学步园

  文章：http://blog.csdn.net/jinglijun/article/details/9337329   

在ios 中 扫瞄二维码，条形码基本有 2中第三方的库，一个是zbar 一个是zxing，zxing 在android中表现的比较出色，但是在ios 中不是很好用，扫瞄效率低，我们一般都用zbar，但是有些 条形码就是很奇葩，用zbar无法识别，下面就是一种

 我用了好多ios 的app 都无法识别， 《我查查》，《快拍二维码》，《微信》，自己用zbar都不行，最后用android 手机轻松扫瞄ok，哪我知道为什么了，是zxing可以搞定这种条形码。马上就换了zxing 来测试。 去github 找到了 zxing 的demo。但是悲剧的时无法识别各种条形码。

而且工程还报错。

  报Private field 'cached_y_' not used 编译通不过，解决办法就是

删除工程“buliding setting”的"Other Warning Flags"  的后面的参数：

"-Werror" ，  "-Wno-unused-parameter"  等等

  然后真机debug 完全ok，但是还是无法扫瞄 条形码！为什么呢？

  我在网上着了下原因 ，问题解决了。

方法是：

 1.修改 OverlayView.m文件中的61行左右

// self.oneDMode = isOneDModeEnabled;

注释掉。

2.在ZXingWidgetController.m中用这个函数替换以前的函数

- (void)captureOutput:(AVCaptureOutput *)captureOutput 
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer 
       fromConnection:(AVCaptureConnection *)connection 
{
  if (!decoding) {
    return;
  }
  CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
  /*Lock the image buffer*/
  CVPixelBufferLockBaseAddress(imageBuffer,0); 
  /*Get information about the image*/
  size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); 
  size_t width = CVPixelBufferGetWidth(imageBuffer); 
  size_t height = CVPixelBufferGetHeight(imageBuffer); 
    
  uint8_t* baseAddress = CVPixelBufferGetBaseAddress(imageBuffer); 
  void* free_me = 0;
  if (true) { // iOS bug?
    uint8_t* tmp = baseAddress;
    int bytes = bytesPerRow*height;
    free_me = baseAddress = (uint8_t*)malloc(bytes);
    baseAddress[0] = 0xdb;
    memcpy(baseAddress,tmp,bytes);
  }

  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
  CGContextRef newContext =
    CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace,
                          kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipFirst); 

  CGImageRef capture = CGBitmapContextCreateImage(newContext); 
  CVPixelBufferUnlockBaseAddress(imageBuffer,0);
  free(free_me);

  CGContextRelease(newContext); 
  CGColorSpaceRelease(colorSpace);

  CGRect cropRect = [overlayView cropRect];
  if (oneDMode) {
    // let's just give the decoder a vertical band right above the red line
//    cropRect.origin.x = cropRect.origin.x + (cropRect.size.width / 2) - (ONE_D_BAND_HEIGHT + 1);
//    cropRect.size.width = ONE_D_BAND_HEIGHT;
//    // do a rotate
//    CGImageRef croppedImg = CGImageCreateWithImageInRect(capture, cropRect);
//    CGImageRelease(capture);
//    capture = [self CGImageRotated90:croppedImg];
//    capture = [self CGImageRotated180:capture];
//    //              UIImageWriteToSavedPhotosAlbum([UIImage imageWithCGImage:capture], nil, nil, nil);
//    CGImageRelease(croppedImg);
//    CGImageRetain(capture);
//    cropRect.origin.x = 0.0;
//    cropRect.origin.y = 0.0;
    cropRect.size.width = CGImageGetWidth(capture);
    cropRect.size.height = CGImageGetHeight(capture);
  }

  // N.B.
  // - Won't work if the overlay becomes uncentered ...
  // - iOS always takes videos in landscape
  // - images are always 4x3; device is not
  // - iOS uses virtual pixels for non-image stuff

  {
    float height = CGImageGetHeight(capture);
    float width = CGImageGetWidth(capture);

    CGRect screen = UIScreen.mainScreen.bounds;
    float tmp = screen.size.width;
    screen.size.width = screen.size.height;;
    screen.size.height = tmp;

    cropRect.origin.x = (width-cropRect.size.width)/2;
    cropRect.origin.y = (height-cropRect.size.height)/2;
  }
  CGImageRef newImage = CGImageCreateWithImageInRect(capture, cropRect);
  CGImageRelease(capture);
 // UIImage *scrn = [[UIImage alloc] initWithCGImage:newImage];
    int backCameraImageOrientation = UIImageOrientationRight;
    UIImage *scrn = [[UIImage alloc] initWithCGImage:newImage scale:
                     (CGFloat)1.0 orientation:backCameraImageOrientation];

  CGImageRelease(newImage);
  Decoder *d = [[Decoder alloc] init];
  d.readers = readers;
  d.delegate = self;
  cropRect.origin.x = 0.0;  
  cropRect.origin.y = 0.0;
  decoding = [d decodeImage:scrn cropRect:cropRect] == YES ? NO : YES;
  [d release];
  [scrn release];
} 

 也就是上面红色的部分做了修改

3.在ViewController.mm 文件中做下面的修改

#import "MultiFormatOneDReader.h"

- (void)pressButton1:(UIButton *)button
{
    ZXingWidgetController *widController = [[ZXingWidgetController alloc] initWithDelegate:self showCancel:YES OneDMode:YES];
    NSMutableSet *readers = [[NSMutableSet alloc] init];
    QRCodeReader *qrcodeReader = [[QRCodeReader alloc] init];

    MultiFormatOneDReader *OneReaders=[[MultiFormatOneDReader alloc]init];
 
    [readers addObject:qrcodeReader];
     [readers addObject:OneReaders];
    widController.readers = readers;
    [self presentViewController:widController animated:YES completion:^{}];
}

然后修改全部ok了，扫瞄条形码就完全ok了。

 看效果：

 二：

三：

四：