169 lines
4.7 KiB
Objective-C
169 lines
4.7 KiB
Objective-C
//
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// Copyright (c) 2019 Open Whisper Systems. All rights reserved.
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//
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#import "ConversationViewLayout.h"
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#import "Session-Swift.h"
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#import "UIView+OWS.h"
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NS_ASSUME_NONNULL_BEGIN
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@interface ConversationViewLayout ()
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@property (nonatomic) CGFloat lastViewWidth;
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@property (nonatomic) CGSize contentSize;
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@property (nonatomic, readonly) NSMutableDictionary<NSNumber *, UICollectionViewLayoutAttributes *> *itemAttributesMap;
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// This dirty flag may be redundant with logic in UICollectionViewLayout,
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// but it can't hurt and it ensures that we can safely & cheaply call
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// prepareLayout from view logic to ensure that we always have a¸valid
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// layout without incurring any of the (great) expense of performing an
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// unnecessary layout pass.
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@property (nonatomic) BOOL hasLayout;
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@property (nonatomic) BOOL hasEverHadLayout;
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@end
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#pragma mark -
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@implementation ConversationViewLayout
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- (instancetype)initWithConversationStyle:(ConversationStyle *)conversationStyle
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{
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if (self = [super init]) {
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_itemAttributesMap = [NSMutableDictionary new];
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_conversationStyle = conversationStyle;
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}
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return self;
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}
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- (void)setHasLayout:(BOOL)hasLayout
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{
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_hasLayout = hasLayout;
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if (hasLayout) {
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self.hasEverHadLayout = YES;
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}
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}
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- (void)invalidateLayout
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{
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[super invalidateLayout];
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[self clearState];
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}
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- (void)invalidateLayoutWithContext:(UICollectionViewLayoutInvalidationContext *)context
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{
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[super invalidateLayoutWithContext:context];
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[self clearState];
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}
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- (void)clearState
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{
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self.contentSize = CGSizeZero;
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[self.itemAttributesMap removeAllObjects];
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self.hasLayout = NO;
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self.lastViewWidth = 0.f;
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}
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- (void)prepareLayout
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{
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[super prepareLayout];
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id<ConversationViewLayoutDelegate> delegate = self.delegate;
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if (!delegate) {
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OWSFailDebug(@"Missing delegate");
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[self clearState];
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return;
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}
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if (self.collectionView.bounds.size.width <= 0.f || self.collectionView.bounds.size.height <= 0.f) {
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OWSFailDebug(@"Collection view has invalid size: %@", NSStringFromCGRect(self.collectionView.bounds));
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[self clearState];
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return;
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}
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if (self.hasLayout) {
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return;
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}
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self.hasLayout = YES;
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[self prepareLayoutOfItems];
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}
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- (void)prepareLayoutOfItems
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{
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const CGFloat viewWidth = self.conversationStyle.viewWidth;
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NSArray<id<ConversationViewLayoutItem>> *layoutItems = self.delegate.layoutItems;
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CGFloat y = self.conversationStyle.contentMarginTop + self.delegate.layoutHeaderHeight;
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CGFloat contentBottom = y;
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NSInteger row = 0;
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id<ConversationViewLayoutItem> _Nullable previousLayoutItem = nil;
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for (id<ConversationViewLayoutItem> layoutItem in layoutItems) {
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if (previousLayoutItem) {
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y += [layoutItem vSpacingWithPreviousLayoutItem:previousLayoutItem];
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}
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CGSize layoutSize = CGSizeCeil([layoutItem cellSize]);
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// Ensure cell fits within view.
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OWSAssertDebug(layoutSize.width <= viewWidth);
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layoutSize.width = MIN(viewWidth, layoutSize.width);
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// All cells are "full width" and are responsible for aligning their own content.
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CGRect itemFrame = CGRectMake(0, y, viewWidth, layoutSize.height);
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NSIndexPath *indexPath = [NSIndexPath indexPathForRow:row inSection:0];
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UICollectionViewLayoutAttributes *itemAttributes =
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[UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
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itemAttributes.frame = itemFrame;
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self.itemAttributesMap[@(row)] = itemAttributes;
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contentBottom = itemFrame.origin.y + itemFrame.size.height;
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y = contentBottom;
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row++;
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previousLayoutItem = layoutItem;
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}
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contentBottom += self.conversationStyle.contentMarginBottom;
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self.contentSize = CGSizeMake(viewWidth, contentBottom);
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self.lastViewWidth = viewWidth;
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}
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- (nullable NSArray<__kindof UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect
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{
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NSMutableArray<UICollectionViewLayoutAttributes *> *result = [NSMutableArray new];
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for (UICollectionViewLayoutAttributes *itemAttributes in self.itemAttributesMap.allValues) {
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if (CGRectIntersectsRect(rect, itemAttributes.frame)) {
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[result addObject:itemAttributes];
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}
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}
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return result;
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}
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- (nullable UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
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{
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return self.itemAttributesMap[@(indexPath.row)];
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}
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- (CGSize)collectionViewContentSize
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{
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return self.contentSize;
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}
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- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds
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{
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return self.lastViewWidth != newBounds.size.width;
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}
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@end
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NS_ASSUME_NONNULL_END
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