Add SVG load support via resvg (#2)

Co-authored-by: Kleis Auke Wolthuizen <github@kleisauke.nl>

libvips/foreign/foreign.c

@@ -3006,11 +3006,13 @@ vips_foreign_operation_init( void )
 	vips_foreign_load_pdf_source_get_type(); 
 #endif /*HAVE_PDFIUM*/
 
-#ifdef HAVE_RSVG
+#if (defined(HAVE_RSVG) || defined(HAVE_RESVG)) && !defined(RESVG_MODULE)
 	vips_foreign_load_svg_file_get_type(); 
 	vips_foreign_load_svg_buffer_get_type(); 
+#ifdef HAVE_RSVG
 	vips_foreign_load_svg_source_get_type(); 
-#endif /*HAVE_RSVG*/
+#endif
+#endif /*defined(HAVE_RSVG) || defined(HAVE_RESVG)*/
 
 #if defined(HAVE_LIBJXL) && !defined(LIBJXL_MODULE)
 	vips_foreign_load_jxl_file_get_type(); 

libvips/foreign/meson.build

@@ -44,7 +44,6 @@ foreign_sources = files(
     'rawsave.c',
     'spngload.c',
     'spngsave.c',
-    'svgload.c',
     'tiff2vips.c',
     'tiff.c',
     'tiffload.c',
@@ -123,6 +122,14 @@ endif
 
 libvips_sources += foreign_sources
 
+resvg_module_sources = files(
+    'svgload.c',
+)
+
+if not resvg_module
+    foreign_sources += resvg_module_sources
+endif
+
 foreign_lib = static_library('foreign',
     foreign_sources,
     foreign_headers,

libvips/foreign/svgload.c

@@ -81,25 +81,38 @@
 #include <cairo.h>
 #include <librsvg/rsvg.h>
 
-/* Render SVGs with tiles this size. They need to be pretty big to limit 
- * overcomputation.
+/* A handy #define for we-will-handle-svgz.
  */
-#define TILE_SIZE (2000)
+#if LIBRSVG_CHECK_FEATURE(SVGZ)
+#define HANDLE_SVGZ
+#endif
 
-/* The <svg tag must appear within this many bytes of the start of the file.
- */
-#define SVG_HEADER_SIZE (1000)
+#elif defined(HAVE_RESVG)
 
-/* A handy #define for we-will-handle-svgz.
- */
-#if LIBRSVG_CHECK_FEATURE(SVGZ) && defined(HAVE_ZLIB)
+#include <resvg.h>
 #define HANDLE_SVGZ
+
+#endif
+
+#if defined(HAVE_RSVG) || defined(HAVE_RESVG)
+
+#ifndef HAVE_ZLIB
+#undef HANDLE_SVGZ
 #endif
 
 #ifdef HANDLE_SVGZ
 #include <zlib.h>
 #endif
 
+/* Render SVGs with tiles this size. They need to be pretty big to limit
+ * overcomputation.
+ */
+#define TILE_SIZE (2000)
+
+/* The <svg tag must appear within this many bytes of the start of the file.
+ */
+#define SVG_HEADER_SIZE (1000)
+
 typedef struct _VipsForeignLoadSvg {
 	VipsForeignLoad parent_object;
 
@@ -119,7 +132,12 @@ typedef struct _VipsForeignLoadSvg {
 	 */
 	gboolean unlimited;
 
+#ifdef HAVE_RSVG
 	RsvgHandle *page;
+#else
+	resvg_options *options;
+	resvg_render_tree *tree;
+#endif
 
 } VipsForeignLoadSvg;
 
@@ -308,7 +326,12 @@ vips_foreign_load_svg_dispose( GObject *gobject )
 {
 	VipsForeignLoadSvg *svg = (VipsForeignLoadSvg *) gobject;
 
+#ifdef HAVE_RSVG
 	VIPS_UNREF( svg->page );
+#else
+	resvg_options_destroy( svg->options );
+	VIPS_FREEF( resvg_tree_destroy, svg->tree );
+#endif
 
 	G_OBJECT_CLASS( vips_foreign_load_svg_parent_class )->
 		dispose( gobject );
@@ -328,6 +351,7 @@ vips_foreign_load_svg_get_flags( VipsForeignLoad *load )
 	return( VIPS_FOREIGN_PARTIAL );
 }
 
+#ifdef HAVE_RSVG
 #if LIBRSVG_CHECK_VERSION( 2, 52, 0 )
 /* Derived from `CssLength::to_user` in librsvg.
  * https://gitlab.gnome.org/GNOME/librsvg/-/blob/e6607c9ae8d8409d4efff6b12993717400b3356e/src/length.rs#L368
@@ -386,6 +410,7 @@ svg_css_length_to_pixels( RsvgLength length, double dpi )
 	return value;
 }
 #endif
+#endif
 
 static int
 vips_foreign_load_svg_get_natural_size( VipsForeignLoadSvg *svg, 
@@ -396,6 +421,7 @@ vips_foreign_load_svg_get_natural_size( VipsForeignLoadSvg *svg,
 	double width;
 	double height;
 
