mirror of
https://github.com/facebook/react-native.git
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Samuel SuslaandFacebook GitHub Bot
d9593ae1b3
Summary: Changelog: [Internal] ScrollView didn't support centerContent prop. The implementation is copied over from Paper. I added an example of this prop in RNTester. Reviewed By: JoshuaGross Differential Revision: D21548270 fbshipit-source-id: 28f6c8d769c5a6bc1d111b33970a06b95c259132
98 lines
2.8 KiB
Plaintext
98 lines
2.8 KiB
Plaintext
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#import "RCTEnhancedScrollView.h"
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#import <React/RCTUtils.h>
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@implementation RCTEnhancedScrollView {
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__weak id<UIScrollViewDelegate> _publicDelegate;
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}
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+ (BOOL)automaticallyNotifiesObserversForKey:(NSString *)key
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{
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if ([key isEqualToString:@"delegate"]) {
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// For `delegate` property, we issue KVO notifications manually.
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// We need that to block notifications caused by setting the original `UIScrollView`s property.
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return NO;
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}
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return [super automaticallyNotifiesObserversForKey:key];
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}
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- (instancetype)initWithFrame:(CGRect)frame
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{
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if (self = [super initWithFrame:frame]) {
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if (@available(iOS 11.0, *)) {
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// We set the default behavior to "never" so that iOS
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// doesn't do weird things to UIScrollView insets automatically
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// and keeps it as an opt-in behavior.
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self.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
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}
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__weak __typeof(self) weakSelf = self;
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_delegateSplitter = [[RCTGenericDelegateSplitter alloc] initWithDelegateUpdateBlock:^(id delegate) {
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[weakSelf setPrivateDelegate:delegate];
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}];
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}
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return self;
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}
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- (void)setPrivateDelegate:(id<UIScrollViewDelegate>)delegate
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{
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[super setDelegate:delegate];
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}
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- (id<UIScrollViewDelegate>)delegate
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{
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return _publicDelegate;
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}
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- (void)setDelegate:(id<UIScrollViewDelegate>)delegate
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{
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if (_publicDelegate == delegate) {
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return;
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}
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if (_publicDelegate) {
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[_delegateSplitter removeDelegate:_publicDelegate];
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}
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[self willChangeValueForKey:@"delegate"];
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_publicDelegate = delegate;
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[self didChangeValueForKey:@"delegate"];
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if (_publicDelegate) {
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[_delegateSplitter addDelegate:_publicDelegate];
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}
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}
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/*
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* Automatically centers the content such that if the content is smaller than the
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* ScrollView, we force it to be centered, but when you zoom or the content otherwise
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* becomes larger than the ScrollView, there is no padding around the content but it
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* can still fill the whole view.
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*/
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- (void)setContentOffset:(CGPoint)contentOffset
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{
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if (_centerContent && !CGSizeEqualToSize(self.contentSize, CGSizeZero)) {
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CGSize scrollViewSize = self.bounds.size;
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if (self.contentSize.width <= scrollViewSize.width) {
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contentOffset.x = -(scrollViewSize.width - self.contentSize.width) / 2.0;
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}
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if (self.contentSize.height <= scrollViewSize.height) {
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contentOffset.y = -(scrollViewSize.height - self.contentSize.height) / 2.0;
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}
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}
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super.contentOffset = CGPointMake(
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RCTSanitizeNaNValue(contentOffset.x, @"scrollView.contentOffset.x"),
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RCTSanitizeNaNValue(contentOffset.y, @"scrollView.contentOffset.y"));
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}
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@end
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