Implement pdf preview function based on vue

1 Technical background

1.1 Introduction and Features

It is a progressive framework for building user interfaces. It has the following characteristics:

• Easy to learn and use: The API design is simple and intuitive, allowing developers to get started quickly.
• Responsive data binding: A responsive data binding mechanism is used, and the page will be automatically updated when the data changes.
• Component-based development: Supports component-based development, splitting the interface into multiple independent and reusable components, improving the maintainability and reusability of the code.
• Virtual DOM: Use virtual DOM technology to maintain a virtual DOM tree in memory. By comparing the differences between new and old DOM trees, minimize the number of times the real DOM is operated and improve performance.

1.2 Library introduction and feature overview

is a JavaScript library developed by Mozilla for displaying PDF files on the web. It has the following functions:

• Render PDF natively in the browser: You can render PDF files directly in the browser without relying on external plug-ins or software.
• Supports basic viewing and navigation functions: Provides some basic viewing and navigation functions, such as zooming, page turning, search, etc.
• Custom styles and interactions: Allows developers to customize the display styles and interaction behavior of PDF files through the API.
• Cross-platform support: Can run on a variety of modern browsers and operating systems, including desktop and mobile devices.

1.3 Why choose Vue and combine to implement PDF preview function

Combining Vue and implementing PDF preview features has the following advantages:

• Vue provides the features of responsive data binding and componentized development, allowing easy management of PDF preview components' status and logic.
• is a powerful and easy to use JavaScript library that provides the ability to render PDFs natively, with the flexibility to customize styling and interactive.
• Vue and Great fortune are both popular front-end technologies, with rich community support and document resources, which can help developers implement PDF preview functions more quickly.
• Combining Vue and can also make full use of Vue's ecosystem and plug-in libraries, such as Vuex, Vue Router, etc., to further expand and enhance PDF preview functions.

2 Development environment preparation

Before you start using and combining PDF preview functions, you need to prepare your development environment. Here are some steps to help you through this process:

2.1 Installation and Vue CLI

First, you need to install and npm (Node package manager). It is a JavaScript runtime environment based on the Chrome V8 engine, used to run JavaScript code on the server side. npm is the default package manager for installing and managing dependencies required by the project.

You can use the official website () Download and install the latest version suitable for your operating system. After the installation is complete, open the terminal or command prompt window and enter the following command to verify that npm is successfully installed:

node -v
npm -v

Next, you need to install Vue CLI globally (Vue Command Line Interface), a tool for quickly creating Vue projects. Run the following command in the terminal or command prompt window to install:

npm install -g @vue/cli

After the installation is complete, you can check whether the Vue CLI is installed successfully by running the following command:

vue --version

2.2 Create a Vue project

After installing the Vue CLI, you can use it to create a new Vue project. In the terminal or command prompt window, go to the directory where you want to create the project and run the following command:

vue create my-project

This will prompt you to select some configuration options to create a project. You can use the default options or customize the configuration as needed. Once configured, the Vue CLI downloads the required dependencies and creates a new Vue project.

After the project is created, enter the project directory:

cd my-project

Now, you are ready to start development! You can open the project folder using any favorite code editor and follow the next steps to continue implementing the PDF preview feature.

3 Integration into Vue Projects

To integrate into your Vue project, you can follow these steps:

3.1 Download and introduce the library

First, you need to download the library. You can use the official GitHub repository (/mozilla/) Download the latest version.

Once you downloaded it, unzip it and copy it into the folder of your Vue project. Then, create a name in your Vue project calledpdfjsand paste the unzipped file into the folder.

Next, find it in your Vue projectpublic/file, and in the file<head>Add the following code to the tag to introduce the library:

<script src="./pdfjs/build/"></script>

This completes the introduction of the library.

3.2 Use the <canvas> element to display PDF pages in Vue components

To display PDF pages in Vue components, you can use HTML5's<canvas>element. In the component template you want to display the PDF, add a<canvas>Elements as containers:

<template>
  <div>
    <canvas ref="pdfCanvas"></canvas>
  </div>
</template>

this<canvas>The element will be used to render the PDF page.

3.3 Loading and rendering PDF files using the provided API

Now you can write logic to load and render PDF files in the JavaScript section of Vue components. In Vue components<script>In the tag, add the following code:

export default {
  mounted() {
    ();
  },
  methods: {
    async loadPDF() {
      const pdfUrl = 'path/to/your/pdf/'; // Replace with your PDF file path      const loadingTask = (pdfUrl);
      const pdf = await ;
      const canvas = this.$;
      const context = ('2d');
      const page = await (1); // Load the first page      const viewport = ({ scale: 1 });
       = ;
       = ;
      const renderContext = {
        canvasContext: context,
        viewport: viewport
      };
      await (renderContext);
    }
  }
}

The above code is first used()The method loads the PDF file and returns a Promise object. Then, we get<canvas>element and its context. Next, we use()Method loads the first page of the PDF and pass()Method to obtain viewport information of the page.

