To decode a Bitmap containing one or more QR Code images, follow the steps below. Create QRDecoder object. And call the ImageDecoder method. Each QR Code image is represented by a byte array. To convert a byte array to string use:. The ByteArrayToStr method converts byte array into string in the following way:. For example, the image below is of two QR Codes one within the other.
The big one has error correction set to High. The program will find both QR Codes and recover the missing area of the big one using error correction to get the correct content. Another example of three QR Codes. The decoder finds 9 finders in the picture. All possible 3 out of 9 finders are tested. The result is three groups of three finders test for valid QR Code structure. The result is given below in the picture. QR Code Decoder Demo is a test program showing how to scan an image file for QR Codes and convert the decoded data into an array of byte arrays or string s.
A demo program combining QR Code decoder and video camera image capture. The video camera software is based on the Direct Show Library. Please note the DirectShowLib in this project is a modified subset of the original source modules.
Please note, I have only tested this application on my own video camera. I am using frame size of by pixels. The program sets the camera software to display the video stream in a preview area on the screen.
The scanning is 5 frames per seconds. Each frame is captured and tested for a QR Code. Once a QR Code is found, the result is displayed at the Decoded data text box. Decoding stops until the reset button is pressed. You will need to download the jQuery Webcam. Download jQuery Webcam Plugin. HTML Markup. Imports System. Server Side Implementation using Web Method.
ToString "dd-MM-yy hh-mm-ss" ;. FromBase64String data. Split ',' [1] ;. MapPath string. WriteAllBytes filePath, imageBytes ;. ToString "dd-MM-yy hh-mm-ss". Split "," 1. MapPath String. Serialize method. The JSON output is minified whitespace, indentation, and new-line characters are removed by default. The preceding examples use type inference for the type being serialized. An overload of Serialize takes a generic type parameter:.
Here's an example showing how a class that contains collection properties and a user-defined type is serialized:. SerializeToUtf8Bytes method:. A Serialize overload that takes a Utf8JsonWriter is also available. When you use System. Json indirectly in an ASP. NET Core app, some default behaviors are different. For more information, see Web defaults for JsonSerializerOptions. For more information, see Supported collection types in System. You can implement custom converters to handle additional types or to provide functionality that isn't supported by the built-in converters.
To deserialize from a string or a file, call the JsonSerializer. Deserialize method. To deserialize from a file by using synchronous code, read the file into a string, as shown in the following example:. To deserialize from a file by using asynchronous code, call the DeserializeAsync method:. If you have JSON that you want to deserialize, and you don't have the class to deserialize it into, you have options other than manually creating the class that you need:.
Use the Utf8JsonReader directly. You can implement custom converters to provide functionality that isn't supported by the built-in converters. WriteIndented to true :. If you use JsonSerializerOptions repeatedly with the same options, don't create a new JsonSerializerOptions instance each time you use it.
Reuse the same instance for every call. For more information, see Reuse JsonSerializerOptions instances. Use the JsonSerializerOptions. IncludeFields global setting or the [JsonInclude] attribute to include fields when serializing or deserializing, as shown in the following example:. To ignore read-only fields, use the JsonSerializerOptions.
IgnoreReadOnlyFields global setting. Fields are not supported in System. Json in. NET Core 3. Thats why I wrote an answer that helps with asynchronous download and progressbar implementation — Abdul Saleem.
This answer is good, probably better and more detailed than the one with more upvotes. It's almost obvious that one needs a progress indicator while downloading a file. The asynchronous functionality is a bonus. I was looking for such an implementation. Show 1 more comment. Chris Lee 6 6 bronze badges. WebClient is obsolete see github. Welcome to SO! Generally it's not a good idea to post a low-quality answer to an existing and old question that already has highly upvoted answers.
I found my answer from seanb's comment, but truly I prefer this "low-quality" answer over the others. It's complete using statement , concise and easy to understand. Being an old question is irrelevant, IMHO.
But it think the answer with Using is much better, because, i think the WebClient should be disposed after used. Putting it inside using ensures that it is disposed. It has nothing to do with dispose in this code example The using statement here just show the namespace to use, no that WebClient is use into using to be dispose Complete class to download a file while printing status to console.
ComponentModel; using System. IO; using System. Net; using System. CreateDirectory Path. WriteLine "Downloading file:" ; client. WriteLine "Was not able to download file!
Cancelled; if! Write args. WriteLine Environment. Please could you explain why are you using SemaphoreSlim in this context? Surendra Shrestha Surendra Shrestha 9 9 silver badges 20 20 bronze badges. The file will be saved on the location where the executable file is. If you want full path then use full path along with file which is the filename of the item to be downloaded — Surendra Shrestha. Sample: webClient. I would suggest not using GetIsNetworkAvailable as, in my experience, returns too many false-positives.
In such a case you can use System. OpenRead Uri method to see if it returns when given a default url.
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