Kulexiu/KulexiuForStudent/Pods/RSKImageCropper/RSKImageCropper/RSKImageScrollView.m

/*
     File: RSKImageScrollView.m
 Abstract: Centers image within the scroll view and configures image sizing and display.
  Version: 1.5 modified by Ruslan Skorb on 11/26/24.
 
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 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
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 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND
 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.
 
 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL
 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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 Copyright (C) 2012 Apple Inc. All Rights Reserved.
 Copyright (C) 2014-present Ruslan Skorb. All Rights Reserved.
 
 */

#import <Foundation/Foundation.h>

#import "RSKImageScrollView.h"
#import "RSKImageScrollViewDelegate.h"

#pragma mark -

@interface RSKImageScrollView () <UIScrollViewDelegate>
{
    CGSize _imageSize;
    UIImageView *_imageView;
    
    CGPoint _pointToCenterAfterResize;
    CGFloat _scaleToRestoreAfterResize;
}

@end

@implementation RSKImageScrollView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self)
    {
        _aspectFill = NO;
        _imageView = [[UIImageView alloc] init];
        self.showsVerticalScrollIndicator = NO;
        self.showsHorizontalScrollIndicator = NO;
        self.scrollsToTop = NO;
        self.decelerationRate = UIScrollViewDecelerationRateFast;
        self.delegate = self;
        
        [self addSubview:_imageView];
    }
    return self;
}

- (void)didAddSubview:(UIView *)subview
{
    [super didAddSubview:subview];
    
    [self centerImageView];
}

- (void)setAspectFill:(BOOL)aspectFill
{
    if (_aspectFill != aspectFill) {
        _aspectFill = aspectFill;
        
        if (_imageView.image) {
            [self setMaxMinZoomScalesForCurrentBounds];
            
            if (self.zoomScale < self.minimumZoomScale) {
                self.zoomScale = self.minimumZoomScale;
            } else if (self.zoomScale > self.maximumZoomScale) {
                self.zoomScale = self.maximumZoomScale;
            }
        }
    }
}

- (UIImage *)image
{
    return _imageView.image;
}

- (void)setImage:(UIImage *)image
{
    _imageView.image = image;
    
    if (CGSizeEqualToSize(_imageSize, CGSizeZero)) {
        self.imageSize = image.size;
    }
}

- (UIColor *)imageViewBackgroundColor
{
    return _imageView.backgroundColor;
}

- (void)setImageViewBackgroundColor:(UIColor *)imageViewBackgroundColor
{
    _imageView.backgroundColor = imageViewBackgroundColor;
}

- (id<UICoordinateSpace>)imageViewCoordinateSpace
{
    return [_imageView coordinateSpace];
}

- (CGRect)imageViewFrame
{
    return _imageView.frame;
}

- (void)setImageSize:(CGSize)imageSize
{
    _imageSize = imageSize;
    
    self.zoomScale = 1.0f;
    _imageView.frame = CGRectMake(0.0f, 0.0f, imageSize.width, imageSize.height);
    self.contentSize = imageSize;
    [self setMaxMinZoomScalesForCurrentBounds];
    [self setInitialZoomScale];
    [self setInitialContentOffset];
    [self centerImageView];
}

- (void)setInitialZoomScaleAndContentOffsetAndCenterImageView
{
    [self setInitialZoomScale];
    [self setInitialContentOffset];
    [self centerImageView];
}

- (void)setInitialZoomScaleAndContentOffsetAnimated:(BOOL)animated
{
    if (animated) {
        UIViewAnimationOptions options = UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationCurveEaseInOut;
        [UIView animateWithDuration:0.4f delay:0.0f options:options animations:^{
            [self setInitialZoomScaleAndContentOffsetAndCenterImageView];
        } completion:nil];
    } else {
        [self setInitialZoomScaleAndContentOffsetAndCenterImageView];
    }
}

- (void)setFrame:(CGRect)frame
{
    if (CGSizeEqualToSize(self.contentSize, CGSizeZero)) {
        [super setFrame:frame];
        return;
    }
    
