[hb-view] Support cairo script as output format

Can be handy for debugging the series of operations cairo performs.

util/helper-cairo.hh

@@ -67,6 +67,9 @@ _cairo_eps_surface_create_for_stream (cairo_write_func_t  write_func,
 #    undef HAS_EPS
 #  endif
 #endif
+#ifdef CAIRO_HAS_SCRIPT_SURFACE
+#   include <cairo-script.h>
+#endif
 
 static inline bool
 helper_cairo_use_hb_draw (const font_options_t *font_opts)
@@ -386,6 +389,24 @@ _cairo_png_surface_create_for_stream (cairo_write_func_t write_func,
 
 #endif
 
+#ifdef CAIRO_HAS_SCRIPT_SURFACE
+
+static cairo_surface_t *
+_cairo_script_surface_create_for_stream (cairo_write_func_t write_func,
+				         void *closure,
+				         double width,
+				         double height,
+				         cairo_content_t content,
+				         image_protocol_t protocol HB_UNUSED)
+{
+  cairo_device_t *script = cairo_script_create_for_stream (write_func, closure);
+  cairo_surface_t *surface = cairo_script_surface_create (script, content, width, height);
+  cairo_device_destroy (script);
+  return surface;
+}
+
+#endif
+
 static cairo_status_t
 stdio_write_func (void                *closure,
 		  const unsigned char *data,
@@ -422,6 +443,9 @@ static const char *helper_cairo_supported_formats[] =
     "eps",
    #endif
   #endif
+  #ifdef CAIRO_HAS_SCRIPT_SURFACE
+  "script",
+  #endif
   nullptr
 };
 
@@ -510,6 +534,10 @@ helper_cairo_create_context (double w, double h,
     else if (0 == g_ascii_strcasecmp (extension, "eps"))
       constructor = _cairo_eps_surface_create_for_stream;
    #endif
+   #ifdef CAIRO_HAS_SCRIPT_SURFACE
+    else if (0 == g_ascii_strcasecmp (extension, "script"))
+      constructor2 = _cairo_script_surface_create_for_stream;
+   #endif
   #endif