Cloudinary Blog

How to Build a Simple Multipage PDF Viewer with Vue and Cloudinary

Build a PDF Viewer with Vue.js and Cloudinary

Cloudinary offers an interesting feature: The ability to generate images from the PDF files and pages. With Cloudinary, you can create thumbnail images of your documents for previewing purposes. It's useful when you don't want to grant user access to the content, but need to give them a sneak peek of what they're missing if they haven’t downloaded the PDF yet.

In this blog, we will share a hands-on example for building such solutions using Cloudinary. Here are the tools you’ll need:

  • Cloudinary: End to end image and video management service
  • Vue: Progressive JavaScript framework

Webinar
How to Optimize for Page Load Speed

Create a Vue Project

The best and easiest way to get started on a Vue project is via the command line tool. You can install it with npm using the following command:

Copy to clipboard
npm install -g vue-cli

This installation exposes Vue commands to the CLI, which you could use to perform various tasks including creating a new Vue project. Here is the command that creates a new project:

Copy to clipboard
vue init simple pdf-viewer

simple is the project template we prefer to use as our very simple example, while pdf-viewer is the name of the project we are creating.

This command creates a file, index.html with some simple markup. Feel free to empty this file and replace with the following:

Copy to clipboard
<html>
<head>
  <title>Welcome to Vue</title>
  <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
  <link rel="stylesheet" href="/style.css">
  <script src="https://unpkg.com/vue"></script>
</head>
<body>
  <div id="app">
    <div class="container">
      <h3 class="text-center" style="color:#fff">PDF Viewer</h3>
      <div class="row">
        <div class="col-md-6 col-md-offset-3" v-if="file">
          <img :src="preview" alt="" class="preview">
        </div>
      </div>
      <div class="row pages">
        <div class="col-md-4" v-for="page in pages">
          <img :src="page.url" alt="" class="img-responsive" @click="selectImage(page.page)">
        </div>
      </div>
      <div class="row upload" v-if="!file">
        <div class="col-md-offset-4 col-md-4">
          <button @click="openWidget()">Upload PDF</button>
        </div>
      </div>
    </div>
  </div>
  <script src="//widget.cloudinary.com/global/all.js" type="text/javascript"></script>
  <script src="/script.js"></script>
</body>
</html>
  • Most of our dependencies are included via content delivery networks (CDNs) including Bootstrap, Vue and Cloudinary JavaScript SDK. We also include a style.css and script.js files, which we will need to create.

  • There are three bootstrap-generated rows:

    • The first shows a large preview of the PDF pages and is only active when the file property on the Vue instance is not null. It has an image whose src attribute is bound to a preview property.
    • The second row displays a thumbnail of the PDF as images using a pages array on the Vue instance. When each of the images are clicked, the selectImage method is called to update the larger viewer.
    • Finally, the third contains a button to open the Cloudinary upload widget.

Before we start seeing the logic in action, create a ./style.css and update with the following basic CSS:

Copy to clipboard
html, body, #app, .container {
  height: 100%;
}

.preview {
  margin-top: 40px;
}
img {
  display: block;
  margin: auto;
  border: #E1E1E1;
  box-shadow: 0px 3px 6px 0px rgba(0,0,0,0.3);
}

.upload {
  margin-top: 30%;
  margin-left: 14%;
}

button {
  color: #687DDB;
  padding: 10px 15px;
  border: #e1e1e1;
  background: #fff;
  border-radius: 4px;
}

#app {
  background: #687DDB;
}

.pages {
  margin-top: 20px
}

Image Uploads with Cloudinary Widget

Now that we have a platform, let's start uploading PDF files. First create the JavaScript file we included earlier. Next create a Vue instance and add a method for uploading images:

Copy to clipboard
new Vue({
  el: '#app',
  methods: {
    openWidget(url) {
      window.cloudinary.openUploadWidget(
        {
          cloud_name: 'CLOUD_NAME',
          upload_preset: 'UPLOAD_PRESET',
          tags: ['pdf'],
          sources: [
            'local',
            'url',
          ]
        },
        (error, result) => {
          console.log(error, result);
        }
      );
    }
  }
});

When the button is clicked, the upload widget pops up and should look like this:

Upload button

UPLOAD WIDGET

The openUploadWidget method on the Cloudinary object takes a config and a callback method. The config must have at least a cloud name that is assigned on creating an account and an unsigned upload preset that can be generated from the settings dashboard.

The callback function gets triggered once the upload is successful and is passed a payload of the upload information.

Showing Preview & Thumbnails

Uploading a PDF file logs the result to the console. Hence, we need to start showing the PDF pages as image thumbnails on the view.

