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7dd94a6102
Introduce `ASTableView`, a UITableView subclass that uses `ASCellNode` instead of UITableViewCell. Add working range support via `ASRangeController`, which observes the visible range, maintains a working range, and handles most ASDK machinery. ASRangeController is loosely-enough coupled that it should be easily adapted to UICollectionView if that's desired in the future. Notable considerations in the ASRangeController architecture: * There's no sense rewriting UITableView -- the real win comes from using nodes instead of UITableViewCells (easily parallelisable computation, large number of cells vs. few table views, etc.). So, use a UITableView with empty cells, using UITableViewCell's contentView as a host for arbitrary node hierarchies. * Instead of lazy-loading cells the instant they're needed by UITableView, load them in advance. Preload a substantial number of nodes in the direction of scroll, as well as a small buffer in the other direction. * Maintain compatibility with UITableView's API, with one primary change -- consumer code yields configured ASCellNodes, not UITableViewCells. * Don't use -tableView:heightForRowAtIndexPath:. Nodes already compute their preferred sizes and cache results for use at layout-time, so ASTableView uses their calculatedSizes directly. * Corollary: ASTableView is only aware of nodes that have been sized. This means that, if a cell appears onscreen, it has layout data and can display a "realistic placeholder", e.g. by making its subnodes' background colour grey. Other improvements: * Remove dead references and update headers (fixes #7, #20). * Rename `-[ASDisplayNode sizeToFit:]` to `-measure:` and fix `constrainedSizeForCalulatedSize` typo (fixes #15). * Rename `-willAppear` and `-didDisappear` to `-willEnterHierarchy` and `-didExitHierarchy`. Remove `-willDisappear` -- it was redundant, and there was no counterpart `-didAppear`. * Rename `viewLoaded` to `nodeLoaded`.
110 lines
2.4 KiB
Objective-C
110 lines
2.4 KiB
Objective-C
/* Copyright (c) 2014-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*/
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#import "ASCellNode.h"
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#import "ASDisplayNode+Subclasses.h"
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#import "ASRangeControllerInternal.h"
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#import "ASTextNode.h"
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#pragma mark -
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#pragma mark ASCellNode
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@interface ASCellNode () {
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// used by ASRangeController machinery
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NSIndexPath *_asyncdisplaykit_indexPath;
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}
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@end
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@implementation ASCellNode
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- (instancetype)init
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{
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if (!(self = [super init]))
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return nil;
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return self;
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}
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// TODO consider making this property an associated object in ASRangeController.mm
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- (NSIndexPath *)asyncdisplaykit_indexPath
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{
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return _asyncdisplaykit_indexPath;
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}
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- (void)setAsyncdisplaykit_indexPath:(NSIndexPath *)asyncdisplaykit_indexPath
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{
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if (_asyncdisplaykit_indexPath == asyncdisplaykit_indexPath)
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return;
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_asyncdisplaykit_indexPath = [asyncdisplaykit_indexPath copy];
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}
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@end
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#pragma mark -
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#pragma mark ASTextCellNode
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@interface ASTextCellNode () {
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NSString *_text;
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ASTextNode *_textNode;
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}
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@end
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@implementation ASTextCellNode
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static const CGFloat kHorizontalPadding = 15.0f;
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static const CGFloat kVerticalPadding = 11.0f;
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static const CGFloat kFontSize = 18.0f;
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- (instancetype)init
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{
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if (!(self = [super init]))
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return nil;
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_textNode = [[ASTextNode alloc] init];
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[self addSubnode:_textNode];
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return self;
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}
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- (CGSize)calculateSizeThatFits:(CGSize)constrainedSize
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{
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CGSize availableSize = CGSizeMake(constrainedSize.width - 2 * kHorizontalPadding,
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constrainedSize.height - 2 * kVerticalPadding);
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CGSize textNodeSize = [_textNode measure:availableSize];
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return CGSizeMake(ceilf(2 * kHorizontalPadding + textNodeSize.width),
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ceilf(2 * kVerticalPadding + textNodeSize.height));
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}
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- (void)layout
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{
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_textNode.frame = CGRectInset(self.bounds, kHorizontalPadding, kVerticalPadding);
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}
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- (void)setText:(NSString *)text
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{
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if (_text == text)
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return;
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_text = [text copy];
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_textNode.attributedString = [[NSAttributedString alloc] initWithString:_text
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attributes:@{NSFontAttributeName: [UIFont systemFontOfSize:kFontSize]}];
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[self invalidateCalculatedSize];
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}
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@end
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