ResearchKit/ResearchKitUI/Common/Step/Video Capture Step/ORKVideoCaptureCameraPreviewView.m

/*
 Copyright (c) 2016, Apple Inc. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:
 
 1.  Redistributions of source code must retain the above copyright notice, this
 list of conditions and the following disclaimer.
 
 2.  Redistributions in binary form must reproduce the above copyright notice,
 this list of conditions and the following disclaimer in the documentation and/or
 other materials provided with the distribution.
 
 3.  Neither the name of the copyright holder(s) nor the names of any contributors
 may be used to endorse or promote products derived from this software without
 specific prior written permission. No license is granted to the trademarks of
 the copyright holders even if such marks are included in this software.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
 FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#import "ORKVideoCaptureCameraPreviewView.h"
#import "ORKTintedImageView.h"
#import "ORKHelpers_Internal.h"
#import <tgmath.h>


@implementation ORKVideoCaptureCameraPreviewView {
    AVCaptureVideoPreviewLayer *_previewLayer;
    ORKTintedImageView *_templateImageView;
    NSLayoutConstraint *_templateImageViewTopInsetConstraint;
    NSLayoutConstraint *_templateImageViewLeftInsetConstraint;
    NSLayoutConstraint *_templateImageViewBottomInsetConstraint;
    NSLayoutConstraint *_templateImageViewRightInsetConstraint;
}

- (instancetype)init {
    self = [super init];
    if (self) {
        _previewLayer = [AVCaptureVideoPreviewLayer new];
        _previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
        _previewLayer.needsDisplayOnBoundsChange = YES;
        [self.layer addSublayer:_previewLayer];
        
        _templateImageView = [ORKTintedImageView new];
        _templateImageView.contentMode = UIViewContentModeScaleAspectFit;
        _templateImageView.shouldApplyTint = YES;
        _templateImageView.hidden = YES;
        _templateImageView.alpha = 0;
        [self addSubview:_templateImageView];
        
        [self setUpConstraints];
    }
    return self;
}

- (void)setUpConstraints {
    NSMutableArray *constraints = [NSMutableArray new];
    
    self.translatesAutoresizingMaskIntoConstraints = NO;
    _templateImageView.translatesAutoresizingMaskIntoConstraints = NO;
    
    // Make the insets for the template image view changeable later
    _templateImageViewTopInsetConstraint = [NSLayoutConstraint constraintWithItem:_templateImageView
                                                                        attribute:NSLayoutAttributeTop
                                                                        relatedBy:NSLayoutRelationEqual
                                                                           toItem:self
                                                                        attribute:NSLayoutAttributeTop
                                                                       multiplier:1.0
                                                                         constant:0.0];
    [constraints addObject:_templateImageViewTopInsetConstraint];
    
    _templateImageViewLeftInsetConstraint = [NSLayoutConstraint constraintWithItem:_templateImageView
                                                                         attribute:NSLayoutAttributeLeft
                                                                         relatedBy:NSLayoutRelationEqual
                                                                            toItem:self
                                                                         attribute:NSLayoutAttributeLeft
                                                                        multiplier:1.0
                                                                          constant:0.0];
    [constraints addObject:_templateImageViewLeftInsetConstraint];
    
    _templateImageViewBottomInsetConstraint = [NSLayoutConstraint constraintWithItem:_templateImageView
                                                                           attribute:NSLayoutAttributeBottom
                                                                           relatedBy:NSLayoutRelationEqual
                                                                              toItem:self
                                                                           attribute:NSLayoutAttributeBottom
                                                                          multiplier:1.0
                                                                            constant:0.0];
    [constraints addObject:_templateImageViewBottomInsetConstraint];
    
    _templateImageViewRightInsetConstraint = [NSLayoutConstraint constraintWithItem:_templateImageView
                                                                         attribute:NSLayoutAttributeRight
                                                                         relatedBy:NSLayoutRelationEqual
                                                                            toItem:self
                                                                         attribute:NSLayoutAttributeRight
                                                                        multiplier:1.0
                                                                          constant:0.0];
    [constraints addObject:_templateImageViewRightInsetConstraint];
    
    [NSLayoutConstraint activateConstraints:constraints];
}

- (AVCaptureSession *)session {
    return _previewLayer.session;
}

- (void)setSession:(AVCaptureSession *)session {
    _previewLayer.session = session;
}

- (UIImage *)templateImage {
    return _templateImageView.image;
}

- (void)setTemplateImage:(UIImage *)templateImage {
    _templateImageView.image = templateImage;
}

- (void)setTemplateImageHidden:(BOOL)templateImageHidden {
    if (!templateImageHidden) {
        _templateImageView.hidden = NO;
    }
    
