Add test for loading 16 bit PNG images

The base image has 16 bits per channel, with colors that do not
have an exact corresponding 8 bit representation. The reference
image uses 8bpc, like the rgb24/argb32 formatted images which
the test outputs.

5 files changed, 81 insertions, 0 deletions

diff --git a/test/create-from-png-16bit.c b/test/create-from-png-16bit.c
new file mode 100644
index 000000000..71c13ecd3
--- /dev/null
+++ b/test/create-from-png-16bit.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright © 2005 Red Hat, Inc.
+ * Copyright © 2021 Manuel Stoeckl
+ *
+ * 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
+ * Red Hat, Inc. not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Red Hat, Inc. makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * RED HAT, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL RED HAT, INC. 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: Carl Worth <cworth@cworth.org>
+ * Author: Manuel Stoeckl <code@mstoeckl.com>
+ */
+
+#include "cairo-test.h"
+
+#include <stdlib.h>
+
+#define WIDTH 2
+#define HEIGHT 2
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    const cairo_test_context_t *ctx = cairo_test_get_context (cr);
+    char *filename;
+    cairo_surface_t *surface;
+
+    xasprintf (&filename, "%s/reference/%s",
+	       ctx->srcdir, "create-from-png-16bit.base.png");
+
+    surface = cairo_image_surface_create_from_png (filename);
+    if (cairo_surface_status (surface)) {
+	cairo_test_status_t result;
+
+	result = cairo_test_status_from_status (ctx,
+						cairo_surface_status (surface));
+	if (result == CAIRO_TEST_FAILURE) {
+	    cairo_test_log (ctx, "Error reading PNG image %s: %s\n",
+			    filename,
+			    cairo_status_to_string (cairo_surface_status (surface)));
+	}
+
+	free (filename);
+	return result;
+    }
+
+    /* Pretend we modify the surface data (which detaches the PNG mime data) */
+    cairo_surface_flush (surface);
+    cairo_surface_mark_dirty (surface);
+
+    cairo_set_source_surface (cr, surface, 0, 0);
+    cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST);
+    cairo_paint (cr);
+
+    cairo_surface_destroy (surface);
+
+    free (filename);
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (create_from_png_16bit,
+	    "Tests the creation of an image surface from a 16 bit PNG file",
+	    "png", /* keywords */
+	    NULL, /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, draw)
diff --git a/test/meson.build b/test/meson.build
index 28047cb04..e670a3937 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -96,6 +96,7 @@ test_sources = [
   'create-for-stream.c',
   'create-from-broken-png-stream.c',
   'create-from-png.c',
+  'create-from-png-16bit.c',
   'create-from-png-stream.c',
   'culled-glyphs.c',
   'curve-to-as-line-to.c',
diff --git a/test/reference/create-from-png-16bit.base.png b/test/reference/create-from-png-16bit.base.png
new file mode 100644
index 000000000..7e0f00e33
--- /dev/null
+++ b/test/reference/create-from-png-16bit.base.png
diff --git a/test/reference/create-from-png-16bit.image16.ref.png b/test/reference/create-from-png-16bit.image16.ref.png
new file mode 100644
index 000000000..9591a12dd
--- /dev/null
+++ b/test/reference/create-from-png-16bit.image16.ref.png
diff --git a/test/reference/create-from-png-16bit.ref.png b/test/reference/create-from-png-16bit.ref.png
new file mode 100644
index 000000000..296c559bc
--- /dev/null
+++ b/test/reference/create-from-png-16bit.ref.png