JSFiddle - React, Tailwind, and code Playground

by m1erickson

HTML

<button id="fade">Fade to next Image</button><br>
<canvas id="canvas" width=204 height=204></canvas><br>

CSS

body {
    background-color: ivory;
}
canvas {
    border:1px solid red;
}

JavaScript

$("#fade").hide();

var imageURLs = []; // put the paths to your images here
var imagesOK = 0;
var imgs = [];
imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-1.jpg");
imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-2.jpg");
imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-3.jpg");
imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-4.jpg");
loadAllImages();
//
function loadAllImages() {
    for (var i = 0; i < imageURLs.length; i++) {
        var img = new Image();
        imgs.push(img);
        img.onload = function () {
            imagesOK++;
            if (imagesOK >= imageURLs.length) {
                $("#fade").show();
                ctx.drawImage(imgs[0], 0, 0);
            }
        };
        img.onerror = function () {
            alert("image load failed");
        }
        img.crossOrigin = "anonymous";
        img.src = imageURLs[i];
    }
}


var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

var fadeOutIndex = imgs.length - 1;
var fadeInIndex = 0;
var fadePct = 0;

function animateFade() {
    if (fadePct > 100) {
        return;
    }
    requestAnimationFrame(animateFade);
    //            ctx.clearRect(0,0,canvas.width,canvas.height);
    draw(imgs[fadeInIndex], fadePct / 100);
    draw(imgs[fadeOutIndex], (1 - fadePct / 100));
    fadePct++;
}

function draw(img, opacity) {
    ctx.save();
    ctx.globalAlpha = opacity;
    ctx.drawImage(img, 0, 0);
    ctx.restore();
}

$("#fade").click(function () {
    fadePct = 0;
    if (++fadeOutIndex == imgs.length) {
        fadeOutIndex = 0;
    }
    if (++fadeInIndex == imgs.length) {
        fadeInIndex = 0;
    }
    animateFade();
});