WuKongJiZhang/JIZHANG/Use/HZMLazyScrol...

//
//  DMLazyScrollView.m
//  Lazy Loading UIScrollView for iOS
//
//  Created by Daniele Margutti (me@danielemargutti.com) on 24/11/12.
//  Copyright (c) 2012 http://www.danielemargutti.com. All rights reserved.
//  Distribuited under MIT License
//

#import "HZMLazyScrollView.h"

enum {
    HZMLazyScrollViewScrollDirectionBackward     = 0,
    HZMLazyScrollViewScrollDirectionForward      = 1
}; typedef NSUInteger HZMLazyScrollViewScrollDirection;

#define kDMLazyScrollViewTransitionDuration     0.2

@interface HZMLazyScrollView() <UIScrollViewDelegate> {
    NSUInteger      currentPage;
    BOOL            isManualAnimating;
}

@end

@implementation HZMLazyScrollView

@synthesize numberOfPages,currentPage;
@synthesize dataSource,controlDelegate;

- (id)init {
    return [self initWithFrame:CGRectZero];
}

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self initializeControl];
    }
    return self;
}

- (BOOL)hasMultiplePages {
    return self.numberOfPages > 1;
}


- (void) awakeFromNib {
    [super awakeFromNib];

    [self initializeControl];
}

- (void) initializeControl {
    self.showsHorizontalScrollIndicator = NO;
    self.showsVerticalScrollIndicator = NO;
    self.pagingEnabled = YES;
    self.delegate = self;
    self.contentSize = CGSizeMake(self.frame.size.width, self.contentSize.height);
    self.bounces = NO;
    self.scrollsToTop = NO;
    currentPage = NSNotFound;
}

- (void) setNumberOfPages:(NSUInteger)pages {
//    if (pages != numberOfPages) {
        numberOfPages = pages;
        NSInteger offset = [self hasMultiplePages] ? numberOfPages : 1;
            self.contentSize = CGSizeMake(self.frame.size.width * offset,
                                          self.contentSize.height);
        [self reloadData];
//    }
}

-(void)setFrame:(CGRect)frame{
    [super setFrame:frame];
    
    if (self.numberOfPages) {
        [self setNumberOfPages:self.numberOfPages];
    }
}

- (void) reloadData {
    [self setCurrentViewController:currentPage!=NSNotFound?currentPage:0];
}

- (void) layoutSubviews {
    [super layoutSubviews];
}

- (CGRect) visibleRect {
    CGRect visibleRect;
    visibleRect.origin = self.contentOffset;
    visibleRect.size = self.bounds.size;
    return visibleRect;
}

- (CGPoint) createPoint:(CGFloat) size {
//    if (_direction == HZMLazyScrollViewDirectionHorizontal) {
        return CGPointMake(size, 0);
//    } else {
//        return CGPointMake(0, size);
//    }
}

-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
    if (nil != controlDelegate && [controlDelegate respondsToSelector:@selector(lazyScrollViewDidEndDragging:)])
        [controlDelegate lazyScrollViewDidEndDragging:self];
}


- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    if (nil != controlDelegate && [controlDelegate respondsToSelector:@selector(lazyScrollViewWillBeginDragging:)])
        [controlDelegate lazyScrollViewWillBeginDragging:self];
}

- (void) scrollViewDidScroll:(UIScrollView *)scrollView {
    CGFloat offset = scrollView.contentOffset.x;
    CGFloat size = self.frame.size.width;

    NSInteger newPageIndex = -1;
    float fractionalPage = offset/size;
    if (fractionalPage -(float)currentPage >= 0) {
        newPageIndex = (int)fractionalPage;
    }else{
        newPageIndex = (int)(ceilf(fractionalPage));
    }
    
    if (newPageIndex > -1 && newPageIndex < self.numberOfPages && newPageIndex != currentPage) {
        if (newPageIndex == 1) {
            NSLog(@"%f",offset);
        }
           [self setCurrentViewController:newPageIndex];
    }
 
