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LineLayout.m
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executable file
·123 lines (114 loc) · 5.99 KB
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#import "LineLayout.h"
//#define ITEM_SIZE 180.0
//#define ITEM_SIZE_witdh 200.0
//#define ITEM_SIZE_height 200.0
//#define ACTIVE_DISTANCE 200
//#define ZOOM_FACTOR 0
@implementation LineLayout
- (id)init:(CGSize)cellSize withMinimumLineSpacing:(CGFloat) minimumLS andMainCellLineSpacing:(CGFloat) mainCellLS{
self = [super init];
if (self) {
sizeOfCell = cellSize;
firstLayout = YES;
minimumLineSpacing = minimumLS;
mainCellLineSpacing = mainCellLS;
self.itemSize = cellSize;
self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
// 确定了缩进，此处为上方、下方各缩进200
self.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);
// 每个item在水平方向的最小间距
self.minimumLineSpacing = minimumLS;
}
return self;
}
- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)oldBounds{
return YES;
}
// 初始的layout外观将由该方法返回的UICollctionViewLayoutAttributes来决定
-(NSArray*)layoutAttributesForElementsInRect:(CGRect)rect{
NSArray* array = [super layoutAttributesForElementsInRect:rect];
CGRect visibleRect;
if (firstLayout) {
[self.collectionView setContentOffset:CGPointMake(10 + sizeOfCell.width * 2 + minimumLineSpacing * 2 - mainCellLineSpacing, 0) animated:NO];
firstLayout = !firstLayout;
}
visibleRect.origin = self.collectionView.contentOffset;
visibleRect.size = self.collectionView.bounds.size;
// for (UICollectionViewLayoutAttributes* attributes in array) {
// if (CGRectIntersectsRect(attributes.frame, rect)) {
// CGFloat distance = CGRectGetMidX(visibleRect) - attributes.center.x;
// CGFloat normalizedDistance = distance / ACTIVE_DISTANCE;
// if (ABS(distance) < ACTIVE_DISTANCE) {
// CGFloat zoom = 1 + ZOOM_FACTOR*(1 - ABS(normalizedDistance));
// attributes.transform3D = CATransform3DMakeScale(zoom, zoom, 1.0);
// attributes.zIndex = 1;
// }
// }
// }
return array;
}
// 自动对齐到网格
- (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity{
// proposedContentOffset是没有对齐到网格时本来应该停下来的位置
/*CGFloat offsetAdjustment = MAXFLOAT;
CGFloat horizontalCenter = proposedContentOffset.x / 2 + (CGRectGetWidth(self.collectionView.bounds) / 2.0);
// 当前显示的区域
CGRect targetRect = CGRectMake(proposedContentOffset.x, proposedContentOffset.y, self.collectionView.bounds.size.width, self.collectionView.bounds.size.height);
// 取当前显示的item
NSArray* array = [super layoutAttributesForElementsInRect:targetRect];
// 对当前屏幕中的UICollectionViewLayoutAttributes逐个与屏幕中心进行比较，找出最接近中心的一个
for (UICollectionViewLayoutAttributes* layoutAttributes in array) {
CGFloat itemHorizontalCenter = layoutAttributes.center.x;
if (ABS(itemHorizontalCenter - horizontalCenter) < ABS(offsetAdjustment)) {
offsetAdjustment = itemHorizontalCenter - horizontalCenter;
}
}*/
CGPoint pointAfterSlide;
CGFloat rightSlideThreshold = 10 + sizeOfCell.width * 2 + minimumLineSpacing * 2 - mainCellLineSpacing + sizeOfCell.width / 2;
// CGFloat rightSlideDoubleItemThreshold = 10 + sizeOfCell.width * 3 + minimumLineSpacing * 3 - mainCellLineSpacing + sizeOfCell.width / 2;
// CGFloat leftSlideDoubleItemThreshold = 10 + sizeOfCell.width / 2;
CGFloat leftSlideThreshold = 10 + sizeOfCell.width + minimumLineSpacing + sizeOfCell.width + minimumLineSpacing - sizeOfCell.width / 2;
if (proposedContentOffset.x >= rightSlideThreshold) {
// if (proposedContentOffset.x > rightSlideDoubleItemThreshold) {
// if (lineLayoutDelegate) {
// [lineLayoutDelegate isSlideToLeft:NO isNeedBeRefresh:YES];
// [lineLayoutDelegate isSlideDouble];
// }
// }else{
// pointAfterSlide = CGPointMake(10 + sizeOfCell.width * 3 + minimumLineSpacing * 3 - mainCellLineSpacing, proposedContentOffset.y);
// if (lineLayoutDelegate) {
// [lineLayoutDelegate isSlideToLeft:NO isNeedBeRefresh:YES];
// }
// }
pointAfterSlide = CGPointMake(10 + sizeOfCell.width * 3 + minimumLineSpacing * 3 - mainCellLineSpacing, proposedContentOffset.y);
// if (lineLayoutDelegate) {
// [lineLayoutDelegate isSlideToLeft:NO isNeedBeRefresh:YES];
// }
}else{
if (proposedContentOffset.x <= leftSlideThreshold) {
// if (proposedContentOffset.x <= leftSlideDoubleItemThreshold) {
// if (lineLayoutDelegate) {
// [lineLayoutDelegate isSlideToLeft:YES isNeedBeRefresh:YES];
// [lineLayoutDelegate isSlideDouble];
// }
// }else{
// pointAfterSlide = CGPointMake(10 + sizeOfCell.width + minimumLineSpacing - mainCellLineSpacing, proposedContentOffset.y);
// if (lineLayoutDelegate) {
// [lineLayoutDelegate isSlideToLeft:YES isNeedBeRefresh:YES];
// }
// }
pointAfterSlide = CGPointMake(10 + sizeOfCell.width + minimumLineSpacing - mainCellLineSpacing, proposedContentOffset.y);
// if (lineLayoutDelegate) {
// [lineLayoutDelegate isSlideToLeft:YES isNeedBeRefresh:YES];
// }
}else{
pointAfterSlide = CGPointMake(10 + sizeOfCell.width * 2 + minimumLineSpacing * 2 - mainCellLineSpacing, proposedContentOffset.y);
// if (lineLayoutDelegate) {
// [lineLayoutDelegate isNeedToBeRefresh:NO];
// }
}
}
return pointAfterSlide;
//return CGPointMake(proposedContentOffset.x + offsetAdjustment, proposedContentOffset.y);
}
@end