid the soft wrap because we have space now
+    try s.resize(10, 3);
+    {
+        const contents = try s.dumpStringAlloc(alloc, .{ .viewport = .{} });
+        defer alloc.free(contents);
+        try testing.expectEqualStrings(str, contents);
+    }
+
+    // Our cursor should still be on the 3
+    {
+        const list_cell = s.pages.getCell(.{ .active = .{
+            .x = s.cursor.x,
+            .y = s.cursor.y,
+        } }).?;
+        try testing.expectEqual(@as(u21, '3'), list_cell.cell.content.codepoint);
+    }
+}