Experimental alignment layout manager using a property on the views

ui/views/anchor_attribute.cc

+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/views/anchor_attribute.h"
+
+namespace views {
+
+AnchorContent::AnchorContent()
+    : attribute_(nullptr),
+      anchors_({Anchor::Top, Anchor::Left}),
+      anchor_basis_(0, 0),
+      last_parent_size_(0, 0) {}
+
+AnchorContent::AnchorContent(Anchors anchors)
+    : attribute_(nullptr),
+      anchors_(anchors),
+      anchor_basis_(0, 0),
+      last_parent_size_(0, 0) {}
+
+AnchorContent::AnchorContent(const AnchorContent& content)
+    : attribute_(content.attribute_),
+      anchors_(content.anchors_),
+      anchor_basis_(content.anchor_basis_),
+      last_parent_size_(content.last_parent_size_) {}
+
+AnchorAttribute::AnchorAttribute() :
+  CustomAttribute<AnchorContent>(AnchorContent()) {
+  GetContent().SetAttribute(this);
+}
+
+AnchorAttribute::AnchorAttribute(Anchors anchors) :
+  CustomAttribute<AnchorContent>(AnchorContent(anchors)) {
+  GetContent().SetAttribute(this);
+}
+
+AnchorAttribute::AnchorAttribute(AnchorContent& content) :
+  CustomAttribute<AnchorContent>(content) {
+  GetContent().SetAttribute(this);
+}
+
+AttributeId AnchorAttribute::Identity() const {
+  return GetAttributeId<AnchorAttribute>();
+}
+
+void AnchorAttribute::Notification(Attribute::NotifyType type,
+                                   Attribute* attribute) {
+  FillAttribute* fill = attribute->AsAttribute<FillAttribute>();
+  if (fill) {
+    if (type == Attribute::NotifyType::AttributeAdded)
+      GetContent().SetAnchors(AnchorContent::AnchorFill(fill->fill()));
+    else
+      GetContent().SetAnchors(Anchors({Anchor::Left, Anchor::Top}));
+  }
+}
+
+void AnchorAttribute::ViewNotification(View* view) {
+  GetContent().UpdateAnchorBasis(view);
+}
+
+Anchors AnchorContent::AnchorFill(Fill fill) {
+  static int anchor_fill[] = {
+    // Fill::Left
+    (1 << static_cast<int>(Anchor::Left)) |
+    (1 << static_cast<int>(Anchor::Top)) |
+    (1 << static_cast<int>(Anchor::Bottom)),
+    // Fill::Top
+    (1 << static_cast<int>(Anchor::Left)) |
+    (1 << static_cast<int>(Anchor::Top)) |
+    (1 << static_cast<int>(Anchor::Right)),
+    // Fill::Right
+    (1 << static_cast<int>(Anchor::Top)) |
+    (1 << static_cast<int>(Anchor::Right)) |
+    (1 << static_cast<int>(Anchor::Bottom)),
+    // Fill::Bottom
+    (1 << static_cast<int>(Anchor::Left)) |
+    (1 << static_cast<int>(Anchor::Right)) |
+    (1 << static_cast<int>(Anchor::Bottom)),
+    // Fill::Content
+    (1 << static_cast<int>(Anchor::Left)) |
+    (1 << static_cast<int>(Anchor::Top)) |
+    (1 << static_cast<int>(Anchor::Right)) |
+    (1 << static_cast<int>(Anchor::Bottom)),
+  };
+  return Anchors(anchor_fill[static_cast<int>(fill)]);
+}
+
+void AnchorContent::SetAnchors(Anchors anchors) {
+  if (anchors_ != anchors) {
+    anchors_ = anchors;
+    UpdateAnchorBasis(attribute_->view());
+  }
+}
+
+void AnchorContent::UpdateAnchorBasis(View* view) {
+  if (anchors_.Equals({Anchor::Left, Anchor::Top})) {
+    last_parent_size_ = gfx::Size(0, 0);
+    return;
+  }
+  gfx::Point center_point = view->bounds().CenterPoint();
+  if (anchors_.Contains(Anchor::Right))
+    if (anchors_.Contains(Anchor::Left))
+      anchor_basis_.set_x(view->width());
+    else
+      anchor_basis_.set_x(view->x());
+  else
+    anchor_basis_.set_x(center_point.x());
+  if (anchors_.Contains(Anchor::Bottom))
+    if (anchors_.Contains(Anchor::Top))
+      anchor_basis_.set_y(view->height());
+    else
+      anchor_basis_.set_y(view->y());
+  else
+    anchor_basis_.set_y(center_point.y());
+  if (view->parent())
+    last_parent_size_ = view->parent()->GetContentsBounds().size();
+}
+
+}  // namespace views