//==========================================================================
// start canvas animation after all the code below has been parsed and executed
setTimeout(()=>requestAnimationFrame(updateCanvas),0);
//==========================================================================
// UI variables
var showFXName = 0;
var cursor = "default";
var overUI = false;
var sliderAlpha = 1;
var listAlpha = 1;
var dragging = false;
var listWidth = null;
var playClick = false;
//==========================================================================
// Media setup
var mediaSource = "http://video.webmfiles.org/big-buck-bunny_trailer.webm";
var mediaSource = "http://upload.wikimedia.org/wikipedia/commons/7/79/Big_Buck_Bunny_small.ogv";
var muted = true;
var canvas = document.getElementById("myCanvas"); // get the canvas from the page
var ctx = canvas.getContext("2d");
var videoContainer; // object to hold video and associated info
var video = document.createElement("video"); // create a video element
video.src = mediaSource;
// the video will now begin to load.
// As some additional info is needed we will place the video in a
// containing object for convenience
video.autoPlay = false; // ensure that the video does not auto play
video.loop = true; // set the video to loop.
video.muted = muted;
videoContainer = { // we will add properties as needed
video : video,
ready : false,
};
// To handle errors. This is not part of the example at the moment. Just fixing for Edge that did not like the ogv format video
video.onerror = function(e){
document.body.removeChild(canvas);
document.body.innerHTML += "<h2>There is a problem loading the video</h2><br>";
document.body.innerHTML += "Users of IE9+ , the browser does not support WebM videos used by this demo";
document.body.innerHTML += "<br><a href='https://tools.google.com/dlpage/webmmf/'> Download IE9+ WebM support</a> from tools.google.com<br> this includes Edge and Windows 10";
}
video.oncanplay = readyToPlayVideo; // set the event to the play function that
// can be found below
//==========================================================================
var FXMix = 1;
var FX = {}
var FXList = [];
var currentFX = "";
var animateFXMix = false; // if true thr FXMix is animated over time. This flag is cleared to false once a frame
//==========================================================================
// Mix noise variables. Created when filter first used.
var canvasNoise;
var ctxNoise;
var rawPixels;
var rawPixel32Arr;
//==========================================================================
// Mix function are in this section
function addOverlay(type){
if(FXMix > 0){
ctx.globalCompositeOperation = type;
ctx.globalAlpha = FXMix;
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.globalAlpha = 1;
ctx.globalCompositeOperation = "source-over";
}
}
function addMix(type,video){
if(FXMix > 0){
ctx.globalCompositeOperation = type;
ctx.globalAlpha = FXMix;
ctx.drawImage(video,0, 0, canvas.width, canvas.height);
ctx.globalAlpha = 1;
ctx.globalCompositeOperation = "source-over";
}
}
function fill(style){ // draws a rectangle over the canvas using style as the colour
ctx.globalAlpha = FXMix;
ctx.fillStyle = style;
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.globalAlpha = 1;
}
function mask(direction){
ctx.globalCompositeOperation = "destination-in";
ctx.fillStyle = "black";
ctx.globalAlpha = 1;
if(direction === "Vertical"){
ctx.fillRect(0, 0, canvas.width, canvas.height * FXMix);
}else if(direction === "Horizontal"){
ctx.fillRect(0, 0, canvas.width * FXMix, canvas.height);
}
ctx.globalCompositeOperation = "destination-atop";
// assuming bacground is black. But you could use anything including a second video
// using "destination-atop" only draws on transparent pixels.
