kmpdfkit_demo/PDFViewer/Source/PDFSlider/PDFSlider.m

//
//  PDFSlider.m
//  PDFReader
//
//  Copyright © 2014-2022 PDF Technologies, Inc. All Rights Reserved.
//
//  The PDF Reader Sample applications are licensed with a modified BSD license.
//  Please see License for details. This notice may not be removed from this file.
//

#import "PDFSlider.h"

@interface PDFSlider ()

@property (nonatomic,retain) UIImageView *valueView;

@property (nonatomic,retain) UILabel *label;

@property (nonatomic,assign) BOOL isTouchBegan;

@end

@implementation PDFSlider

#pragma mark - Init Methods

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        _valueView = [[UIImageView alloc] initWithFrame:CGRectMake(frame.size.width-21, 0, 21, 69)];
        _valueView.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin;
        _valueView.image = [UIImage imageNamed:@"slidepage.png"];
        [self addSubview:_valueView];
        
        _label = [[UILabel alloc] init];
        _label.textAlignment = NSTextAlignmentCenter;
        _label.textColor = [UIColor blackColor];
        _label.backgroundColor = [UIColor whiteColor];
        _label.layer.cornerRadius = 2.0;
        _label.layer.borderWidth = 1.0;
        _label.layer.borderColor = [UIColor lightGrayColor].CGColor;
        _label.hidden = YES;
        [self addSubview:_label];
    }
    return self;
}

- (void)dealloc {
    [_label release];
    [_valueView release];
    [super dealloc];
}

#pragma mark - Public Methods

- (void)reloadData {
    CGPoint center = self.valueView.center;
    NSInteger pageIndex = [self.pdfViewController.pdfView currentPageIndex];
    CGFloat height = CGRectGetHeight(self.valueView.frame);
    CGFloat pageHeight = CGRectGetHeight(self.frame)/[self.pdfViewController.pdfView.document pageCount];
    if (center.y >= pageIndex*pageHeight &&
        center.y <= (pageIndex+1)*pageHeight) {
        return;
    }
    center.y = pageIndex*pageHeight+pageHeight/2.0;
    center.y = MAX(height/2.0, center.y);
    center.y = MIN(center.y, CGRectGetHeight(self.frame)-height/2.0);
    self.valueView.center = center;
}

- (void)updateLabelFrame {
    CGPoint center = self.valueView.center;
    CGFloat height = CGRectGetHeight(self.valueView.frame);
    CGFloat pageHeight = (CGRectGetHeight(self.frame)-height)/[self.pdfViewController.pdfView.document pageCount];
    NSInteger pageIndex = (center.y-height/2.0)/pageHeight;
    pageIndex = MAX(0, pageIndex);
    pageIndex = MIN(pageIndex, [self.pdfViewController.pdfView.document pageCount]-1);
    
    self.label.text = [NSString stringWithFormat:@"%@",@(pageIndex+1)];
    [self.label sizeToFit];
    self.label.frame = CGRectMake(0, 0,
                                  CGRectGetWidth(self.label.frame)+20,
                                  CGRectGetHeight(self.label.frame)+10);
    self.label.center = CGPointMake(-CGRectGetWidth(self.label.frame)/2.0-30, center.y);
}

#pragma mark - Touch Methods

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInView:self];
    self.isTouchBegan = CGRectContainsPoint(self.valueView.frame, location);
    if (self.isTouchBegan) {
        self.label.hidden = NO;
        [self updateLabelFrame];
    }
}

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    if (!self.isTouchBegan) {
        return;
    }
    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInView:self];
    CGPoint center = self.valueView.center;
    if (location.y < CGRectGetHeight(self.valueView.frame)/2.0) {
        center.y = CGRectGetHeight(self.valueView.frame)/2.0;
    } else if (location.y > CGRectGetHeight(self.frame)-CGRectGetHeight(self.valueView.frame)/2.0) {
        center.y = CGRectGetHeight(self.frame)-CGRectGetHeight(self.valueView.frame)/2.0;
    } else {
        center.y = location.y;
    }
    self.valueView.center = center;
    [self updateLabelFrame];
}

- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    if (!self.isTouchBegan) {
        return;
    }
    self.label.hidden = YES;
    NSInteger pageIndex = [self.label.text integerValue]-1;
    [self.pdfViewController.pdfView goToPageIndex:pageIndex animated:NO];
}

@end