[gnome-shell/wip/carlosg/weak-ref-source: 1/6] st/viewport: Add clip-to-view property

[Carlos Garnacho <carlosg src gnome org>]

commit 94130808476bc4f302dc418b21fdc42280fc16dd
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Feb 3 12:03:11 2021 +0100

    st/viewport: Add clip-to-view property
    
    This property controls whether the viewport clips the content to its own
    allocation or not. This will be necessary in special modes that we want to
    render past the viewport inside a scrollview.

 src/st/st-viewport.c | 48 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 4 deletions(-)
---
diff --git a/src/st/st-viewport.c b/src/st/st-viewport.c
index c663ae4cd3..632e19161d 100644
--- a/src/st/st-viewport.c
+++ b/src/st/st-viewport.c
@@ -55,14 +55,19 @@ static void st_viewport_scrollable_interface_init (StScrollableInterface *iface)
 
 enum {
   PROP_0,
+  PROP_CLIP_TO_VIEW,
+  N_PROPS,
   PROP_HADJUST,
   PROP_VADJUST
 };
 
+static GParamSpec *props[N_PROPS] = { 0 };
+
 typedef struct
 {
   StAdjustment *hadjustment;
   StAdjustment *vadjustment;
+  gboolean clip_to_view;
 } StViewportPrivate;
 
 G_DEFINE_TYPE_WITH_CODE (StViewport, st_viewport, ST_TYPE_WIDGET,
@@ -163,12 +168,28 @@ st_viewport_scrollable_interface_init (StScrollableInterface *iface)
   iface->get_adjustments = scrollable_get_adjustments;
 }
 
+static void
+st_viewport_set_clip_to_view (StViewport *viewport,
+                              gboolean    clip_to_view)
+{
+  StViewportPrivate *priv =
+    st_viewport_get_instance_private (viewport);
+
+  if (!!priv->clip_to_view != !!clip_to_view)
+    {
+      priv->clip_to_view = clip_to_view;
+      clutter_actor_queue_redraw (CLUTTER_ACTOR (viewport));
+    }
+}
+
 static void
 st_viewport_get_property (GObject    *object,
                           guint       property_id,
                           GValue     *value,
                           GParamSpec *pspec)
 {
+  StViewportPrivate *priv =
+    st_viewport_get_instance_private (ST_VIEWPORT (object));
   StAdjustment *adjustment;
 
   switch (property_id)
@@ -183,6 +204,10 @@ st_viewport_get_property (GObject    *object,
       g_value_set_object (value, adjustment);
       break;
 
+    case PROP_CLIP_TO_VIEW:
+      g_value_set_boolean (value, priv->clip_to_view);
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
     }
@@ -212,6 +237,10 @@ st_viewport_set_property (GObject      *object,
                                   g_value_get_object (value));
       break;
 
+    case PROP_CLIP_TO_VIEW:
+      st_viewport_set_clip_to_view (viewport, g_value_get_boolean (value));
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
     }
@@ -405,7 +434,7 @@ st_viewport_paint (ClutterActor        *actor,
   /* The content area forms the viewport into the scrolled contents, while
    * the borders and background stay in place; after drawing the borders and
    * background, we clip to the content area */
-  if (priv->hadjustment || priv->vadjustment)
+  if (priv->clip_to_view && (priv->hadjustment || priv->vadjustment))
     {
       cogl_framebuffer_push_rectangle_clip (fb,
                                             (int)content_box.x1,
@@ -419,7 +448,7 @@ st_viewport_paint (ClutterActor        *actor,
        child = clutter_actor_get_next_sibling (child))
     clutter_actor_paint (child, paint_context);
 
-  if (priv->hadjustment || priv->vadjustment)
+  if (priv->clip_to_view && (priv->hadjustment || priv->vadjustment))
     cogl_framebuffer_pop_clip (fb);
 }
 
@@ -480,7 +509,7 @@ st_viewport_get_paint_volume (ClutterActor       *actor,
 
   /* When have an adjustment we are clipped to the content box, so base
    * our paint volume on that. */
-  if (priv->hadjustment || priv->vadjustment)
+  if (priv->clip_to_view && (priv->hadjustment || priv->vadjustment))
     {
       double width, height;
 
@@ -558,6 +587,14 @@ st_viewport_class_init (StViewportClass *klass)
   actor_class->get_paint_volume = st_viewport_get_paint_volume;
   actor_class->pick = st_viewport_pick;
 
+  props[PROP_CLIP_TO_VIEW] =
+    g_param_spec_boolean ("clip-to-view",
+                          "Clip to view",
+                          "Clip to view",
+                          TRUE,
+                          ST_PARAM_READWRITE);
+  g_object_class_install_properties (object_class, N_PROPS, props);
+
   /* StScrollable properties */
   g_object_class_override_property (object_class,
                                     PROP_HADJUST,
@@ -566,10 +603,13 @@ st_viewport_class_init (StViewportClass *klass)
   g_object_class_override_property (object_class,
                                     PROP_VADJUST,
                                     "vadjustment");
-
 }
 
 static void
 st_viewport_init (StViewport *self)
 {
+  StViewportPrivate *priv =
+    st_viewport_get_instance_private (self);
+
+  priv->clip_to_view = TRUE;
 }