Support color fonts that use the foreground color

COLR fonts can have a layer with the same color as the current text
color. This change passes the current color (if solid) through to
the font backend where it can be used to render color fonts.

scaled_glyph_lookup checks if the foreground color has changed (for
glyph that require it) and requests a new color surface if required.

This also fixes a bug where scaled_glyph_lookup would always request a
color surface for glyphs for glyphs in color fonts that do not have
color.

1 files changed, 38 insertions, 3 deletions

diff --git a/src/cairo-scaled-font.c b/src/cairo-scaled-font.c
index 65c1d2595..ef0db0506 100755
--- a/src/cairo-scaled-font.c
+++ b/src/cairo-scaled-font.c
@@ -1611,6 +1611,7 @@ cairo_scaled_font_glyph_extents (cairo_scaled_font_t   *scaled_font,
 	status = _cairo_scaled_glyph_lookup (scaled_font,
 					     glyphs[i].index,
 					     CAIRO_SCALED_GLYPH_INFO_METRICS,
+					     NULL, /* foreground color */
 					     &scaled_glyph);
 	if (unlikely (status)) {
 	    status = _cairo_scaled_font_set_error (scaled_font, status);
@@ -1732,6 +1733,7 @@ cairo_scaled_font_text_to_glyphs_internal_cached (cairo_scaled_font_t		 *scaled_
 	    status = _cairo_scaled_glyph_lookup (scaled_font,
 						 g,
 						 CAIRO_SCALED_GLYPH_INFO_METRICS,
+						 NULL, /* foreground color */
 						 &scaled_glyph);
 	    if (unlikely (status))
 		return status;
@@ -1792,6 +1794,7 @@ cairo_scaled_font_text_to_glyphs_internal_uncached (cairo_scaled_font_t	 *scaled
 	    status = _cairo_scaled_glyph_lookup (scaled_font,
 					     g,
 					     CAIRO_SCALED_GLYPH_INFO_METRICS,
+					     NULL, /* foreground color */
 					     &scaled_glyph);
 	    if (unlikely (status))
 		return status;
@@ -2176,6 +2179,7 @@ _cairo_scaled_font_single_glyph_device_extents (cairo_scaled_font_t	 *scaled_fon
     status = _cairo_scaled_glyph_lookup (scaled_font,
 					 glyph->index,
 					 CAIRO_SCALED_GLYPH_INFO_METRICS,
+					 NULL, /* foreground color */
 					 &scaled_glyph);
     if (likely (status == CAIRO_STATUS_SUCCESS)) {
 	cairo_bool_t round_xy = _cairo_font_options_get_round_glyph_positions (&scaled_font->options) == CAIRO_ROUND_GLYPH_POS_ON;
@@ -2246,6 +2250,7 @@ _cairo_scaled_font_glyph_device_extents (cairo_scaled_font_t	 *scaled_font,
 	    status = _cairo_scaled_glyph_lookup (scaled_font,
 						 glyphs[i].index,
 						 CAIRO_SCALED_GLYPH_INFO_METRICS,
+						 NULL, /* foreground color */
 						 &scaled_glyph);
 	    if (unlikely (status))
 		break;
@@ -2402,6 +2407,7 @@ _cairo_scaled_font_show_glyphs (cairo_scaled_font_t	*scaled_font,
 	status = _cairo_scaled_glyph_lookup (scaled_font,
 					     glyphs[i].index,
 					     CAIRO_SCALED_GLYPH_INFO_SURFACE,
+					     NULL, /* foreground color */
 					     &scaled_glyph);
 
 	if (unlikely (status))
@@ -2656,6 +2662,7 @@ _cairo_scaled_font_glyph_path (cairo_scaled_font_t *scaled_font,
 	status = _cairo_scaled_glyph_lookup (scaled_font,
 					     glyphs[i].index,
 					     CAIRO_SCALED_GLYPH_INFO_PATH,
+					     NULL, /* foreground color */
 					     &scaled_glyph);
 	if (status == CAIRO_INT_STATUS_SUCCESS) {
 	    status = _cairo_path_fixed_append (path,
@@ -2670,6 +2677,7 @@ _cairo_scaled_font_glyph_path (cairo_scaled_font_t *scaled_font,
 	    status = _cairo_scaled_glyph_lookup (scaled_font,
 						 glyphs[i].index,
 						 CAIRO_SCALED_GLYPH_INFO_SURFACE,
+						 NULL, /* foreground color */
 						 &scaled_glyph);
 	    if (unlikely (status))
 		goto BAIL;
@@ -2830,7 +2838,8 @@ _cairo_scaled_glyph_set_recording_surface (cairo_scaled_glyph_t *scaled_glyph,
 void
 _cairo_scaled_glyph_set_color_surface (cairo_scaled_glyph_t *scaled_glyph,
 	                               cairo_scaled_font_t *scaled_font,
-	                               cairo_image_surface_t *surface)
+	                               cairo_image_surface_t *surface,
+				       cairo_bool_t uses_foreground_color)
 {
     if (scaled_glyph->color_surface != NULL)
 	cairo_surface_destroy (&scaled_glyph->color_surface->base);
@@ -2838,6 +2847,7 @@ _cairo_scaled_glyph_set_color_surface (cairo_scaled_glyph_t *scaled_glyph,
     /* sanity check the backend glyph contents */
     _cairo_debug_check_image_surface_is_defined (&surface->base);
     scaled_glyph->color_surface = surface;
+    scaled_glyph->uses_foreground_color = uses_foreground_color;
 
