QRCode - 二维码识别与生成

来源：Yi\’mouleng（@丶伊眸冷）

链接：http://t.cn/R40WxcM

前言

有关二维码的介绍，我这里不做过多说明，可以直接去基维百科查看，附上链接QR code（https://en.wikipedia.org/wiki/QR_code）.

IOS7之前，开发者进行扫码编程时，一般会借助第三方库。常用的是ZBarSDKa和ZXingObjC，IOS7之后，系统的AVMetadataObject类中，为我们提供了解析二维码的接口。经过测试，使用原生API扫描和处理的效率非常高，远远高于第三方库。

扫描

官方提供的接口非常简单，直接看代码，主要使用的是AVFoundation。

@interface ViewController ()AVCaptureMetadataOutputObjectsDelegate>//用于处理采集信息的代理

{

    AVCaptureSession * session;//输入输出的中间桥梁

}

@end

@implementation ViewController

– (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    //获取摄像设备

    AVCaptureDevice * device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    //创建输入流

    AVCaptureDeviceInput * input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];

    if (!input) return;

    //创建输出流

    AVCaptureMetadataOutput * output = [[AVCaptureMetadataOutput alloc]init];

    //设置代理在主线程里刷新

    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];

    //设置有效扫描区域

    CGRect scanCrop=[self getScanCrop:_scanWindow.bounds readerViewBounds:self.view.frame];

     output.rectOfInterest = scanCrop;

    //初始化链接对象

    _session = [[AVCaptureSession alloc]init];

    //高质量采集率

    [_session setSessionPreset:AVCaptureSessionPresetHigh];



    [_session addInput:input];

    [_session addOutput:output];

    //设置扫码支持的编码格式(如下设置条形码和二维码兼容)

    output.metadataObjectTypes=@[AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode128Code];



    AVCaptureVideoPreviewLayer * layer = [AVCaptureVideoPreviewLayer layerWithSession:_session];

    layer.videoGravity=AVLayerVideoGravityResizeAspectFill;

    layer.frame=self.view.layer.bounds;

    [self.view.layer insertSublayer:layer atIndex:0];

    //开始捕获

    [_session startRunning];

}

–(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{

    if (metadataObjects.count>0) {

        //[session stopRunning];

        AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex : 0 ];

        //输出扫描字符串

        NSLog(@”%@”,metadataObject.stringValue);

    }

}

一些初始化的代码加上实现代理方法便完成了二维码扫描的工作，这里我们需要注意的是，在二维码扫描的时候，我们一般都会在屏幕中间放一个方框，用来显示二维码扫描的大小区间，这里我们在个AVCaptureMetadataOutput类中有一个rectOfInterest属性，它的作用就是设置扫描范围。

这个CGRect参数和普通的Rect范围不太一样，它的四个值的范围都是0-1，表示比例。
rectOfInterest都是按照横屏来计算的所以当竖屏的情况下 x轴和y轴要交换一下。
宽度和高度设置的情况也是类似。

我们在上面设置有效扫描区域的方法如下

#pragma mark-> 获取扫描区域的比例关系

–(CGRect)getScanCrop:(CGRect)rect readerViewBounds:(CGRect)readerViewBounds

{



    CGFloat x,y,width,height;



    x = (CGRectGetHeight(readerViewBounds)–CGRectGetHeight(rect))/2/CGRectGetHeight(readerViewBounds);

    y = (CGRectGetWidth(readerViewBounds)–CGRectGetWidth(rect))/2/CGRectGetWidth(readerViewBounds);

    width = CGRectGetHeight(rect)/CGRectGetHeight(readerViewBounds);

    height = CGRectGetWidth(rect)/CGRectGetWidth(readerViewBounds);



    return CGRectMake(x, y, width, height);



}

读取

读取主要用到CoreImage 不过要强调的是读取二维码的功能只有在iOS8之后才支持，我们需要在相册中调用一个二维码，将其读取，代码如下

#pragma mark-> 我的相册

–(void)myAlbum{



    NSLog(@”我的相册”);

    if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]){

        //1.初始化相册拾取器

        UIImagePickerController *controller = [[UIImagePickerController alloc] init];

        //2.设置代理

        controller.delegate = self;

        //3.设置资源：

        /**

         UIImagePickerControllerSourceTypePhotoLibrary,相册

         UIImagePickerControllerSourceTypeCamera,相机

         UIImagePickerControllerSourceTypeSavedPhotosAlbum,照片库

         */

        controller.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;

        //4.随便给他一个转场动画

        controller.modalTransitionStyle=UIModalTransitionStyleFlipHorizontal;

        [self presentViewController:controller animated:YES completion:NULL];



    }else{



        UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@”提示” message:@”设备不支持访问相册，请在设置->隐私->照片中进行设置！” delegate:nil cancelButtonTitle:@”确定” otherButtonTitles:nil, nil];

        [alert show];

    }



}

完成相册代理，我们在代理中添加读取二维码方法

#pragma mark-> imagePickerController delegate

– (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info

{

    //1.获取选择的图片

    UIImage *image = info[UIImagePickerControllerOriginalImage];

    //2.初始化一个监测器

    CIDetector*detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{ CIDetectorAccuracy : CIDetectorAccuracyHigh }];



