Optional page offset mode

This commit is build on the idea of Renato Florentino to be able to
correct the page offset that some documents have. His patch, where
most of the code has been adapted to this commit ( thanks! ), made
it able to correct the current page and automatically calculate the
correct page offset. Now this patch will introduce a third mode to
the bcmd_goto command: You are now able to set the page directly,
calculate it over the offset or search the labels for it.

config.def.h

@@ -17,6 +17,7 @@ static const char BOOKMARK_FILE[] = "bookmarks";
 
 /* bookmarks */
 static const char BM_PAGE_ENTRY[]  = "page";
+static const char BM_PAGE_OFFSET[] = "offset";
 
 /* look */
 static const char font[]                   = "monospace normal 9";
@@ -55,7 +56,7 @@ static const char DEFAULT_TEXT[] = "[No Name]";
 #define SHOW_SCROLLBARS 0
 #define ADJUST_OPEN ADJUST_BESTFIT
 #define RECOLOR_OPEN 0
-#define ENABLE_LABELS 1
+#define GOTO_MODE GOTO_LABELS /* GOTO_DEFAULT, GOTO_LABELS, GOTO_OFFSET */
 
 /* shortcuts */
 Shortcut shortcuts[] = {
@@ -74,6 +75,7 @@ Shortcut shortcuts[] = {
   {0,                  GDK_K,             sc_navigate,          NORMAL,   { PREVIOUS } },
   {GDK_MOD1_MASK,      GDK_Right,         sc_navigate,          NORMAL,   { NEXT } },
   {GDK_MOD1_MASK,      GDK_Left,          sc_navigate,          NORMAL,   { PREVIOUS } },
+  {0,                  GDK_O,             sc_switch_goto_mode,  NORMAL,   {0} },
   {0,                  GDK_space,         sc_navigate,          NORMAL,   { NEXT } },
   {0,                  GDK_Escape,        sc_abort,             -1,       {0} },
   {0,                  GDK_i,             sc_change_mode,       NORMAL,   { INSERT } },
@@ -124,6 +126,7 @@ Command commands[] = {
   {"bmark",     "b",            cmd_bookmark,        0,            "Bookmark current page" },
   {"blist",     0,              cmd_open_bookmark,   cc_bookmark,  "List and open bookmark" },
   {"close",     "c",            cmd_close,           0,            "Close current file" },
+  {"coffset",   0,              cmd_correct_offset,  0,            "Correct page offset" },
   {"delbmark",  0,              cmd_delete_bookmark, cc_bookmark,  "Bookmark current page" },
   {"export",    "e",            cmd_export,          cc_export,    "Export images or attached files" },
   {"info",      "i",            cmd_info,            0,            "Show information about the document" },
@@ -160,5 +163,5 @@ Setting settings[] = {
   /* name,         variable,                        type,  render,  description */
   {"recolor",      &(Zathura.Global.recolor),       'b',   TRUE,    "Invert the image"},
   {"password",     &(Zathura.PDF.password),         's',   FALSE,   "The password of the document"},
-  {"labels",       &(Zathura.Global.enable_labels), 'b',   FALSE,   "Use labels for pages"},
+  {"offset",       &(Zathura.PDF.page_offset),      'i',   FALSE,   "Optional page offset"},
 };

zathura.c

@@ -27,7 +27,8 @@ enum { NEXT, PREVIOUS, LEFT, RIGHT, UP, DOWN,
        ZOOM_IN, ZOOM_OUT, ZOOM_ORIGINAL, ZOOM_SPECIFIC,
        FORWARD, BACKWARD, ADJUST_BESTFIT, ADJUST_WIDTH,
        ADJUST_NONE, CONTINUOUS, DELETE_LAST, ADD_MARKER,
-       EVAL_MARKER, INDEX, EXPAND, COLLAPSE, SELECT };
+       EVAL_MARKER, INDEX, EXPAND, COLLAPSE, SELECT,
+       GOTO_DEFAULT, GOTO_LABELS, GOTO_OFFSET};
 
