New tag %ss() which lets you get a substring of another tag.

%ss(start, length, tag) - i.e %ss(0,1,%TL) will get the first letter of the current lines text.
use - for the length to get the rest of the tag (e.g %ss(1,-,%TL) will get everything after the first letter).

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30500 a1c6a512-1295-4272-9138-f99709370657

apps/gui/skin_engine/skin_parser.c

@@ -720,6 +720,24 @@ static int parse_timeout_tag(struct skin_element *element,
     return 0;
 }
 
+static int parse_substring_tag(struct skin_element* element,
+                                 struct wps_token *token,
+                                 struct wps_data *wps_data)
+{
+    (void)wps_data;
+    struct substring *ss = (struct substring*)skin_buffer_alloc(sizeof(struct substring));
+    if (!ss)
+        return 1;
+    ss->start = element->params[0].data.number;
+    if (element->params[1].type == DEFAULT)
+        ss->length = -1;
+    else
+        ss->length = element->params[1].data.number;
+    ss->token = element->params[2].data.code->data;
+    token->value.data = ss;
+    return 0;
+}
+
 static int parse_progressbar_tag(struct skin_element* element,
                                  struct wps_token *token,
                                  struct wps_data *wps_data)
@@ -1788,6 +1806,9 @@ static int skin_element_callback(struct skin_element* element, void* data)
                 case SKIN_TOKEN_LOGICAL_IF:
                     function = parse_logical_if;
                     break;
+                case SKIN_TOKEN_SUBSTRING:
+                    function = parse_substring_tag;
+                    break;
                 case SKIN_TOKEN_PROGRESSBAR:
                 case SKIN_TOKEN_VOLUME:
                 case SKIN_TOKEN_BATTERY_PERCENT:

apps/gui/skin_engine/skin_tokens.c

@@ -868,7 +868,34 @@ const char *get_token_value(struct gui_wps *gwps,
             struct logical_if *lif = token->value.data;
             return get_lif_token_value(gwps, lif, offset, buf, buf_size);
         }
-        break;           
+        break;
+        case SKIN_TOKEN_SUBSTRING:
+        {
+            struct substring *ss = token->value.data;
+            const char *token_val = get_token_value(gwps, ss->token, offset,
+                                                    buf, buf_size, intval);
+            int ret_len = ss->length;
+            if (token_val)
+            {
+                int len = strlen(token_val);
+                if (len < ss->start)
+                    return NULL;
+                if (ret_len < 0)
+                    ret_len = strlen(token_val) - ss->start;
+                if (token_val != buf)
+                {
+                    memcpy(buf, &token_val[ss->start], ret_len);
+                }
+                else
+                {
+                    buf = &buf[ss->start];
+                }
+                buf[ret_len] = '\0';
+                return buf;
+            }
+            return NULL;
+        }
+        break;        
             
         case SKIN_TOKEN_CHARACTER:
             if (token->value.c == '\n')

apps/gui/skin_engine/wps_internals.h

@@ -288,6 +288,12 @@ struct logical_if {
     int num_options;
 };
 
+struct substring {
+    int start;
+    int length;
+    struct wps_token *token;
+};
+
 #ifdef HAVE_SKIN_VARIABLES
 struct skin_var {
     const char *label;

lib/skin_parser/tag_table.c

@@ -236,7 +236,8 @@ static const struct tag_info legal_tags[] =
     { SKIN_TOKEN_VAR_SET,               "vs",   "SSI|I", SKIN_REFRESH_STATIC },
     { SKIN_TOKEN_VAR_GETVAL,            "vg",   "S", SKIN_REFRESH_DYNAMIC },
     { SKIN_TOKEN_VAR_TIMEOUT,           "vl",   "S|D", SKIN_REFRESH_DYNAMIC },
-    
+
+    { SKIN_TOKEN_SUBSTRING,             "ss",   "IiT", SKIN_REFRESH_DYNAMIC },
     { SKIN_TOKEN_UNKNOWN,                ""   , "", 0 }
     /* Keep this here to mark the end of the table */
 };

lib/skin_parser/tag_table.h

@@ -279,6 +279,8 @@ enum skin_token_type {
     SKIN_TOKEN_VAR_SET,
     SKIN_TOKEN_VAR_GETVAL,
     SKIN_TOKEN_VAR_TIMEOUT,
+
+    SKIN_TOKEN_SUBSTRING,
 };
 
 /*