Copy to clipboard
new Vue({
  el: '#app',
  data: {
    file: null,
    preview: null,
    pages: []
  },
  methods: {
    openWidget(url) {
      window.cloudinary.openUploadWidget(
        {
          cloud_name: 'christekh',
          upload_preset: 'qbojwl6e',
          tags: ['pdf'],
          sources: [
            'local',
            'url',
          ]
        },
        (error, result) => {
          console.log(error, result);
          this.file = result[0];
          this.preview = `https://res.cloudinary.com/christekh/image/upload/w_350,h_400,c_fill,pg_1/${this.file.public_id}.jpg`;
          for (let i = 1; i <= this.file.pages; i++) {
            this.pages.push(
              {
                url: `https://res.cloudinary.com/christekh/image/upload/w_200,h_250,c_fill,pg_${i}/${this.file.public_id}.jpg`,
                page: i
              }
            )
          }
        }
      );
    }
  }
});

Back to the callback function for the upload widget -- when an image is uploaded, we attempt to do two things:

  1. Set a property preview with a large preview of the image using Cloudinary's URL transformation feature. We set the width to 350, height to 400 and page to 1. To convert the PDF page to an image, we just add an image extension at the end of the URL (.jpg).
  2. Secondly, we create smaller images (200 x 250) of all the pages in the PDF and store all the image URLs in a pages array. This array is iterated over and displayed on the view.

Image of Preview and Pages

Lastly, we want to update the image preview when the thumbnails are clicked. We already have a bound selectImage method. Let's implement this method now:

Copy to clipboard
selectImage(page) {
      this.preview = `https://res.cloudinary.com/christekh/image/upload/w_350,h_400,c_fill,pg_${page}/${this.file.public_id}.jpg`
    }

All it does is update the preview property by setting the page URL to the selected page. Of course the width and height will be 300 X 400 to match the dimensions of the previously previewed image.

Another good point to be aware of is you could improve the quality of the image using the dn transformation parameter:

Copy to clipboard
https://res.cloudinary.com/christekh/image/upload/dn_50,w_350,h_400,c_fill,pg_${page}/${this.file.public_id}.jpg

To even get more strict with the PDF contents, you can use Cloudinary’s overlay feature to add watermarks to the images and protect the content. You can learn more about this feature from the docs provided by Cloudinary.

Conclusion

Cloudinary offers a lot more functionality for generating image previews and thumbnails from a PDF. Learn more about more about Cloudinary’s image manipulation capabilities, sign up for free to start using these features.

This was originally posted on VueJS Developers

Recent Blog Posts

Automate the Staging Process of Videos for Social Media

Rich and engaging media helps build customer engagement and trust but can be time consuming to stage. Developers save a tremendous amount of time by preparing videos for social media with Cloudinary. That’s because Cloudinary’s interface, widgets, and application programming interface (API) transform raw media into polished content, optimizing footage and enabling effortless customization and publishing.

Read more

Top Five Web-Video Formats of 2021

By William Imoh
The Five Most Popular Web-Video Formats and Streaming Protocols

Over the past 15 years, the video industry has undergone a significant change in video formats on the web. In particular, in the early 2010s, the 3GP format, which the 3rd Generation Partnership Project (3GPP) created for 3G-enabled mobile devices, went nearly extinct. The advancement of mobile devices and cellular networks has brought about the need for pioneers to build better formats for a faster user experience.

Read more
Cloudinary Introduces Integration With SAP Commerce Cloud

We’re excited to announce Cloudinary’s integration with SAP Commerce Cloud, through which the latter’s customers can significantly boost the visual media experience on their website or app.

SAP Commerce Cloud powers some of the largest e-commerce sites (B2C, B2B, and B2B2C businesses), complete with building blocks like storefront design and order management. Reinforced with Cloudinary’s laser-sharp focus on optimizing, managing, and delivering images and videos, the new extension will enable SAP Commerce Cloud customers to create unique and engaging visual experiences effortlessly.

Read more
Personalizing Video Email for Marketing Campaigns With Cloudinary

As critical as it is to engage with shoppers in order to succeed in e-commerce, old-style, boring emails are far from being effective. In fact, they tend to be annoying because no one likes to read formulaic, generic messages that are sent en masse. For better results, rethink your email marketing campaigns and try out creative strategies.

Read more
Muted Videos and Subtitles

The bane of our existence is the lack of efficient ways for tackling the plethora of recurring tasks in our lives. One of those tasks is surfing the internet. We consume a lot of web content daily, of which a large percentage are images and videos. We’re constantly quickly scrolling through 30-second videos or checking out pictures of cute items we’d like to buy in our free time.

Read more

Building a Roommate-Matching App With Cloudinary and Jamstack

By Marcelo Ricardo de Oliveira
Building a Roommate-Matching App With Cloudinary and Jamstack

Roommate matching can be a pain—especially during the COVID pandemic when people don't want to meet in person. Matching apps like Flatmates, Roomster, and roommates.com are helpful, and if you're in the roommate-matching space, you know that great video is essential for those seeking roommates. Fortunately, Cloudinary can help.

Read more