| // Copyright 2017 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef GARNET_LIB_UI_GFX_RESOURCES_NODES_TRAVERSAL_H_ |
| #define GARNET_LIB_UI_GFX_RESOURCES_NODES_TRAVERSAL_H_ |
| |
| #include "garnet/lib/ui/gfx/resources/import.h" |
| #include "garnet/lib/ui/gfx/resources/nodes/node.h" |
| |
| namespace scenic_impl { |
| namespace gfx { |
| |
| // |
| // Front-to-back traversals. |
| // Applies the functor to direct descendants in front-to-back order. |
| // |
| // This is the order in which they should be drawn to ensure that objects |
| // at the same elevation correctly obscure one another. |
| // |
| // This is also the order in which hit testing should be performed to ensure |
| // that the objects at the same elevation are evaluated from most to least |
| // specifically hit. |
| // |
| // The functor's signature must be |void(Node* node)|. |
| // |
| template <typename Callable> |
| void ForEachChildFrontToBack(const Node& node, const Callable& func) { |
| // Process most recently added children first. |
| for (auto it = node.children().rbegin(); it != node.children().rend(); ++it) { |
| func(it->get()); |
| } |
| } |
| |
| template <typename Callable> |
| void ForEachImportFrontToBack(const Node& node, const Callable& func) { |
| // Process most recently added imports first. |
| for (auto it = node.imports().rbegin(); it != node.imports().rend(); ++it) { |
| func(static_cast<Node*>((*it)->delegate())); |
| } |
| } |
| |
| template <typename Callable> |
| void ForEachChildAndImportFrontToBack(const Node& node, const Callable& func) { |
| ForEachChildFrontToBack(node, func); |
| ForEachImportFrontToBack(node, func); |
| } |
| |
| template <typename Callable> |
| void ForEachDirectDescendantFrontToBack(const Node& node, const Callable& func) { |
| ForEachChildAndImportFrontToBack(node, func); |
| } |
| |
| // |
| // Traversals with early termination once the functor returns true. |
| // |
| // The functor's signature must be |bool(const Node* node)|. |
| // |
| template <typename Callable> |
| bool ForEachChildFrontToBackUntilTrue(const Node& node, const Callable& func) { |
| // Process most recently added children first. |
| for (auto it = node.children().rbegin(); it != node.children().rend(); ++it) { |
| if (func(it->get())) |
| return true; |
| } |
| return false; |
| } |
| |
| template <typename Callable> |
| bool ForEachImportFrontToBackUntilTrue(const Node& node, const Callable& func) { |
| // Process most recently added imports first. |
| for (auto it = node.imports().rbegin(); it != node.imports().rend(); ++it) { |
| if (func(static_cast<Node*>((*it)->delegate()))) |
| return true; |
| } |
| return false; |
| } |
| |
| template <typename Callable> |
| bool ForEachChildAndImportFrontToBackUntilTrue(const Node& node, const Callable& func) { |
| return ForEachChildFrontToBackUntilTrue(node, func) || |
| ForEachImportFrontToBackUntilTrue(node, func); |
| } |
| |
| } // namespace gfx |
| } // namespace scenic_impl |
| |
| #endif // GARNET_LIB_UI_GFX_RESOURCES_NODES_TRAVERSAL_H_ |