+#ifdef HAVE_RSVG
 #if LIBRSVG_CHECK_VERSION( 2, 52, 0 )
 
 	if( !rsvg_handle_get_intrinsic_size_in_pixels( svg->page, 
@@ -483,6 +509,11 @@ vips_foreign_load_svg_get_natural_size( VipsForeignLoadSvg *svg,
 }
 
 #endif /*LIBRSVG_CHECK_VERSION( 2, 52, 0 )*/
+#else /* HAVE_RSVG */
+	resvg_size size = resvg_get_image_size( svg->tree );
+	width = size.width;
+	height = size.height;
+#endif
 
 	/* width or height below 0.5 can't be rounded to 1.
 	 */
@@ -505,9 +536,11 @@ vips_foreign_load_svg_get_scaled_size( VipsForeignLoadSvg *svg,
 	double width;
 	double height;
 
+#ifdef HAVE_RSVG
 	/* Get dimensions with the default dpi.
 	 */
 	rsvg_handle_set_dpi( svg->page, 72.0 );
+#endif
 	if( vips_foreign_load_svg_get_natural_size( svg, &width, &height ) )
 		return( -1 );
 
@@ -565,23 +598,25 @@ vips_foreign_load_svg_generate( VipsRegion *or,
 	void *seq, void *a, void *b, gboolean *stop )
 {
 	const VipsForeignLoadSvg *svg = (VipsForeignLoadSvg *) a;
-	const VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( svg );
 	const VipsRect *r = &or->valid;
 
-	cairo_surface_t *surface;
-	cairo_t *cr;
-	int y;
-
 #ifdef DEBUG
 	printf( "vips_foreign_load_svg_generate:\n     "
 		"left = %d, top = %d, width = %d, height = %d\n", 
 		r->left, r->top, r->width, r->height ); 
 #endif /*DEBUG*/
 
-	/* rsvg won't always paint the background.
+	/* SVG won't always paint the background.
 	 */
 	vips_region_black( or ); 
 
+#ifdef HAVE_RSVG
+	const VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( svg );
+
+	cairo_surface_t *surface;
+	cairo_t *cr;
+	int y;
+
 	surface = cairo_image_surface_create_for_data( 
 		VIPS_REGION_ADDR( or, r->left, r->top ), 
 		CAIRO_FORMAT_ARGB32, 
@@ -644,6 +679,42 @@ vips_foreign_load_svg_generate( VipsRegion *or,
                 vips__premultiplied_bgra2rgba( 
 			(guint32 *) VIPS_REGION_ADDR( or, r->left, r->top + y ),
 			r->width ); 
+#else
+
+	VipsPel *q = VIPS_REGION_ADDR( or, r->left, r->top );
+
+	resvg_render(
+		svg->tree,
+		(resvg_fit_to) { .type = RESVG_FIT_TO_TYPE_ORIGINAL },
+		(resvg_transform) {
+			.a = svg->cairo_scale,
+			.d = svg->cairo_scale,
+			.e = -r->left,
+			.f = -r->top,
+		},
+		r->width,
+		r->height,
+		(char *) q
+	);
+
+	/* Just unpremultiply.
+	 */
+	for( int i = 0; i < r->width * r->height; i++ ) {
+		VipsPel * restrict p = &q[i * 4];
+		VipsPel x = p[3];
+
+		/* Skip transparent and fully opaque pixels.
+		 */
+		if( x == 0 || x == 255 )
+			continue;
+
+		/* Any compiler will unroll it.
+		 */
+		for( int j = 0; j < 3; j++ )
+			p[j] = 255 * p[j] / x;
+	}
+
+#endif
 
 	return( 0 ); 
 }
@@ -731,8 +802,16 @@ vips_foreign_load_svg_init( VipsForeignLoadSvg *svg )
 	svg->dpi = 72.0;
 	svg->scale = 1.0;
 	svg->cairo_scale = 1.0;
+#ifdef HAVE_RESVG
+	svg->options = resvg_options_create();
+
+	/* Get dimensions with the default dpi.
+	 */
+	resvg_options_set_dpi( svg->options, 72.0 );
+#endif
 }
 
+#ifdef HAVE_RSVG
 typedef struct _VipsForeignLoadSvgSource {
 	VipsForeignLoadSvg parent_object;
 
@@ -783,7 +862,6 @@ vips_foreign_load_svg_source_header( VipsForeignLoad *load )
 		return( -1 ); 
 	}
 	g_object_unref( gstream );
-
 	return( vips_foreign_load_svg_header( load ) );
 }
 
