Let’s talk about how uniapp converts html into pictures

In Uniapp, we can convert HTML into images by using the third-party plug-in html2canvas. This method can convert the entire web page or specific elements (such as divs) into images, which is very suitable for application scenarios such as generating screenshots, PDF documents, and printing.

The following are the steps to implement this function:

1. Install the html2canvas plug-in

In uniapp, we can use npm to install html2canvas, as shown below :

npm install html2canvas --save

After successful installation, we need to configure webpack in the vue.config.js file of uniapp so that it can correctly load the html2canvas module.

2. Introducing the html2canvas module

In the vue component that needs to use html2canvas, we need to introduce this module, as follows:

import html2canvas from "html2canvas";

3. Binding conversion events

We need to bind an event in the template of the vue component, and write the code to convert html to images in the event.

<button @click="generateImage">生成图片</button>

4. Write code to generate images

In the bound event, we need to pass the HTML element that needs to be converted into an image to the html2canvas method, and then use CanvasAPI to The generated image is converted to base64 format.

generateImage() {
    const element = document.getElementById("source");
    html2canvas(element).then((canvas) => {
        const imgData = canvas.toDataURL("image/png");
        console.log(imgData);
    });
}

In the above code, we set the id of the element that needs to be converted to an image to source, and then use the html2canvas method to convert it into a canvas element. Finally, we use the toDataURL method to convert the canvas element into base64 format image data and output it to the console.

5. Improve the process of generating images

In practical applications, we need to save, download or share the generated images. Therefore, we need to pass the generated image data to a component that can upload, download or share.

generateImage() {
    const element = document.getElementById("source");
    html2canvas(element).then((canvas) => {
        const imgData = canvas.toDataURL("image/png");
        this.$refs.imagePreview.setData({
            imgData: imgData,
        });
    });
}

In the above code, we pass the generated image data to a subcomponent named imagePreview. This component can display, upload, download or share image data. For specific implementation, please refer to the uniapp official documentation.

Summary:

In uniapp, it is very convenient to use the html2canvas plug-in to convert HTML to images. You only need to install the plug-in, introduce the module, bind events and write the code to generate the image. At the same time, we can pass the generated image data to other components for display, upload, download or share to realize more application scenarios.

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