QRCode - 二维码识别与生成

2022-10-28 09:13:13

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);

}