From fd2a0255b1d8c0f112b3e2a5e01ff2e510d05def Mon Sep 17 00:00:00 2001
From: Russell McClellan <russell.mcclellan@gmail.com>
Date: Sun, 21 Aug 2022 18:30:08 -0400
Subject: Support `sb_clear` callback if present

---
 CMakeLists.txt |  7 +++++--
 vterm-module.c | 55 ++++++++++++++++++++++++++++++++++++++++---------------
 vterm-module.h |  1 +
 3 files changed, 46 insertions(+), 17 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d909076..24c09ec 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -47,7 +47,10 @@ if (USE_SYSTEM_LIBVTERM)
 #    add_compile_definitions(VTermStringFragmentNotExists)
     add_definitions(-DVTermSelectionMaskNotExists)
     endif()
-
+    execute_process(COMMAND  grep -c "sb_clear" "${LIBVTERM_INCLUDE_DIR}/vterm.h" OUTPUT_VARIABLE VTermSBClearExists)
+    if (${VTermSBClearExists} EQUAL "0")
+      add_definitions(-VTermSBClearNotExists)
+    endif()
   else()
     message(STATUS "System libvterm not found: libvterm will be downloaded and compiled as part of the build process")
   endif()
@@ -70,7 +73,7 @@ else()
 
   ExternalProject_add(libvterm
     GIT_REPOSITORY https://github.com/Sbozzolo/libvterm-mirror.git
-    GIT_TAG 15133bba2c0bce32baabbf91610a2450495fea02
+    GIT_TAG 64f1775952dbe001e989f2ab679563b54f2fca55
     CONFIGURE_COMMAND ""
     BUILD_COMMAND ${LIBVTERM_BUILD_COMMAND} "CFLAGS='-fPIC'"
     BUILD_IN_SOURCE ON
diff --git a/vterm-module.c b/vterm-module.c
index a41188a..93942e1 100644
--- a/vterm-module.c
+++ b/vterm-module.c
@@ -154,6 +154,32 @@ static int term_sb_pop(int cols, VTermScreenCell *cells, void *data) {
   return 1;
 }
 
+static int term_sb_clear(void *data) {
+  Term *term = (Term *)data;
+
+  if (term->sb_clear_pending) {
+    // Another scrollback clear is already pending, so skip this one.
+    return 0;
+  }
+
+  for (int i = 0; i < term->sb_current; i++) {
+    if (term->sb_buffer[i]->info != NULL) {
+      free_lineinfo(term->sb_buffer[i]->info);
+      term->sb_buffer[i]->info = NULL;
+    }
+    free(term->sb_buffer[i]);
+  }
+  free(term->sb_buffer);
+  term->sb_buffer = malloc(sizeof(ScrollbackLine *) * term->sb_size);
+  term->sb_clear_pending = true;
+  term->sb_current = 0;
+  term->sb_pending = 0;
+  term->sb_pending_by_height_decr = 0;
+  invalidate_terminal(term, -1, -1);
+
+  return 0;
+}
+
 static int row_to_linenr(Term *term, int row) {
   return row != INT_MAX ? row + (int)term->sb_current + 1 : INT_MAX;
 }
@@ -436,6 +462,14 @@ static int term_resize(int rows, int cols, void *user_data) {
 static void refresh_scrollback(Term *term, emacs_env *env) {
   int max_line_count = (int)term->sb_current + term->height;
   int del_cnt = 0;
+  if (term->sb_clear_pending) {
+    del_cnt = term->linenum - term->height;
+    if (del_cnt > 0) {
+      delete_lines(env, 1, del_cnt, true);
+      term->linenum -= del_cnt;
+    }
+    term->sb_clear_pending = false;
+  }
   if (term->sb_pending > 0) {
     // This means that either the window height has decreased or the screen
     // became full and libvterm had to push all rows up. Convert the first
@@ -628,6 +662,9 @@ static VTermScreenCallbacks vterm_screen_callbacks = {
     .resize = term_resize,
     .sb_pushline = term_sb_push,
     .sb_popline = term_sb_pop,
+#if !defined(VTermSBClearNotExists)
+    .sb_clear = term_sb_clear,
+#endif
 };
 
 static bool compare_cells(VTermScreenCell *a, VTermScreenCell *b) {
@@ -846,24 +883,11 @@ static void term_flush_output(Term *term, emacs_env *env) {
 }
 
 static void term_clear_scrollback(Term *term, emacs_env *env) {
+  term_sb_clear(term);
   vterm_screen_flush_damage(term->vts);
   term_redraw(term, env);
-  if (term->sb_pending > 0) { // Pending rows must be processed first.
-    return;
-  }
-  for (int i = 0; i < term->sb_current; i++) {
-    if (term->sb_buffer[i]->info != NULL) {
-      free_lineinfo(term->sb_buffer[i]->info);
-      term->sb_buffer[i]->info = NULL;
-    }
-    free(term->sb_buffer[i]);
-  }
-  free(term->sb_buffer);
-  term->sb_buffer = malloc(sizeof(ScrollbackLine *) * term->sb_size);
-  delete_lines(env, 1, term->sb_current, true);
-  term->linenum -= term->sb_current;
-  term->sb_current = 0;
 }
+
 static void term_process_key(Term *term, emacs_env *env, unsigned char *key,
                              size_t len, VTermModifier modifier) {
   if (is_key(key, len, "<clear_scrollback>")) {
@@ -1221,6 +1245,7 @@ emacs_value Fvterm_new(emacs_env *env, ptrdiff_t nargs, emacs_value args[],
   term->sb_size = MIN(SB_MAX, sb_size);
   term->sb_current = 0;
   term->sb_pending = 0;
+  term->sb_clear_pending = false;
   term->sb_pending_by_height_decr = 0;
   term->sb_buffer = malloc(sizeof(ScrollbackLine *) * term->sb_size);
   term->invalid_start = 0;
diff --git a/vterm-module.h b/vterm-module.h
index e8bb01b..1699cbc 100644
--- a/vterm-module.h
+++ b/vterm-module.h
@@ -79,6 +79,7 @@ typedef struct Term {
   // window height has increased) and must be deleted from the terminal buffer
   int sb_pending;
   int sb_pending_by_height_decr;
+  bool sb_clear_pending;
   long linenum;
   long linenum_added;
 
-- 
cgit v1.0