Add stack layout.

1 files changed, 91 insertions, 0 deletions

diff --git a/include/cru/ui/render/layout_render_object.hpp b/include/cru/ui/render/layout_render_object.hpp
new file mode 100644
index 00000000..db6daba9
--- /dev/null
+++ b/include/cru/ui/render/layout_render_object.hpp
@@ -0,0 +1,91 @@
+#pragma once
+#include "render_object.hpp"
+
+#include "cru/platform/graph/util/painter.hpp"
+
+#include <cassert>
+#include <functional>
+
+namespace cru::ui::render {
+template <typename TChildLayoutData>
+class LayoutRenderObject : public RenderObject {
+ public:
+  using ChildLayoutData = TChildLayoutData;
+
+ protected:
+  LayoutRenderObject() : RenderObject(ChildMode::Multiple) {}
+
+ public:
+  CRU_DELETE_COPY(LayoutRenderObject)
+  CRU_DELETE_MOVE(LayoutRenderObject)
+
+  ~LayoutRenderObject() override = default;
+
+  ChildLayoutData* GetChildLayoutData(int position) {
+    assert(position >= 0 &&
+           position < static_cast<int>(child_layout_data_.size()));
+    return &child_layout_data_[position];
+  }
+
+  void Draw(platform::graph::IPainter* painter) override;
+
+  RenderObject* HitTest(const Point& point) override;
+
+ protected:
+  void OnAddChild(RenderObject* new_child, int position) override;
+  void OnRemoveChild(RenderObject* removed_child, int position) override;
+
+ private:
+  std::vector<ChildLayoutData> child_layout_data_{};
+};
+
+template <typename TChildLayoutData>
+void LayoutRenderObject<TChildLayoutData>::Draw(
+    platform::graph::IPainter* painter) {
+  for (const auto child : GetChildren()) {
+    auto offset = child->GetOffset();
+    platform::graph::util::WithTransform(
+        painter, platform::Matrix::Translation(offset.x, offset.y),
+        [child](auto p) { child->Draw(p); });
+  }
+}
+
+template <typename TChildLayoutData>
+RenderObject* LayoutRenderObject<TChildLayoutData>::HitTest(
+    const Point& point) {
+  const auto& children = GetChildren();
+  for (auto i = children.crbegin(); i != children.crend(); ++i) {
+    auto offset = (*i)->GetOffset();
+    Point p{point.x - offset.x, point.y - offset.y};
+    const auto result = (*i)->HitTest(p);
+    if (result != nullptr) {
+      return result;
+    }
+  }
+
+  const auto margin = GetMargin();
+  const auto size = GetSize();
+  return Rect{margin.left, margin.top,
+              std::max(size.width - margin.GetHorizontalTotal(), 0.0f),
+              std::max(size.height - margin.GetVerticalTotal(), 0.0f)}
+                 .IsPointInside(point)
+             ? this
+             : nullptr;
+}  // namespace cru::ui::render
+
+template <typename TChildLayoutData>
+void LayoutRenderObject<TChildLayoutData>::OnAddChild(RenderObject* new_child,
+                                                      int position) {
+  CRU_UNUSED(new_child)
+
+  child_layout_data_.emplace(child_layout_data_.cbegin() + position);
+}
+
+template <typename TChildLayoutData>
+void LayoutRenderObject<TChildLayoutData>::OnRemoveChild(
+    RenderObject* removed_child, int position) {
+  CRU_UNUSED(removed_child)
+
+  child_layout_data_.erase(child_layout_data_.cbegin() + position);
+}
+}  // namespace cru::ui::render