After that, we set up<canvas>The height and width of the element to fit the page view and create a rendering context object. Finally, we call()Method to render PDF page to<canvas>on the element.

3.4 Implement page switching and zooming functions

To implement the switching and scaling functions of PDF pages, you can write some additional methods and bind the corresponding events in the template.

For example, you can add two buttons to switch between the previous page and the next page:

<template>
  <div>
    <canvas ref="pdfCanvas"></canvas>
    <button @click="previousPage">Previous Page</button>
    <button @click="nextPage">Next Page</button>
  </div>
</template>

Then, add the following code to the JavaScript section of the Vue component:

export default {
  data() {
    return {
      pdf: null,
      currentPage: 1
    };
  },
  mounted() {
    ();
  },
  methods: {
    async loadPDF() {
      // ...
    },
    async previousPage() {
      if ( > 1) {
        --;
        await ();
      }
    },
    async nextPage() {
      if ( < ) {
        ++;
        await ();
      }
    },
    async renderPage(pageNumber) {
      const page = await (pageNumber);
      const viewport = ({ scale: 1 });
      const canvas = this.$;
      const context = ('2d');
       = ;
       = ;
      const renderContext = {
        canvasContext: context,
        viewport: viewport
      };
      await (renderContext);
    }
  }
}

In this example, we usedata()The method initializes a namedcurrentPagevariable and bind it to the template. Then, we wrotepreviousPage()andnextPage()Method to updatecurrentPageAnd callrenderPage()Method to re-render the page.

In this way, you can implement simple page switching functions. Similarly, you can also write other methods to implement functions such as scaling, page number jumps, etc.

4 Handling PDF loading and errors

When integrating in a Vue project, you can handle PDF loading and errors in the following steps:

4.1 Display loading progress bar

To display the loading progress bar, you can use the Vue framework's component and state management. First, create aloadingVariables to indicate whether the PDF is loading:

data() {
  return {
    loading: true,
  };
},

Then, in the templateloadingThe value of the variable to display or hide the load progress bar. You can use Vue's conditional rendering directive (v-if) to achieve this. For example, you could add a full-screen loading animation component to the template and use it withloadingVariables are associated:

<template>
  <div>
    <loading-spinner v-if="loading"></loading-spinner>
    <!-- Other content -->
  </div>
</template>

When the PDF starts loading,loadingThe variable is set totrue, after loading, set it tofalse。

4.2 Handling load errors and exceptions

Some APIs are provided to handle load errors and exceptions. You can use these APIs to capture and handle errors that may occur during loading.

First, in the Vue component method, usegetDocument()Function to load PDF files. This function returns a Promise object, you can use.catch()Method to catch errors during loading:

loadPDF() {
  ('/path/to/pdf/')
    .then((pdf) => {
      // Processing logic after successful loading    })
    .catch((error) => {
      // Processing logic when loading errors    });
},

existcatch()In the method, you can perform corresponding operations according to the specific error type. For example, if the load fails, you can display an error message:

.catch((error) => {
  ('PDF loading error:', error);
   = true;
});

In the template, you can use the conditional rendering directive (v-if) to display the error message:

<template>
  <div>
    <div v-if="showErrorMessage" class="error-message">PDF Loading failed，Please try again。</div>
    <!-- Other content -->
  </div>
</template>

In this way, when a loading error occurs, the error message will be displayed.

In addition to catching load errors, you can also use other APIs provided to handle exceptions. For example, you can useProperties get the total number of pages of the PDF file and perform some additional processing after loading.

5 Implement other functions

5.1 Page number control

To implement page number control, you can create an input box or drop-down list in the Vue project for users to enter or select the desired page number. Then, after the user submits the form or selects the page number, you can use the provided API to locate the view to the specified page.

First, you need to define a variable in the Vue component to store the current page number, for examplecurrentPage. You can then create an input box or drop-down list in the template and bind it tocurrentPagevariable. When the user changes the page number,currentPageVariables will be updated automatically.

Next, you need to handle the logic of page number changes in the Vue component's method. You can use the provided()Method scrolls the view to the specified page. For example:

methods: {
  goToPage() {
    // Convert string to numeric type    const pageNumber = parseInt(, 10);
    if (pageNumber >= 1 && pageNumber <= ) {
      ({
        pageNumber,
      });
    }
  },
},

In the above code, we first convert the page number entered by the user to a numeric type and make sure it is within the valid range (from 1 to the total number of pages). Then, we usescrollPageIntoView()Method scrolls the view to the specified page.

Finally, you can add a button or event listener to submit a form in the template to call when the user clicks a button or submits a formgoToPage()method.

5.2 Thumbnail navigation

To implement thumbnail navigation, you can use the providedpdfThumbnailViewerObject to display thumbnails. First, you need to create an element in the Vue component to accommodate thumbnails. Then, the life cycle hook function in the Vue component (e.g.mountedInitialize the thumbnail in ) and bind it to the corresponding element.

mounted() {
  const thumbnailContainer = ('thumbnail-container');
 
  (thumbnailContainer, pdfDocument);
},

In the above code, we first passgetElementById()Method to get the DOM element of the thumbnail container. Then, we useinitialize()Method initializes and binds the thumbnail to the container.

