Upstream Chrome on iOS source code [4/11].

ios/chrome/browser/ui/contextual_search/panel_configuration.h

+// Copyright 2015 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_CONTEXTUAL_SEARCH_PANEL_CONFIGURATION_H_
+#define IOS_CHROME_BROWSER_UI_CONTEXTUAL_SEARCH_PANEL_CONFIGURATION_H_
+
+#import <UIKit/UIKit.h>
+
+namespace ContextualSearch {
+
+// Possible states (static positions) of the panel.
+typedef NS_ENUM(NSInteger, PanelState) {
+  // TODO(crbug.com/546210): Rename to match Android implementation.
+  // Ordering matters for these values.
+  UNDEFINED = -1,
+  DISMISSED,   // (CLOSED) Offscreen
+  PEEKING,     // (PEEKED) Showing a small amount at the bottom of the screen
+  PREVIEWING,  // (EXPANDED) Panel covers 2/3 of the tab.
+  COVERING,    // (MAXIMIZED) Panel covers entire tab.
+};
+
+}  // namespace ContextualSearch
+
+// A PanelConfiguration object manages the panel's size, and the mapping between
+// states and y-coordinates for the panel. Nothing in the configuration object
+// changes the position or state of the panel; it just provides information for
+// other classes that make such changes.
+// PanelConfiguration is an abstract superclass; one of the device-specific
+// classes should be instantiated instead.
+@interface PanelConfiguration : NSObject
+
+// Size of the view that contains the panel.
+@property(nonatomic, assign) CGSize containerSize;
+// Current horizontal size class of the view that contains the panel.
+@property(nonatomic, assign) UIUserInterfaceSizeClass horizontalSizeClass;
+// Height that the panel peeks into the containing view when peeking.
+@property(nonatomic, readonly) CGFloat peekingHeight;
+
+// Creates and returns a configuration object for a container of the given size.
++ (instancetype)configurationForContainerSize:(CGSize)containerSize
+                          horizontalSizeClass:
+                              (UIUserInterfaceSizeClass)horizontalSizeClass;
+
+// Given the current configuration, returns the y-coordinate for the top of the
+// panel in |state|. This can be called "the position for |state|".
+- (CGFloat)positionForPanelState:(ContextualSearch::PanelState)state;
+
+// Given the current configuration, returns the state for a panel whose top
+// edge is at |positions|. The range of positions for a state are the half-
+// closed interval (J .. I], where I is position for |state| and J is the
+// position for |state| + 1. (Note that positions decrease, moving towards
+// the y-origin, as states increase).
+- (ContextualSearch::PanelState)panelStateForPosition:(CGFloat)position;
+
+// Returns the gradation (a value in [0.0 .. 1.0]) of |position| in terms of the
+// distance from |fromState| to |toState|. A gradation of 0.0 means |position|
+// is equal to the position for |fromState|; a gradation of 1.0 means it is
+// equal to the position for |toState|, and intermediate values correspond
+// linearly to intermediate values.
+- (CGFloat)gradationToState:(ContextualSearch::PanelState)toState
+                  fromState:(ContextualSearch::PanelState)fromState
+                 atPosition:(CGFloat)position;
+
+// Given |panel|, a view being used as the panel that the receiver configures,
+// return constraints to size the panel as defined by the receiver.
+- (NSArray*)constraintsForSizingPanel:(UIView*)panel;
+
+// Given a |guide|, which must have a non-nil owning view, constructs and
+// returns an autoreleased layout constraint that correctly sets the height of
+// |guide| for |guide| to act as a positioning guide for a panel in |state|.
+- (NSLayoutConstraint*)
+constraintForPositioningGuide:(UILayoutGuide*)view
+                      atState:(ContextualSearch::PanelState)state;
+
+@end
+
+// Panel configuration for phone formats.
+@interface PhonePanelConfiguration : PanelConfiguration
+@end
+
+// Panel configuration for iPad interface idioms.
+@interface PadPanelConfiguration : PanelConfiguration
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_CONTEXTUAL_SEARCH_PANEL_CONFIGURATION_H_