kmpdfkit_demo/PDFViewer/Source/PDFBackground/PDFDrawBackgroundView.m

//
//  CPDFDrawBackgroundView.m
//  PDFViewer
//
//  Created by kdanmobile_2 on 2023/1/3.
//

#import "PDFDrawBackgroundView.h"

@implementation PDFDrawBackgroundView

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    
    if (self) {
        self.backgroundColor = [UIColor whiteColor];
    }
    
    return self;
}

- (void)drawRect:(CGRect)rect {
    [super drawRect:rect];
    
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    [self showDraw:context];
}

- (void)showDraw:(CGContextRef)context {
    CGContextSetFillColorWithColor(context, self.dataModel.backgroundColor.CGColor);
    
    CGContextSetAlpha(context, self.dataModel.backgroundOpacity);
    
    CGFloat ctm = (self.dataModel.backgroundRotation * M_PI) / 180;
    CGFloat centerWidth = self.bounds.size.width / 2;
    CGFloat centerHeigth = self.bounds.size.height / 2;
    
    CGContextTranslateCTM(context, self.dataModel.horizontalSpacing, - self.dataModel.verticalSpacing);

    CGContextTranslateCTM(context, centerWidth, centerHeigth);
    CGContextRotateCTM(context, ctm);
    
    CGContextScaleCTM(context, self.dataModel.backgroudScale, self.dataModel.backgroudScale);
    if (_dataModel.image) {
        [_dataModel.image drawInRect:CGRectMake(- centerWidth,  - centerHeigth, self.frame.size.width,self.frame.size.height) blendMode:kCGBlendModeNormal alpha:self.dataModel.backgroundOpacity];
    } else {
        CGContextFillRect(context, CGRectMake( - centerWidth, - centerHeigth, self.bounds.size.width, self.bounds.size.height));
    }
    
    CGContextRotateCTM(context, -ctm);
    CGContextTranslateCTM(context, - centerWidth, - centerHeigth);
}

@end