Add preliminary support for resvg

It claims better SVG support, but it sucks for a plethora of reasons.

fiv-io.c

@@ -43,6 +43,9 @@
 #ifdef HAVE_LIBRAW
 #include <libraw.h>
 #endif  // HAVE_LIBRAW
+#ifdef HAVE_RESVG
+#include <resvg.h>
+#endif  // HAVE_RESVG
 #ifdef HAVE_LIBRSVG
 #include <librsvg/rsvg.h>
 #endif  // HAVE_LIBRSVG
@@ -92,9 +95,9 @@ const char *fiv_io_supported_media_types[] = {
 #ifdef HAVE_LIBRAW
 	"image/x-dcraw",
 #endif  // HAVE_LIBRAW
-#ifdef HAVE_LIBRSVG
+#if defined HAVE_RESVG || defined HAVE_LIBRSVG
 	"image/svg+xml",
-#endif  // HAVE_LIBRSVG
+#endif  // HAVE_RESVG || HAVE_LIBRSVG
 #ifdef HAVE_XCURSOR
 	"image/x-xcursor",
 #endif  // HAVE_XCURSOR
@@ -1320,6 +1323,85 @@ open_libraw(const gchar *data, gsize len, GError **error)
 }
 
 #endif  // HAVE_LIBRAW ---------------------------------------------------------
+#ifdef HAVE_RESVG  // ----------------------------------------------------------
+
+static const char *
+load_resvg_error(int err)
+{
+	switch (err) {
+	case RESVG_ERROR_NOT_AN_UTF8_STR:
+		return "not a UTF-8 string";
+	case RESVG_ERROR_FILE_OPEN_FAILED:
+		return "I/O failure";
+	case RESVG_ERROR_MALFORMED_GZIP:
+		return "malformed gzip";
+	case RESVG_ERROR_ELEMENTS_LIMIT_REACHED:
+		return "element limit reached";
+	case RESVG_ERROR_INVALID_SIZE:
+		return "invalid or unspecified image size";
+	case RESVG_ERROR_PARSING_FAILED:
+		return "parsing failed";
+	default:
+		return "general failure";
+	}
+}
+
+static cairo_surface_t *
+open_resvg(const gchar *data, gsize len, const gchar *uri, GError **error)
+{
+	GFile *file = g_file_new_for_uri(uri);
+	GFile *base_file = g_file_get_parent(file);
+	g_object_unref(file);
+
+	resvg_options *opt = resvg_options_create();
+	resvg_options_load_system_fonts(opt);
+	resvg_options_set_resources_dir(opt, g_file_peek_path(base_file));
+	resvg_render_tree *tree = NULL;
+	int err = resvg_parse_tree_from_data(data, len, opt, &tree);
+	resvg_options_destroy(opt);
+	g_object_unref(base_file);
+	if (err != RESVG_OK) {
+		set_error(error, load_resvg_error(err));
+		return NULL;
+	}
+
+	// TODO(p): Support retrieving a scaled-up/down version.
+	// TODO(p): See if there is a situation for resvg_get_image_viewbox().
+	resvg_size size = resvg_get_image_size(tree);
+	int w = ceil(size.width), h = ceil(size.height);
+	if (w > SHRT_MAX || h > SHRT_MAX) {
+		set_error(error, "image dimensions overflow");
+		resvg_tree_destroy(tree);
+		return NULL;
+	}
+
+	cairo_surface_t *surface =
+		cairo_image_surface_create(CAIRO_FORMAT_ARGB32, w, h);
+	cairo_status_t surface_status = cairo_surface_status(surface);
+	if (surface_status != CAIRO_STATUS_SUCCESS) {
+		set_error(error, cairo_status_to_string(surface_status));
+		cairo_surface_destroy(surface);
+		return NULL;
+	}
+
+	uint32_t *pixels = (uint32_t *) cairo_image_surface_get_data(surface);
+	resvg_fit_to fit_to = { RESVG_FIT_TO_TYPE_ORIGINAL, 1. };
+	resvg_render(tree, fit_to, resvg_transform_identity(),
+		cairo_image_surface_get_width(surface),
+		cairo_image_surface_get_height(surface), (char *) pixels);
+	resvg_tree_destroy(tree);
+
+	// TODO(p): Also apply colour management, we'll need to un-premultiply.
+	for (int i = 0; i < w * h; i++) {
+		uint32_t rgba = g_ntohl(pixels[i]);
+		pixels[i] = rgba << 24 | rgba >> 8;
+	}
+
+	cairo_surface_mark_dirty(surface);
+	return surface;
+}
+
+#endif  // HAVE_RESVG ----------------------------------------------------------
 #ifdef HAVE_LIBRSVG  // --------------------------------------------------------
 
