Fix number of issues with percentage spacing as well as negative spac…

…ing.

src/raqm.c

@@ -1267,7 +1267,7 @@ _raqm_set_spacing (raqm_t *rq,
   if (!rq->text_info)
     return false;
 
-  for (size_t i = start; i < end-1; i++)
+  for (size_t i = start; i < end; i++)
     if (word_spacing)
     {
       for (size_t j = 0; j < word_separators_len; j++)
@@ -1291,16 +1291,16 @@ _raqm_set_spacing (raqm_t *rq,
 /**
  * raqm_set_letter_spacing_range:
  * @rq: a #raqm_t.
- * @spacing: amount of spacing in Freetype Font Units (26.6 format), or percentages of the letter (0 - 100)
+ * @spacing: amount of spacing in Freetype Font Units (26.6 format), or percentages of the advance (0 - 100)
  * @percentage: whether to interpret the @spacing amount as a percentage of
  * the character advance.
  * @start: index of first character that should use @spacing.
  * @len: number of characters using @spacing.
  * 
  * Set the letter spacing or tracking for a given range, the value
  * will be added onto the advance and offset for RTL, and the advance for
- * other directions. Letter spacing will be applied after all characters in
- * the range.
+ * other directions. Letter spacing will be applied between characters, so
+ * the last character will not have spacing applied after it.
  * Note that not all scripts have a letter-spacing tradition,
  * for example, Arabic does not, while Devanagari does.
  *
@@ -1316,7 +1316,7 @@ raqm_set_letter_spacing_range(raqm_t *rq,
                               size_t start,
                               size_t len)
 {
-  size_t end = start + len;
+  size_t end = start + (len-1);
 
   if (!rq)
     return false;
@@ -1341,7 +1341,7 @@ raqm_set_letter_spacing_range(raqm_t *rq,
 /**
  * raqm_set_word_spacing_range:
  * @rq: a #raqm_t.
- * @spacing: amount of spacing in Freetype Font Units (26.6 format), or percentages of the letter (0 - 100)
+ * @spacing: amount of spacing in Freetype Font Units (26.6 format), or percentages of the advance (0 - 100)
  * @percentage: whether to interpret the @spacing amount as a percentage of
  * the character advance.
  * @start: index of first character that should use @spacing.
@@ -2358,24 +2358,26 @@ _raqm_shape (raqm_t *rq)
         _raqm_ft_transform (&pos[i].x_advance, &pos[i].y_advance, matrix);
         _raqm_ft_transform (&pos[i].x_offset, &pos[i].y_offset, matrix);
 
-        if (rq->text_info[info[i].cluster].spacing_after > 0)
+        if (rq->text_info[info[i].cluster].spacing_after != 0)
         {
           if (run->direction == HB_DIRECTION_TTB)
           {
             if (rq->text_info[info[i].cluster].spacing_is_percentage)
             {
-              pos[i].y_advance *= 1.0 + (rq->text_info[info[i].cluster].spacing_after * 0.01);
+              int spacing = pos[i].y_advance * (rq->text_info[info[i].cluster].spacing_after * 0.01);
+              pos[i].y_advance += spacing;
             }
             else {
-              pos[i].y_advance += rq->text_info[info[i].cluster].spacing_after;
+              pos[i].y_advance -= rq->text_info[info[i].cluster].spacing_after;
             }
           }
           else if (run->direction == HB_DIRECTION_RTL)
-          { 
+          {
             if (rq->text_info[info[i].cluster].spacing_is_percentage)
             {
-              pos[i].x_offset += pos[i].x_advance * (rq->text_info[info[i].cluster].spacing_after * 0.01);
-              pos[i].x_advance *= 1.0 + (rq->text_info[info[i].cluster].spacing_after * 0.01);
+              int spacing = pos[i].x_advance * (rq->text_info[info[i].cluster].spacing_after * 0.01);
+              pos[i].x_offset += spacing;
+              pos[i].x_advance += spacing;
             }
             else {
               pos[i].x_advance += rq->text_info[info[i].cluster].spacing_after;