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RCTScrollViewComponentView.mm
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/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#import "RCTScrollViewComponentView.h"
#import <React/RCTAssert.h>
#import <React/RCTBridge+Private.h>
#import <React/RCTConstants.h>
#import <React/RCTScrollEvent.h>
#import <react/renderer/components/scrollview/RCTComponentViewHelpers.h>
#import <react/renderer/components/scrollview/ScrollViewComponentDescriptor.h>
#import <react/renderer/components/scrollview/ScrollViewEventEmitter.h>
#import <react/renderer/components/scrollview/ScrollViewProps.h>
#import <react/renderer/components/scrollview/ScrollViewState.h>
#import <react/renderer/components/scrollview/conversions.h>
#import "RCTConversions.h"
#import "RCTCustomPullToRefreshViewProtocol.h"
#import "RCTEnhancedScrollView.h"
#import "RCTFabricComponentsPlugins.h"
using namespace facebook::react;
static const CGFloat kClippingLeeway = 44.0;
static UIScrollViewKeyboardDismissMode RCTUIKeyboardDismissModeFromProps(const ScrollViewProps &props)
{
switch (props.keyboardDismissMode) {
case ScrollViewKeyboardDismissMode::None:
return UIScrollViewKeyboardDismissModeNone;
case ScrollViewKeyboardDismissMode::OnDrag:
return UIScrollViewKeyboardDismissModeOnDrag;
case ScrollViewKeyboardDismissMode::Interactive:
return UIScrollViewKeyboardDismissModeInteractive;
}
}
static UIScrollViewIndicatorStyle RCTUIScrollViewIndicatorStyleFromProps(const ScrollViewProps &props)
{
switch (props.indicatorStyle) {
case ScrollViewIndicatorStyle::Default:
return UIScrollViewIndicatorStyleDefault;
case ScrollViewIndicatorStyle::Black:
return UIScrollViewIndicatorStyleBlack;
case ScrollViewIndicatorStyle::White:
return UIScrollViewIndicatorStyleWhite;
}
}
// Once Fabric implements proper NativeAnimationDriver, this should be removed.
// This is just a workaround to allow animations based on onScroll event.
// This is only used to animate sticky headers in ScrollViews, and only the contentOffset and tag is used.
// TODO: T116850910 [Fabric][iOS] Make Fabric not use legacy RCTEventDispatcher for native-driven AnimatedEvents
static void RCTSendScrollEventForNativeAnimations_DEPRECATED(UIScrollView *scrollView, NSInteger tag)
{
static uint16_t coalescingKey = 0;
RCTScrollEvent *scrollEvent = [[RCTScrollEvent alloc] initWithEventName:@"onScroll"
reactTag:[NSNumber numberWithInt:tag]
scrollViewContentOffset:scrollView.contentOffset
scrollViewContentInset:scrollView.contentInset
scrollViewContentSize:scrollView.contentSize
scrollViewFrame:scrollView.frame
scrollViewZoomScale:scrollView.zoomScale
userData:nil
coalescingKey:coalescingKey];
RCTBridge *bridge = [RCTBridge currentBridge];
if (bridge) {
[bridge.eventDispatcher sendEvent:scrollEvent];
} else {
NSDictionary *userInfo = [NSDictionary dictionaryWithObjectsAndKeys:scrollEvent, @"event", nil];
[[NSNotificationCenter defaultCenter] postNotificationName:@"RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED"
object:nil
userInfo:userInfo];
}
}
@interface RCTScrollViewComponentView () <
UIScrollViewDelegate,
RCTScrollViewProtocol,
RCTScrollableProtocol,
RCTEnhancedScrollViewOverridingDelegate>
@end
@implementation RCTScrollViewComponentView {
ScrollViewShadowNode::ConcreteState::Shared _state;
CGSize _contentSize;
NSTimeInterval _lastScrollEventDispatchTime;
NSTimeInterval _scrollEventThrottle;
// Flag indicating whether the scrolling that is currently happening
// is triggered by user or not.
// This helps to only update state from `scrollViewDidScroll` in case
// some other part of the system scrolls scroll view.