    [UIView animateWithDuration:0.15
                     animations:^{
                         _templateImageView.alpha = templateImageHidden ? 0 : 1;
                     } completion:^(BOOL finished) {
                         _templateImageView.hidden = templateImageHidden;
                     }];
    
}

- (BOOL)isTemplateImageHidden {
    return _templateImageView.hidden;
}

- (void)setVideoFileURL:(NSURL *)videoFileURL {
    _videoFileURL = videoFileURL;
    _previewLayer.hidden = videoFileURL!=nil;
}

- (void)layoutSubviews {
    [super layoutSubviews];
    
    // Ensure that the preview layer takes up all the space
    _previewLayer.frame = self.frame;
    
    // Update the insets for the template image view.
    [self updateInsets];
}

- (void)updateInsets {
    // Update the layoutMargins to match those being used by the preview layer content, if needed
    UIEdgeInsets previewLayerContentFrameInsets = [self getPreviewLayerContentFrameInsets];
    if (!UIEdgeInsetsEqualToEdgeInsets(previewLayerContentFrameInsets, self.layoutMargins)) {
        self.layoutMargins = previewLayerContentFrameInsets;
    }
    
    // Update the insets on the template image view, if needed
    CGRect previewLayerContentFrame = UIEdgeInsetsInsetRect(_previewLayer.frame, previewLayerContentFrameInsets);
    UIEdgeInsets insets = UIEdgeInsetsMake(round(self.templateImageInsets.top * previewLayerContentFrame.size.height),
                                           round(self.templateImageInsets.left * previewLayerContentFrame.size.width),
                                           round(self.templateImageInsets.bottom * previewLayerContentFrame.size.height),
                                           round(self.templateImageInsets.right * previewLayerContentFrame.size.width));
    
    if (_templateImageViewTopInsetConstraint.constant != insets.top) {
        _templateImageViewTopInsetConstraint.constant = insets.top;
    }
    if (_templateImageViewLeftInsetConstraint.constant != insets.left) {
        _templateImageViewLeftInsetConstraint.constant = insets.left;
    }
    if (_templateImageViewBottomInsetConstraint.constant != -insets.bottom) {
        _templateImageViewBottomInsetConstraint.constant = -insets.bottom;
    }
    if (_templateImageViewRightInsetConstraint.constant != -insets.right) {
        _templateImageViewRightInsetConstraint.constant = -insets.right;
    }
}

- (UIEdgeInsets)getPreviewLayerContentFrameInsets {
    // Determine the insets on the preview layer frame that correspond to the actual video content
    // when using a videoGravity of AVLayerVideoGravityResizeAspect;
    NSArray *inputs = _previewLayer.session.inputs;
    if (!inputs || inputs.count == 0)
        return UIEdgeInsetsZero;
    AVCaptureDeviceInput* input = (AVCaptureDeviceInput*)inputs[0];
    CMVideoDimensions cmd = CMVideoFormatDescriptionGetDimensions(input.device.activeFormat.formatDescription);
    AVCaptureVideoOrientation avcvo = _previewLayer.connection.videoOrientation;
    BOOL landscape = avcvo == AVCaptureVideoOrientationLandscapeLeft || avcvo == AVCaptureVideoOrientationLandscapeRight;
    
    CGRect contentFrame = AVMakeRectWithAspectRatioInsideRect(CGSizeMake(landscape ? cmd.width : cmd.height, landscape ? cmd.height : cmd.width), _previewLayer.frame);
    CGRect overallFrame = _previewLayer.frame;
    return UIEdgeInsetsMake(contentFrame.origin.y - overallFrame.origin.y,
                            contentFrame.origin.x - overallFrame.origin.x,
                            (overallFrame.origin.y + overallFrame.size.height) - (contentFrame.origin.y + contentFrame.size.height),
                            (overallFrame.origin.x + overallFrame.size.width) - (contentFrame.origin.x + contentFrame.size.width));
}

- (AVCaptureVideoOrientation)videoOrientation {
    return _previewLayer.connection.videoOrientation;
}

- (void)setVideoOrientation:(AVCaptureVideoOrientation)videoOrientation {
    _previewLayer.connection.videoOrientation = videoOrientation;
}

#pragma mark - Accessibility

- (BOOL)isAccessibilityElement {
    return self.videoFileURL == nil;
}

- (NSString *)accessibilityLabel {
    return ORKLocalizedString(@"AX_VIDEO_CAPTURE_LABEL", nil);
}

- (UIAccessibilityTraits)accessibilityTraits {
    return [super accessibilityTraits] | UIAccessibilityTraitStartsMediaSession;
}

@end