Add very basic SVG support

We need to refactor, so that SVGs are pre-rendered on each change
of scaling by librsvg directly, because some elements may be rasterized.

It would be best to also support building against resvg.

7 files changed, 151 insertions, 23 deletions

diff --git a/README.adoc b/README.adoc
index bd0584f..0b1b04f 100644
--- a/README.adoc
+++ b/README.adoc
@@ -2,7 +2,7 @@ fastiv
 ======
 
 'fastiv' is a fast image viewer, supporting BMP, PNG, GIF, JPEG, and optionally
-RAW pictures.  Currently, it's not particularly usable.
+RAW and SVG pictures.  Currently, it's not particularly usable.
 
 Non-goals
 ---------
@@ -19,7 +19,7 @@ Building and Running
 --------------------
 Build dependencies: Meson, pkg-config +
 Runtime dependencies: gtk+-3.0, pixman-1, shared-mime-info, libpng>=1.5.4,
-libturbojpeg, LibRaw (optional)
+libturbojpeg, LibRaw (optional), librsvg-2.0 (optional)
 
  $ git clone --recursive https://git.janouch.name/p/fastiv.git
  $ meson builddir
diff --git a/fastiv-io.c b/fastiv-io.c
index a450b73..14f4e3b 100644
--- a/fastiv-io.c
+++ b/fastiv-io.c
@@ -23,6 +23,9 @@
 #ifdef HAVE_LIBRAW
 #include <libraw.h>
 #endif  // HAVE_LIBRAW
+#ifdef HAVE_LIBRSVG
+#include <librsvg/rsvg.h>
+#endif  // HAVE_LIBRSVG
 
 #define WUFFS_IMPLEMENTATION
 #define WUFFS_CONFIG__MODULES
@@ -38,6 +41,7 @@
 #include "wuffs-mirror-release-c/release/c/wuffs-v0.3.c"
 
 #include "xdg.h"
+#include "fastiv-io.h"
 
 // A subset of shared-mime-info that produces an appropriate list of
 // file extensions. Chiefly motivated by the suckiness of RAW images:
@@ -50,6 +54,9 @@ const char *fastiv_io_supported_media_types[] = {
 #ifdef HAVE_LIBRAW
 	"image/x-dcraw",
 #endif  // HAVE_LIBRAW
+#ifdef HAVE_LIBRSVG
+	"image/svg+xml",
+#endif  // HAVE_LIBRSVG
 	NULL
 };
 
@@ -384,6 +391,81 @@ open_libraw(const gchar *data, gsize len, GError **error)
 }
 
 #endif  // HAVE_LIBRAW ---------------------------------------------------------
+#ifdef HAVE_LIBRSVG  // --------------------------------------------------------
+
+#ifdef FASTIV_RSVG_DEBUG
+#include <cairo/cairo-script.h>
+#include <cairo/cairo-svg.h>
+#endif
+
+// FIXME: librsvg rasterizes filters, so this method isn't fully appropriate.
+static cairo_surface_t *
+open_librsvg(const gchar *data, gsize len, GError **error)
+{
+	RsvgHandle *handle =
+		rsvg_handle_new_from_data((const guint8 *) data, len, error);
+	if (!handle)
+		return NULL;
+
+	// TODO(p): Acquire this from somewhere else.
+	rsvg_handle_set_dpi(handle, 96);
+
+	double w = 0, h = 0;
+	if (!rsvg_handle_get_intrinsic_size_in_pixels(handle, &w, &h)) {
+		set_error(error, "cannot compute pixel dimensions");
+		g_object_unref(handle);
+		return NULL;
+	}
+
+	cairo_rectangle_t extents = {
+		.x = 0, .y = 0, .width = ceil(w), .height = ceil(h)};
+	cairo_surface_t *surface =
+		cairo_recording_surface_create(CAIRO_CONTENT_COLOR_ALPHA, &extents);
+
+#ifdef FASTIV_RSVG_DEBUG
+	cairo_device_t *script = cairo_script_create("cairo.script");
+	cairo_surface_t *tee =
+		cairo_script_surface_create_for_target(script, surface);
+	cairo_t *cr = cairo_create(tee);
+	cairo_device_destroy(script);
+	cairo_surface_destroy(tee);
+#else
+	cairo_t *cr = cairo_create(surface);
+#endif
+
+	RsvgRectangle viewport = {.x = 0, .y = 0, .width = w, .height = h};
+	if (!rsvg_handle_render_document(handle, cr, &viewport, error)) {
+		cairo_surface_destroy(surface);
+		cairo_destroy(cr);
+		g_object_unref(handle);
+		return NULL;
+	}
+
+	cairo_destroy(cr);
+	g_object_unref(handle);
+
+#ifdef FASTIV_RSVG_DEBUG
+	cairo_surface_t *svg = cairo_svg_surface_create("cairo.svg", w, h);
+	cr = cairo_create(svg);
+	cairo_set_source_surface(cr, surface, 0, 0);
+	cairo_paint(cr);
+	cairo_destroy(cr);
+	cairo_surface_destroy(svg);
+
+	cairo_surface_t *png =
+		cairo_image_surface_create(CAIRO_FORMAT_ARGB32, w * 10, h * 10);
+	cr = cairo_create(png);
+	cairo_scale(cr, 10, 10);
+	cairo_set_source_surface(cr, surface, 0, 0);
+	cairo_paint(cr);
+	cairo_destroy(cr);
+	cairo_surface_write_to_png(png, "cairo.png");
+	cairo_surface_destroy(png);
+#endif
+	return surface;
+}
+
+#endif  // HAVE_LIBRSVG --------------------------------------------------------
 