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.globalCompositeOperation = "source-over";
}
function glowBar(RGB, direction){ // RGB is array of channel values 0-255
var grad;
var col = "rgba("+RGB[0]+","+RGB[1]+","+RGB[2]+",";
if(direction === "Vertical"){
grad = ctx.createLinearGradient(0,0,0,canvas.height * 0.1);
}else if(direction === "Horizontal"){
grad = ctx.createLinearGradient(0,0,canvas.width * 0.1,0);
}
grad.addColorStop(0.0, col + "0.0)");
grad.addColorStop(0.3, col + "0.8)");
grad.addColorStop(0.4, col + "1.0)");
grad.addColorStop(0.6, col + "1.0)");
grad.addColorStop(0.7, col + "0.8)");
grad.addColorStop(1.0, col + "0.0)");
ctx.fillStyle = grad;
if(direction === "Vertical"){
ctx.setTransform(1,0,0,1,0,canvas.height * FXMix - canvas.height * 0.05);
ctx.fillRect(0, 0, canvas.width, canvas.height * 0.1);
ctx.setTransform(1,0,0,1.1,0,canvas.height * FXMix -canvas.height * 0.05 * 1.1 );
ctx.globalCompositeOperation = "lighter";
ctx.fillRect(0, 0, canvas.width, canvas.height * 0.1);
}else if(direction === "Horizontal"){
ctx.setTransform(1,0,0,1,canvas.width * FXMix -canvas.width * 0.05, 0);
ctx.fillRect(0, 0, canvas.width * 0.1, canvas.height);
ctx.setTransform(1.1,0,0,1,canvas.width * FXMix -canvas.width * 0.05 * 1.1, 0);
ctx.globalCompositeOperation = "lighter";
ctx.fillRect(0, 0, canvas.width * 0.1, canvas.height);
}
ctx.globalCompositeOperation = "source-over";
ctx.setTransform(1,0,0,1,0,0);
}
function noise(type) {
var i,d;
if(canvasNoise === undefined){
canvasNoise = document.createElement("canvas");
canvasNoise.width = Math.floor(canvas.width / 3);
canvasNoise.height = canvas.height;
ctxNoise = canvasNoise.getContext("2d");
rawPixels = ctxNoise.createImageData(canvasNoise.width, canvasNoise.height);
rawPixel32Arr = new Uint32Array(rawPixels.data.buffer);
randomPix = new Uint32Array(canvasNoise.width * 10);
i = canvasNoise.width * 10;
d = randomPix; // alias to make code readable
while(i--){
var r = Math.floor(Math.random() * 255);
// create slight croma noise
var g = Math.min(255, Math.max(0,Math.floor(r + (Math.random()-0.5) * 32)));
var b = Math.min(255, Math.max(0,Math.floor(r + (Math.random()-0.5) * 32)));
d[i] = 0xFF000000 + (r<<16) + (g<<8) + b;
}
}
i = rawPixel32Arr.length;
d = rawPixel32Arr; // alias to make code readable
while(i){
var len = Math.floor(Math.random() * 100) + 20;
var start = Math.floor(Math.random() * randomPix.length - len);
i -= len;
i = i < 0 ? 0 : i;
d.set(randomPix.subarray(start,start + len), i);
}
ctxNoise.putImageData(rawPixels, 0, 0);
if(type === "Addative"){
ctx.globalAlpha = FXMix;
ctx.globalCompositeOperation = "multiply";
ctx.drawImage(canvasNoise,0,0,canvas.width,canvas.height)
ctx.globalCompositeOperation = "lighter";
ctx.drawImage(canvasNoise,0,0,canvas.width,canvas.height)
ctx.globalCompositeOperation = "source-over";
ctx.drawImage(canvasNoise,0,0,canvas.width,canvas.height)
ctx.globalAlpha = 1;
}else{
ctx.globalAlpha = FXMix;
ctx.globalCompositeOperation = "multiply";
ctx.drawImage(canvasNoise,0,0,canvas.width,canvas.height)
ctx.globalCompositeOperation = "source-over";
ctx.drawImage(canvasNoise,0,0,canvas.width,canvas.height)
ctx.globalAlpha = 1;
}
}
function addFX(name, func) {
FXList.push(name);
FX[name] = func;
currentFX = name;
}
//==========================================================================