    BOOL sizeChanging = !CGSizeEqualToSize(frame.size, self.frame.size);
    
    if (sizeChanging) {
        [self prepareToResize];
    }
    
    [super setFrame:frame];
    
    if (sizeChanging) {
        [self recoverFromResizing];
    }
    
    [self centerImageView];
}

- (void)zoomToLocation:(CGPoint)location animated:(BOOL)animated
{
    CGPoint locationInImageView = [_imageView convertPoint:location fromView:self];
    CGSize size = CGSizeMake(self.bounds.size.width / MIN(self.zoomScale * 5.0f, self.maximumZoomScale),
                             self.bounds.size.height / MIN(self.zoomScale * 5.0f, self.maximumZoomScale));
    CGPoint origin = CGPointMake(locationInImageView.x - size.width * 0.5f,
                                 locationInImageView.y - size.height * 0.5f);
    CGRect rect = CGRectMake(origin.x, origin.y, size.width, size.height);
    
    [self zoomToRect:rect animated:animated];
}

#pragma mark - UIScrollViewDelegate

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return _imageView;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if ([self.imageScrollViewDelegate respondsToSelector:@selector(imageScrollViewDidScroll)]) {
        [self.imageScrollViewDelegate imageScrollViewDidScroll];
    }
}

- (void)scrollViewDidZoom:(__unused UIScrollView *)scrollView
{
    [self centerImageView];
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    if ([self.imageScrollViewDelegate respondsToSelector:@selector(imageScrollViewWillBeginDragging)]) {
        [self.imageScrollViewDelegate imageScrollViewWillBeginDragging];
    }
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    if ([self.imageScrollViewDelegate respondsToSelector:@selector(imageScrollViewDidEndDragging:)]) {
        [self.imageScrollViewDelegate imageScrollViewDidEndDragging:decelerate];
    }
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    if ([self.imageScrollViewDelegate respondsToSelector:@selector(imageScrollViewDidEndDecelerating)]) {
        [self.imageScrollViewDelegate imageScrollViewDidEndDecelerating];
    }
}

- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view
{
    if ([self.imageScrollViewDelegate respondsToSelector:@selector(imageScrollViewWillBeginZooming)]) {
        [self.imageScrollViewDelegate imageScrollViewWillBeginZooming];
    }
}

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale
{
    if ([self.imageScrollViewDelegate respondsToSelector:@selector(imageScrollViewDidEndZooming)]) {
        [self.imageScrollViewDelegate imageScrollViewDidEndZooming];
    }
}

#pragma mark - Center imageView within scrollView

- (void)centerImageView
{
    // center imageView as it becomes smaller than the size of the screen
    
    CGFloat top = 0.0f;
    CGFloat left = 0.0f;
    
    // center vertically
    if (self.contentSize.height < CGRectGetHeight(self.bounds)) {
        top = (CGRectGetHeight(self.bounds) - self.contentSize.height) * 0.5f;
    }
    
    // center horizontally
    if (self.contentSize.width < CGRectGetWidth(self.bounds)) {
        left = (CGRectGetWidth(self.bounds) - self.contentSize.width) * 0.5f;
    }
    
    UIEdgeInsets contentInset = UIEdgeInsetsMake(top, left, top, left);
    
    if (!UIEdgeInsetsEqualToEdgeInsets(self.contentInset, contentInset)) {
        self.contentInset = contentInset;
    }
}

#pragma mark - Configure scrollView to display new image

- (void)setMaxMinZoomScalesForCurrentBounds
{
    if (CGSizeEqualToSize(self.bounds.size, CGSizeZero)) {
        return;
    }
    
    if (CGSizeEqualToSize(_imageSize, CGSizeZero)) {
        self.maximumZoomScale = 1.0f;
        self.minimumZoomScale = 1.0f;

        return;
    }
    
    CGSize boundsSize = self.bounds.size;
    
    // calculate min/max zoomscale
    CGFloat xScale = boundsSize.width  / _imageSize.width;    // the scale needed to perfectly fit the image width-wise
    CGFloat yScale = boundsSize.height / _imageSize.height;   // the scale needed to perfectly fit the image height-wise
    
    CGFloat minScale;
    if (_aspectFill) {
        minScale = MAX(xScale, yScale); // use maximum of these to allow the image to fill the screen
    } else {
        minScale = MIN(xScale, yScale); // use minimum of these to allow the image to become fully visible
    }
    
    CGFloat maxScale = MAX(xScale, yScale);
    
    // Image must fit/fill the screen, even if its size is smaller.
    CGFloat xImageScale = maxScale * _imageSize.width / boundsSize.width;
    CGFloat yImageScale = maxScale * _imageSize.height / boundsSize.height;
    