@@ -833,6 +911,7 @@ static void
 vips_foreign_load_svg_source_init( VipsForeignLoadSvgSource *source )
 {
 }
+#endif
 
 typedef struct _VipsForeignLoadSvgFile {
 	VipsForeignLoadSvg parent_object;
@@ -859,11 +938,34 @@ vips_foreign_load_svg_file_is_a( const char *filename )
 		vips_foreign_load_svg_is_a( buf, bytes ) );
 }
 
+#ifdef HAVE_RESVG
+static const char *
+resvg_error_msg( resvg_error e ) {
+	switch( e ) {
+	case RESVG_ERROR_NOT_AN_UTF8_STR:
+		return "only UTF-8 content is supported";
+	case RESVG_ERROR_FILE_OPEN_FAILED:
+		return "failed to open the provided file";
+	case RESVG_ERROR_MALFORMED_GZIP:
+		return "compressed SVG must use the GZip algorithm";
+	case RESVG_ERROR_ELEMENTS_LIMIT_REACHED:
+		return "we do not allow SVG with more than 1_000_000 elements for security reasons";
+	case RESVG_ERROR_INVALID_SIZE:
+		return "SVG doesn't have a valid size";
+	case RESVG_ERROR_PARSING_FAILED:
+		return "failed to parse SVG data";
+	default:
+		return "unknown error";
+	}
+}
+#endif
+
 static int
 vips_foreign_load_svg_file_header( VipsForeignLoad *load )
 {
 	VipsForeignLoadSvg *svg = (VipsForeignLoadSvg *) load;
 	VipsForeignLoadSvgFile *file = (VipsForeignLoadSvgFile *) load;
+#ifdef HAVE_RSVG
 	RsvgHandleFlags flags = svg->unlimited ? RSVG_HANDLE_FLAG_UNLIMITED : 0;
 
 	GError *error = NULL;
@@ -878,7 +980,15 @@ vips_foreign_load_svg_file_header( VipsForeignLoad *load )
 		return( -1 ); 
 	}
 	g_object_unref( gfile );
-
+#else
+	resvg_error error = resvg_parse_tree_from_file(
+		file->filename, svg->options, &svg->tree );
+	if( error != RESVG_OK ) {
+		vips_error( VIPS_OBJECT_GET_CLASS( svg )->nickname,
+			"%s", resvg_error_msg( error ) );
+		return( -1 );
+	}
+#endif
 	VIPS_SETSTR( load->out->filename, file->filename );
 
 	return( vips_foreign_load_svg_header( load ) );
@@ -888,7 +998,7 @@ static const char *vips_foreign_svg_suffs[] = {
 	".svg",
 	/* librsvg supports svgz directly, no need to check for zlib here.
 	 */
-#if LIBRSVG_CHECK_FEATURE(SVGZ)
+#ifdef HANDLE_SVGZ
 	".svgz",
 	".svg.gz",
 #endif
@@ -948,6 +1058,7 @@ vips_foreign_load_svg_buffer_header( VipsForeignLoad *load )
 	VipsForeignLoadSvg *svg = (VipsForeignLoadSvg *) load;
 	VipsForeignLoadSvgBuffer *buffer = 
 		(VipsForeignLoadSvgBuffer *) load;
+#ifdef HAVE_RSVG
 	RsvgHandleFlags flags = svg->unlimited ? RSVG_HANDLE_FLAG_UNLIMITED : 0;
 
 	GError *error = NULL;
@@ -963,7 +1074,15 @@ vips_foreign_load_svg_buffer_header( VipsForeignLoad *load )
 		return( -1 ); 
 	}
 	g_object_unref( gstream );
-
+#else
+	resvg_error error = resvg_parse_tree_from_data(
+		buffer->buf->data, buffer->buf->length, svg->options, &svg->tree );
+	if( error != RESVG_OK ) {
+		vips_error( VIPS_OBJECT_GET_CLASS( svg )->nickname,
+			"%s", resvg_error_msg( error ) );
+		return( -1 );
+	}
+#endif
 	return( vips_foreign_load_svg_header( load ) );
 }
 
@@ -1146,4 +1265,3 @@ vips_svgload_source( VipsSource *source, VipsImage **out, ... )
 
 	return( result );
 }
-

libvips/meson.build

@@ -170,3 +170,18 @@ if openslide_module
         install_dir: module_dir
     )
 endif
+
+if resvg_module
+    shared_module('vips-resvg',
+        'module/resvg.c',
+        resvg_module_sources,
+        c_args: module_c_args,
+        link_args: module_link_args,
+        name_prefix: '',
+        name_suffix: module_suffix,
+        dependencies: [module_dep, resvg_dep],
+        gnu_symbol_visibility: 'hidden',
+        install: true,
+        install_dir: module_dir
+    )
+endif