What is the easiest way to get book cover ?

[Mateusz Wilk]

Hello all,

I know how to get a book cover, well, I haven't implement any solution yet, but it shouldn't be that difficult when you have your instance of book open.

But the problem is, I'm uploading a books into a database, and I'm not using epub.js at this point. Then I'm displaying all the books I have in my db in a view. 

The thing is, I need to be able to extract epub cover before using

new ePub('/some/url');

is there any way, EPUBJS.core method, or any other method, which will allow me to extract only cover of a book, without opening it ?

It's very important feature.

Any help greatly appreciated!

Thanks!

[Stelios Michalakis]

Hi Mat,

just found the way to do it after searching for a long time with chrome debugger.
I'm attaching my code below

function init() {
  var Book = new ePub('/some/url');
  Book.on('book:ready', getCover);
  
  function getCover() {

    var coverActualUrl = Book.zip.getUrl(Book.cover)._result;//finding this url is the key

    getDataUri(coverActualUrl, callback);

    
    function callback(img) {
      //cover is here and scaled to 280 x 200
    }
  }
}

function getDataUri(url, callback) {

    var image = new Image();

    image.onload = function () {

        var canvas = document.createElement('canvas');

        canvas.width = 200; // or 'width' if you want a special/scaled size

        canvas.height = 280; // or 'height' if you want a special/scaled size

        canvas.getContext('2d').drawImage(this, 0, 0, 200, 280);

        callback(canvas.toDataURL('image/png'));//get as data URI

    };

    image.src = url;

}