[scaled-font] Eliminate intermediate path when tracing glyphs

Currently the tracing code for glyphs constructs an temporary path in
order to replay and append to the output. This temporary allocation is
extremely wasteful as we can just directly append the glyph path to
the output path.

1 files changed, 22 insertions, 29 deletions

diff --git a/src/cairo-scaled-font.c b/src/cairo-scaled-font.c
index 9280f725..9de92e06 100644
--- a/src/cairo-scaled-font.c
+++ b/src/cairo-scaled-font.c
@@ -2208,13 +2208,13 @@ CLEANUP_MASK:
 
 /* Add a single-device-unit rectangle to a path. */
 static cairo_status_t
-_add_unit_rectangle_to_path (cairo_path_fixed_t *path, int x, int y)
+_add_unit_rectangle_to_path (cairo_path_fixed_t *path,
+			     cairo_fixed_t x,
+			     cairo_fixed_t y)
 {
     cairo_status_t status;
 
-    status = _cairo_path_fixed_move_to (path,
-					_cairo_fixed_from_int (x),
-					_cairo_fixed_from_int (y));
+    status = _cairo_path_fixed_move_to (path, x, y);
     if (unlikely (status))
 	return status;
 
@@ -2236,11 +2236,7 @@ _add_unit_rectangle_to_path (cairo_path_fixed_t *path, int x, int y)
     if (unlikely (status))
 	return status;
 
-    status = _cairo_path_fixed_close_path (path);
-    if (unlikely (status))
-	return status;
-
-    return CAIRO_STATUS_SUCCESS;
+    return _cairo_path_fixed_close_path (path);
 }
 
 /**
@@ -2262,12 +2258,15 @@ _add_unit_rectangle_to_path (cairo_path_fixed_t *path, int x, int y)
  **/
 static cairo_status_t
 _trace_mask_to_path (cairo_image_surface_t *mask,
-		     cairo_path_fixed_t *path)
+		     cairo_path_fixed_t *path,
+		     double tx, double ty)
 {
     const uint8_t *row;
     int rows, cols, bytes_per_row;
     int x, y, bit;
     double xoff, yoff;
+    cairo_fixed_t x0, y0;
+    cairo_fixed_t px, py;
     cairo_status_t status;
 
     mask = _cairo_image_surface_coerce (mask, CAIRO_FORMAT_A1);
@@ -2276,12 +2275,15 @@ _trace_mask_to_path (cairo_image_surface_t *mask,
 	return status;
 
     cairo_surface_get_device_offset (&mask->base, &xoff, &yoff);
+    x0 = _cairo_fixed_from_double (tx - xoff);
+    y0 = _cairo_fixed_from_double (ty - yoff);
 
     bytes_per_row = (mask->width + 7) / 8;
     row = mask->data;
     for (y = 0, rows = mask->height; rows--; row += mask->stride, y++) {
 	const uint8_t *byte_ptr = row;
 	x = 0;
+	py = _cairo_fixed_from_int (y);
 	for (cols = bytes_per_row; cols--; ) {
 	    uint8_t byte = *byte_ptr++;
 	    if (byte == 0) {
@@ -2292,8 +2294,10 @@ _trace_mask_to_path (cairo_image_surface_t *mask,
 	    byte = CAIRO_BITSWAP8_IF_LITTLE_ENDIAN (byte);
 	    for (bit = 1 << 7; bit && x < mask->width; bit >>= 1, x++) {
 		if (byte & bit) {
+		    px = _cairo_fixed_from_int (x);
 		    status = _add_unit_rectangle_to_path (path,
-							  x - xoff, y - yoff);
+							  px + x0,
+							  py + y0);
 		    if (unlikely (status))
 			goto BAIL;
 		}
@@ -2315,8 +2319,6 @@ _cairo_scaled_font_glyph_path (cairo_scaled_font_t *scaled_font,
 {
     cairo_status_t status;
     int	i;
-    cairo_path_fixed_t glyph_path_static;
-    cairo_path_fixed_t *glyph_path;
 
     status = scaled_font->status;
     if (unlikely (status))
@@ -2331,7 +2333,11 @@ _cairo_scaled_font_glyph_path (cairo_scaled_font_t *scaled_font,
 					     CAIRO_SCALED_GLYPH_INFO_PATH,
 					     &scaled_glyph);
 	if (status == CAIRO_STATUS_SUCCESS) {
-	    glyph_path = scaled_glyph->path;
+	    status = _cairo_path_fixed_append (path,
+					       scaled_glyph->path, CAIRO_DIRECTION_FORWARD,
+					       _cairo_fixed_from_double (glyphs[i].x),
+					       _cairo_fixed_from_double (glyphs[i].y));
+
 	} else if (status == CAIRO_INT_STATUS_UNSUPPORTED) {
 	    /* If the font is incapable of providing a path, then we'll
 	     * have to trace our own from a surface.
@@ -2343,23 +2349,10 @@ _cairo_scaled_font_glyph_path (cairo_scaled_font_t *scaled_font,
 	    if (unlikely (status))
 		goto BAIL;
 
-	    _cairo_path_fixed_init (&glyph_path_static);
-	    glyph_path = &glyph_path_static;
-	    status = _trace_mask_to_path (scaled_glyph->surface, glyph_path);
-	    if (unlikely (status))
-		goto BAIL;
-	} else {
-	    goto BAIL;
+	    status = _trace_mask_to_path (scaled_glyph->surface, path,
+					  glyphs[i].x, glyphs[i].y);
 	}
 
-	status = _cairo_path_fixed_append (path,
-					   glyph_path, CAIRO_DIRECTION_FORWARD,
-					   _cairo_fixed_from_double (glyphs[i].x),
-					   _cairo_fixed_from_double (glyphs[i].y));
-
-	if (glyph_path != scaled_glyph->path)
-	    _cairo_path_fixed_fini (glyph_path);
-
 	if (unlikely (status))
 	    goto BAIL;
     }