BOOL _isUserTriggeredScrolling;
BOOL _shouldUpdateContentInsetAdjustmentBehavior;
CGPoint _contentOffsetWhenClipped;
__weak UIView *_contentView;
CGRect _prevFirstVisibleFrame;
__weak UIView *_firstVisibleView;
CGFloat _endDraggingSensitivityMultiplier;
}
+ (RCTScrollViewComponentView *_Nullable)findScrollViewComponentViewForView:(UIView *)view
{
do {
view = view.superview;
} while (view != nil && ![view isKindOfClass:[RCTScrollViewComponentView class]]);
return (RCTScrollViewComponentView *)view;
}
- (instancetype)initWithFrame:(CGRect)frame
{
if (self = [super initWithFrame:frame]) {
_props = ScrollViewShadowNode::defaultSharedProps();
_scrollView = [[RCTEnhancedScrollView alloc] initWithFrame:self.bounds];
_scrollView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
_scrollView.delaysContentTouches = NO;
((RCTEnhancedScrollView *)_scrollView).overridingDelegate = self;
_isUserTriggeredScrolling = NO;
_shouldUpdateContentInsetAdjustmentBehavior = YES;
[self addSubview:_scrollView];
_containerView = [[UIView alloc] initWithFrame:CGRectZero];
[_scrollView addSubview:_containerView];
[self.scrollViewDelegateSplitter addDelegate:self];
_scrollEventThrottle = 0;
_endDraggingSensitivityMultiplier = 1;
}
return self;
}
- (void)dealloc
{
// Removing all delegates from the splitter nils the actual delegate which prevents a crash on UIScrollView
// deallocation.
[self.scrollViewDelegateSplitter removeAllDelegates];
}
- (RCTGenericDelegateSplitter<id<UIScrollViewDelegate>> *)scrollViewDelegateSplitter
{
return ((RCTEnhancedScrollView *)_scrollView).delegateSplitter;
}
#pragma mark - RCTMountingTransactionObserving
- (void)mountingTransactionWillMount:(const facebook::react::MountingTransaction &)transaction
withSurfaceTelemetry:(const facebook::react::SurfaceTelemetry &)surfaceTelemetry
{
[self _prepareForMaintainVisibleScrollPosition];
}
- (void)mountingTransactionDidMount:(const MountingTransaction &)transaction
withSurfaceTelemetry:(const facebook::react::SurfaceTelemetry &)surfaceTelemetry
{
[self _remountChildren];
[self _adjustForMaintainVisibleContentPosition];
}
#pragma mark - RCTComponentViewProtocol
+ (ComponentDescriptorProvider)componentDescriptorProvider
{
return concreteComponentDescriptorProvider<ScrollViewComponentDescriptor>();
}
- (void)updateLayoutMetrics:(const LayoutMetrics &)layoutMetrics
oldLayoutMetrics:(const LayoutMetrics &)oldLayoutMetrics
{
[super updateLayoutMetrics:layoutMetrics oldLayoutMetrics:oldLayoutMetrics];
if (layoutMetrics.layoutDirection != oldLayoutMetrics.layoutDirection) {
CGAffineTransform transform = (layoutMetrics.layoutDirection == LayoutDirection::LeftToRight)
? CGAffineTransformIdentity
: CGAffineTransformMakeScale(-1, 1);
_containerView.transform = transform;
_scrollView.transform = transform;
}
}
- (void)updateProps:(const Props::Shared &)props oldProps:(const Props::Shared &)oldProps
{
const auto &oldScrollViewProps = static_cast<const ScrollViewProps &>(*_props);
const auto &newScrollViewProps = static_cast<const ScrollViewProps &>(*props);
#define REMAP_PROP(reactName, localName, target) \
if (oldScrollViewProps.reactName != newScrollViewProps.reactName) { \
target.localName = newScrollViewProps.reactName; \
}
#define REMAP_VIEW_PROP(reactName, localName) REMAP_PROP(reactName, localName, self)
#define MAP_VIEW_PROP(name) REMAP_VIEW_PROP(name, name)
#define REMAP_SCROLL_VIEW_PROP(reactName, localName) \
REMAP_PROP(reactName, localName, ((RCTEnhancedScrollView *)_scrollView))
#define MAP_SCROLL_VIEW_PROP(name) REMAP_SCROLL_VIEW_PROP(name, name)
// FIXME: Commented props are not supported yet.
