Fix predict_text_width by using xcb_query_text_extents

This fixes ticket #173, at least for the rendering errors.
I don’t really know why I implemented predict_text_width like it
was before (querying the whole table and pulling out information
one by one). Maybe I have overlooked xcb_query_text_extents. In
any case, it works better now.

diff --git a/src/xcb.c b/src/xcb.c
index ee75ca25df3911dae05cde8e264f123f05c36ec2..fa7091bb53159e4bf7d47a2c5994ef2feacbfd57 100644 (file)
--- a/src/xcb.c
+++ b/src/xcb.c
@@ -295,84 +295,29 @@ void cached_pixmap_prepare(xcb_connection_t *conn, struct Cached_Pixmap *pixmap)
 }
 
 /*
- * Returns the xcb_charinfo_t for the given character (specified by row and
- * column in the lookup table) if existing, otherwise the minimum bounds.
- *
- */
-static xcb_charinfo_t *get_charinfo(int col, int row, xcb_query_font_reply_t *font_info,
-                                    xcb_charinfo_t *table, bool dont_fallback) {
-        xcb_charinfo_t *result;
-
-        /* Bounds checking */
-        if (row < font_info->min_byte1 || row > font_info->max_byte1 ||
-            col < font_info->min_char_or_byte2 || col > font_info->max_char_or_byte2)
-                return NULL;
-
-        /* If we don’t have a table to lookup the infos per character, return the
-         * minimum bounds */
-        if (table == NULL)
-                return &font_info->min_bounds;
-
-        result = &table[((row - font_info->min_byte1) *
-                         (font_info->max_char_or_byte2 - font_info->min_char_or_byte2 + 1)) +
-                        (col - font_info->min_char_or_byte2)];
-
-        /* If the character has an entry in the table, return it */
-        if (result->character_width != 0 ||
-            (result->right_side_bearing |
-             result->left_side_bearing |
-             result->ascent |
-             result->descent) != 0)
-                return result;
-
-        /* Otherwise, get the default character and return its charinfo */
-        if (dont_fallback)
-                return NULL;
-
-        return get_charinfo((font_info->default_char >> 8),
-                            (font_info->default_char & 0xFF),
-                            font_info,
-                            table,
-                            true);
-}
-
-/*
- * Calculate the width of the given text (16-bit characters, UCS) with given
- * real length (amount of glyphs) using the given font.
+ * Query the width of the given text (16-bit characters, UCS) with given real
+ * length (amount of glyphs) using the given font.
  *
  */
 int predict_text_width(xcb_connection_t *conn, const char *font_pattern, char *text, int length) {
-        xcb_query_font_reply_t *font_info;
-        xcb_charinfo_t *table;
-        xcb_generic_error_t *error;
-        int i, width = 0;
         i3Font *font = load_font(conn, font_pattern);
 
-        font_info = xcb_query_font_reply(conn, xcb_query_font(conn, font->id), &error);
-        if (error != NULL) {
-                fprintf(stderr, "ERROR: query font (X error code %d)\n", error->error_code);
+        xcb_query_text_extents_cookie_t cookie;
+        xcb_query_text_extents_reply_t *reply;
+        xcb_generic_error_t *error;
+        int width;
+
+        cookie = xcb_query_text_extents(conn, font->id, length, (xcb_char2b_t*)text);
+        if ((reply = xcb_query_text_extents_reply(conn, cookie, &error)) == NULL) {
+                ELOG("Could not get text extents (X error code %d)\n",
+                     error->error_code);
                 /* We return the rather safe guess of 7 pixels, because a
                  * rendering error is better than a crash. Plus, the user will
-                 * see the error on his stderr. */
+                 * see the error in his log. */
                 return 7;
         }
 
-        /* If no per-char info is available for this font, we use the default */
-        if (xcb_query_font_char_infos_length(font_info) == 0) {
-                LOG("Falling back on default char_width of %d pixels\n", font_info->max_bounds.character_width);
-                return (font_info->max_bounds.character_width * length);
-        }
-
-        table = xcb_query_font_char_infos(font_info);
-
-        for (i = 0; i < 2 * length; i += 2) {
-                xcb_charinfo_t *info = get_charinfo(text[i+1], text[i], font_info, table, false);
-                if (info == NULL)
-                        continue;
-                width += info->character_width;
-        }
-
-        free(font_info);
-
+        width = reply->overall_width;
+        free(reply);
         return width;
 }