 cairo_surface_t *
 fastiv_io_open(const gchar *path, GError **error)
@@ -399,6 +481,14 @@ fastiv_io_open(const gchar *path, GError **error)
 	if (!g_file_get_contents(path, &data, &len, error))
 		return NULL;
 
+	cairo_surface_t *surface = fastiv_io_open_from_data(data, len, error);
+	free(data);
+	return surface;
+}
+
+cairo_surface_t *
+fastiv_io_open_from_data(const char *data, size_t len, GError **error)
+{
 	wuffs_base__slice_u8 prefix =
 		wuffs_base__make_slice_u8((uint8_t *) data, len);
 
@@ -433,11 +523,17 @@ fastiv_io_open(const gchar *path, GError **error)
 		// notably only continue with LIBRAW_FILE_UNSUPPORTED.
 		g_clear_error(error);
 #endif  // HAVE_LIBRAW ---------------------------------------------------------
+#ifdef HAVE_LIBRSVG  // --------------------------------------------------------
+		if ((surface = open_librsvg(data, len, error)))
+			break;
+
+		// XXX: It doesn't look like librsvg can return sensible errors.
+		g_clear_error(error);
+#endif  // HAVE_LIBRSVG --------------------------------------------------------
 
 		// TODO(p): Integrate gdk-pixbuf as a fallback (optional dependency).
 		set_error(error, "unsupported file type");
 	}
-	free(data);
 	return surface;
 }
 
diff --git a/fastiv-io.h b/fastiv-io.h
index 96b4929..616bfc8 100644
--- a/fastiv-io.h
+++ b/fastiv-io.h
@@ -23,4 +23,6 @@
 extern const char *fastiv_io_supported_media_types[];
 
 cairo_surface_t *fastiv_io_open(const gchar *path, GError **error);
+cairo_surface_t *fastiv_io_open_from_data(
+	const char *data, size_t len, GError **error);
 cairo_surface_t *fastiv_io_lookup_thumbnail(const gchar *target);
diff --git a/fastiv-view.c b/fastiv-view.c
index da4aa12..948db9e 100644
--- a/fastiv-view.c
+++ b/fastiv-view.c
@@ -29,22 +29,28 @@ struct _FastivView {
 
 G_DEFINE_TYPE(FastivView, fastiv_view, GTK_TYPE_WIDGET)
 
-static int
-get_display_width(FastivView *self)
-{
-	if (!self->surface)
-		return 0;
-
-	return ceil(cairo_image_surface_get_width(self->surface) * self->scale);
-}
-
-static int
-get_display_height(FastivView *self)
+static void
+get_display_dimensions(FastivView *self, int *width, int *height)
 {
+	*width = *height = 0;
 	if (!self->surface)
-		return 0;
+		return;
+
+	cairo_rectangle_t extents = {};
+	switch (cairo_surface_get_type(self->surface)) {
+	case CAIRO_SURFACE_TYPE_IMAGE:
+		extents.width = cairo_image_surface_get_width(self->surface);
+		extents.height = cairo_image_surface_get_height(self->surface);
+		break;
+	case CAIRO_SURFACE_TYPE_RECORDING:
+		(void) cairo_recording_surface_get_extents(self->surface, &extents);
+		break;
+	default:
+		g_assert_not_reached();
+	}
 
