ResearchKit/ResearchKitUI/Common/Step/Image Capture Step/ORKImageCaptureCameraPreviewView.m

/*
 Copyright (c) 2015, Bruce Duncan. 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 "ORKImageCaptureCameraPreviewView.h"

#import "ORKTintedImageView.h"

#import "ORKHelpers_Internal.h"

#import <tgmath.h>


@implementation ORKImageCaptureCameraPreviewView {
    AVCaptureVideoPreviewLayer *_previewLayer;
    ORKTintedImageView *_templateImageView;
    NSLayoutConstraint *_templateImageViewTopInsetConstraint;
    NSLayoutConstraint *_templateImageViewLeftInsetConstraint;
    NSLayoutConstraint *_templateImageViewBottomInsetConstraint;
    NSLayoutConstraint *_templateImageViewRightInseConstraint;
    UIImageView *_capturedImageView;
}

- (instancetype)init {
    self = [super init];
    if (self) {
        _previewLayer = [[AVCaptureVideoPreviewLayer alloc] init];
        _previewLayer.videoGravity = AVLayerVideoGravityResizeAspect;
        _previewLayer.needsDisplayOnBoundsChange = YES;
        [self.layer addSublayer:_previewLayer];
        
        _capturedImageView = [[UIImageView alloc] init];
        _capturedImageView.contentMode = UIViewContentModeScaleAspectFit;
        [self addSubview:_capturedImageView];
    
        _templateImageView = [[ORKTintedImageView alloc] init];
        _templateImageView.contentMode = UIViewContentModeScaleAspectFit;
        _templateImageView.shouldApplyTint = YES;
        _templateImageView.hidden = YES;
        _templateImageView.alpha = 0;
        [_capturedImageView addSubview:_templateImageView];

        self.translatesAutoresizingMaskIntoConstraints = NO;
        _templateImageView.translatesAutoresizingMaskIntoConstraints = NO;
        _capturedImageView.translatesAutoresizingMaskIntoConstraints = NO;
        [self setUpConstraints];
    }
    return self;
}

- (void)setUpConstraints {
    NSMutableArray *constraints = [NSMutableArray new];
    
    [_templateImageView setContentHuggingPriority:0 forAxis:UILayoutConstraintAxisHorizontal];
    [_templateImageView setContentHuggingPriority:0 forAxis:UILayoutConstraintAxisVertical];
    [_templateImageView setContentCompressionResistancePriority:0 forAxis:UILayoutConstraintAxisHorizontal];
    [_templateImageView setContentCompressionResistancePriority:0 forAxis:UILayoutConstraintAxisVertical];
    [_capturedImageView setContentHuggingPriority:0 forAxis:UILayoutConstraintAxisHorizontal];
    [_capturedImageView setContentHuggingPriority:0 forAxis:UILayoutConstraintAxisVertical];
    [_capturedImageView setContentCompressionResistancePriority:0 forAxis:UILayoutConstraintAxisHorizontal];
    [_capturedImageView setContentCompressionResistancePriority:0 forAxis:UILayoutConstraintAxisVertical];
    
    // Make the insets for the template image view changeable later
    _templateImageViewTopInsetConstraint = [NSLayoutConstraint constraintWithItem:_templateImageView
                                                              attribute:NSLayoutAttributeTop
                                                              relatedBy:NSLayoutRelationEqual
                                                                 toItem:_capturedImageView
                                                              attribute:NSLayoutAttributeTop
                                                             multiplier:1.0
                                                               constant:0.0];
    [constraints addObject:_templateImageViewTopInsetConstraint];
    
    _templateImageViewLeftInsetConstraint = [NSLayoutConstraint constraintWithItem:_templateImageView
                                                               attribute:NSLayoutAttributeLeft
                                                               relatedBy:NSLayoutRelationEqual
                                                                  toItem:_capturedImageView
                                                               attribute:NSLayoutAttributeLeft
                                                              multiplier:1.0
                                                                constant:0.0];
    [constraints addObject:_templateImageViewLeftInsetConstraint];
    
    _templateImageViewBottomInsetConstraint = [NSLayoutConstraint constraintWithItem:_templateImageView
                                                                 attribute:NSLayoutAttributeBottom
                                                                 relatedBy:NSLayoutRelationEqual
                                                                    toItem:_capturedImageView
                                                                 attribute:NSLayoutAttributeBottom
                                                                multiplier:1.0
                                                                  constant:0.0];
    [constraints addObject:_templateImageViewBottomInsetConstraint];
    
    _templateImageViewRightInseConstraint = [NSLayoutConstraint constraintWithItem:_templateImageView
                                                                attribute:NSLayoutAttributeRight
                                                                relatedBy:NSLayoutRelationEqual
                                                                   toItem:_capturedImageView
                                                                attribute:NSLayoutAttributeRight
                                                               multiplier:1.0
                                                                 constant:0.0];
    [constraints addObject:_templateImageViewRightInseConstraint];
    
    // Make the captured image view use the available space (taking into account the layout margins)
    NSDictionary *views = @{ @"capturedImageView": _capturedImageView };
    [constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[capturedImageView]-|"
                                                                             options:NSLayoutFormatDirectionLeadingToTrailing
                                                                             metrics:nil
                                                                               views:views]];
    [constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[capturedImageView]-|"
                                                                             options:NSLayoutFormatDirectionLeadingToTrailing
                                                                             metrics:nil
                                                                               views:views]];
    
    [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)hidden {
    if (!hidden) {
        _templateImageView.hidden = NO;
    }
    [UIView animateWithDuration:0.15
                     animations:^{
                         _templateImageView.alpha = hidden ? 0 : 1;
                     } completion:^(BOOL finished) {
                         _templateImageView.hidden = hidden;
                     }];
}

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

- (UIImage *)capturedImage {
    return _capturedImageView.image;
}

- (void)setCapturedImage:(UIImage *)capturedImage {
    _capturedImageView.image = capturedImage;
    _previewLayer.hidden = (capturedImage != 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 and catpured image views
    [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 (_templateImageViewRightInseConstraint.constant != -insets.right) {
        _templateImageViewRightInseConstraint.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 videoDimensions = CMVideoFormatDescriptionGetDimensions(input.device.activeFormat.formatDescription);
    AVCaptureVideoOrientation orientation = _previewLayer.connection.videoOrientation;
    BOOL landscape = (orientation == AVCaptureVideoOrientationLandscapeLeft || orientation == AVCaptureVideoOrientationLandscapeRight);
    
    CGRect contentFrame = AVMakeRectWithAspectRatioInsideRect(CGSizeMake(landscape ? videoDimensions.width : videoDimensions.height, landscape ? videoDimensions.height : videoDimensions.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 YES;
}

- (NSString *)accessibilityLabel {
    return ORKLocalizedString(self.capturedImage ? @"AX_IMAGE_CAPTURED_LABEL" : @"AX_IMAGE_CAPTURE_LABEL", nil);
}

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

@end