Apply css text shadows in text views

For now, this just applies the shadow from the widget's style,
there is no way to apply different shadows to text ranges (except
for the selection, which already has its own css style).

gtk/gskpango.c

@@ -28,6 +28,7 @@
 #include "gtkwidgetprivate.h"
 #include "gtkcsscolorvalueprivate.h"
 #include "gdk/gdkrgbaprivate.h"
+#include "gtkcssshadowvalueprivate.h"
 
 #include <math.h>
 
@@ -97,6 +98,11 @@ gsk_pango_renderer_draw_glyph_item (PangoRenderer  *renderer,
 {
   GskPangoRenderer *crenderer = (GskPangoRenderer *) (renderer);
   GdkRGBA color;
+  gboolean has_shadow = FALSE;
+
+  if (crenderer->shadow_style)
+    has_shadow = gtk_css_shadow_value_push_snapshot (crenderer->shadow_style->font->text_shadow,
+                                                     crenderer->snapshot);
 
   get_color (crenderer, PANGO_RENDER_PART_FOREGROUND, &color);
 
@@ -106,6 +112,9 @@ gsk_pango_renderer_draw_glyph_item (PangoRenderer  *renderer,
                             &color,
                             (float) x / PANGO_SCALE,
                             (float) y / PANGO_SCALE);
+
+  if (has_shadow)
+    gtk_snapshot_pop (crenderer->snapshot);
 }
 
 static void
@@ -382,6 +391,15 @@ gsk_pango_renderer_prepare_run (PangoRenderer  *renderer,
     }
   else
     text_renderer_set_rgba (crenderer, PANGO_RENDER_PART_UNDERLINE, fg_rgba);
+
+  crenderer->shadow_style = NULL;
+  if (GTK_IS_TEXT_VIEW (crenderer->widget))
+    {
+      if (crenderer->state == GSK_PANGO_RENDERER_SELECTED)
+        crenderer->shadow_style = gtk_css_node_get_style (gtk_text_view_get_selection_node ((GtkTextView *)crenderer->widget));
+      else if (crenderer->state != GSK_PANGO_RENDERER_CURSOR)
+        crenderer->shadow_style = gtk_css_node_get_style (gtk_widget_get_css_node (crenderer->widget));
+    }
 }
 
 static void
@@ -439,6 +457,7 @@ gsk_pango_renderer_release (GskPangoRenderer *renderer)
     {
       renderer->widget = NULL;
       renderer->snapshot = NULL;
+      renderer->shadow_style = NULL;
 
       if (renderer->error_color)
         {

gtk/gskpangoprivate.h

@@ -20,6 +20,7 @@
 
 #include <pango/pango.h>
 #include "gtk/gtksnapshot.h"
+#include "gtk/gtkcssstyleprivate.h"
 
 G_BEGIN_DECLS
 
@@ -58,6 +59,7 @@ struct _GskPangoRenderer
   GtkWidget             *widget;
   GtkSnapshot           *snapshot;
   const GdkRGBA         *fg_color;
+  GtkCssStyle           *shadow_style;
 
   /* Error underline color for this widget */
   GdkRGBA               *error_color;