// avialable composite operations
// multiply,screen,overlay,color-dodge,color-burn,hard-light,soft-light,difference,
// exclusion,hue,saturation,color,luminosity
addFX("Noise", (vid)=>{ noise() })
addFX("Noise 2", (vid)=>{ noise("Addative") })
addFX("V scanner", (vid)=>{ animateFXMix = true; mask("Vertical"); glowBar([100,200,255], "Vertical") })
addFX("H scanner", (vid)=>{ animateFXMix = true; mask("Horizontal"); glowBar([100,255,200], "Horizontal") })
addFX("Ligher", (vid)=>{ addMix("lighter",vid) } );
addFX("Ligher+", (vid)=>{ addMix("lighter", vid); addMix("lighter",vid); addMix("lighter", vid) } );
addFX("Darken", (vid)=>{ addMix("multiply", vid) } );
addFX("Darken+", (vid)=>{ addMix("multiply", vid); addMix("multiply",vid); addMix("multiply", vid) } );
addFX("Saturate", () =>{ ctx.fillStyle = "#F00"; addOverlay("saturation") });
addFX("Negative", (vid)=>{ ctx.fillStyle = "#FFF"; addOverlay("difference") } );
addFX("Sepia", (vid)=>{ fill("#F94"); addMix("luminosity", vid) } );
addFX("BlackWhite", (vid)=>{ ctx.fillStyle = "#888"; addOverlay("color") } );
addFX("B&W Negative",(vid)=>{ ctx.fillStyle = "#FFF"; addOverlay("difference"); ctx.fillStyle = "#888"; addOverlay("color") } );
addFX("B&W Lighten", (vid)=>{ addMix("lighter", vid); ctx.fillStyle = "#888"; addOverlay("color") } );
addFX("None", () =>{});
// end of FX mixing
//==========================================================================
function readyToPlayVideo(event){ // this is a referance to the video
// the video may not match the canvas size so find a scale to fit
videoContainer.scale = Math.min(
canvas.width / this.videoWidth,
canvas.height / this.videoHeight);
videoContainer.ready = true;
// the video can be played so hand it off to the display function
// add instruction
document.getElementById("playPause").textContent = "Click video to play/pause.";
document.querySelector(".mute").textContent = "Mute";
}
function updateCanvas(time){
ctx.fillStyle = "#222";
ctx.fillRect(0,0,canvas.width,canvas.height)
// only draw if loaded and ready
if(videoContainer !== undefined && videoContainer.ready){
// find the top left of the video on the canvas
video.muted = muted;
var scale = videoContainer.scale;
var vidH = videoContainer.video.videoHeight;
var vidW = videoContainer.video.videoWidth;
var top = canvas.height / 2 - (vidH /2 ) * scale;
var left = canvas.width / 2 - (vidW /2 ) * scale;
// now just draw the video the correct size
ctx.drawImage(videoContainer.video, left, top, vidW * scale, vidH * scale);
FX[currentFX](videoContainer.video);
if(videoContainer.video.paused){ // if not playing show the paused screen
drawPayIcon();
}
overUI = false;
cursor = "default";
drawSlider();
drawList();
if(mouse.over){
if(!overUI){
if((mouse.button&1)===1){ // bit field
playClick = true;
}
if((mouse.button&1)===0 && playClick){ // bit field
playClick = false;
playPauseClick();
}
cursor = "pointer";
}
}
if(showFXName > 0){
showFXName = Math.max(0,showFXName - 0.05);
ctx.globalAlpha = Math.min(1,showFXName);
ctx.font = "32px Arial";
ctx.textAlign = "center";
ctx.textbaseLine = "middle";
ctx.fillStyle = "white";
ctx.strokeStyle = "black";
ctx.lineJoin = "round"
ctx.strokeText(currentFX,canvas.width/2,canvas.height/2);
ctx.fillText(currentFX,canvas.width/2,canvas.height/2);
ctx.globalAlpha = 1;