-	return ceil(cairo_image_surface_get_height(self->surface) * self->scale);
+	*width = ceil(extents.width * self->scale);
+	*height = ceil(extents.height * self->scale);
 }
 
 static void
@@ -60,15 +66,17 @@ static void
 fastiv_view_get_preferred_height(
 	GtkWidget *widget, gint *minimum, gint *natural)
 {
-	FastivView *self = FASTIV_VIEW(widget);
-	*minimum = *natural = get_display_height(self);
+	int width, height;
+	get_display_dimensions(FASTIV_VIEW(widget), &width, &height);
+	*minimum = *natural = height;
 }
 
 static void
 fastiv_view_get_preferred_width(GtkWidget *widget, gint *minimum, gint *natural)
 {
-	FastivView *self = FASTIV_VIEW(widget);
-	*minimum = *natural = get_display_width(self);
+	int width, height;
+	get_display_dimensions(FASTIV_VIEW(widget), &width, &height);
+	*minimum = *natural = width;
 }
 
 static void
@@ -115,8 +123,8 @@ fastiv_view_draw(GtkWidget *widget, cairo_t *cr)
 	gtk_render_background(gtk_widget_get_style_context(widget), cr, 0, 0,
 		allocation.width, allocation.height);
 
-	int w = get_display_width(self);
-	int h = get_display_height(self);
+	int w, h;
+	get_display_dimensions(self, &w, &h);
 
 	double x = 0;
 	double y = 0;
@@ -125,6 +133,23 @@ fastiv_view_draw(GtkWidget *widget, cairo_t *cr)
 	if (h < allocation.height)
 		y = round((allocation.height - h) / 2.);
 
+	// FIXME: Recording surfaces do not work well with CAIRO_SURFACE_TYPE_XLIB,
+	// we always get a shitty pixmap, where transparency contains junk.
+	if (cairo_surface_get_type(self->surface) == CAIRO_SURFACE_TYPE_RECORDING) {
+		cairo_surface_t *image =
+			cairo_image_surface_create(CAIRO_FORMAT_ARGB32, w, h);
+		cairo_t *tcr = cairo_create(image);
+		cairo_scale(tcr, self->scale, self->scale);
+		cairo_set_source_surface(tcr, self->surface, 0, 0);
+		cairo_paint(tcr);
+		cairo_destroy(tcr);
+
+		cairo_set_source_surface(cr, image, x, y);
+		cairo_paint(cr);
+		cairo_surface_destroy(image);
+		return TRUE;
+	}
+
 	// XXX: The rounding together with padding may result in up to
 	// a pixel's worth of made-up picture data.
 	cairo_rectangle(cr, x, y, w, h);
diff --git a/fastiv.desktop b/fastiv.desktop
index f048f98..9ef47d0 100644
--- a/fastiv.desktop
+++ b/fastiv.desktop
@@ -8,4 +8,4 @@ Terminal=false
 StartupNotify=true
 Categories=Graphics;2DGraphics;Viewer;
 # TODO(p): Generate this list from source files.
-MimeType=image/png;image/bmp;image/gif;image/jpeg;image/x-dcraw;
+MimeType=image/png;image/bmp;image/gif;image/jpeg;image/x-dcraw;image/svg+xml;
diff --git a/meson.build b/meson.build
index 4e1d299..d5acea1 100644
--- a/meson.build
+++ b/meson.build
@@ -2,12 +2,14 @@ project('fastiv', 'c', default_options : ['c_std=gnu99'], version : '0.1.0')
 
 # TODO(p): Use libraw_r later, when we start parallelizing/preloading.
 libraw = dependency('libraw', required : get_option('libraw'))
+librsvg = dependency('librsvg-2.0', required : get_option('librsvg'))
 dependencies = [
 	dependency('gtk+-3.0'),
 	dependency('libturbojpeg'),
 	dependency('libpng', version : '>=1.5.4'),
 	dependency('pixman-1'),
 	libraw,
+	librsvg,
 	meson.get_compiler('c').find_library('m', required : false),
 ]
 
@@ -15,6 +17,7 @@ conf = configuration_data()
 conf.set_quoted('PROJECT_NAME', meson.project_name())
 conf.set_quoted('PROJECT_VERSION', meson.project_version())
 conf.set('HAVE_LIBRAW', libraw.found())
+conf.set('HAVE_LIBRSVG', librsvg.found())
 configure_file(
 	output : 'config.h',
 	configuration : conf,
diff --git a/meson_options.txt b/meson_options.txt
index 0d56b56..3d89ed8 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -1,2 +1,4 @@
 option('libraw', type : 'feature', value : 'auto',
     description : 'Build with RAW support, requires LibRaw')
+option('librsvg', type : 'feature', value : 'auto',
+	description : 'Build with SVG support, requires librsvg')