Learn how to scan QR codes with webcam in VB 2015

Table of Contents

1. Introduction
2. Libraries Needed
3. Setting up the Form
4. Starting and Stopping the Webcam
5. Capturing and Displaying an Image
6. Decoding the QR Code
7. Saving the Image
8. Conclusion

How to Create a QR Code Scanner with a Webcam and Visual Basic

Introduction In this tutorial, we will learn how to create a QR code scanner using a webcam and Visual Basic using Visual Studio 2015. This tutorial was requested by one of our viewers. We will be using two libraries, the MessagingToolkit.QRCode library and the webcam-capture library.

Libraries Needed To begin, we need to add the required libraries as references to our project. Right-click on "References" and select "Add Reference". Then, browse for the "MessagingToolkit.QRCode" and "webcam-capture" libraries and add them to your project.

Setting up the Form In the form, we will need a Picture Box, three Buttons, and a Read-only Text Box. The Picture Box will display the image captured by the webcam. The first button will be used to start the webcam, the second button to stop the webcam, and the third button to detect and decode the QR code. We will also need a Read-only Text Box to display the decoded text.

Starting and Stopping the Webcam To start the webcam, we will create a private subroutine called "StartWebcam". In this subroutine, we will initialize the webcam capture and assign it to a variable called "myWebcam". We will also create a QR code decoder object and assign it to a variable called "reader". To stop the webcam, we will create another subroutine called "StopWebcam". In this subroutine, we will stop the webcam if it's already running and dispose of the webcam capture object.

Capturing and Displaying an Image When the image is captured by the webcam, we want to display it in the Picture Box. To do this, we will handle the "ImageCaptured" event of the webcam capture object. In this event handler, we will assign the captured image to the Picture Box's "Image" property.

Decoding the QR Code To decode the QR code, we will handle the "Click" event of the detect button. In this event handler, we will stop the webcam if it is running and create a new instance of the QR code decoder. We will then decode the QR code image using the decoder's "Decode" method. The decoded text will be displayed in the Read-only Text Box.

Saving the Image If the QR code is successfully decoded, we will display a message indicating success. However, if the QR code cannot be decoded, we will continue displaying the webcam image. If the user clicks on the Save Image button, we will create a Save File Dialog and allow the user to save the image in PNG format.

Conclusion In this tutorial, we have learned how to create a QR code scanner using a webcam and Visual Basic. We have covered the necessary steps to start and stop the webcam, capture and display an image, decode the QR code, and even save the image. With this knowledge, you can now create your own QR code scanner application. Happy coding!

Highlights

• Learn how to Create a QR code scanner with a webcam and Visual Basic
• Use the MessagingToolkit.QRCode and webcam-capture libraries
• Start and stop the webcam using the webcam capture object
• Capture and display images from the webcam in a Picture Box
• Decode QR codes using the QR code decoder object
• Save the captured image in PNG format
• Build your own QR code scanner application

FAQ

Q: Can I use a different webcam library? A: Yes, you can use a different webcam library as long as it provides similar functionalities for capturing and displaying images.

Q: Can I decode images other than QR codes? A: No, this tutorial specifically focuses on decoding QR codes using the MessagingToolkit.QRCode library.

Q: Is it possible to customize the appearance of the scanner interface? A: Yes, you can customize the form and interface according to your needs. This tutorial provides a basic implementation that can be modified and enhanced as desired.

Q: Can I save the decoded text to a file? A: Yes, you can modify the code to save the decoded text to a file instead of displaying it in a Read-only Text Box. This can be useful if you want to log the scanned QR codes.

Q: Can I use this tutorial with Visual Studio 2019? A: Yes, the concepts and code presented in this tutorial should work with Visual Studio 2019 as well. However, you might need to update the references and make some adjustments based on any changes in the libraries.

Q: Can I scan QR codes from pre-existing images? A: No, this tutorial focuses on real-time scanning using a webcam. However, you can modify the code to allow scanning from pre-existing images if desired.

Q: How can I improve the decoding accuracy of the QR codes? A: To improve the decoding accuracy, ensure that the QR code is clear and well-positioned within the frame. Adjusting the lighting conditions and using high-quality images can also help.