 #ifdef FIV_RSVG_DEBUG
@@ -2391,6 +2473,14 @@ fiv_io_open_from_data(const char *data, size_t len, const gchar *uri,
 			g_clear_error(error);
 		}
 #endif  // HAVE_LIBRAW ---------------------------------------------------------
+#ifdef HAVE_RESVG  // ----------------------------------------------------------
+		if ((surface = open_resvg(data, len, uri, error)))
+			break;
+		if (error) {
+			g_debug("%s", (*error)->message);
+			g_clear_error(error);
+		}
+#endif  // HAVE_RESVG ----------------------------------------------------------
 #ifdef HAVE_LIBRSVG  // --------------------------------------------------------
 		if ((surface = open_librsvg(data, len, uri, error)))
 			break;

meson.build

@@ -2,17 +2,16 @@
 project('fiv', 'c',
 	default_options : ['c_std=gnu99', 'warning_level=2'],
 	version : '0.1.0')
+
+cc = meson.get_compiler('c')
 add_project_arguments(
-	meson.get_compiler('c').get_supported_arguments('-Wno-cast-function-type'),
-	language : 'c',
-)
+	cc.get_supported_arguments('-Wno-cast-function-type'), language : 'c')
 
 # This, annoyingly, enables the leak sanitizer by default,
 # which requires some tuning to not stand in the way.
 # Use -Db_sanitize=address,undefined and adjust LSAN_OPTIONS yourself.
 #if get_option('buildtype').startswith('debug')
-#	flags = meson.get_compiler('c').get_supported_arguments(
-#		'-fsanitize=address,undefined')
+#	flags = cc.get_supported_arguments('-fsanitize=address,undefined')
 #	add_project_arguments(flags, language : ['c'])
 #	add_project_link_arguments(flags, language : ['c'])
 #endif
@@ -23,6 +22,19 @@ libjpegqs = dependency('libjpegqs',
 	allow_fallback : true,
 )
 
+# As of writing, the API is unstable, and no pkg-config file is produced.
+# Trying to wrap Cargo in Meson is a recipe for pain, so no version pinning.
+resvg = disabler()
+if not get_option('resvg').disabled()
+	resvg = dependency('resvg', required : false)
+	if not resvg.found()
+		resvg = cc.find_library('libresvg', required : get_option('resvg'))
+		if resvg.found() and not cc.has_header('resvg.h')
+			error('resvg.h not found')
+		endif
+	endif
+endif
+
 lcms2 = dependency('lcms2', required : get_option('lcms2'))
 # Note that only libraw_r is thread-safe, but we'll just run it out-of process.
 libraw = dependency('libraw', required : get_option('libraw'))
@@ -35,6 +47,7 @@ dependencies = [
 	dependency('gtk+-3.0'),
 	dependency('pixman-1'),
 
+	# Wuffs is included as a submodule.
 	dependency('libturbojpeg'),
 	dependency('libwebp'),
 	dependency('libwebpdemux'),
@@ -49,12 +62,14 @@ dependencies = [
 	lcms2,
 	libjpegqs,
 	libraw,
+	resvg,
 	librsvg,
 	xcursor,
 	libheif,
 	libtiff,
 	gdkpixbuf,
-	meson.get_compiler('c').find_library('m', required : false),
+
+	cc.find_library('m', required : false),
 ]
 
 conf = configuration_data()
@@ -63,6 +78,7 @@ conf.set_quoted('PROJECT_VERSION', meson.project_version())
 conf.set('HAVE_JPEG_QS', libjpegqs.found())
 conf.set('HAVE_LCMS2', lcms2.found())
 conf.set('HAVE_LIBRAW', libraw.found())
+conf.set('HAVE_RESVG', resvg.found())
 conf.set('HAVE_LIBRSVG', librsvg.found())
 conf.set('HAVE_XCURSOR', xcursor.found())
 conf.set('HAVE_LIBHEIF', libheif.found())

meson_options.txt

@@ -4,6 +4,8 @@ option('libjpegqs', type : 'feature', value : 'auto',
 	description : 'Build with JPEG Quant Smooth integration')
 option('libraw', type : 'feature', value : 'auto',
 	description : 'Build with raw photo support, requires LibRaw')
+option('resvg', type : 'feature', value : 'disabled',
+	description : 'Build with SVG support via resvg (pre-1.0 unstable API)')
 option('librsvg', type : 'feature', value : 'auto',
 	description : 'Build with SVG support, requires librsvg')
 option('xcursor', type : 'feature', value : 'auto',