//
//  GetScreenImage.m
//  截图
//
//  Created by jcymac on 2018/4/23.
//  Copyright © 2018年 jcymac. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "GetScreenImage.h"
#import "KBScreenshotShareView.h"
@interface GetScreenImage()
@property(nonatomic,strong)NSObject *observer;
@property(nonatomic,strong)UIView *baseView;
@property(nonatomic,strong)KBScreenshotShareView *screenshotShareView;
@end

@implementation GetScreenImage


static GetScreenImage *staticInstance=nil;


#pragma mark -暴露方法
+(instancetype)shareInstance{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        staticInstance=[[GetScreenImage alloc]init];
        
    });
    return staticInstance;
    
}


-(void)startListening{
    [self stopListening];
    _observer=[[NSNotificationCenter defaultCenter] addObserverForName:UIApplicationUserDidTakeScreenshotNotification
                                                      object:nil
                                                       queue:nil
                                                  usingBlock:^(NSNotification *note) {
                                                      NSLog(@"截屏咯");
                                                      [self userDidTakeScreenshot];
                                                  }];
}

-(void)stopListening{
    if(_observer){
         [[NSNotificationCenter defaultCenter] removeObserver:_observer];
        _observer=nil;
    }
}





#pragma mark -内部方法
//截屏响应
- (void)userDidTakeScreenshot
{
    NSLog(@"检测到截屏");
    //人为截屏, 模拟用户截屏行为, 获取所截图片
    UIImage *image = [self imageWithScreenshot];
    _screenImage=image;
    _screenshotShareView=[[KBScreenshotShareView alloc]initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT)];
    [self.screenshotShareView.imageView setImage:image];
    [[UIApplication sharedApplication].keyWindow addSubview:self.screenshotShareView];
    
    
    if (self.resultBlock) {
        self.resultBlock();
    }
}


-(UIImage *)screenImage{
    if (!_screenImage) {
        _screenImage=[self imageWithScreenshot];
    }
    return _screenImage;
}


- (UIImage *)imageWithScreenshot
{
    NSData *imageData = [self dataWithScreenshotInPNGFormat];
    return [UIImage imageWithData:imageData];
}




//获取数据
- (NSData *)dataWithScreenshotInPNGFormat
{
    CGSize imageSize = CGSizeZero;
    //获取设备方向
    UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
    if (UIInterfaceOrientationIsPortrait(orientation))//如果是竖直
        imageSize = [UIScreen mainScreen].bounds.size;
    else
        //水平
        imageSize = CGSizeMake([UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width);
    
    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);//绘制绘画区域
    CGContextRef context = UIGraphicsGetCurrentContext();//获取绘图上下文
    for (UIWindow *window in [[UIApplication sharedApplication] windows])//遍历windows
    {
        //函数的作用是将当前图形状态推入堆栈
        CGContextSaveGState(context);
        //内容放到window的中心
        CGContextTranslateCTM(context, window.center.x, window.center.y);
        //仿射变换
        CGContextConcatCTM(context, window.transform);
        CGContextTranslateCTM(context, -window.bounds.size.width * window.layer.anchorPoint.x, -window.bounds.size.height * window.layer.anchorPoint.y);
        if (orientation == UIInterfaceOrientationLandscapeLeft)//home在左
        {
            CGContextRotateCTM(context, M_PI_2);
            CGContextTranslateCTM(context, 0, -imageSize.width);
        }
        else if (orientation == UIInterfaceOrientationLandscapeRight)//home在左
        {
            CGContextRotateCTM(context, -M_PI_2);
            CGContextTranslateCTM(context, -imageSize.height, 0);
        } else if (orientation == UIInterfaceOrientationPortraitUpsideDown) {
            CGContextRotateCTM(context, M_PI);
            CGContextTranslateCTM(context, -imageSize.width, -imageSize.height);
        }
        if ([window respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)])
        {
            //截图 放到内容上下文
            
            [window drawViewHierarchyInRect:window.bounds afterScreenUpdates:YES];
        }
        else
        {
            [window.layer renderInContext:context];
        }
        //更新渲染
        CGContextRestoreGState(context);
    }
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();//关闭上下文
    
    return UIImagePNGRepresentation(image);//转换成png的数据
}




@end