MAP_SCROLL_VIEW_PROP(alwaysBounceHorizontal);
MAP_SCROLL_VIEW_PROP(alwaysBounceVertical);
MAP_SCROLL_VIEW_PROP(bounces);
MAP_SCROLL_VIEW_PROP(bouncesZoom);
MAP_SCROLL_VIEW_PROP(canCancelContentTouches);
MAP_SCROLL_VIEW_PROP(centerContent);
// MAP_SCROLL_VIEW_PROP(automaticallyAdjustContentInsets);
MAP_SCROLL_VIEW_PROP(decelerationRate);
MAP_SCROLL_VIEW_PROP(directionalLockEnabled);
MAP_SCROLL_VIEW_PROP(maximumZoomScale);
MAP_SCROLL_VIEW_PROP(minimumZoomScale);
MAP_SCROLL_VIEW_PROP(scrollEnabled);
MAP_SCROLL_VIEW_PROP(pagingEnabled);
MAP_SCROLL_VIEW_PROP(pinchGestureEnabled);
MAP_SCROLL_VIEW_PROP(scrollsToTop);
MAP_SCROLL_VIEW_PROP(showsHorizontalScrollIndicator);
MAP_SCROLL_VIEW_PROP(showsVerticalScrollIndicator);
if (oldScrollViewProps.scrollIndicatorInsets != newScrollViewProps.scrollIndicatorInsets) {
_scrollView.scrollIndicatorInsets = RCTUIEdgeInsetsFromEdgeInsets(newScrollViewProps.scrollIndicatorInsets);
}
if (oldScrollViewProps.indicatorStyle != newScrollViewProps.indicatorStyle) {
_scrollView.indicatorStyle = RCTUIScrollViewIndicatorStyleFromProps(newScrollViewProps);
}
_endDraggingSensitivityMultiplier = newScrollViewProps.endDraggingSensitivityMultiplier;
if (oldScrollViewProps.scrollEventThrottle != newScrollViewProps.scrollEventThrottle) {
// Zero means "send value only once per significant logical event".
// Prop value is in milliseconds.
// iOS implementation uses `NSTimeInterval` (in seconds).
CGFloat throttleInSeconds = newScrollViewProps.scrollEventThrottle / 1000.0;
CGFloat msPerFrame = 1.0 / 60.0;
if (throttleInSeconds < 0) {
_scrollEventThrottle = INFINITY;
} else if (throttleInSeconds <= msPerFrame) {
_scrollEventThrottle = 0;
} else {
_scrollEventThrottle = throttleInSeconds;
}
}
MAP_SCROLL_VIEW_PROP(zoomScale);
if (oldScrollViewProps.contentInset != newScrollViewProps.contentInset) {
_scrollView.contentInset = RCTUIEdgeInsetsFromEdgeInsets(newScrollViewProps.contentInset);
}
RCTEnhancedScrollView *scrollView = (RCTEnhancedScrollView *)_scrollView;
if (oldScrollViewProps.contentOffset != newScrollViewProps.contentOffset) {
_scrollView.contentOffset = RCTCGPointFromPoint(newScrollViewProps.contentOffset);
}
if (oldScrollViewProps.snapToAlignment != newScrollViewProps.snapToAlignment) {
scrollView.snapToAlignment = RCTNSStringFromString(toString(newScrollViewProps.snapToAlignment));
}
scrollView.snapToStart = newScrollViewProps.snapToStart;
scrollView.snapToEnd = newScrollViewProps.snapToEnd;
if (oldScrollViewProps.snapToOffsets != newScrollViewProps.snapToOffsets) {
NSMutableArray<NSNumber *> *snapToOffsets = [NSMutableArray array];
for (const auto &snapToOffset : newScrollViewProps.snapToOffsets) {
[snapToOffsets addObject:[NSNumber numberWithFloat:snapToOffset]];
}
scrollView.snapToOffsets = snapToOffsets;
}
if (oldScrollViewProps.automaticallyAdjustsScrollIndicatorInsets !=
newScrollViewProps.automaticallyAdjustsScrollIndicatorInsets) {
scrollView.automaticallyAdjustsScrollIndicatorInsets = newScrollViewProps.automaticallyAdjustsScrollIndicatorInsets;
}
if ((oldScrollViewProps.contentInsetAdjustmentBehavior != newScrollViewProps.contentInsetAdjustmentBehavior) ||
_shouldUpdateContentInsetAdjustmentBehavior) {
const auto contentInsetAdjustmentBehavior = newScrollViewProps.contentInsetAdjustmentBehavior;
if (contentInsetAdjustmentBehavior == ContentInsetAdjustmentBehavior::Never) {
scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
} else if (contentInsetAdjustmentBehavior == ContentInsetAdjustmentBehavior::Automatic) {
scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentAutomatic;
} else if (contentInsetAdjustmentBehavior == ContentInsetAdjustmentBehavior::ScrollableAxes) {
scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentScrollableAxes;
