/*	NSLayoutAnchor.h
	Copyright (c) 2015, Apple Inc. All rights reserved.
*/

#import <Foundation/Foundation.h>

@class NSLayoutConstraint, NSLayoutAnchor;


/* An NSLayoutAnchor represents an edge or dimension of a layout item.  Its concrete 
 subclasses allow concise creation of constraints.  
    Instead of invoking 
 
 +[NSLayoutConstraint constraintWithItem:attribute:relatedBy:toItem:attribute:multiplier:constant:] 
 
 directly, you can instead do something like this:
 
 [myView.topAnchor constraintEqualToAnchor:otherView.topAnchor constant:10];
 
 The -constraint* methods are available in multiple flavors to support use of different
 relations and omission of unused options.
 */
NS_CLASS_AVAILABLE_IOS(9_0)
@interface NSLayoutAnchor<AnchorType> : NSObject

/* These methods return an inactive constraint of the form thisAnchor = otherAnchor.
 */
- (NSLayoutConstraint *)constraintEqualToAnchor:(NSLayoutAnchor<AnchorType> *)anchor;
- (NSLayoutConstraint *)constraintGreaterThanOrEqualToAnchor:(NSLayoutAnchor<AnchorType> *)anchor;
- (NSLayoutConstraint *)constraintLessThanOrEqualToAnchor:(NSLayoutAnchor<AnchorType> *)anchor;

/* These methods return an inactive constraint of the form thisAnchor = otherAnchor + constant.
 */
- (NSLayoutConstraint *)constraintEqualToAnchor:(NSLayoutAnchor<AnchorType> *)anchor constant:(CGFloat)c;
- (NSLayoutConstraint *)constraintGreaterThanOrEqualToAnchor:(NSLayoutAnchor<AnchorType> *)anchor constant:(CGFloat)c;
- (NSLayoutConstraint *)constraintLessThanOrEqualToAnchor:(NSLayoutAnchor<AnchorType> *)anchor constant:(CGFloat)c;
@end


/* Axis-specific subclasses for location anchors: top/bottom, leading/trailing, baseline, etc.
 */
@class NSLayoutXAxisAnchor, NSLayoutYAxisAnchor;
NS_CLASS_AVAILABLE_IOS(9_0)
@interface NSLayoutXAxisAnchor : NSLayoutAnchor<NSLayoutXAxisAnchor *>
@end
NS_CLASS_AVAILABLE_IOS(9_0)
@interface NSLayoutYAxisAnchor : NSLayoutAnchor<NSLayoutYAxisAnchor *>
@end


/* This layout anchor subclass is used for sizes (width & height).
 */
@class NSLayoutDimension;
NS_CLASS_AVAILABLE_IOS(9_0)
@interface NSLayoutDimension : NSLayoutAnchor<NSLayoutDimension *>

/* These methods return an inactive constraint of the form 
    thisVariable = constant.
*/
- (NSLayoutConstraint *)constraintEqualToConstant:(CGFloat)c;
- (NSLayoutConstraint *)constraintGreaterThanOrEqualToConstant:(CGFloat)c;
- (NSLayoutConstraint *)constraintLessThanOrEqualToConstant:(CGFloat)c;

/* These methods return an inactive constraint of the form 
    thisAnchor = otherAnchor * multiplier.
*/
- (NSLayoutConstraint *)constraintEqualToAnchor:(NSLayoutDimension *)anchor multiplier:(CGFloat)m;
- (NSLayoutConstraint *)constraintGreaterThanOrEqualToAnchor:(NSLayoutDimension *)anchor multiplier:(CGFloat)m;
- (NSLayoutConstraint *)constraintLessThanOrEqualToAnchor:(NSLayoutDimension *)anchor multiplier:(CGFloat)m;

/* These methods return an inactive constraint of the form 
    thisAnchor = otherAnchor * multiplier + constant.
*/
- (NSLayoutConstraint *)constraintEqualToAnchor:(NSLayoutDimension *)anchor multiplier:(CGFloat)m constant:(CGFloat)c;
- (NSLayoutConstraint *)constraintGreaterThanOrEqualToAnchor:(NSLayoutDimension *)anchor multiplier:(CGFloat)m constant:(CGFloat)c;
- (NSLayoutConstraint *)constraintLessThanOrEqualToAnchor:(NSLayoutDimension *)anchor multiplier:(CGFloat)m constant:(CGFloat)c;
@end