    
    // alert delegate
    if (nil != controlDelegate && [controlDelegate respondsToSelector:@selector(lazyScrollViewDidScroll:at:withSelfDrivenAnimation:)]) {
        [controlDelegate lazyScrollViewDidScroll:self at:[self visibleRect].origin withSelfDrivenAnimation:NO];
    }
    else if (nil != controlDelegate && [controlDelegate respondsToSelector:@selector(lazyScrollViewDidScroll:at:)]) {
        [controlDelegate lazyScrollViewDidScroll:self at:[self visibleRect].origin];
    }
}

- (void) setCurrentViewController:(NSInteger) index {
    if (index == currentPage) return;
    currentPage = index;
   
    if (_isForbiddenLazyLoad) {
        [self loadControllerAtIndex:index];
    }else{
        [self loadControllerAtIndex:index];
        [self loadControllerAtIndex:index-1];
        [self loadControllerAtIndex:index+1];
    }
    
    if ([self.controlDelegate respondsToSelector:@selector(lazyScrollView:currentPageChanged:)])
        [self.controlDelegate lazyScrollView:self currentPageChanged:self.currentPage];
}


- (NSInteger) pageIndexByAdding:(NSInteger) offset from:(NSInteger) index {
    if (offset <0) {
        return currentPage==0?-1:index-1;
    }else{
        return currentPage==self.numberOfPages-1?-1:index+1;
    }
}

- (void) moveByPages:(NSInteger) offset animated:(BOOL) animated {
    NSUInteger finalIndex = [self pageIndexByAdding:offset from:self.currentPage];
    HZMLazyScrollViewTransition transition = (offset >= 0 ?  HZMLazyScrollViewTransitionForward :
                                             HZMLazyScrollViewTransitionBackward);
    [self setPage:finalIndex transition:transition];
}

- (void) setPage:(NSInteger) newIndex{
    [self setPage:newIndex transition:HZMLazyScrollViewTransitionForward];
}

- (void) setPage:(NSInteger) newIndex transition:(HZMLazyScrollViewTransition) transition{
    if (newIndex == currentPage) return;
//        CGFloat size =(_direction==HZMLazyScrollViewDirectionHorizontal) ? self.frame.size.width : self.frame.size.height;
//        CGPoint finalOffset =(_direction==HZMLazyScrollViewDirectionHorizontal) ? CGPointMake(size* newIndex,0):CGPointMake(0,size* newIndex);
    
    CGFloat size =self.frame.size.width;
    CGPoint finalOffset =CGPointMake(size* newIndex,0);
    
    [self setCurrentViewController:newIndex];
    self.contentOffset = finalOffset;
    }

- (void) setCurrentPage:(NSUInteger)newCurrentPage {
    [self setCurrentViewController:newCurrentPage];
}

- (void) loadControllerAtIndex:(NSInteger) index{
    if (index < 0) {
        return;
    }
    
    if (index >= self.numberOfPages) {
        return;
    }
    
    
    UIViewController *viewController = dataSource(index);
    if (viewController == nil) {
        return;
    }

    if (viewController.view.superview ==nil) {
        CGRect viewFrame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
//        if (_direction == HZMLazyScrollViewDirectionHorizontal) {
        viewFrame = CGRectOffset(viewFrame, self.frame.size.width * index, 0);
//        } else {
//            viewFrame = CGRectOffset(viewFrame, 0, self.frame.size.height * index);
//        }
        
        viewController.view.frame = viewFrame;
        
        [self addSubview:viewController.view];
    }
}



- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView {
    if (nil != controlDelegate && [controlDelegate respondsToSelector:@selector(lazyScrollViewWillBeginDecelerating:)])
        [controlDelegate lazyScrollViewWillBeginDecelerating:self];
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    if (nil != controlDelegate && [controlDelegate respondsToSelector:@selector(lazyScrollViewDidEndDecelerating:atPageIndex:)])
        [controlDelegate lazyScrollViewDidEndDecelerating:self atPageIndex:self.currentPage];
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]
        && [otherGestureRecognizer isKindOfClass:[UIScreenEdgePanGestureRecognizer class]])
    {
        return YES;
    }
    else
    {
        return  NO;
    }
}
@end