} else if (contentInsetAdjustmentBehavior == ContentInsetAdjustmentBehavior::Always) {
scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentAlways;
}
_shouldUpdateContentInsetAdjustmentBehavior = NO;
}
MAP_SCROLL_VIEW_PROP(disableIntervalMomentum);
MAP_SCROLL_VIEW_PROP(snapToInterval);
if (oldScrollViewProps.keyboardDismissMode != newScrollViewProps.keyboardDismissMode) {
scrollView.keyboardDismissMode = RCTUIKeyboardDismissModeFromProps(newScrollViewProps);
}
[super updateProps:props oldProps:oldProps];
}
- (void)updateState:(const State::Shared &)state oldState:(const State::Shared &)oldState
{
assert(std::dynamic_pointer_cast<const ScrollViewShadowNode::ConcreteState>(state));
_state = std::static_pointer_cast<const ScrollViewShadowNode::ConcreteState>(state);
auto &data = _state->getData();
auto contentOffset = RCTCGPointFromPoint(data.contentOffset);
if (!oldState && !CGPointEqualToPoint(contentOffset, CGPointZero)) {
_scrollView.contentOffset = contentOffset;
}
CGSize contentSize = RCTCGSizeFromSize(data.getContentSize());
if (CGSizeEqualToSize(_contentSize, contentSize)) {
return;
}
_contentSize = contentSize;
_containerView.frame = CGRect{RCTCGPointFromPoint(data.contentBoundingRect.origin), contentSize};
[self _preserveContentOffsetIfNeededWithBlock:^{
self->_scrollView.contentSize = contentSize;
}];
}
/*
* Disables programmatical changing of ScrollView's `contentOffset` if a touch gesture is in progress.
*/
- (void)_preserveContentOffsetIfNeededWithBlock:(void (^)())block
{
if (!block) {
return;
}
if (!_isUserTriggeredScrolling) {
return block();
}
[((RCTEnhancedScrollView *)_scrollView) preserveContentOffsetWithBlock:block];
}
- (void)mountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index
{
[_containerView insertSubview:childComponentView atIndex:index];
if (![childComponentView conformsToProtocol:@protocol(RCTCustomPullToRefreshViewProtocol)]) {
_contentView = childComponentView;
}
}
- (void)unmountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index
{
[childComponentView removeFromSuperview];
if (![childComponentView conformsToProtocol:@protocol(RCTCustomPullToRefreshViewProtocol)] &&
_contentView == childComponentView) {
_contentView = nil;
}
}
/*
* Returns whether or not the scroll view interaction should be blocked because
* JavaScript was found to be the responder.
*/
- (BOOL)_shouldDisableScrollInteraction
{
UIView *ancestorView = self.superview;
while (ancestorView) {
if ([ancestorView respondsToSelector:@selector(isJSResponder)]) {
BOOL isJSResponder = ((UIView<RCTComponentViewProtocol> *)ancestorView).isJSResponder;
if (isJSResponder) {
return YES;
}
}
ancestorView = ancestorView.superview;
}
return NO;
}
- (ScrollViewEventEmitter::Metrics)_scrollViewMetrics
{
auto metrics = ScrollViewEventEmitter::Metrics{
.contentSize = RCTSizeFromCGSize(_scrollView.contentSize),
.contentOffset = RCTPointFromCGPoint(_scrollView.contentOffset),
.contentInset = RCTEdgeInsetsFromUIEdgeInsets(_scrollView.contentInset),
.containerSize = RCTSizeFromCGSize(_scrollView.bounds.size),
.zoomScale = _scrollView.zoomScale,
};
if (_layoutMetrics.layoutDirection == LayoutDirection::RightToLeft) {
metrics.contentOffset.x = metrics.contentSize.width - metrics.containerSize.width - metrics.contentOffset.x;
}
return metrics;
}
- (void)_updateStateWithContentOffset
{
if (!_state) {
return;
}
auto contentOffset = RCTPointFromCGPoint(_scrollView.contentOffset);
_state->updateState([contentOffset](const ScrollViewShadowNode::ConcreteState::Data &data) {
auto newData = data;
newData.contentOffset = contentOffset;
return std::make_shared<const ScrollViewShadowNode::ConcreteState::Data>(newData);
});
}
- (void)prepareForRecycle
{
[super prepareForRecycle];
// Must invalidate state before setting contentOffset on ScrollView.
