layout_manager_base.h | Explore in Territory

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_VIEWS_LAYOUT_LAYOUT_MANAGER_BASE_H_
#define UI_VIEWS_LAYOUT_LAYOUT_MANAGER_BASE_H_

#include <map>
#include <memory>
#include <optional>
#include <set>
#include <utility>
#include <vector>

#include "base/dcheck_is_on.h"
#include "base/memory/raw_ptr.h"
#include "base/scoped_multi_source_observation.h"
#include "base/types/pass_key.h"
#include "ui/gfx/geometry/insets.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"
#include "ui/views/layout/layout_manager.h"
#include "ui/views/layout/layout_types.h"
#include "ui/views/layout/proposed_layout.h"
#include "ui/views/view_observer.h"
#include "ui/views/views_export.h"

namespace views {

class View;

// Base class for layout managers that can do layout calculation separately
// from layout application. Derived classes must implement
// CalculateProposedLayout(). Used in interpolating and animating layouts.
class VIEWS_EXPORT LayoutManagerBase : public LayoutManager,
                                       public ViewObserver { … };

// Provides methods for doing additional, manual manipulation of a
// `LayoutManagerBase` and its managed Views inside its host View's
// layout implementation, ideally before `LayoutManager::Layout()` is invoked.
//
// In most cases, the layout manager should do all of the layout. However, in
// some cases, specific children of the host may be explicitly manipulated; for
// example, to conditionally show a button which (if visible) should be included
// in the layout.
//
// All of the direct manipulation functions on `LayoutManagerBase` and `View`,
// such as `View::SetVisible()` and
// `LayoutManagerBase::SetChildIncludedInLayout()`, cause cascades of layout
// invalidation up the Views tree, so are not appropriate to be used inside of a
// `Layout()` override. In the case that manual layout manipulation is required
// alongside the use of a layout manager, a `ManualLayoutUtil` should be used
// instead of callin those other methods directly.
//
// This class should only be instantiated and used inside the `Layout()` method
// of a `View` or derived class, before `LayoutManager::Layout()` is invoked.
class VIEWS_EXPORT ManualLayoutUtil { … };

}  // namespace views

#endif  // UI_VIEWS_LAYOUT_LAYOUT_MANAGER_BASE_H_
chromium/ui/views/layout/layout_manager_base.h
