[英]How to scan driver's license (PDF417) using xamarin forms + zxing on iOS 10.2
I am using Xamarin forms to write an iOS app and using the ZXing library to scan barcodes. 我正在使用Xamarin表单编写iOS应用程序,并使用ZXing库扫描条形码。 I am trying to read a driver's license (PDF417) barcode, but the library is not able to recognize that barcode.
我正在尝试读取驾驶执照(PDF417)条码,但该库无法识别该条码。
If I include UPC or other barcodes in the PossibleFormats, they are scanned correctly. 如果我在“可能的格式”中包含UPC或其他条形码,则它们将被正确扫描。
I am also certain the barcode I am trying to read is PDF417 barcode because Scandit is able to recognize it correctly while using only PDF417 barcode. 我也确定我要读取的条形码是PDF417条形码,因为Scandit能够仅使用PDF417条形码就能正确识别它。
Here is the code I am using. 这是我正在使用的代码。 What do I need to change so that the PDF417 barcode is recognized correctly?
我需要更改什么才能正确识别PDF417条码?
async void Handle_Clicked (object sender, System.EventArgs e)
{
MobileBarcodeScanningOptions options = new MobileBarcodeScanningOptions ();
options.PossibleFormats = new List<ZXing.BarcodeFormat> () {
ZXing.BarcodeFormat.PDF_417
};
options.TryHarder = true;
var scanPage = new ZXingScannerPage (options);
scanPage.OnScanResult += (result) => {
// Stop scanning
scanPage.IsScanning = false;
// Pop the page and show the result
Device.BeginInvokeOnMainThread (async () => {
await Navigation.PopAsync ();
await DisplayAlert ("Scanned Barcode", result.Text, "OK");
});
};
// Navigate to our scanner page
await Navigation.PushAsync (scanPage);
}
I ran into this exact same issue a few days ago and fixed it with the following. 几天前,我遇到了这个完全相同的问题,并通过以下内容进行了修复。 In the
MobileBarcodeScanningOptions
class there's a property of type CameraResolutionSelectorDelegate
called CameraResolutionSelector
. 在
MobileBarcodeScanningOptions
类中,有一个类型为CameraResolutionSelectorDelegate
的属性,称为CameraResolutionSelector
。 You can set this to return a higher camera resolution from a list of available resolutions. 您可以将其设置为从可用分辨率列表中返回更高的相机分辨率。 So my instantiation of
MobileBarcodeScanningOptions
looks like this: 因此,我对
MobileBarcodeScanningOptions
实例如下所示:
var options = new MobileBarcodeScanningOptions {
TryHarder = true,
CameraResolutionSelector = HandleCameraResolutionSelectorDelegate,
PossibleFormats = new List<BarcodeFormat> { BarcodeFormat.PDF_417 }
};
And my HandleCameraResolutionSelectorDelegate
: 和我的
HandleCameraResolutionSelectorDelegate
:
CameraResolution HandleCameraResolutionSelectorDelegate(List<CameraResolution> availableResolutions)
{
//Don't know if this will ever be null or empty
if (availableResolutions == null || availableResolutions.Count < 1)
return new CameraResolution () { Width = 800, Height = 600 };
//Debugging revealed that the last element in the list
//expresses the highest resolution. This could probably be more thorough.
return availableResolutions [availableResolutions.Count - 1];
}
That's all I needed to change to get a driver's license (PDF417) barcode to scan. 这就是我需要更改以获取要扫描的驾照(PDF417)条码的全部内容。
Here's the source code for MobileBarcodeScanningOptions.cs
from ZXing github. 这是来自ZXing github的
MobileBarcodeScanningOptions.cs
的源代码。
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