// Otherwise the state will be propagated to shadow tree.
_state.reset();
const auto &props = static_cast<const ScrollViewProps &>(*_props);
_scrollView.contentOffset = RCTCGPointFromPoint(props.contentOffset);
// We set the default behavior to "never" so that iOS
// doesn't do weird things to UIScrollView insets automatically
// and keeps it as an opt-in behavior.
_scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
_shouldUpdateContentInsetAdjustmentBehavior = YES;
_isUserTriggeredScrolling = NO;
CGRect oldFrame = self.frame;
self.frame = CGRectZero;
self.frame = oldFrame;
_contentView = nil;
_prevFirstVisibleFrame = CGRectZero;
_firstVisibleView = nil;
}
#pragma mark - UIScrollViewDelegate
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView
withVelocity:(CGPoint)velocity
targetContentOffset:(inout CGPoint *)targetContentOffset
{
if (fabs(_endDraggingSensitivityMultiplier - 1) > 0.0001f) {
if (targetContentOffset->y > 0) {
const CGFloat travel = targetContentOffset->y - scrollView.contentOffset.y;
targetContentOffset->y = scrollView.contentOffset.y + travel * _endDraggingSensitivityMultiplier;
}
}
}
- (BOOL)touchesShouldCancelInContentView:(__unused UIView *)view
{
// Historically, `UIScrollView`s in React Native do not cancel touches
// started on `UIControl`-based views (as normal iOS `UIScrollView`s do).
return ![self _shouldDisableScrollInteraction];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
const auto &props = static_cast<const ScrollViewProps &>(*_props);
auto scrollMetrics = [self _scrollViewMetrics];
if (props.enableSyncOnScroll) {
if (_eventEmitter) {
const auto &eventEmitter = static_cast<const ScrollViewEventEmitter &>(*_eventEmitter);
// TODO: temporary API to unblock testing of synchronous rendering.
eventEmitter.experimental_flushSync([&eventEmitter, &scrollMetrics, &self]() {
[self _updateStateWithContentOffset];
// TODO: temporary API to unblock testing of synchronous rendering.
eventEmitter.experimental_onDiscreteScroll(scrollMetrics);
});
}
} else {
if (!_isUserTriggeredScrolling || CoreFeatures::enableGranularScrollViewStateUpdatesIOS) {
[self _updateStateWithContentOffset];
}
NSTimeInterval now = CACurrentMediaTime();
if ((_lastScrollEventDispatchTime == 0) || (now - _lastScrollEventDispatchTime > _scrollEventThrottle)) {
_lastScrollEventDispatchTime = now;
if (_eventEmitter) {
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onScroll(scrollMetrics);
}
RCTSendScrollEventForNativeAnimations_DEPRECATED(scrollView, self.tag);
}
}
[self _remountChildrenIfNeeded];
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
[self scrollViewDidScroll:scrollView];
}
- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView
{
_isUserTriggeredScrolling = YES;
return YES;
}
- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView
{
if (!_eventEmitter) {
return;
}
_isUserTriggeredScrolling = NO;
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onScrollToTop([self _scrollViewMetrics]);
[self _updateStateWithContentOffset];
}
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
[self _forceDispatchNextScrollEvent];
if (!_eventEmitter) {
return;
}
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onScrollBeginDrag([self _scrollViewMetrics]);
_isUserTriggeredScrolling = YES;
}
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
[self _forceDispatchNextScrollEvent];
if (!_eventEmitter) {
return;
}
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onScrollEndDrag([self _scrollViewMetrics]);
[self _updateStateWithContentOffset];
if (!decelerate) {
// ScrollView will not decelerate and `scrollViewDidEndDecelerating` will not be called.
// `_isUserTriggeredScrolling` must be set to NO here.
