flex_layout.h | Explore in Territory

// Copyright 2018 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_FLEX_LAYOUT_H_
#define UI_VIEWS_LAYOUT_FLEX_LAYOUT_H_

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

#include "base/memory/raw_ptr.h"
#include "ui/base/class_property.h"
#include "ui/gfx/geometry/insets.h"
#include "ui/views/layout/flex_layout_types.h"
#include "ui/views/layout/layout_manager_base.h"
#include "ui/views/view_class_properties.h"
#include "ui/views/views_export.h"

namespace views {

class NormalizedSize;
class NormalizedSizeBounds;
class View;

// Provides CSS-like layout for a one-dimensional (vertical or horizontal)
// arrangement of child views. Independent alignment can be specified for the
// main and cross axes.
//
// Per-View margins (provided by view property kMarginsKey) specify how much
// space to leave around each child view. The |interior_margin| says how much
// empty space to leave at the edges of the parent view. If |collapse_margins|
// is false, these values are additive; if true, the greater of the two values
// is used. The |default_child_margins| provides a fallback for views without
// kMarginsKey set.
//
// collapse_margins = false:
//
// | interior margin>                      <margin [view]...
// |                 <margin [view] margin>
//
// collapse_margins = true:
//
// | interior margin>      <margin [view]
// |         <margin [view] margin>       ...
//
// Views can have their own internal padding, using the kInternalPaddingKey
// property, which is subtracted from the margin space between child views.
//
// Calling SetVisible(false) on a child view outside of the FlexLayout will
// result in the child view being hidden until SetVisible(true) is called. This
// is irrespective of whether the FlexLayout has set the child view to be
// visible or not based on, for example, flex rules.
//
// If you want the host view to maintain control over a child view, you can
// exclude it from the layout. Excluded views are completely ignored during
// layout and do not have their properties modified.
//
// FlexSpecification objects determine how child views are sized. You can set
// individual flex rules for each child view, or a default for any child views
// without individual flex rules set. If you don't set anything, each view will
// take up its preferred size in the layout.
//
// The core function of this class is contained in
// GetPreferredSize(maximum_size) and Layout(). In both cases, a layout will be
// cached and typically not recalculated as long as none of the layout's
// properties or the preferred size or visibility of any of its children has
// changed.
class VIEWS_EXPORT FlexLayout : public LayoutManagerBase { … };

}  // namespace views

#endif  // UI_VIEWS_LAYOUT_FLEX_LAYOUT_H_
chromium/ui/views/layout/flex_layout.h
