//
//  UIScrollView.h
//  UIKit
//
//  Copyright (c) 2007-2013, Apple Inc. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <CoreGraphics/CoreGraphics.h>
#import <UIKit/UIView.h>
#import <UIKit/UIGeometry.h>
#import <UIKit/UIKitDefines.h>

typedef NS_ENUM(NSInteger, UIScrollViewIndicatorStyle) {
    UIScrollViewIndicatorStyleDefault,     // black with white border. good against any background
    UIScrollViewIndicatorStyleBlack,       // black only. smaller. good against a white background
    UIScrollViewIndicatorStyleWhite        // white only. smaller. good against a black background
};

typedef NS_ENUM(NSInteger, UIScrollViewKeyboardDismissMode) {
    UIScrollViewKeyboardDismissModeNone,
    UIScrollViewKeyboardDismissModeOnDrag,      // dismisses the keyboard when a drag begins
    UIScrollViewKeyboardDismissModeInteractive, // the keyboard follows the dragging touch off screen, and may be pulled upward again to cancel the dismiss
} NS_ENUM_AVAILABLE_IOS(7_0);

UIKIT_EXTERN const CGFloat UIScrollViewDecelerationRateNormal NS_AVAILABLE_IOS(3_0);
UIKIT_EXTERN const CGFloat UIScrollViewDecelerationRateFast NS_AVAILABLE_IOS(3_0);

@class UIEvent, UIImageView, UIPanGestureRecognizer, UIPinchGestureRecognizer;
@protocol UIScrollViewDelegate;

NS_CLASS_AVAILABLE_IOS(2_0) @interface UIScrollView : UIView <NSCoding> {
  @package
    id                _delegate;
}

@property(nonatomic)         CGPoint                      contentOffset;  // 刚进入时，左上角开始滚动的位置
@property(nonatomic)         CGSize                       contentSize;    // 滚动范围
@property(nonatomic)         UIEdgeInsets                 contentInset;   // 四周增加额外的滚动范围与按钮的相反，是外边的

@property(nonatomic,assign) id<UIScrollViewDelegate>      delegate;  // 设置代理，实现代理的某些方法

// 是否锁定某个方向上的滚动，如果设置成yes，在进行水平滚动的时候，垂直方向不会滚动
@property(nonatomic,getter=isDirectionalLockEnabled) BOOL directionalLockEnabled;
// 超出范围以后是否弹回到边界上，默认是yes
@property(nonatomic)         BOOL                         bounces;
@property(nonatomic)         BOOL                         alwaysBounceVertical;
@property(nonatomic)         BOOL                         alwaysBounceHorizontal;
// 是否分页显示
@property(nonatomic,getter=isPagingEnabled) BOOL          pagingEnabled;

// 是否能滚动，默认是yes
@property(nonatomic,getter=isScrollEnabled) BOOL          scrollEnabled;

// 显示水平滚动指示器
@property(nonatomic)         BOOL       showsHorizontalScrollIndicator;
// 显示垂直滚动指示器
@property(nonatomic)         BOOL       showsVerticalScrollIndicator;

@property(nonatomic)         UIEdgeInsets                 scrollIndicatorInsets;          // default is UIEdgeInsetsZero. adjust indicators inside of insets
@property(nonatomic)         UIScrollViewIndicatorStyle   indicatorStyle;                 // default is UIScrollViewIndicatorStyleDefault
// 手指抬起以后，减速滚动的数独
@property(nonatomic)         CGFloat                      decelerationRate NS_AVAILABLE_IOS(3_0);

// 改变ContentOffset的值，并执行动画
- (void)setContentOffset:(CGPoint)contentOffset animated:(BOOL)animated;
- (void)scrollRectToVisible:(CGRect)rect animated:(BOOL)animated;         // scroll so rect is just visible (nearest edges). nothing if rect completely visible

