Upstream Chrome on iOS source code [8/11].

ios/chrome/browser/ui/stack_view/stack_card.h

+// Copyright 2012 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.
+
+#ifndef IOS_CHROME_BROWSER_UI_STACK_VIEW_STACK_CARD_H_
+#define IOS_CHROME_BROWSER_UI_STACK_VIEW_STACK_CARD_H_
+
+#import <UIKit/UIKit.h>
+
+@class CardView;
+struct LayoutRect;
+@class StackCard;
+
+@protocol StackCardViewProvider
+// Returns the view to use for the given card.
+- (CardView*)cardViewWithFrame:(CGRect)frame forStackCard:(StackCard*)card;
+@end
+
+// Abstract representation of a card in the card stack. Allows operating on
+// the layout aspects of the card without the card actually having a view, so
+// that the view can easily be constructed lazily, purged for low memory, etc.
+// |StackCard| does not pixel-align its coordinates to avoid losing precision,
+// but does ensure that the origin of its view is always pixel-aligned.
+@interface StackCard : NSObject
+
+// The view corresponding to this card.
+// WARNING: The coordinates of the view should not be set directly, as doing so
+// will result in inconsistency.
+@property(nonatomic, readonly, retain) CardView* view;
+// The layout of the underyling CardView.
+@property(nonatomic, readwrite, assign) LayoutRect layout;
+// The size of the underlying CardView.  Setting this property updates |layout|
+// with thew new size while maintaining the center of the card.
+@property(nonatomic, readwrite, assign) CGSize size;
+// If set to |YES|, updates to the frame/bounds/center of the card will also
+// update the corresponding properties of its view; if |NO|, they will not
+// (but immediate synchronization will occur the next time that the property is
+// set to |YES|). Default is |YES|.
+// NOTE: This property exists to enable updating a card's coordinates multiple
+// times within an animation, as setting the coordinates of a |UIView| more
+// than once inside an animation can result in undesired animation. Use this
+// property with care.
+@property(nonatomic, readwrite, assign) BOOL synchronizeView;
+// |YES| if this card represents the current active tab.
+@property(nonatomic, assign) BOOL isActiveTab;
+// Opaque value representing the Tab to which this card corresponds. Do not add
+// uses of this property.
+// TODO(blundell): Remove this. b/8321162
+@property(nonatomic, assign) NSUInteger tabID;
+// Returns YES if the view for the card currently exists. Normally clients don't
+// need to know this, since |view| will create the view on demand, but this can
+// be used in cases where an operation should only be done if the view exists.
+@property(nonatomic, readonly) BOOL viewIsLive;
+
+// Initializes a new card which uses |viewProvider| to create its view.
+// |viewProvider| is not retained, and must outlive this object.
+- (instancetype)initWithViewProvider:(id<StackCardViewProvider>)viewProvider
+    NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+// Releases the view; it will be re-created on next access. Can be used to
+// temporarily free memory.
+- (void)releaseView;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_STACK_VIEW_STACK_CARD_H_