77 lines
2.7 KiB
Objective-C
77 lines
2.7 KiB
Objective-C
//
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// SCManagedCapturerARSessionHandler.m
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// Snapchat
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//
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// Created by Xiaokang Liu on 16/03/2018.
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//
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#import "SCManagedCapturerARSessionHandler.h"
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#import "SCCaptureResource.h"
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#import "SCManagedCaptureSession.h"
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#import <SCBase/SCAvailability.h>
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#import <SCFoundation/SCAssertWrapper.h>
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#import <SCFoundation/SCQueuePerformer.h>
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@import ARKit;
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static CGFloat const kSCManagedCapturerARKitShutdownTimeoutDuration = 2;
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@interface SCManagedCapturerARSessionHandler () {
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SCCaptureResource *__weak _captureResource;
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dispatch_semaphore_t _arSesssionShutdownSemaphore;
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}
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@end
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@implementation SCManagedCapturerARSessionHandler
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- (instancetype)initWithCaptureResource:(SCCaptureResource *)captureResource
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{
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self = [super init];
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if (self) {
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SCAssert(captureResource, @"");
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_captureResource = captureResource;
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_arSesssionShutdownSemaphore = dispatch_semaphore_create(0);
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}
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return self;
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}
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- (void)stopObserving
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{
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[[NSNotificationCenter defaultCenter] removeObserver:self
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name:AVCaptureSessionDidStopRunningNotification
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object:nil];
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}
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- (void)stopARSessionRunning
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{
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SCAssertPerformer(_captureResource.queuePerformer);
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SCAssert(SC_AT_LEAST_IOS_11, @"Shoule be only call from iOS 11+");
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if (@available(iOS 11.0, *)) {
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// ARSession stops its internal AVCaptureSession asynchronously. We listen for its callback and actually restart
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// our own capture session once it's finished shutting down so the two ARSessions don't conflict.
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[[NSNotificationCenter defaultCenter] addObserver:self
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selector:@selector(_completeARSessionShutdown:)
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name:AVCaptureSessionDidStopRunningNotification
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object:nil];
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[_captureResource.arSession pause];
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dispatch_semaphore_wait(
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_arSesssionShutdownSemaphore,
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dispatch_time(DISPATCH_TIME_NOW, (int64_t)(kSCManagedCapturerARKitShutdownTimeoutDuration * NSEC_PER_SEC)));
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}
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}
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- (void)_completeARSessionShutdown:(NSNotification *)note
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{
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// This notification is only registered for IMMEDIATELY before arkit shutdown.
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// Explicitly guard that the notification object IS NOT the main session's.
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SC_GUARD_ELSE_RETURN(![note.object isEqual:_captureResource.managedSession.avSession]);
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[[NSNotificationCenter defaultCenter] removeObserver:self
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name:AVCaptureSessionDidStopRunningNotification
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object:nil];
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dispatch_semaphore_signal(_arSesssionShutdownSemaphore);
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}
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@end
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