Add CFF CID Fallback

Switching to CID font embedding requires a fallback font for
the case where CFF CID or TrueType CID subsetting fails.

The new function _cairo_type2_charstrings_init() added to
cairo-type1-fallback.c creates Type2 charstrings from glyph
paths. _cairo_cff_fallback_init() in cairo-cff-subset.c
wraps these charstrings in a CFF CID font.

1 files changed, 68 insertions, 0 deletions

diff --git a/src/cairo-scaled-font-subsets-private.h b/src/cairo-scaled-font-subsets-private.h
index 4c8221e14..03076c86e 100644
--- a/src/cairo-scaled-font-subsets-private.h
+++ b/src/cairo-scaled-font-subsets-private.h
@@ -305,6 +305,37 @@ _cairo_cff_subset_init (cairo_cff_subset_t          *cff_subset,
 cairo_private void
 _cairo_cff_subset_fini (cairo_cff_subset_t *cff_subset);
 
+/**
+ * _cairo_cff_fallback_init:
+ * @cff_subset: a #cairo_cff_subset_t to initialize
+ * @font_subset: the #cairo_scaled_font_subset_t to initialize from
+ *
+ * If possible (depending on the format of the underlying
+ * cairo_scaled_font_t and the font backend in use) generate a cff
+ * file corresponding to @font_subset and initialize @cff_subset
+ * with information about the subset and the cff data.
+ *
+ * Return value: CAIRO_STATUS_SUCCESS if successful,
+ * CAIRO_INT_STATUS_UNSUPPORTED if the font can't be subset as a
+ * cff file, or an non-zero value indicating an error.  Possible
+ * errors include CAIRO_STATUS_NO_MEMORY.
+ **/
+cairo_private cairo_status_t
+_cairo_cff_fallback_init (cairo_cff_subset_t          *cff_subset,
+                          const char                  *name,
+                          cairo_scaled_font_subset_t  *font_subset);
+
+/**
+ * _cairo_cff_fallback_fini:
+ * @cff_subset: a #cairo_cff_subset_t
+ *
+ * Free all resources associated with @cff_subset.  After this
+ * call, @cff_subset should not be used again without a
+ * subsequent call to _cairo_cff_subset_init() again first.
+ **/
+cairo_private void
+_cairo_cff_fallback_fini (cairo_cff_subset_t *cff_subset);
+
 typedef struct _cairo_truetype_subset {
     char *base_font;
     double *widths;
@@ -446,6 +477,43 @@ _cairo_type1_fallback_init_hex (cairo_type1_subset_t	   *type_subset,
 cairo_private void
 _cairo_type1_fallback_fini (cairo_type1_subset_t *subset);
 
+typedef struct _cairo_type2_charstrings {
+    int *widths;
+    long x_min, y_min, x_max, y_max;
+    long ascent, descent;
+    cairo_array_t charstrings;
+} cairo_type2_charstrings_t;
+
+/**
+ * _cairo_type2_charstrings_init:
+ * @type2_subset: a #cairo_type2_subset_t to initialize
+ * @font_subset: the #cairo_scaled_font_subset_t to initialize from
+ *
+ * If possible (depending on the format of the underlying
+ * cairo_scaled_font_t and the font backend in use) generate type2
+ * charstrings to @font_subset and initialize @type2_subset
+ * with information about the subset.
+ *
+ * Return value: CAIRO_STATUS_SUCCESS if successful,
+ * CAIRO_INT_STATUS_UNSUPPORTED if the font can't be subset as a type2
+ * charstrings, or an non-zero value indicating an error.  Possible errors
+ * include CAIRO_STATUS_NO_MEMORY.
+ **/
+cairo_private cairo_status_t
+_cairo_type2_charstrings_init (cairo_type2_charstrings_t   *charstrings,
+                               cairo_scaled_font_subset_t  *font_subset);
+
+/**
+ * _cairo_type2_charstrings_fini:
+ * @subset: a #cairo_type2_charstrings_t
+ *
+ * Free all resources associated with @type2_charstring.  After this call,
+ * @type2_charstring should not be used again without a subsequent call to
+ * _cairo_type2_charstring_init() again first.
+ **/
+cairo_private void
+_cairo_type2_charstrings_fini (cairo_type2_charstrings_t *charstrings);
+
 /**
  * _cairo_truetype_create_glyph_to_unicode_map:
  * @font_subset: the #cairo_scaled_font_subset_t to initialize from