kmpdfkit_demo/compdfkit-tools/compdfkit-tools/PDFBOTA/PDFThumbnail/CPDFThumbnailViewController.m

//
//  PDFThumbnailViewController.m
//  compdfkit-tools
//
//  Copyright © 2014-2023 PDF Technologies, Inc. All Rights Reserved.
//
//  THIS SOURCE CODE AND ANY ACCOMPANYING DOCUMENTATION ARE PROTECTED BY INTERNATIONAL COPYRIGHT LAW
//  AND MAY NOT BE RESOLD OR REDISTRIBUTED. USAGE IS BOUND TO THE ComPDFKit LICENSE AGREEMENT.
//  UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS SUBJECT TO CIVIL AND CRIMINAL PENALTIES.
//  This notice may not be removed from this file.
//

#import "CPDFThumbnailViewController.h"
#import "CPDFThumbnailViewCell.h"

#import <ComPDFKit/ComPDFKit.h>

@interface CPDFThumbnailViewController () <UICollectionViewDelegate,UICollectionViewDataSource>

@property (nonatomic, assign) CGPDFDocumentRef documentRef;
@property (nonatomic, strong) UICollectionView *collectionView;

@end

@implementation CPDFThumbnailViewController

#pragma mark - Initializers

- (instancetype)initWithPDFView:(CPDFView *)pdfView {
    if (self = [super init]) {
        _pdfView = pdfView;
    }
    return self;
}

#pragma mark - Accessors

- (UICollectionView *)collectionView {
    if (!_collectionView) {
        UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
        layout.itemSize = CGSizeMake(110, 185);
        layout.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5);
        layout.minimumInteritemSpacing = 5;
        layout.minimumLineSpacing = 5;
        
        _collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
        [_collectionView registerClass:[CPDFThumbnailViewCell class] forCellWithReuseIdentifier:@"cell"];
        _collectionView.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
        _collectionView.delegate = self;
        _collectionView.dataSource = self;
        _collectionView.alwaysBounceVertical = YES;
        if (@available(iOS 11.0, *)) {
            _collectionView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentAlways;
        }
    }
    return _collectionView;
}

#pragma mark - UIViewController Methods

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    [self.view addSubview:self.collectionView];
    
    NSURL *documentURL = [self.pdfView.document documentURL];
    if (documentURL) {
        _documentRef = CGPDFDocumentCreateWithURL((CFURLRef)documentURL);
        if ([self.pdfView.document password]) {
            CGPDFDocumentUnlockWithPassword(_documentRef, [[self.pdfView.document password] UTF8String]);
        }
    } else {
        _documentRef = NULL;
    }
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    
    [self.collectionView reloadData];
    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:self.pdfView.currentPageIndex inSection:0];
    [self.collectionView selectItemAtIndexPath:indexPath
                                      animated:NO
                                scrollPosition:UICollectionViewScrollPositionCenteredVertically];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    
    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:self.pdfView.currentPageIndex inSection:0];
    [self.collectionView scrollToItemAtIndexPath:indexPath
                                atScrollPosition:UICollectionViewScrollPositionCenteredVertically
                                        animated:YES];
}

#pragma mark - Class method

- (void)setCollectViewSize:(CGSize)size {
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    layout.itemSize = size;
    layout.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5);
    layout.minimumInteritemSpacing = 5;
    layout.minimumLineSpacing = 5;
    
    self.collectionView.collectionViewLayout = layout;
}

#pragma mark - UICollectionViewDataSource

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return CGPDFDocumentGetNumberOfPages(_documentRef);
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    CPDFThumbnailViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
    CPDFPage *page = [self.pdfView.document pageAtIndex:indexPath.item];
    CGSize pageSize = [self.pdfView.document pageSizeAtIndex:indexPath.item];
    CGFloat multiple = MAX(pageSize.width / 110, pageSize.height / 173);
    cell.imageSize = CGSizeMake(pageSize.width / multiple, pageSize.height / multiple);
    [cell setNeedsLayout];
    cell.imageView.image = [page thumbnailOfSize:CGSizeMake(pageSize.width / multiple, pageSize.height / multiple)];
    cell.textLabel.text = [NSString stringWithFormat:@"%@",@(indexPath.item+1)];
    return cell;
}

#pragma mark - UICollectionViewDelegate

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
    [self dismissViewControllerAnimated:YES completion:^{
        [self.delegate thumbnailViewController:self forPageIndex:indexPath.item];
        [self.navigationController popViewControllerAnimated:YES];
    }];
}

@end