}
canvas.style.cursor = cursor;
if(animateFXMix){
FXMix = Math.sin(time / 400) * 0.5 + 0.5;
FXMix = FXMix < 0 ? 0 : FXMix > 1 ? 1 : FXMix; // Clamp to 0-1 or may get flicker on some FX
animateFXMix = false;
}
}else{
drawLoadingAnim(time);
}
// all done for display
// request the next frame in 1/60th of a second
requestAnimationFrame(updateCanvas);
}
function getMaxListWidth(){
ctx.font = "12px arial";
FXList.forEach(text => {listWidth = Math.max(listWidth,ctx.measureText(text).width)})
}
function drawList(){
if(listWidth === null){
getMaxListWidth();
listWidth += 10;
}
if(!overUI && mouse.over && mouse.x > canvas.width - listWidth){
listAlpha = 1;
overUI = true;
}else{
listAlpha = Math.max(0,listAlpha - 0.05);
}
if(listAlpha > 0){
ctx.font = "12px arial";
var textH = 14;
var border = 10;
ctx.textAlign = "right";
ctx.textBaseline = "middle";
ctx.globalAlpha = listAlpha;
ctx.fillStyle = "black";
ctx.strokeStyle = "white";
var len = FXList.length;
var h = len * textH;
var y = canvas.height / 2 - h/2;
var x = canvas.width - border * 2;
ctx.fillRect(x - listWidth,y - border, listWidth+border,h + border );
ctx.strokeRect(x - listWidth,y - border, listWidth + border,h + border );
ctx.fillStyle = "white"
for(var i = 0; i < len; i ++){
var yy = y + i * textH;
if(FXList[i] === currentFX){
ctx.fillStyle = "#0FF";
ctx.fillText(FXList[i],x,yy);
ctx.fillStyle = "white"
}else
if(mouse.x > canvas.width - listWidth && mouse.y > yy - textH/2 && mouse.y < yy + textH /2){
ctx.fillStyle = "#0F0";
ctx.fillText(FXList[i],x,yy);
ctx.fillStyle = "white"
cursor = "pointer";
if((mouse.button & 1) === 1){
currentFX =FXList[i];
showFXName = 4;
}
}else{
ctx.fillText(FXList[i],x,yy);
}
}
ctx.globalAlpha = 1;
}
}
function drawSlider(){
if(currentFX === "None"){
sliderAlpha = 0;
return;
}
if(dragging){
animateFXMix = false; // dont animate if slider being dragged
}
var cw = canvas.width;
var ch = canvas.height;
var handle = 5;
var inset = 10
var x = inset;
var w = cw - inset*2;
var h = 20;
var y = ch - inset - h;
var pos = FXMix * w + x;;
if(mouse.y > y - h* 1.2){
cursor = "e-resize";
overUI = true;
if((mouse.button&1) && !dragging){ // bit field
dragging = true;
}
}else{
cursor = "pointer";
}
if(dragging){
overUI = true;
cursor = "e-resize";
sliderAlpha = 1;
pos = mouse.x - x;
FXMix = Math.min(1,Math.max(0,pos / w));
if( (mouse.button&1) === 0 ){ //bit field
dragging = false;
}
}
if(!dragging && mouse.y > y-h*2 && mouse.over){
sliderAlpha = 1;
}else{
if(sliderAlpha > 0){
sliderAlpha = Math.max(0,sliderAlpha- 0.05);
}
}
if(sliderAlpha === 0){
return;
}
ctx.globalAlpha = sliderAlpha;
ctx.font = "18px arial";
ctx.textAlign = "center";
ctx.textBaseline = "middle";
var amount = FXMix;
ctx.fillStyle = "black";
ctx.strokeStyle = "white";
ctx.fillRect(x,y,w,h);
ctx.strokeRect(x,y,w,h);
ctx.fillStyle = "white";
ctx.fillText(currentFX + " "+ (FXMix * 100).toFixed(0)+"%",w/2,y + h / 2);
pos = amount * w + x;
ctx.fillStyle = "white";
ctx.strokeStyle = "black";
ctx.fillRect(pos-handle*2,y-handle,handle* 4,h + handle * 2);
ctx.strokeRect(pos-handle*2,y-handle,handle* 4,h + handle * 2);
ctx.strokeRect(pos-1,y-handle * 0.5,2,h + handle);
ctx.globalAlpha = 1;
}
function drawPayIcon(){
ctx.fillStyle = "#DDD"; // colour of play icon
ctx.globalAlpha = 0.75; // partly transparent
ctx.beginPath(); // create the path for the icon