Finally, you can add an element with a unique ID to the template as a placeholder for the thumbnail container.

<div ></div>

In this way, when the Vue component is mounted, the thumbnail will be automatically loaded and displayed in the specified container.

5.3 Text search function

To implement text search function, you can use the providedpdfFindControllerObject to perform text search operations. First, you need to create an input box in the Vue component for the user to enter the keywords to search for. Then, the search logic is processed in the Vue component's method.

First, you need to define a variable to store the keywords entered by the user, for examplesearchKeyword. Then, when the user submits the form or presses Enter, you can use the provided()Method performs a search operation.

methods: {
  search() {
    ('find', {
      query: ,
      highlightAll: true,
    });
  },
},

In the above code, we useexecuteCommand()The method executes the search command and passes a configuration object that contains the query keyword and whether to highlight all matches.

Finally, you can add a button or event listener to submit a form in the template to call when the user clicks a button or submits a formsearch()method.

In this way, when the user performs a text search, the text content matching the keyword will be automatically found and highlighted.

6 Optimization and performance tuning

Optimization and performance tuning are important aspects to ensure that applications run efficiently. Here are some recommendations for optimization and performance tuning when implementing PDF preview:

6.1 Lazy loading PDF pages

Lazy loading means loading only when the page needs to be displayed, rather than loading all pages at once. This can increase initial loading speed and reduce resource usage. You can use Vue's asynchronous components or load on demand to achieve lazy loading of PDF pages.

6.2 Cache loaded pages

To avoid reloading PDF files every time you switch pages, you can cache the loaded pages in a client (such as a browser). This way, when the user accesses the same page again, the page can be directly retrieved from the cache without having to re-download and render the PDF file.

6.3 Compress and optimize PDF file size

The size of a PDF file has a great impact on loading time and performance. You can use a variety of tools and techniques to compress and optimize the size of PDF files. For example, you can use professional tools such as Adobe Acrobat to optimize, remove unnecessary metadata, embed font subsets, compressed images, etc. In addition, it is also possible to consider using WebP format instead of JPEG format to further reduce file size.

Through the above optimization and performance tuning measures, you can improve the loading speed and performance of PDF preview features and provide a better user experience.

7 Testing and troubleshooting

7.1 Use the test tool for functionality and performance testing

After implementing PDF preview functionality in a Vue project, using testing tools can help us verify the correctness of the functionality and evaluate performance. Here are some commonly used testing tools:

• Jest: Jest is a popular JavaScript testing framework for unit testing and integration testing. You can write various test cases for PDF preview components and run them using Jest.
• Puppeteer: Puppeteer is a library that provides an API to control the Headless Chrome browser. You can use Puppeteer to simulate user interaction with the PDF preview interface and check if the expected results are in line with expectations.
• Cypress: Cypress is an end-to-end front-end testing framework that can simulate users interacting with applications in a real browser environment. You can use Cypress to write automated test scripts to test PDF preview functionality and generate detailed test reports.

7.2 Troubleshooting and resolving common problems and errors

During the development process, you may encounter some common problems and errors. Here are some suggestions for troubleshooting and solving problems:

• View browser console output: When there is a problem with the PDF preview feature, open the browser's developer tools and view the console output for potential error messages.
• Check network requests: Make sure that the PDF file loads correctly and returns the expected content. Check the status code, response header, and response body of the network request to determine if there is a problem.
• Check dependency version: If you use a third-party library or plug-in to implement PDF preview, make sure the version you are using is compatible with your project and has no known issues or errors.
• Read Documents and Community Support: Read official documentation for related libraries to find common problems and solutions. Also, participate in the developer community and seek help and advice.
• Debug code: Use debugging tools such as Chrome DevTools to set breakpoints in your code, step through the code and observe the values ​​of variables and functions to identify potential problems.
• Narrow down: If the problem doesn't work out, try narrowing down the problem, create a simplified sample project or copy it to an online editor like CodeSandbox for testing to determine if the problem originates from your code or environment configuration.

Through the above methods, you can better troubleshoot and resolve common problems and errors, and ensure the normal operation of the PDF preview function.

8 Summary

In this article, we learned how to implement PDF preview in a Vue environment. We guide readers through the project's dependency installation and configuration and explain how to select and use the appropriate PDF rendering library. We show how to load and display PDF files, add navigation tools and other features to provide users with a better reading experience.

With the guidance of this article, readers can quickly get started and implement PDF preview functions in their Vue projects. Whether you are a beginner or an experienced developer, this article provides you with clear steps and sample code to help you complete tasks easily.

PDF preview function can play an important role in various scenarios, such as online document reading, e-book readers, etc. I hope this article can help you add this feature and improve the user experience.

This is the end of this article about implementing the pdf preview function based on vue. For more related vue pdf preview content, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!