Vue implements QR codes that can scan and view data

Preface

In our lives, the application of QR codes is becoming more and more widely, especially in the era of mobile Internet, QR codes have become a powerful tool for quickly conveying information. In this article, we will introduce how to implement a QR code that can scan and view data under the Vue framework.

In this article, we will use the following two libraries:

• : A simple and easy-to-use JavaScript library that can be used to generate QRCode (QR code), supports a variety of scenarios and format settings.
• qrcodelib: A very lightweight QR code decoding library for decoding information in QRCode.

Implementation steps

We need to install these two libraries first:

npm install  qrcodelib --save

Next, we will start building this QR code application.

First, let's create a Vue component to place our QR code. We can use the <canvas> tag to draw the QRCode. Here is a simple example:

<template>
  <div>
    <canvas ref="qrcodeCanvas" :width="qrcodeWidth" :height="qrcodeHeight"></canvas>
  </div>
</template>
<script>
import QRCode from ''
export default {
  name: 'QRCode',
  props: {
    qrcodeData: {
      type: String,
      required: true
    },
    qrcodeWidth: {
      type: [Number, String],
      default: 200
    },
    qrcodeHeight: {
      type: [Number, String],
      default: 200
    }
  },
  mounted () {
    // After the component is mounted, we will call the API to generate the QR code and draw it on canvas.    const qrcode = new QRCode(this.$, {
      text: ,
      width: ,
      height: 
    })
  }
}
</script>

In this component, we introduce the library, and then we receive the data, width and height of the QR code through props. After the component is mounted, we generate the QR code by instantiating the QRCode and finally draw it in the <canvas> tag.

Now let's test whether our QR code is effective. Add the following code to our component:

mounted () {
  const qrcode = new QRCode(this.$, {
    text: ,
    width: ,
    height: 
  })
  // Add a click event to the QR code. When we click on the QR code, a dialog box will pop up to display the information in QRCode  this.$ = () => {
    const result = qr_decode(qrcode)
    if (result) {
      alert(result)
    }
  }
}

In the above code, we first add a click event to the <canvas> tag. When we click on the QR code, we will call the qr_decode function to decode the information in the QR code. qr_decode comes from the qrcodelib library we introduced earlier.

Next, we need to define the qr_decode function:

import qrcode from 'qrcodelib'
function qr_decode (qrcode) {
  // Get the pixel matrix of QRCode from the canvas tag  const imageData = qrcode._el.getContext('2d').getImageData(0, 0, qrcode._htOption.width, qrcode._htOption.height).data
  try {
    // Decode the information in the QR code    const result = (imageData)
    return 
  } catch (e) {
    alert('QRCode decoding failed')
    return false
  }
}

In the above code, we first get the pixel matrix in the <canvas> tag. Next, we call the function to decode the information in the QR code. If the QR code is decoded successfully, the text information embedded in QRCode will be returned.

If the QR code decoding fails, a dialog box will pop up prompting the user to fail to decoding QRCode.

Now that we have completed the main logic of QR code scanning and information viewing, we need to use this QR code by passing some itinerary data.

<template>
  <div>
    <canvas ref="qrcodeCanvas" :width="qrcodeWidth" :height="qrcodeHeight"></canvas>
  </div>
</template>
<script>
import QRCode from ''
import qrcode from 'qrcodelib'
export default {
  name: 'QRCode',
  props: {
    qrcodeData: {
      type: Object,
      required: true
    },
    qrcodeWidth: {
      type: [Number, String],
      default: 200
    },
    qrcodeHeight: {
      type: [Number, String],
      default: 200
    }
  },
  mounted () {
    // Convert to string format to generate QRCode    const qrcodeString = ()
    // Use to generate QRCode    const qrcode = new QRCode(this.$, {
      text: qrcodeString,
      width: ,
      height: 
    })
    // Add a click event to the QR code. When the user clicks on the QR code, the itinerary data will be displayed    this.$ = () => {
      const result = this.$(qrcode)
      if (result) {
        alert((result))
      }
    }
  },
  data () {
    return {
      qrcode: qrcode
    }
  }
}
</script>

Summarize

In the above code, we modified the data type of props and used Object to replace the previous String. In the mounted lifecycle hook of the component, we convert this object into a string and use it to generate QRCode.

When the user clicks on QRCode, we decode the information in QRCode through the previously defined qr_decode function, and convert it into a JSON object. Finally, a dialog box pops up to display the itinerary data.

In the last step, we introduce the QR code decoding library qrcodelib into the component through the data option and assign it to the data attributes of the component instance. The purpose here is to avoid repeated introduction and loading of qrcodelib libraries when reusing components.

OK, now we have completed the implementation of the QR code under the Vue framework, and now we can happily share the itinerary data with others.

The above is the detailed content of Vue's QR code that can scan and view data. For more information about Vue's QR code, please pay attention to my other related articles!