var size = (canvas.height / 2) * 0.5; // the size of the icon
ctx.moveTo(canvas.width/2 + size/2, canvas.height / 2); // start at the pointy end
ctx.lineTo(canvas.width/2 - size/2, canvas.height / 2 + size);
ctx.lineTo(canvas.width/2 - size/2, canvas.height / 2 - size);
ctx.closePath();
ctx.fill();
ctx.globalAlpha = 1; // restore alpha
}
function drawLoadingAnim(time){
ctx.strokeStyle = "#8DF"; // colour of play icon
ctx.lineCap = "round";
ctx.globalAlpha = 0.75; // partly transparent
ctx.lineWidth = 6;
ctx.beginPath(); // create the path for the icon
var size = (canvas.height / 2) * 0.5; // the size of the icon
ctx.arc(canvas.width / 2 , canvas.height / 2, size, time / 100, time / 100 + 2);
ctx.stroke();
ctx.lineWidth = 1;
ctx.globalAlpha = 1; // restore alpha
}
mouse = (function(){
var mouse = {
x : 0, y : 0, w : 0,
button : 0,
over : false,
bm : [1, 2, 4, 6, 5, 3],
active : false,
bounds : null,
border : {top : 10, left : 10},
mouseEvents : "mousemove,mousedown,mouseup,mouseout,mouseover,contextmenu".split(",")
};
var m = mouse;
function mouseMove(e) {
var t = e.type;
m.bounds = m.element.getBoundingClientRect();
m.x = e.clientX - m.bounds.left - m.border.left;
m.y = e.clientY - m.bounds.top - m.border.top;
if (t === "mousedown") {
m.button |= m.bm[e.which-1];
} else if (t === "mouseup") {
m.button &= m.bm[e.which + 2];
}else if (t === "mouseout") {
m.button = 0;
m.over = false;
}else if (t === "mouseover") {
m.over = true;
}
e.preventDefault();
}
m.start = function (element) {
m.element = element;
m.mouseEvents.forEach( n => { m.element.addEventListener(n, mouseMove); } );
m.active = true;
//m.border.top = Number(element.style.borderTopWidth.replace(/[a-zA-Z]/g,""));
//m.border.left = Number(element.style.borderLeftWidth.replace(/[a-zA-Z]/g,""));
}
m.remove = function () {
if (m.element !== undefined) {
m.mouseEvents.forEach(n => { m.element.removeEventListener(n, mouseMove); } );
m.active = false;
m.element = undefined;
}
}
return mouse;
})();
function playPauseClick(){
if(videoContainer !== undefined && videoContainer.ready){
if(videoContainer.video.paused){
videoContainer.video.play();
}else{
videoContainer.video.pause();
}
}
}
function videoMute(){
muted = !muted;
if(muted){
document.querySelector(".mute").textContent = "Mute";
}else{
document.querySelector(".mute").textContent= "Sound on";
}
}
// register the event
//canvas.addEventListener("click",playPauseClick);
document.querySelector(".mute").addEventListener("click",videoMute)
setTimeout(()=>{mouse.start(canvas)},100);
body {
font :14px arial;
text-align : center;
background : #36A;
}
h2 {
color : white;
}
canvas {
border : 10px white solid;
cursor : pointer;
}
a {
color : #F93;
}
.mute {
cursor : pointer;
display: initial;
}
<h2>Simple video FX via canvas "globalCompositeOperation"</h2>
<p>This example show how to use the 2d context "globalCompositeOperation" property to create a variety of FX. Video may take a few moment to load.
</p>
<p>Play pause video with click. Move to bottom of video to see FX mix slider (Not available if filter None). Move to right to get filter selection and select the filter example. Happy filtering</p>
<canvas id="myCanvas" width = "532" height ="300" ></canvas><br>
<h3><div id = "playPause">Loading content.</div></h3>
<div class="mute"></div><br>