_isUserTriggeredScrolling = NO;
}
}
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView
{
[self _forceDispatchNextScrollEvent];
if (!_eventEmitter) {
return;
}
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onMomentumScrollBegin([self _scrollViewMetrics]);
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
[self _forceDispatchNextScrollEvent];
if (!_eventEmitter) {
return;
}
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onMomentumScrollEnd([self _scrollViewMetrics]);
[self _updateStateWithContentOffset];
_isUserTriggeredScrolling = NO;
}
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView
{
[self _handleFinishedScrolling:scrollView];
}
- (void)_handleFinishedScrolling:(UIScrollView *)scrollView
{
[self _forceDispatchNextScrollEvent];
[self scrollViewDidScroll:scrollView];
if (!_eventEmitter) {
return;
}
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onMomentumScrollEnd([self _scrollViewMetrics]);
[self _updateStateWithContentOffset];
}
- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(nullable UIView *)view
{
[self _forceDispatchNextScrollEvent];
if (!_eventEmitter) {
return;
}
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onScrollBeginDrag([self _scrollViewMetrics]);
}
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(nullable UIView *)view atScale:(CGFloat)scale
{
[self _forceDispatchNextScrollEvent];
if (!_eventEmitter) {
return;
}
static_cast<const ScrollViewEventEmitter &>(*_eventEmitter).onScrollEndDrag([self _scrollViewMetrics]);
[self _updateStateWithContentOffset];
}
- (UIView *)viewForZoomingInScrollView:(__unused UIScrollView *)scrollView
{
return _containerView;
}
#pragma mark -
- (void)_forceDispatchNextScrollEvent
{
_lastScrollEventDispatchTime = 0;
}
#pragma mark - Native commands
- (void)handleCommand:(const NSString *)commandName args:(const NSArray *)args
{
RCTScrollViewHandleCommand(self, commandName, args);
}
- (void)flashScrollIndicators
{
[_scrollView flashScrollIndicators];
}
- (void)scrollTo:(double)x y:(double)y animated:(BOOL)animated
{
CGPoint offset = CGPointMake(x, y);
CGRect maxRect = CGRectMake(
fmin(-_scrollView.contentInset.left, 0),
fmin(-_scrollView.contentInset.top, 0),
fmax(
_scrollView.contentSize.width - _scrollView.bounds.size.width + _scrollView.contentInset.right +
fmax(_scrollView.contentInset.left, 0),
0.01),
fmax(
_scrollView.contentSize.height - _scrollView.bounds.size.height + _scrollView.contentInset.bottom +
fmax(_scrollView.contentInset.top, 0),
0.01)); // Make width and height greater than 0
const auto &props = static_cast<const ScrollViewProps &>(*_props);
if (!CGRectContainsPoint(maxRect, offset) && !props.scrollToOverflowEnabled) {
CGFloat localX = fmax(offset.x, CGRectGetMinX(maxRect));
localX = fmin(localX, CGRectGetMaxX(maxRect));
CGFloat localY = fmax(offset.y, CGRectGetMinY(maxRect));
localY = fmin(localY, CGRectGetMaxY(maxRect));
offset = CGPointMake(localX, localY);
}
[self scrollToOffset:offset animated:animated];
}
- (void)scrollToEnd:(BOOL)animated
{
BOOL isHorizontal = _scrollView.contentSize.width > self.frame.size.width;
CGPoint offset;
if (isHorizontal) {
CGFloat offsetX = _scrollView.contentSize.width - _scrollView.bounds.size.width + _scrollView.contentInset.right;
offset = CGPointMake(fmax(offsetX, 0), 0);
} else {
CGFloat offsetY = _scrollView.contentSize.height - _scrollView.bounds.size.height + _scrollView.contentInset.bottom;
offset = CGPointMake(0, fmax(offsetY, 0));
}
[self scrollToOffset:offset animated:animated];
}
#pragma mark - Child views mounting
- (void)updateClippedSubviewsWithClipRect:(CGRect)clipRect relativeToView:(UIView *)clipView
{
// Do nothing. ScrollView manages its subview clipping individually in `_remountChildren`.
}
- (void)_remountChildrenIfNeeded
{
CGPoint contentOffset = _scrollView.contentOffset;
if (std::abs(_contentOffsetWhenClipped.x - contentOffset.x) < kClippingLeeway &&
std::abs(_contentOffsetWhenClipped.y - contentOffset.y) < kClippingLeeway) {
return;
}
_contentOffsetWhenClipped = contentOffset;
[self _remountChildren];
}
- (void)_remountChildren
{
[_scrollView updateClippedSubviewsWithClipRect:CGRectInset(_scrollView.bounds, -kClippingLeeway, -kClippingLeeway)
relativeToView:_scrollView];
}
#pragma mark - RCTScrollableProtocol
- (CGSize)contentSize
{
return _contentSize;
}
- (void)scrollToOffset:(CGPoint)offset
{
[self scrollToOffset:offset animated:YES];
}
- (void)scrollToOffset:(CGPoint)offset animated:(BOOL)animated
{
if (_layoutMetrics.layoutDirection == LayoutDirection::RightToLeft) {
// Adjusting offset.x in right to left layout direction.