 /* typedefs */
 struct CElement
@@ -186,7 +187,7 @@ struct
     int      mode;
     int      viewing_mode;
     gboolean recolor;
-    gboolean enable_labels;
+    int       goto_mode;
     GtkLabel *status_text;
     GtkLabel *status_buffer;
     GtkLabel *status_state;
@@ -228,6 +229,7 @@ struct
     char            *password;
     Page           **pages;
     int              page_number;
+    int              page_offset;
     int              number_of_pages;
     int              scale;
     int              rotate;
@@ -291,6 +293,7 @@ void sc_recolor(Argument*);
 void sc_rotate(Argument*);
 void sc_scroll(Argument*);
 void sc_search(Argument*);
+void sc_switch_goto_mode(Argument*);
 void sc_navigate_index(Argument*);
 void sc_toggle_index(Argument*);
 void sc_toggle_inputbar(Argument*);
@@ -307,6 +310,7 @@ void isc_string_manipulation(Argument*);
 gboolean cmd_bookmark(int, char**);
 gboolean cmd_open_bookmark(int, char**);
 gboolean cmd_close(int, char**);
+gboolean cmd_correct_offset(int, char**);
 gboolean cmd_delete_bookmark(int, char**);
 gboolean cmd_export(int, char**);
 gboolean cmd_info(int, char**);
@@ -412,7 +416,7 @@ init_zathura()
   Zathura.Global.viewing_mode  = NORMAL;
   Zathura.Global.recolor       = RECOLOR_OPEN;
   Zathura.Global.adjust_mode   = ADJUST_OPEN;
-  Zathura.Global.enable_labels = ENABLE_LABELS;
+  Zathura.Global.goto_mode     = GOTO_MODE;
 
   Zathura.State.filename          = (char*) DEFAULT_TEXT;
   Zathura.State.pages             = "";
@@ -862,15 +866,21 @@ open_file(char* path, char* password)
 
   /* start page */
   int start_page          = 0;
+  Zathura.PDF.page_offset = 0;
 
   /* bookmarks */
-  if(Zathura.Bookmarks.data)
+  if(Zathura.Bookmarks.data && g_key_file_has_group(Zathura.Bookmarks.data, file))
   {
     /* get last opened page */
-    if(g_key_file_has_group(Zathura.Bookmarks.data, file))
     if(g_key_file_has_key(Zathura.Bookmarks.data, file, BM_PAGE_ENTRY, NULL))
       start_page = g_key_file_get_integer(Zathura.Bookmarks.data, file, BM_PAGE_ENTRY, NULL);
 
+    /* get page offset */
+    if(g_key_file_has_key(Zathura.Bookmarks.data, file, BM_PAGE_OFFSET, NULL))
+      Zathura.PDF.page_offset = g_key_file_get_integer(Zathura.Bookmarks.data, file, BM_PAGE_OFFSET, NULL);
+    if((Zathura.PDF.page_offset != 0) && (Zathura.PDF.page_offset != GOTO_OFFSET))
+      Zathura.PDF.page_offset = GOTO_OFFSET;
+
     /* open and read bookmark file */
     gsize i              = 0;
     gsize number_of_keys = 0;
@@ -878,7 +888,7 @@ open_file(char* path, char* password)
 
     for(i = 0; i < number_of_keys; i++)
     {
-      if(strcmp(keys[i], BM_PAGE_ENTRY))
+      if(strcmp(keys[i], BM_PAGE_ENTRY) && strcmp(keys[i], BM_PAGE_OFFSET))
       {
         Zathura.Bookmarks.bookmarks = realloc(Zathura.Bookmarks.bookmarks, 
             (Zathura.Bookmarks.number_of_bookmarks + 1) * sizeof(Bookmark)); 
@@ -916,16 +926,20 @@ update_status()
   if( Zathura.PDF.document && Zathura.PDF.pages )
   {
     int page = Zathura.PDF.page_number;
-    if(Zathura.Global.enable_labels && Zathura.PDF.pages[page]->label)
+    /*
+    if((Zathura.Global.goto_mode == GOTO_LABELS) && Zathura.PDF.pages[page]->label)
       Zathura.State.pages = g_strdup_printf("[%s/%i]", 
           Zathura.PDF.pages[page]->label, Zathura.PDF.number_of_pages);
     else
+    */
       Zathura.State.pages = g_strdup_printf("[%i/%i]", page + 1, Zathura.PDF.number_of_pages);
   }
 