    [picker dismissViewControllerAnimated:YES completion:^{

        //监测到的结果数组

        NSArray *features = [detector featuresInImage:[CIImage imageWithCGImage:image.CGImage]];

        if (features.count >=1) {

            /**结果对象 */

            CIQRCodeFeature *feature = [features objectAtIndex:0];

            NSString *scannedResult = feature.messageString;

            UIAlertView * alertView = [[UIAlertView alloc]initWithTitle:@”扫描结果” message:scannedResult delegate:nil cancelButtonTitle:@”确定” otherButtonTitles:nil, nil];

            [alertView show];



        }

        else{

            UIAlertView * alertView = [[UIAlertView alloc]initWithTitle:@”提示” message:@”该图片没有包含一个二维码！” delegate:nil cancelButtonTitle:@”确定” otherButtonTitles:nil, nil];

            [alertView show];



        }





    }];





}

因为没用真机，所以这里没有给出太多的截图，用模拟器读取自带图片，结果如下

生成

生成二维码，其实也是用到CoreImage，但是步骤繁琐一些，代码如下

#pragma mark-> 二维码生成

–(void)create{



    UIImage *image=[UIImage imageNamed:@”6824500_006_thumb.jpg”];

    NSString*tempStr;

    if(self.textField.text.length==0){



        tempStr=@”ddddddddd”;



    }else{



        tempStr=self.textField.text;



    }

    UIImage*tempImage=[QRCodeGenerator qrImageForString:tempStr imageSize:360 Topimg:image withColor:RandomColor];



    _outImageView.image=tempImage;



}

+(UIImage*)qrImageForString:(NSString *)string imageSize:(CGFloat)size Topimg:(UIImage *)topimg withColor:(UIColor*)color{



    if (![string length]) {

        return nil;

    }



    QRcode *code = QRcode_encodeString([string UTF8String], 0, QR_ECLEVEL_L, QR_MODE_8, 1);

    if (!code) {

        return nil;

    }



    // create context

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGContextRef ctx = CGBitmapContextCreate(0, size, size, 8, size * 4, colorSpace, kCGImageAlphaPremultipliedLast);



    CGAffineTransform translateTransform = CGAffineTransformMakeTranslation(0, –size);

    CGAffineTransform scaleTransform = CGAffineTransformMakeScale(1, –1);

    CGContextConcatCTM(ctx, CGAffineTransformConcat(translateTransform, scaleTransform));



    // draw QR on this context

    [QRCodeGenerator drawQRCode:code context:ctx size:size withPointType:0 withPositionType:0 withColor:color];



    // get image

    CGImageRef qrCGImage = CGBitmapContextCreateImage(ctx);

    UIImage * qrImage = [UIImage imageWithCGImage:qrCGImage];



    if(topimg)

    {

        UIGraphicsBeginImageContext(qrImage.size);



        //Draw image2

        [qrImage drawInRect:CGRectMake(0, 0, qrImage.size.width, qrImage.size.height)];



        //Draw image1

        float r=qrImage.size.width*35/240;

        [topimg drawInRect:CGRectMake((qrImage.size.width–r)/2, (qrImage.size.height–r)/2 ,r, r)];

        qrImage=UIGraphicsGetImageFromCurrentImageContext();



        UIGraphicsEndImageContext();

    }

    // some releases

    CGContextRelease(ctx);

    CGImageRelease(qrCGImage);

    CGColorSpaceRelease(colorSpace);

    QRcode_free(code);



    return qrImage;



}

+ (void)drawQRCode:(QRcode *)code context:(CGContextRef)ctx size:(CGFloat)size withPointType:(QRPointType)pointType withPositionType:(QRPositionType)positionType withColor:(UIColor *)color {

unsigned char *data = 0;

int width;

data = code->data;

width = code->width;

float zoom = (double)size / (code->width + 2.0 * qr_margin);

CGRect rectDraw = CGRectMake(0, 0, zoom, zoom);



// draw

    const CGFloat *components;

    if (color) {

        components = CGColorGetComponents(color.CGColor);

    }else {

        components = CGColorGetComponents([UIColor blackColor].CGColor);

    }

    CGContextSetRGBFillColor(ctx, components[0], components[1], components[2], 1.0);

    NSLog(@”aad :%f  bbd :%f   ccd:%f”,components[0],components[1],components[2]);

for(int i = 0; i

for(int j = 0; j

if(*data & 1) {

rectDraw.origin = CGPointMake((j + qr_margin) * zoom,(i + qr_margin) * zoom);

                if (positionType == QRPositionNormal) {

                    switch (pointType) {

                        case QRPointRect:

                            CGContextAddRect(ctx, rectDraw);

                            break;

                        case QRPointRound:

                            CGContextAddEllipseInRect(ctx, rectDraw);

                            break;

                        default:

                            break;

                    }

                }else if(positionType == QRPositionRound) {

                    switch (pointType) {

                        case QRPointRect:

                            CGContextAddRect(ctx, rectDraw);

                            break;

                        case QRPointRound:

                            if ((i>=0 && i6 && j>=0 && j6) || (i>=0 && i6 && j>=width–7–1 && j–1) || (i>=width–7–1 && i–1 && j>=0 && j6)) {

                                CGContextAddRect(ctx, rectDraw);

                            }else {

                                CGContextAddEllipseInRect(ctx, rectDraw);

                            }

                            break;

                        default:

                            break;

                    }

                }

}

++data;

}

}

CGContextFillPath(ctx);

}