gsk: Replace gsk_render_node_set_opacity()

... with gsk_opacity_node_new().

Also implement support for opacity in gtk_widget_snapshot() using this
new node.

7 files changed, 136 insertions, 58 deletions

diff --git a/gsk/gskenums.h b/gsk/gskenums.h
index 579e3d9c50..caba77f6ab 100644
--- a/gsk/gskenums.h
+++ b/gsk/gskenums.h
@@ -31,6 +31,7 @@
  * @GSK_TEXTURE_NODE: A node drawing a #GskTexture
  * @GSK_TRANSFORM_NODE: A node that renders its child after applying a
  *     matrix transform
+ * @GSK_OPACITY_NODE: A node that changes the opacity of its child
  *
  * The type of a node determines what the node is rendering.
  *
@@ -42,7 +43,8 @@ typedef enum {
   GSK_CAIRO_NODE,
   GSK_COLOR_NODE,
   GSK_TEXTURE_NODE,
-  GSK_TRANSFORM_NODE
+  GSK_TRANSFORM_NODE,
+  GSK_OPACITY_NODE
 } GskRenderNodeType;
 
 /**
diff --git a/gsk/gskglrenderer.c b/gsk/gskglrenderer.c
index bb98e2ff42..7812121131 100644
--- a/gsk/gskglrenderer.c
+++ b/gsk/gskglrenderer.c
@@ -592,11 +592,6 @@ project_item (const graphene_matrix_t *projection,
 static gboolean
 render_node_needs_render_target (GskRenderNode *node)
 {
-  double opacity = gsk_render_node_get_opacity (node);
-
-  if (opacity < 1.0)
-    return TRUE;
-
   return FALSE;
 }
 
@@ -647,7 +642,7 @@ gsk_gl_renderer_add_render_item (GskGLRenderer           *self,
   graphene_matrix_multiply (modelview, &self->mvp, &item.mvp);
   item.z = project_item (projection, modelview);
 
-  item.opacity = gsk_render_node_get_opacity (node);
+  item.opacity = 1.0;
 
   item.blend_mode = gsk_render_node_get_blend_mode (node);
 
diff --git a/gsk/gskrendernode.c b/gsk/gskrendernode.c
index 1a343ae852..ab41235c4d 100644
--- a/gsk/gskrendernode.c
+++ b/gsk/gskrendernode.c
@@ -97,8 +97,6 @@ gsk_render_node_new (const GskRenderNodeClass *node_class)
 
   self->ref_count = 1;
 
-  self->opacity = 1.0;
-
   self->min_filter = GSK_SCALING_FILTER_NEAREST;
   self->mag_filter = GSK_SCALING_FILTER_NEAREST;
 
@@ -185,44 +183,6 @@ gsk_render_node_get_bounds (GskRenderNode   *node,
   node->node_class->get_bounds (node, bounds);
 }
 
-/**
- * gsk_render_node_set_opacity:
- * @node: a #GskRenderNode
- * @opacity: the opacity of the node, between 0 (fully transparent) and
- *   1 (fully opaque)
- *
- * Sets the opacity of the @node.
- *
- * Since: 3.90
- */
-void
-gsk_render_node_set_opacity (GskRenderNode *node,
-                             double         opacity)
-{
-  g_return_if_fail (GSK_IS_RENDER_NODE (node));
-  g_return_if_fail (node->is_mutable);
-
-  node->opacity = CLAMP (opacity, 0.0, 1.0);
-}
-
-/**
- * gsk_render_node_get_opacity:
- * @node: a #GskRenderNode
- *
- * Retrieves the opacity set using gsk_render_node_set_opacity().
- *
- * Returns: the opacity of the #GskRenderNode
- *
- * Since: 3.90
- */
-double
-gsk_render_node_get_opacity (GskRenderNode *node)
-{
-  g_return_val_if_fail (GSK_IS_RENDER_NODE (node), 0.0);
-
-  return node->opacity;
-}
-
 void
 gsk_render_node_set_scaling_filters (GskRenderNode    *node,
                                      GskScalingFilter  min_filter,
diff --git a/gsk/gskrendernode.h b/gsk/gskrendernode.h
index 2119dfb760..3be25035b1 100644
--- a/gsk/gskrendernode.h
+++ b/gsk/gskrendernode.h
@@ -74,8 +74,10 @@ GDK_AVAILABLE_IN_3_90
 GskRenderNode *         gsk_transform_node_get_child            (GskRenderNode            *node);
 
 GDK_AVAILABLE_IN_3_90
-void                    gsk_render_node_set_opacity             (GskRenderNode *node,
-                                                                 double         opacity);
+GskRenderNode *         gsk_opacity_node_new                    (GskRenderNode            *child,
+                                                                 double                    opacity);
+GDK_AVAILABLE_IN_3_90
+GskRenderNode *         gsk_opacity_node_get_child              (GskRenderNode            *node);
 
 GDK_AVAILABLE_IN_3_90
 void                    gsk_render_node_set_blend_mode          (GskRenderNode *node,
diff --git a/gsk/gskrendernodeimpl.c b/gsk/gskrendernodeimpl.c
index feb7f0891c..764b702df8 100644
--- a/gsk/gskrendernodeimpl.c
+++ b/gsk/gskrendernodeimpl.c
@@ -692,3 +692,130 @@ gsk_transform_node_get_transform (GskRenderNode     *node,
   graphene_matrix_init_from_matrix (transform, &self->transform);
 }
 
