/*

 Copyright (C) 2017 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 The view controller responsible for showing the actual CKRecord photo.

 */

#import "APLPhotoViewController.h"

@interface APLPhotoViewController () <UIScrollViewDelegate>

@property (nonatomic, weak) IBOutlet UIImageView *imageView;

@property (nonatomic) CGFloat lastZoomScale;

@property (nonatomic, weak) IBOutlet UIScrollView *scrollView;

@property (nonatomic, weak) IBOutlet NSLayoutConstraint *constraintLeft;

@property (nonatomic, weak) IBOutlet NSLayoutConstraint *constraintRight;

@property (nonatomic, weak) IBOutlet NSLayoutConstraint *constraintTop;

@property (nonatomic, weak) IBOutlet NSLayoutConstraint *constraintBottom;

@end

#pragma mark -

@implementation APLPhotoViewController

- (void)viewDidAppear:(BOOL)animated

{

    [super viewDidAppear:animated];

    self.imageView.image = self.photo;

    self.scrollView.delegate = self;

    [self updateZoom];

}

#pragma mark - UIScrollViewDelegate

- (void)scrollViewDidZoom:(UIScrollView *)scrollView

{

    [self updateConstraints];

}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView

{

    return self.imageView;

}

#pragma mark - Updating

- (void)updateConstraints

{

    CGFloat imageWidth = self.imageView.image.size.width;

    CGFloat imageHeight = self.imageView.image.size.height;

    CGFloat viewWidth = self.view.bounds.size.width;

    CGFloat viewHeight = self.view.bounds.size.height;

    // center the photo if it is smaller than screen

    CGFloat hPadding = (viewWidth - self.scrollView.zoomScale * imageWidth) / 2;

    if (hPadding < 0)

    {

        hPadding = 0;

    }

    CGFloat vPadding = (viewHeight - self.scrollView.zoomScale * imageHeight) / 2;

    if (vPadding < 0)

    {

        vPadding = 0;

    }

    self.constraintLeft.constant = self.constraintRight.constant = hPadding;

    self.constraintTop.constant = self.constraintBottom.constant = vPadding;

    [self.view layoutIfNeeded];

}

- (void)updateZoom

{

    CGFloat minZoom = MIN(self.view.bounds.size.width / self.imageView.image.size.width,

                        self.view.bounds.size.height / self.imageView.image.size.height);

    if (minZoom > 1)

    {

        minZoom = 1;

    }

    self.scrollView.minimumZoomScale = minZoom;

    // this will call "scrollViewDidZoom" if zoom did not change

    if (minZoom == self.lastZoomScale)

    {

        minZoom += 0.000001;

    }

    self.lastZoomScale = self.scrollView.zoomScale = minZoom;

}

@end