From b4c5f80fbfaf912553eca1b12da6fc49de4ae37f Mon Sep 17 00:00:00 2001
From: Michael Chang <mchang@suse.com>
Date: Mon, 7 Jan 2019 17:55:05 +0800
Subject: [PATCH] gfxmenu: support scrolling menu entry's text

If menu entry's title text is longer than its display width, the
overlong text simply get truncated. The only possible way to view the
full text is through the menu editing mode, but is a hassle switching
over the mode back and forth. Also menu editing mode could be password
protected which makes it not generally available to everyone.

This patch implemented scrolling text support to the title of grub's
gfxmenu to make it convenient for viewing the truncated text by pressing
the ctrl+l and ctrl+r to scroll the highlighted text left and right. The
scrolled result will remain in place to help memorizing it after
changing highlight to other entry.

V1:
  * Use grub_calloc for overflow check and return NULL when it would
    occur.
---
 grub-core/gfxmenu/gfxmenu.c   |  3 +++
 grub-core/gfxmenu/gui_label.c |  2 ++
 grub-core/gfxmenu/gui_list.c  | 38 ++++++++++++++++++++++++++++++++++
 grub-core/gfxmenu/view.c      | 48 +++++++++++++++++++++++++++++++++++++++++++
 grub-core/normal/menu.c       | 16 +++++++++++++++
 include/grub/gfxmenu_view.h   |  4 ++++
 include/grub/menu_viewer.h    |  1 +
 7 files changed, 112 insertions(+)

--- a/grub-core/gfxmenu/gfxmenu.c
+++ b/grub-core/gfxmenu/gfxmenu.c
@@ -108,6 +108,15 @@
   view->menu = menu;
   view->nested = nested;
   view->first_timeout = -1;
+  if (menu->size)
+    {
+      view->menu_title_offset = grub_calloc (menu->size, sizeof (*view->menu_title_offset));
+      if (!view->menu_title_offset)
+	{
+	  grub_free (instance);
+	  return grub_errno;
+	}
+    }
 
   grub_video_set_viewport (0, 0, mode_info.width, mode_info.height);
   if (view->double_repaint)
@@ -123,6 +132,7 @@
   instance->fini = grub_gfxmenu_viewer_fini;
   instance->print_timeout = grub_gfxmenu_print_timeout;
   instance->clear_timeout = grub_gfxmenu_clear_timeout;
+  instance->scroll_chosen_entry = grub_gfxmenu_scroll_chosen_entry;
 
   grub_menu_register_viewer (instance);
 
--- a/grub-core/gfxmenu/gui_label.c
+++ b/grub-core/gfxmenu/gui_label.c
@@ -192,6 +192,8 @@
 	       "or `c' for a command-line.");
 	   else if (grub_strcmp (value, "@KEYMAP_SHORT@") == 0)
 	    value = _("enter: boot, `e': options, `c': cmd-line");
+	   else if (grub_strcmp (value, "@SUSE_KEYMAP_SCROLL_ENTRY@") == 0)
+	    value = _("ctrl+l: scroll entry left, ctrl+r: scroll entry right");
 	   /* FIXME: Add more templates here if needed.  */
 
 	  if (grub_printf_fmt_check(value, "%d") != GRUB_ERR_NONE)
--- a/grub-core/gfxmenu/gui_list.c
+++ b/grub-core/gfxmenu/gui_list.c
@@ -24,6 +24,7 @@
 #include <grub/gfxmenu_view.h>
 #include <grub/gfxwidgets.h>
 #include <grub/color.h>
+#include <grub/charset.h>
 
 enum scrollbar_slice_mode {
   SCROLLBAR_SLICE_WEST,
@@ -314,6 +315,33 @@
   thumb->draw (thumb, thumbx, thumby);
 }
 
+static const char *
+grub_utf8_offset_code (const char *src, grub_size_t srcsize, int num)
+{
+  int count = 0;
+  grub_uint32_t code = 0;
+
+  while (srcsize && num)
+    {
+      if (srcsize != (grub_size_t)-1)
+	srcsize--;
+      if (!grub_utf8_process ((grub_uint8_t)*src++, &code, &count))
+	return 0;
+      if (count != 0)
+	continue;
+      if (code == 0)
+	return 0;
+      if (code > GRUB_UNICODE_LAST_VALID)
+	return 0;
+      --num;
+    }
+
+  if (!num)
+    return src;
+
+  return 0;
+}
+
 /* Draw the list of items.  */
 static void
 draw_menu (list_impl_t self, int num_shown_items)
@@ -433,6 +461,16 @@
       const char *item_title =
         grub_menu_get_entry (self->view->menu, menu_index)->title;
 