     if (surface != NULL)
 	scaled_glyph->has_info |= CAIRO_SCALED_GLYPH_INFO_COLOR_SURFACE;
@@ -2956,6 +2966,8 @@ _cairo_scaled_font_free_last_glyph (cairo_scaled_font_t *scaled_font,
  * @index: the glyph to create
  * @info: a #cairo_scaled_glyph_info_t marking which portions of
  * the glyph should be filled in.
+ * @foreground_color - foreground color to use when rendering color fonts. Use NULL
+ * if not requesting CAIRO_SCALED_GLYPH_INFO_COLOR_SURFACE or foreground color is unknown.
  * @scaled_glyph_ret: a #cairo_scaled_glyph_t where the glyph
  * is returned.
  *
@@ -2976,11 +2988,14 @@ _cairo_scaled_font_free_last_glyph (cairo_scaled_font_t *scaled_font,
  *  %CAIRO_SCALED_GLYPH_INFO_METRICS - glyph metrics and bounding box
  *  %CAIRO_SCALED_GLYPH_INFO_SURFACE - surface holding glyph image
  *  %CAIRO_SCALED_GLYPH_INFO_PATH - path holding glyph outline in device space
+ *  %CAIRO_SCALED_GLYPH_INFO_RECORDING_SURFACE - surface holding recording of glyph
+ *  %CAIRO_SCALED_GLYPH_INFO_COLOR_SURFACE - surface holding color glyph image
  **/
 cairo_int_status_t
 _cairo_scaled_glyph_lookup (cairo_scaled_font_t *scaled_font,
 			    unsigned long index,
 			    cairo_scaled_glyph_info_t info,
+			    const cairo_color_t   *foreground_color,
 			    cairo_scaled_glyph_t **scaled_glyph_ret)
 {
     cairo_int_status_t		 status = CAIRO_INT_STATUS_SUCCESS;
@@ -2998,6 +3013,9 @@ _cairo_scaled_glyph_lookup (cairo_scaled_font_t *scaled_font,
     if (CAIRO_INJECT_FAULT ())
 	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
 
+    if (foreground_color == NULL)
+	foreground_color = CAIRO_COLOR_BLACK;
+
     /*
      * Check cache for glyph
      */
@@ -3016,7 +3034,8 @@ _cairo_scaled_glyph_lookup (cairo_scaled_font_t *scaled_font,
 	status =
 	    scaled_font->backend->scaled_glyph_init (scaled_font,
 						     scaled_glyph,
-						     info | CAIRO_SCALED_GLYPH_INFO_METRICS);
+						     info | CAIRO_SCALED_GLYPH_INFO_METRICS,
+						     foreground_color);
 	if (unlikely (status)) {
 	    _cairo_scaled_font_free_last_glyph (scaled_font, scaled_glyph);
 	    goto err;
@@ -3035,10 +3054,26 @@ _cairo_scaled_glyph_lookup (cairo_scaled_font_t *scaled_font,
      * already has the requested data and amend it if not
      */
     need_info = info & ~scaled_glyph->has_info;
+
+    /* If this is not a color glyph, don't try loading the color surface again. */
+    if ((need_info & CAIRO_SCALED_GLYPH_INFO_COLOR_SURFACE) && scaled_glyph->not_color_glyph)
+	return CAIRO_INT_STATUS_UNSUPPORTED;
+
+    /* If requesting a color surface for a glyph that has used the
+     * foreground color to render the color_surface, and the
+     * foreground color has changed, request a new image. */
+    if ((info & CAIRO_SCALED_GLYPH_INFO_COLOR_SURFACE) &&
+	scaled_glyph->uses_foreground_color &&
+	!_cairo_color_equal (foreground_color, &scaled_glyph->foreground_color))
+    {
+	need_info |= CAIRO_SCALED_GLYPH_INFO_COLOR_SURFACE;
+    }
+
     if (need_info) {
 	status = scaled_font->backend->scaled_glyph_init (scaled_font,
 							  scaled_glyph,
-							  need_info);
+							  need_info,
+							  foreground_color);
 	if (unlikely (status))
 	    goto err;