offset.x = self.contentSize.width - _scrollView.frame.size.width - offset.x;
}
if (CGPointEqualToPoint(_scrollView.contentOffset, offset)) {
return;
}
[self _forceDispatchNextScrollEvent];
[_scrollView setContentOffset:offset animated:animated];
if (!animated) {
// When not animated, the expected workflow in ``scrollViewDidEndScrollingAnimation`` after scrolling is not going
// to get triggered. We will need to manually execute here.
[self _handleFinishedScrolling:_scrollView];
}
}
- (void)zoomToRect:(CGRect)rect animated:(BOOL)animated
{
[_scrollView zoomToRect:rect animated:animated];
}
- (void)addScrollListener:(NSObject<UIScrollViewDelegate> *)scrollListener
{
[self.scrollViewDelegateSplitter addDelegate:scrollListener];
}
- (void)removeScrollListener:(NSObject<UIScrollViewDelegate> *)scrollListener
{
[self.scrollViewDelegateSplitter removeDelegate:scrollListener];
}
#pragma mark - Maintain visible content position
- (void)_prepareForMaintainVisibleScrollPosition
{
const auto &props = static_cast<const ScrollViewProps &>(*_props);
if (!props.maintainVisibleContentPosition) {
return;
}
BOOL horizontal = _scrollView.contentSize.width > self.frame.size.width;
int minIdx = props.maintainVisibleContentPosition.value().minIndexForVisible;
for (NSUInteger ii = minIdx; ii < _contentView.subviews.count; ++ii) {
// Find the first view that is partially or fully visible.
UIView *subview = _contentView.subviews[ii];
BOOL hasNewView = NO;
if (horizontal) {
hasNewView = subview.frame.origin.x + subview.frame.size.width > _scrollView.contentOffset.x;
} else {
hasNewView = subview.frame.origin.y + subview.frame.size.height > _scrollView.contentOffset.y;
}
if (hasNewView || ii == _contentView.subviews.count - 1) {
_prevFirstVisibleFrame = subview.frame;
_firstVisibleView = subview;
break;
}
}
}
- (void)_adjustForMaintainVisibleContentPosition
{
const auto &props = static_cast<const ScrollViewProps &>(*_props);
if (!props.maintainVisibleContentPosition) {
return;
}
std::optional<int> autoscrollThreshold = props.maintainVisibleContentPosition.value().autoscrollToTopThreshold;
BOOL horizontal = _scrollView.contentSize.width > self.frame.size.width;
// TODO: detect and handle/ignore re-ordering
if (horizontal) {
CGFloat deltaX = _firstVisibleView.frame.origin.x - _prevFirstVisibleFrame.origin.x;
if (ABS(deltaX) > 0.5) {
CGFloat x = _scrollView.contentOffset.x;
[self _forceDispatchNextScrollEvent];
_scrollView.contentOffset = CGPointMake(_scrollView.contentOffset.x + deltaX, _scrollView.contentOffset.y);
if (autoscrollThreshold) {
// If the offset WAS within the threshold of the start, animate to the start.
if (x <= autoscrollThreshold.value()) {
[self scrollToOffset:CGPointMake(0, _scrollView.contentOffset.y) animated:YES];
}
}
}
} else {
CGRect newFrame = _firstVisibleView.frame;
CGFloat deltaY = newFrame.origin.y - _prevFirstVisibleFrame.origin.y;
if (ABS(deltaY) > 0.5) {
CGFloat y = _scrollView.contentOffset.y;
[self _forceDispatchNextScrollEvent];
_scrollView.contentOffset = CGPointMake(_scrollView.contentOffset.x, _scrollView.contentOffset.y + deltaY);
if (autoscrollThreshold) {
// If the offset WAS within the threshold of the start, animate to the start.
if (y <= autoscrollThreshold.value()) {
[self scrollToOffset:CGPointMake(_scrollView.contentOffset.x, 0) animated:YES];
}
}
}
}
}
@end
Class<RCTComponentViewProtocol> RCTScrollViewCls(void)
{
return RCTScrollViewComponentView.class;
}