+/*** GSK_OPACITY_NODE ***/
+
+typedef struct _GskOpacityNode GskOpacityNode;
+
+struct _GskOpacityNode
+{
+  GskRenderNode render_node;
+
+  GskRenderNode *child;
+  double opacity;
+};
+
+static void
+gsk_opacity_node_finalize (GskRenderNode *node)
+{
+  GskOpacityNode *self = (GskOpacityNode *) node;
+
+  gsk_render_node_unref (self->child);
+}
+
+static void
+gsk_opacity_node_make_immutable (GskRenderNode *node)
+{
+  GskOpacityNode *self = (GskOpacityNode *) node;
+
+  gsk_render_node_make_immutable (self->child);
+}
+
+static void
+gsk_opacity_node_draw (GskRenderNode *node,
+                       cairo_t       *cr)
+{
+  GskOpacityNode *self = (GskOpacityNode *) node;
+  graphene_rect_t bounds;
+
+  cairo_save (cr);
+
+  /* clip so the push_group() creates a smaller surface */
+  gsk_render_node_get_bounds (self->child, &bounds);
+  cairo_rectangle (cr, bounds.origin.x, bounds.origin.y, bounds.size.width, bounds.size.height);
+  cairo_clip (cr);
+
+  cairo_push_group (cr);
+
+  gsk_render_node_draw (self->child, cr);
+
+  cairo_pop_group_to_source (cr);
+  cairo_paint_with_alpha (cr, self->opacity);
+
+  cairo_restore (cr);
+}
+
+static void
+gsk_opacity_node_get_bounds (GskRenderNode   *node,
+                             graphene_rect_t *bounds)
+{
+  GskOpacityNode *self = (GskOpacityNode *) node;
+
+  gsk_render_node_get_bounds (self->child, bounds);
+}
+
+static const GskRenderNodeClass GSK_OPACITY_NODE_CLASS = {
+  GSK_OPACITY_NODE,
+  sizeof (GskOpacityNode),
+  "GskOpacityNode",
+  gsk_opacity_node_finalize,
+  gsk_opacity_node_make_immutable,
+  gsk_opacity_node_draw,
+  gsk_opacity_node_get_bounds
+};
+
+/**
+ * gsk_opacity_node_new:
+ * @child: The node to draw
+ * @opacity: The opacity to apply
+ *
+ * Creates a #GskRenderNode that will drawn the @child with reduced
+ * @opacity.
+ *
+ * Returns: A new #GskRenderNode
+ *
+ * Since: 3.90
+ */
+GskRenderNode *
+gsk_opacity_node_new (GskRenderNode *child,
+                      double         opacity)
+{
+  GskOpacityNode *self;
+
+  g_return_val_if_fail (GSK_IS_RENDER_NODE (child), NULL);
+
+  self = (GskOpacityNode *) gsk_render_node_new (&GSK_OPACITY_NODE_CLASS);
+
+  self->child = gsk_render_node_ref (child);
+  self->opacity = CLAMP (opacity, 0.0, 1.0);
+
+  return &self->render_node;
+}
+
+/**
+ * gsk_opacity_node_get_child:
+ * @node: a opacity @GskRenderNode
+ *
+ * Gets the child node that is getting opacityed by the given @node.
+ *
+ * Returns: (transfer none): The child that is getting opacityed
+ **/
+GskRenderNode *
+gsk_opacity_node_get_child (GskRenderNode *node)
+{
+  GskOpacityNode *self = (GskOpacityNode *) node;
+
+  g_return_val_if_fail (GSK_IS_RENDER_NODE_TYPE (node, GSK_OPACITY_NODE), NULL);
+
+  return self->child;
+}
+
+double
+gsk_opacity_node_get_opacity (GskRenderNode *node)
+{
+  GskOpacityNode *self = (GskOpacityNode *) node;
+
+  g_return_val_if_fail (GSK_IS_RENDER_NODE_TYPE (node, GSK_OPACITY_NODE), 1.0);
+
+  return self->opacity;
+}
+
diff --git a/gsk/gskrendernodeprivate.h b/gsk/gskrendernodeprivate.h
index c4e3c48751..3ad5c43658 100644
--- a/gsk/gskrendernodeprivate.h
+++ b/gsk/gskrendernodeprivate.h
@@ -52,7 +52,7 @@ void gsk_render_node_make_immutable (GskRenderNode *node);
 
 void gsk_render_node_get_bounds (GskRenderNode   *node,
                                  graphene_rect_t *frame);
-double gsk_render_node_get_opacity (GskRenderNode *node);
+double gsk_opacity_node_get_opacity (GskRenderNode *node);
 
 cairo_surface_t *gsk_cairo_node_get_surface (GskRenderNode *node);
 
diff --git a/gsk/gskvulkanrenderpass.c b/gsk/gskvulkanrenderpass.c
index 86ac1a198b..9b28951a23 100644
--- a/gsk/gskvulkanrenderpass.c
+++ b/gsk/gskvulkanrenderpass.c
@@ -66,9 +66,6 @@ gsk_vulkan_render_pass_add_node (GskVulkanRenderPass     *self,
     .node = node
   };
 
-  if (gsk_render_node_get_opacity (node) < 1.0)
-    goto fallback;
-
   switch (gsk_render_node_get_node_type (node))
     {
     case GSK_NOT_A_RENDER_NODE:
@@ -115,11 +112,6 @@ gsk_vulkan_render_pass_add_node (GskVulkanRenderPass     *self,
       break;
 
     }
-
-  return;
-
-fallback:
-  g_array_append_val (self->render_ops, op);
 }
 
 void