From 9d5f0a0028626c985b887257a3ca838e7a8c40d5 Mon Sep 17 00:00:00 2001
From: Xiangcheng Kuo <1159946129@qq.com>
Date: Thu, 28 Aug 2025 15:05:15 +0800
Subject: [PATCH] fix(terminal): optimize cursor rendering and handle empty
 column ranges

- Add check for empty column ranges in display_set_columns
- Improve cursor rendering by considering character width
- Adjust cursor position and size based on the current character
- Optimize cursor redraw in guac_terminal_set_columns
---
 src/terminal/display.c  |  5 +++++
 src/terminal/terminal.c | 42 ++++++++++++++++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/src/terminal/display.c b/src/terminal/display.c
index 68c056b3f3..eac9af9a61 100644
--- a/src/terminal/display.c
+++ b/src/terminal/display.c
@@ -486,6 +486,11 @@ void guac_terminal_display_set_columns(guac_terminal_display* display, int row,
     start_column = guac_terminal_fit_to_range(start_column, 0, display->width - 1);
     end_column   = guac_terminal_fit_to_range(end_column,   0, display->width - 1);
 
+    if (start_column > end_column) {
+        guac_client_log(display->client, GUAC_LOG_TRACE, "display_set_columns: Adjusted range is empty [%d,%d], returning.", start_column, end_column);
+        return;
+    }
+
     size_t start_offset = guac_mem_ckd_add_or_die(guac_mem_ckd_mul_or_die(row, display->width), start_column);
     guac_terminal_operation* current = &(display->operations[start_offset]);
 
diff --git a/src/terminal/terminal.c b/src/terminal/terminal.c
index ffcb63012f..e8479a2317 100644
--- a/src/terminal/terminal.c
+++ b/src/terminal/terminal.c
@@ -764,10 +764,19 @@ void guac_terminal_commit_cursor(guac_terminal* term) {
 
         guac_terminal_char* characters;
         int length = guac_terminal_buffer_get_columns(term->current_buffer, &characters, NULL, term->visible_cursor_row);
-        if (term->visible_cursor_col < length)
-            guac_terminal_display_set_columns(term->display, term->visible_cursor_row + term->scroll_offset,
-                    term->visible_cursor_col, term->visible_cursor_col, &characters[term->visible_cursor_col]);
+        if (term->visible_cursor_col < length) {
+            guac_terminal_char* char_at_cursor = &characters[term->visible_cursor_col];
+            int char_width = char_at_cursor->width;
+
+            int clear_start_col = term->visible_cursor_col;
+            int clear_end_col = term->visible_cursor_col + char_width - 1;
+
+            if (clear_end_col >= length)
+                clear_end_col = length - 1;
 
+            guac_terminal_display_set_columns(term->display, term->visible_cursor_row + term->scroll_offset,
+                                              clear_start_col, clear_end_col, char_at_cursor);
+        }
     }
 
     /* Set cursor if should be visible */
@@ -777,9 +786,19 @@ void guac_terminal_commit_cursor(guac_terminal* term) {
 
         guac_terminal_char* characters;
         int length = guac_terminal_buffer_get_columns(term->current_buffer, &characters, NULL, term->cursor_row);
-        if (term->cursor_col < length)
+        if (term->cursor_col < length) {
+            guac_terminal_char* char_at_cursor = &characters[term->cursor_col];
+            int char_width = char_at_cursor->width;
+
+            int set_start_col = term->cursor_col;
+            int set_end_col = term->cursor_col + char_width - 1;
+
+            if (set_end_col >= length)
+                set_end_col = length - 1;
+
             guac_terminal_display_set_columns(term->display, term->cursor_row + term->scroll_offset,
-                    term->cursor_col, term->cursor_col, &characters[term->cursor_col]);
+                                              set_start_col, set_end_col, char_at_cursor);
+        }
 
         term->visible_cursor_row = term->cursor_row;
         term->visible_cursor_col = term->cursor_col;
@@ -1156,9 +1175,18 @@ void guac_terminal_set_columns(guac_terminal* terminal, int row,
         guac_terminal_char cursor_character = *character;
         cursor_character.attributes.cursor = true;
 
-        __guac_terminal_set_columns(terminal, row,
-                terminal->visible_cursor_col, terminal->visible_cursor_col, &cursor_character);
+        int cursor_redraw_start_col = terminal->visible_cursor_col;
+        int cursor_redraw_end_col = terminal->visible_cursor_col + character->width - 1;
+
+        if (cursor_redraw_start_col < start_column)
+            cursor_redraw_start_col = start_column;
+        if (cursor_redraw_end_col > end_column)
+            cursor_redraw_end_col = end_column;
 
+        __guac_terminal_set_columns(terminal, row,
+                                    cursor_redraw_start_col,
+                                    cursor_redraw_end_col,
+                                    &cursor_character);
     }
 
 }