+      {
+	int off = self->view->menu_title_offset[menu_index];
+	const char *scrolled_title;
+
+	scrolled_title = grub_utf8_offset_code (item_title, grub_strlen (item_title), off);
+
+	if (scrolled_title)
+	  item_title = scrolled_title;
+      }
+
       sviewport.y = item_top + top_pad;
       sviewport.width = viewport_width;
       grub_gui_set_viewport (&sviewport, &svpsave);
--- a/grub-core/gfxmenu/view.c
+++ b/grub-core/gfxmenu/view.c
@@ -37,6 +37,7 @@
 #include <grub/gui_string_util.h>
 #include <grub/icon_manager.h>
 #include <grub/i18n.h>
+#include <grub/charset.h>
 
 static void
 init_terminal (grub_gfxmenu_view_t view);
@@ -103,6 +104,7 @@
   view->title_text = grub_strdup (_("GRUB Boot Menu"));
   view->progress_message_text = 0;
   view->theme_path = 0;
+  view->menu_title_offset = 0;
 
   /* Set the timeout bar's frame.  */
   view->progress_message_frame.width = view->screen.width * 4 / 5;
@@ -142,6 +144,7 @@
   grub_free (view->title_text);
   grub_free (view->progress_message_text);
   grub_free (view->theme_path);
+  grub_free (view->menu_title_offset);
   if (view->canvas)
     view->canvas->component.ops->destroy (view->canvas);
   grub_free (view);
@@ -410,6 +413,52 @@
   grub_gfxmenu_redraw_menu (view);
 }
 
+static int
+grub_utf8_get_num_code (const char *src, grub_size_t srcsize)
+{
+  int count = 0;
+  grub_uint32_t code = 0;
+  int num = 0;
+
+  while (srcsize)
+    {
+      if (srcsize != (grub_size_t)-1)
+	srcsize--;
+      if (!grub_utf8_process ((grub_uint8_t)*src++, &code, &count))
+	return 0;
+      if (count != 0)
+	continue;
+      if (code == 0)
+	return num;
+      if (code > GRUB_UNICODE_LAST_VALID)
+	return 0;
+      ++num;
+    }
+
+  return num;
+}
+
+void
+grub_gfxmenu_scroll_chosen_entry (void *data, int diren)
+{
+  grub_gfxmenu_view_t view = data;
+  const char *item_title;
+  int off;
+
+  if (!view->menu->size)
+    return;
+
+  item_title =grub_menu_get_entry (view->menu, view->selected)->title;
+  off = view->menu_title_offset[view->selected] + diren;
+
+  if (off < 0
+      || off > grub_utf8_get_num_code (item_title, grub_strlen(item_title)))
+    return;
+
+  view->menu_title_offset[view->selected] = off;
+  grub_gfxmenu_redraw_menu (view);
+}
+
 static void
 grub_gfxmenu_draw_terminal_box (void)
 {
--- a/grub-core/normal/menu.c
+++ b/grub-core/normal/menu.c
@@ -400,6 +400,15 @@
 }
 
 static void
+menu_scroll_chosen_entry (int diren)
+{
+  struct grub_menu_viewer *cur;
+  for (cur = viewers; cur; cur = cur->next)
+    if (cur->scroll_chosen_entry)
+      cur->scroll_chosen_entry (cur->data, diren);
+}
+
+static void
 menu_print_timeout (int timeout)
 {
   struct grub_menu_viewer *cur;
@@ -829,6 +838,13 @@
 	      menu_set_chosen_entry (current_entry);
 	      break;
 
+	    case GRUB_TERM_CTRL | 'w':
+	      menu_scroll_chosen_entry (1);
+	      break;
+	    case GRUB_TERM_CTRL | 'r':
+	      menu_scroll_chosen_entry (-1);
+	      break;
+
 	    case '\n':
 	    case '\r':
 	    case GRUB_TERM_KEY_RIGHT:
--- a/include/grub/gfxmenu_view.h
+++ b/include/grub/gfxmenu_view.h
@@ -61,6 +61,8 @@
 grub_gfxmenu_print_timeout (int timeout, void *data);
 void
 grub_gfxmenu_set_chosen_entry (int entry, void *data);
+void
+grub_gfxmenu_scroll_chosen_entry (void *data, int diren);
 
 grub_err_t grub_font_draw_string (const char *str,
 				  grub_font_t font,
@@ -119,6 +121,8 @@
   int nested;
 
   int first_timeout;
+
+  int *menu_title_offset;
 };
 
 #endif /* ! GRUB_GFXMENU_VIEW_HEADER */
--- a/include/grub/menu_viewer.h
+++ b/include/grub/menu_viewer.h
@@ -33,6 +33,7 @@
   void (*set_chosen_entry) (int entry, void *data);
   void (*print_timeout) (int timeout, void *data);
   void (*clear_timeout) (void *data);
+  void (*scroll_chosen_entry) (void *data, int diren);
   void (*fini) (void *fini);
 };