Fix cairo_glyph_path() early clipping

src/cairo-gstate.c

@@ -66,7 +66,8 @@ _cairo_gstate_transform_glyphs_to_backend (cairo_gstate_t      *gstate,
 					   cairo_text_cluster_flags_t cluster_flags,
                                            cairo_glyph_t       *transformed_glyphs,
 					   int			*num_transformed_glyphs,
-					   cairo_text_cluster_t *transformed_clusters);
+					   cairo_text_cluster_t *transformed_clusters,
+					   cairo_bool_t          perform_early_clip);
 
 static void
 _cairo_gstate_update_device_transform (cairo_observer_t *observer,
@@ -2035,14 +2036,16 @@ _cairo_gstate_show_text_glyphs (cairo_gstate_t		   *gstate,
 						   info->cluster_flags,
 						   transformed_glyphs,
 						   &num_glyphs,
-						   transformed_clusters);
+						   transformed_clusters,
+						   TRUE);
     } else {
 	_cairo_gstate_transform_glyphs_to_backend (gstate,
 						   glyphs, num_glyphs,
 						   NULL, 0, 0,
 						   transformed_glyphs,
 						   &num_glyphs,
-						   NULL);
+						   NULL,
+						   TRUE);
     }
 
     if (num_glyphs == 0)
@@ -2144,7 +2147,7 @@ _cairo_gstate_glyph_path (cairo_gstate_t      *gstate,
 					       glyphs, num_glyphs,
 					       NULL, 0, 0,
 					       transformed_glyphs,
-					       &num_glyphs, NULL);
+					       &num_glyphs, NULL, FALSE);
 
     status = _cairo_scaled_font_glyph_path (gstate->scaled_font,
 					    transformed_glyphs, num_glyphs,
@@ -2198,7 +2201,8 @@ _cairo_gstate_transform_glyphs_to_backend (cairo_gstate_t	*gstate,
 					   cairo_text_cluster_flags_t cluster_flags,
                                            cairo_glyph_t	*transformed_glyphs,
 					   int			*num_transformed_glyphs,
-					   cairo_text_cluster_t *transformed_clusters)
+					   cairo_text_cluster_t *transformed_clusters,
+					   cairo_bool_t         perform_early_clip)
 {
     cairo_rectangle_int_t surface_extents;
     cairo_matrix_t *ctm = &gstate->ctm;
@@ -2209,7 +2213,7 @@ _cairo_gstate_transform_glyphs_to_backend (cairo_gstate_t	*gstate,
     int i, j, k;
 
     drop = TRUE;
-    if (! _cairo_gstate_int_clip_extents (gstate, &surface_extents)) {
+    if (!perform_early_clip || !_cairo_gstate_int_clip_extents (gstate, &surface_extents)) {
 	drop = FALSE; /* unbounded surface */
     } else {
 	double scale10 = 10 * _cairo_scaled_font_get_max_scale (gstate->scaled_font);

test/glyph-path.c

@@ -0,0 +1,82 @@
+/*
+ * Copyright © 2024 worldiety GmbH
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of
+ * worldiety not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. worldiety makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * WORLDIETY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL WORLDIETY BE LIABLE FOR ANY SPECIAL,
+ * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+ * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Author: Heiko Lewin <hlewin@worldiety.de>
+ */
+#include "cairo-test.h"
+
+#define WIDTH  128
+#define HEIGHT 64
+
+
+static cairo_test_status_t
+draw(cairo_t *cr, int width, int height) {
+    cairo_glyph_t *glyphs = NULL;
+    int num_glyphs = 0;
+    cairo_path_t *path = NULL, *path2 = NULL;
+    (void)width;
+    (void)height;
+
+    /* black on white color */
+    cairo_set_source_rgb(cr, 1., 1., 1.);
+    cairo_paint(cr);
+    cairo_set_source_rgb(cr, 0, 0, 0);
+
+
+    /* translate to some point well outside the surface */
+    cairo_translate(cr, -width * 100, 0);
+
+    /* create a simple path to illustrate the correct behaviour */
+    cairo_rectangle(cr, 0, 0, width/2.0, 2);
+    path = cairo_copy_path(cr);
+    cairo_new_path(cr);
+
+    /* create another path from glyphs - this is broken when clipping to early */
+    {
+        cairo_set_font_size(cr, 32);
+        cairo_scaled_font_t *sf = cairo_get_scaled_font(cr);
+        cairo_scaled_font_text_to_glyphs(sf, 0, 0, "Test", 4, &glyphs, &num_glyphs, 0, 0, 0);
+        cairo_glyph_path(cr, glyphs, num_glyphs);
+        path2 = cairo_copy_path(cr);
+    }
+
+    /* translate to a visible point and draw both paths */
+    cairo_identity_matrix(cr);
+    cairo_translate(cr, width/4.0, 48);
+
+    cairo_append_path(cr, path);
+    cairo_append_path(cr, path2);
+    cairo_fill(cr);
+
+    cairo_path_destroy(path);
+    cairo_path_destroy(path2);
+    free(glyphs);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (glyph_path,
+            "Tests cairo_glyph_path",
+            "text, glyph, path", /* keywords */
+            "target=raster", /* should be enough */
+            WIDTH, HEIGHT,
+            NULL, draw)

test/meson.build

@@ -154,6 +154,7 @@ test_sources = [
   'font-matrix-translation.c',
   'font-options.c',
   'glyph-cache-pressure.c',
+  'glyph-path.c',
   'get-and-set.c',
   'get-clip.c',
   'get-group-target.c',