[libhandy] css: Add hdy_css_draw()

[Adrien Plazas <aplazas src gnome org>]

commit 1573a5d5d131b99d1313cf32be29853f2cb1fed7
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Sun Sep 13 02:18:59 2020 +0500

    css: Add hdy_css_draw()

 src/hdy-css-private.h |  3 +++
 src/hdy-css.c         | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)
---
diff --git a/src/hdy-css-private.h b/src/hdy-css-private.h
index 34ed4512..09a5197c 100644
--- a/src/hdy-css-private.h
+++ b/src/hdy-css-private.h
@@ -28,4 +28,7 @@ void hdy_css_size_allocate_self (GtkWidget     *widget,
 void hdy_css_size_allocate_children (GtkWidget     *widget,
                                      GtkAllocation *allocation);
 
+void hdy_css_draw (GtkWidget *widget,
+                   cairo_t   *cr);
+
 G_END_DECLS
diff --git a/src/hdy-css.c b/src/hdy-css.c
index 1bafcbf8..6e11a619 100644
--- a/src/hdy-css.c
+++ b/src/hdy-css.c
@@ -112,3 +112,37 @@ hdy_css_size_allocate_children (GtkWidget     *widget,
   allocation->x += border.left + padding.left;
   allocation->y += border.top + padding.top;
 }
+
+void
+hdy_css_draw (GtkWidget *widget,
+              cairo_t   *cr)
+{
+  gint width = gtk_widget_get_allocated_width (widget);
+  gint height = gtk_widget_get_allocated_height (widget);
+  GtkStyleContext *style_context;
+
+  if (width <= 0 || height <= 0)
+    return;
+
+  /* Manually apply the border, the padding and the margin as we can't use the
+   * private GtkGagdet.
+   */
+  style_context = gtk_widget_get_style_context (widget);
+
+  gtk_render_background (style_context, cr, 0, 0, width, height);
+  gtk_render_frame (style_context, cr, 0, 0, width, height);
+
+  if (gtk_widget_has_visible_focus (widget)) {
+    GtkStateFlags state_flags;
+    GtkBorder border;
+
+    state_flags = gtk_widget_get_state_flags (widget);
+
+    gtk_style_context_get_border (style_context, state_flags, &border);
+
+    gtk_render_focus (style_context, cr,
+                      border.left, border.top,
+                      width - border.left - border.right,
+                      height - border.top - border.bottom);
+  }
+}