- (void)flashScrollIndicators;             // 短时间显示滚动条，在scroll view进入最前面的时候手动调用



@property(nonatomic,readonly,getter=isTracking)     BOOL tracking;        // returns YES if user has touched. may not yet have started dragging
@property(nonatomic,readonly,getter=isDragging)     BOOL dragging;        // returns YES if user has started scrolling. this may require some time and or distance to move to initiate dragging
@property(nonatomic,readonly,getter=isDecelerating) BOOL decelerating;    // returns YES if user isn't dragging (touch up) but scroll view is still moving

@property(nonatomic) BOOL delaysContentTouches;       // default is YES. if NO, we immediately call -touchesShouldBegin:withEvent:inContentView:
@property(nonatomic) BOOL canCancelContentTouches;    // default is YES. if NO, then once we start tracking, we don't try to drag if the touch moves

// override points for subclasses to control delivery of touch events to subviews of the scroll view
// called before touches are delivered to a subview of the scroll view. if it returns NO the touches will not be delivered to the subview
// default returns YES
- (BOOL)touchesShouldBegin:(NSSet *)touches withEvent:(UIEvent *)event inContentView:(UIView *)view;
// called before scrolling begins if touches have already been delivered to a subview of the scroll view. if it returns NO the touches will continue to be delivered to the subview and scrolling will not occur
// not called if canCancelContentTouches is NO. default returns YES if view isn't a UIControl
- (BOOL)touchesShouldCancelInContentView:(UIView *)view;

#pragma - mark 缩放相关
@property(nonatomic) CGFloat minimumZoomScale;     // 最小的缩小范围  default is 1.0
@property(nonatomic) CGFloat maximumZoomScale;     // 最大的放大范围  default is 1.0. must be > minimum zoom scale to enable zooming

@property(nonatomic) CGFloat zoomScale NS_AVAILABLE_IOS(3_0);            // default is 1.0
- (void)setZoomScale:(CGFloat)scale animated:(BOOL)animated NS_AVAILABLE_IOS(3_0);
- (void)zoomToRect:(CGRect)rect animated:(BOOL)animated NS_AVAILABLE_IOS(3_0);

@property(nonatomic) BOOL  bouncesZoom;          // 默认是yes，设置成no以后，放大到最大后不能再放大，没有回弹的效果

@property(nonatomic,readonly,getter=isZooming)       BOOL zooming;       // 是否正在缩放
@property(nonatomic,readonly,getter=isZoomBouncing)  BOOL zoomBouncing;  // returns YES if we are in the middle of zooming back to the min/max value


#pragma - mark 手势相关
@property(nonatomic) BOOL  scrollsToTop; // 是否允许滚动到最顶部，默认yes
@property(nonatomic, readonly) UIPanGestureRecognizer *panGestureRecognizer NS_AVAILABLE_IOS(5_0);
@property(nonatomic, readonly) UIPinchGestureRecognizer *pinchGestureRecognizer NS_AVAILABLE_IOS(5_0);
@property(nonatomic) UIScrollViewKeyboardDismissMode keyboardDismissMode NS_AVAILABLE_IOS(7_0);

@end


#pragma - mark - 代理方法
@protocol UIScrollViewDelegate<NSObject>

@optional

// 正在滚动时调用
- (void)scrollViewDidScroll:(UIScrollView *)scrollView;

// 正在缩放的时候调用
- (void)scrollViewDidZoom:(UIScrollView *)scrollView NS_AVAILABLE_IOS(3_2);

// 开始拖拽表格的时候就会调用这个方法
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView;

// 结束拖拽时调用，velocity是在x和y方向上的减速度,向左滑动，x > 0 ,向下滑动 y > 0
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset NS_AVAILABLE_IOS(5_0);

// 拖拽结束，将要开始减速调用这个
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate;

// 手指一离开马上调用这个方法
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView;

// 停止滚动时调用这个方法
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView;

// 停止动画时调用
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView;

// 用户进行捏合手势的时候会调用这个方法，返回要缩放的控件
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView;

// 将要开始缩放会调用这个方法
- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view NS_AVAILABLE_IOS(3_2);

// 缩放结束调用这个方法，scale是缩放的倍数，在最大值和最小值之间
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale;

// 是否返回最顶部
- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView;

// 返回最顶部调用
- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView;

@end