129 lines
3.3 KiB
Objective-C
129 lines
3.3 KiB
Objective-C
/*
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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 <React/RCTDecayAnimation.h>
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#import <UIKit/UIKit.h>
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#import <React/RCTConvert.h>
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#import <React/RCTAnimationUtils.h>
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#import <React/RCTValueAnimatedNode.h>
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@interface RCTDecayAnimation ()
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@property (nonatomic, strong) NSNumber *animationId;
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@property (nonatomic, strong) RCTValueAnimatedNode *valueNode;
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@property (nonatomic, assign) BOOL animationHasBegun;
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@property (nonatomic, assign) BOOL animationHasFinished;
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@end
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@implementation RCTDecayAnimation
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{
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CGFloat _velocity;
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CGFloat _deceleration;
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NSTimeInterval _frameStartTime;
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CGFloat _fromValue;
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CGFloat _lastValue;
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NSInteger _iterations;
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NSInteger _currentLoop;
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RCTResponseSenderBlock _callback;
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}
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- (instancetype)initWithId:(NSNumber *)animationId
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config:(NSDictionary *)config
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forNode:(RCTValueAnimatedNode *)valueNode
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callBack:(nullable RCTResponseSenderBlock)callback
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{
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if ((self = [super init])) {
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_callback = [callback copy];
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_animationId = animationId;
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_valueNode = valueNode;
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_fromValue = 0;
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_lastValue = 0;
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_velocity = [RCTConvert CGFloat:config[@"velocity"]]; // initial velocity
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[self resetAnimationConfig:config];
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}
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return self;
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}
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- (void)resetAnimationConfig:(NSDictionary *)config
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{
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NSNumber *iterations = [RCTConvert NSNumber:config[@"iterations"]] ?: @1;
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_fromValue = _lastValue;
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_deceleration = [RCTConvert CGFloat:config[@"deceleration"]];
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_iterations = iterations.integerValue;
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_currentLoop = 1;
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_animationHasFinished = iterations.integerValue == 0;
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}
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RCT_NOT_IMPLEMENTED(- (instancetype)init)
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- (void)startAnimation
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{
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_frameStartTime = -1;
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_animationHasBegun = YES;
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}
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- (void)stopAnimation
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{
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_valueNode = nil;
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if (_callback) {
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_callback(@[@{
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@"finished": @(_animationHasFinished)
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}]);
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}
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}
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- (void)stepAnimationWithTime:(NSTimeInterval)currentTime
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{
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if (!_animationHasBegun || _animationHasFinished) {
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// Animation has not begun or animation has already finished.
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return;
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}
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if (_frameStartTime == -1) {
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// Since this is the first animation step, consider the start to be on the previous frame.
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_frameStartTime = currentTime - RCTSingleFrameInterval;
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if (_fromValue == _lastValue) {
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// First iteration, assign _fromValue based on _valueNode.
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_fromValue = _valueNode.value;
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} else {
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// Not the first iteration, reset _valueNode based on _fromValue.
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[self updateValue:_fromValue];
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}
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_lastValue = _valueNode.value;
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}
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CGFloat value = _fromValue +
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(_velocity / (1 - _deceleration)) *
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(1 - exp(-(1 - _deceleration) * (currentTime - _frameStartTime) * 1000.0 / RCTAnimationDragCoefficient()));
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[self updateValue:value];
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if (fabs(_lastValue - value) < 0.1) {
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if (_iterations == -1 || _currentLoop < _iterations) {
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// Set _frameStartTime to -1 to reset instance variables on the next runAnimationStep.
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_frameStartTime = -1;
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_currentLoop++;
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} else {
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_animationHasFinished = true;
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return;
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}
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}
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_lastValue = value;
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}
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- (void)updateValue:(CGFloat)outputValue
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{
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_valueNode.value = outputValue;
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[_valueNode setNeedsUpdate];
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}
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@end
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