   /* update state */
   char* zoom_level  = (Zathura.PDF.scale != 0) ? g_strdup_printf("%d%%", Zathura.PDF.scale) : "";
-  char* status_text  = g_strdup_printf("%s %s", zoom_level, Zathura.State.pages);
+  char* goto_mode   = (Zathura.Global.goto_mode == GOTO_LABELS) ? "L" : 
+    (Zathura.Global.goto_mode == GOTO_OFFSET) ? "O" : "D";
+  char* status_text = g_strdup_printf("%s [%s] %s", zoom_level, goto_mode, Zathura.State.pages);
   gtk_label_set_markup((GtkLabel*) Zathura.Global.status_state, status_text);
 }
 
@@ -1440,6 +1454,25 @@ sc_search(Argument* argument)
   g_static_mutex_unlock(&(Zathura.Lock.search_lock));
 }
 
+void
+sc_switch_goto_mode(Argument* argument)
+{
+  switch(Zathura.Global.goto_mode)
+  {
+    case GOTO_LABELS:
+      Zathura.Global.goto_mode = GOTO_OFFSET;
+      break;
+    case GOTO_OFFSET:
+      Zathura.Global.goto_mode = GOTO_DEFAULT;
+      break;
+    default:
+      Zathura.Global.goto_mode = GOTO_LABELS;
+      break;
+  }
+
+  update_status();
+}
+
 gboolean cb_index_row_activated(GtkTreeView* treeview, GtkTreePath* path,
   GtkTreeViewColumn* column, gpointer user_data)
 {
@@ -2060,6 +2093,10 @@ cmd_close(int argc, char** argv)
     g_key_file_set_integer(Zathura.Bookmarks.data, Zathura.PDF.file,
         BM_PAGE_ENTRY, Zathura.PDF.page_number);
 
+    /* set page offset */
+    g_key_file_set_integer(Zathura.Bookmarks.data, Zathura.PDF.file,
+        BM_PAGE_OFFSET, Zathura.PDF.page_offset);
+
     /* save bookmarks */
     int i;
     for(i = 0; i < Zathura.Bookmarks.number_of_bookmarks; i++)
@@ -2077,7 +2114,6 @@ cmd_close(int argc, char** argv)
     inotify_rm_watch(Zathura.Inotify.fd, Zathura.Inotify.wd);
 
   Zathura.Inotify.wd = -1;
-  /*pthread_cancel(Zathura.Thread.inotify_thread);*/
 
   /* reset values */
   free(Zathura.PDF.pages);
@@ -2095,6 +2131,7 @@ cmd_close(int argc, char** argv)
   Zathura.PDF.number_of_pages = 0;
   Zathura.PDF.scale           = 0;
   Zathura.PDF.rotate          = 0;
+  Zathura.PDF.page_offset     = 0;
 
   /* destroy index */
   if(Zathura.UI.index)
@@ -2121,6 +2158,24 @@ cmd_close(int argc, char** argv)
   return TRUE;
 }
 
+gboolean
+cmd_correct_offset(int argc, char** argv)
+{
+  if(!Zathura.PDF.document || argc == 0)
+    return TRUE;
+
+  Zathura.PDF.page_offset = (Zathura.PDF.page_number + 1) - atoi(argv[0]);
+
+  if(Zathura.PDF.page_offset != 0)
+    Zathura.Global.goto_mode = GOTO_OFFSET;
+  else
+    Zathura.Global.goto_mode = GOTO_MODE;
+
+  update_status();
+
+  return TRUE;
+}
+
 gboolean
 cmd_delete_bookmark(int argc, char** argv)
 {
@@ -2765,13 +2820,15 @@ bcmd_goto(char* buffer, Argument* argument)
     char* id = g_strndup(buffer, b_length - 1);
     int  pid = atoi(id);
 
-    if(Zathura.Global.enable_labels)
+    if(Zathura.Global.goto_mode == GOTO_LABELS)
     {
       int i;
       for(i = 0; i < Zathura.PDF.number_of_pages; i++)
         if(!strcmp(id, Zathura.PDF.pages[i]->label))
           pid = Zathura.PDF.pages[i]->id;
     }
+    else if(Zathura.Global.goto_mode == GOTO_OFFSET)
+      pid += Zathura.PDF.page_offset;
 
     set_page(pid - 1);
     g_free(id);