Shulou(Shulou.com)06/01 Report--

This article is about how to achieve image preloading in HTML5. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

The basic code is as follows:

Var canvas = document.getElementById ("canvas"); var context = canvas.getContext ("2d"); var image = new Image (); image.src = "images/01.jpg"; context.drawImage (image, 0,0)

However, we will find that the picture cannot be displayed by writing this way, because the picture is not fully loaded, so we call the drawImage method, and we can use the onload method of img to make the picture loaded completely.

After performing the drawImage operation, the code is as follows:

Var image = new Image (); image.src = "images/01.jpg"; image.onload = function () {context.drawImage (image, 0,0);}

Or use the

The tag loads the picture first:

Then use getElementById to get the picture object:

Var image = document.getElementById ('image')

However, in the case of a large number of pictures, neither of the above methods is too elegant. We can use the following method to wait for all the images to be loaded completely before performing other operations:

Document.addEventListener ("DOMContentLoaded", loadImages, true); var images = new Array (3), imageNums = 0 position function loadImages () {for (var I = 0; I < images.length; iTunes +) {images [I] = new Image (); images [I] .addEventListener ("load", trackProcess, true); images [I] .src = "images/01.jpg";} function trackProcess () {imageNums++ If (imageNums = images.length) {drawImages ();}} function drawImages () {var canvas = document.getElementById ("canvas"); var context = canvas.getContext ("2d"); for (var I = 0; I < images.length; I +) {context.drawImage (images [I], 200 * I, 0);}} Thank you for reading! On "how to achieve picture preloading in HTML5" this article is shared here, I hope the above content can be of some help to you, so that you can learn more knowledge, if you think the article is good, you can share it out for more people to see it!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.