/*

 Copyright (C) 2016 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Camera preview view, with automatic "flash" animation

 */

#import "BracketStripesCapturePreviewView.h"

// Keypath for when still image capture is taking place

static NSString *kCapturingStillImageKeypath = @"capturingStillImage";

@implementation BracketStripesCapturePreviewView {

    UIView *_flashView;

    AVCaptureVideoPreviewLayer *_previewLayer;

    AVCaptureOutput *_captureOutput;

}

- (void)configureCaptureSession:(AVCaptureSession *)captureSession

                  captureOutput:(AVCaptureOutput *)captureOutput

{

    if (_previewLayer) {

        [_previewLayer removeFromSuperlayer];

        _previewLayer = nil;

    }

    // Add preview layer

    _previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:captureSession];

    _previewLayer.videoGravity = AVLayerVideoGravityResizeAspect;

    _previewLayer.frame = self.bounds;

    [self.layer addSublayer:_previewLayer];

    // Visually animate still image capture

    _captureOutput = captureOutput;

    [_captureOutput addObserver:self forKeyPath:kCapturingStillImageKeypath options:NSKeyValueObservingOptionNew context:NULL];

}

- (void)dealloc

{

    [_captureOutput removeObserver:self forKeyPath:kCapturingStillImageKeypath];

}

- (void)observeValueForKeyPath:(NSString *)keyPath

                      ofObject:(id)object

                        change:(NSDictionary *)change

                       context:(void *)context

{

    // Still image capture state

    if ( (object == _captureOutput) &&

         [keyPath isEqualToString:kCapturingStillImageKeypath] ) {

        NSNumber *value = change[NSKeyValueChangeNewKey];

        [self _animateVisualShutter:[value boolValue]];

        return;

    }

    // Unhandled, pass up the chain

    [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];

}

- (void)_animateVisualShutter:(BOOL)start

{

    if (start) {

        [_flashView removeFromSuperview];

        _flashView = [[UIView alloc] initWithFrame:self.bounds];

        _flashView.backgroundColor = [UIColor whiteColor];

        _flashView.alpha = 0.0;

        [self addSubview:_flashView];

        [UIView animateWithDuration:0.1 animations:^{

            _flashView.alpha = 1.0;

        }];

    }

    else {

        [UIView animateWithDuration:0.1 animations:^{

            _flashView.alpha = 0.0;

        } completion:^(BOOL finished) {

            [_flashView removeFromSuperview];

            _flashView = nil;

        }];

    }

}

@end