    CGFloat maxImageScale = MAX(xImageScale, yImageScale);
    
    maxImageScale = MAX(minScale, maxImageScale);
    maxScale = MAX(maxScale, maxImageScale);
    
    // don't let minScale exceed maxScale. (If the image is smaller than the screen, we don't want to force it to be zoomed.)
    if (minScale > maxScale) {
        minScale = maxScale;
    }
    
    self.maximumZoomScale = maxScale;
    self.minimumZoomScale = minScale;
}

- (void)setInitialZoomScale
{
    if (self.zoomScale != self.minimumZoomScale) {
        self.zoomScale = self.minimumZoomScale;
    }
}

- (void)setInitialContentOffset
{
    CGSize boundsSize = self.bounds.size;
    CGRect frameToCenter = _imageView.frame;
    
    CGPoint contentOffset = self.contentOffset;
    if (CGRectGetWidth(frameToCenter) > boundsSize.width) {
        contentOffset.x = (CGRectGetWidth(frameToCenter) - boundsSize.width) * 0.5f;
    }
    if (CGRectGetHeight(frameToCenter) > boundsSize.height) {
        contentOffset.y = (CGRectGetHeight(frameToCenter) - boundsSize.height) * 0.5f;
    }
    
    if (!CGPointEqualToPoint(self.contentOffset, contentOffset)) {
        self.contentOffset = contentOffset;
    }
}

#pragma mark -
#pragma mark Methods called during rotation to preserve the zoomScale and the visible portion of the image

#pragma mark - Rotation support

- (void)prepareToResize
{
    if (_imageView == nil) {
        return;
    }
    
    CGPoint boundsCenter = CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds));
    _pointToCenterAfterResize = [self convertPoint:boundsCenter toView:_imageView];
    
    _scaleToRestoreAfterResize = self.zoomScale;
    
    // If we're at the minimum zoom scale, preserve that by returning 0, which will be converted to the minimum
    // allowable scale when the scale is restored.
    if (_scaleToRestoreAfterResize <= self.minimumZoomScale + FLT_EPSILON)
        _scaleToRestoreAfterResize = 0;
}

- (void)recoverFromResizing
{
    if (_imageView == nil) {
        return;
    }
    
    [self setMaxMinZoomScalesForCurrentBounds];
    
    // Step 1: restore zoom scale, first making sure it is within the allowable range.
    CGFloat maxZoomScale = MAX(self.minimumZoomScale, _scaleToRestoreAfterResize);
    self.zoomScale = MIN(self.maximumZoomScale, maxZoomScale);
    
    // Step 2: restore center point, first making sure it is within the allowable range.
    
    // 2a: convert our desired center point back to our own coordinate space
    CGPoint boundsCenter = [self convertPoint:_pointToCenterAfterResize fromView:_imageView];
    
    // 2b: calculate the content offset that would yield that center point
    CGPoint offset = CGPointMake(boundsCenter.x - self.bounds.size.width * 0.5f,
                                 boundsCenter.y - self.bounds.size.height * 0.5f);
    
    // 2c: restore offset, adjusted to be within the allowable range
    CGPoint maxOffset = [self maximumContentOffset];
    CGPoint minOffset = [self minimumContentOffset];
    
    CGFloat realMaxOffset = MIN(maxOffset.x, offset.x);
    offset.x = MAX(minOffset.x, realMaxOffset);
    
    realMaxOffset = MIN(maxOffset.y, offset.y);
    offset.y = MAX(minOffset.y, realMaxOffset);
    
    if (self.contentSize.height < self.bounds.size.height) {
        
        offset.y = -(self.bounds.size.height - self.contentSize.height) * 0.5f;
    }
    if (self.contentSize.width < self.bounds.size.width) {
        
        offset.x = -(self.bounds.size.width - self.contentSize.width) * 0.5f;
    }
    
    self.contentOffset = offset;
}

- (CGPoint)maximumContentOffset
{
    CGSize contentSize = self.contentSize;
    CGSize boundsSize = self.bounds.size;
    return CGPointMake(contentSize.width - boundsSize.width, contentSize.height - boundsSize.height);
}

- (CGPoint)minimumContentOffset
{
    return CGPointZero;
}

@end