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How to enable proper scrolling after scrub effect in a webpage using javascript?

I found a code from codepen to use it for scrub effect in video. After the video has ended I want to enable complete scrolling. How can I acheive that? Thanks in advance!
var frameNumber = 0, // start video at frame 0
// lower numbers = faster playback
playbackConst = 500,
// get page height from video duration
setHeight = document.getElementById("set-height"),
// select video element
vid = document.getElementById('v0');
// var vid = $('#v0')[0]; // jquery option
// dynamically set the page height according to video length
vid.addEventListener('loadedmetadata', function() {
setHeight.style.height = Math.floor(vid.duration) * playbackConst + "px";
});
// Use requestAnimationFrame for smooth playback
function scrollPlay(){
var frameNumber = window.pageYOffset/playbackConst;
vid.currentTime = frameNumber;
window.requestAnimationFrame(scrollPlay);
}
window.requestAnimationFrame(scrollPlay);

Do DOM events work with pointer lock?

I have used the pointer lock on my canvas element, and the canvas is on full screen. I want to detect right clicks and left clicks to respond to them. Is it possible to respond to clicks in full screen and pointer lock? I already know how to use the pointer lock api and the fullscreen api, I don't want any answers explaining how to use them. Any help would be appreciated.

Based on the experiments I've done, the short answer is "it depends." Take a look at the following demo. There is a canvas scaled to be a quarter of the screen size in each dimension. When you move the cursor over it, a white circle appears on the canvas. When you left click, you'll draw a red circle to the canvas, and when you right click, you'll draw a cyan circle to the canvas. When you click the "Full screen" button, you'll activate pointer lock and enter fullscreen mode. If you press the "Esc" key, you'll exit pointer lock and fullscreen mode.
Note that you'll need to copy and paste the code into a file and load it. The demo won't run if you just click "Run code snippet."
As far as your question, there are two issues, I'm aware of:
In Chrome, both right- and left-click events are triggered even while in fullscreen/pointer lock. However, in Firefox, only left-click events are triggered; I was unable to get right-click events using any of the handlers I tried (click, mousedown, mouseup, contextmenu). When not in fullscreen/pointer lock, both left- and right-click events get triggered as expected in both browsers. If anyone has any solutions for listening to right-click events while in fullscreen/pointer lock, I'd love to hear them.
It seems that in pointer lock in both Chrome/Firefox, events no longer trickle down to elements contained in the element with pointer lock, but they continue to bubble up to parent elements. So in the demo, the canvas is inside a div. The div has pointer lock. onclick handlers are attached to the canvas, div, and document to report click events in the console. Without pointer lock, clicking on the canvas triggers onclick handlers for all three elements (canvas, div, and document). However, with pointer lock on the div, the onclick handler for the canvas never gets triggered, though the handlers for the div and the document do.
I also identified a couple other quirks to Firefox that, while not directly related to your initial question, might be helpful to folks interested in implementing this sort of thing:
When fullscreen mode is entered, Firefox will apply styles to the fullscreen element to get it to fill the screen. I was unable to get the canvas styled correctly (i.e. to take up the full screen) when it was placed full screen. Rather, I had to wrap the canvas in a div and enter full screen on the div. See the Fullscreen API documentation on MDN for more info:
if you're trying to emulate WebKit's behavior on Gecko, you need to place the element you want to present inside another element, which you'll make fullscreen instead, and use CSS rules to adjust the inner element to match the appearance you want.
In Firefox, activating fullscreen mode deactivated pointer lock. In order to get both activated, I had to first activate fullscreen mode and then activate pointer lock. However the simple two lines of code:
canvasContainer.requestFullscreen();
canvasContainer.requestPointerLock();
did not work. My understanding of what was happening is that the call to requestPointerLock got initiated before full screen mode was fully established. This led to pointer lock being activated and then quickly deactivated again. I found it necessary to wait until fullscreen mode was fully established before calling requestPointerLock(). Checking that document.mozFullScreenElement !== null seemed to be sufficient for checking that full screen mode was completely operational. The following following click handler definition worked to solve this problem for me:
document.getElementById('fullscreen_button').onclick = function(e) {
// When button is clicked, enter both full screen and pointer lock
canvasContainer.requestFullscreen();
var timeout = 2000;
var interval = window.setInterval(function() {
if (document.mozFullScreenElement !== null) {
window.clearInterval(interval);
canvasContainer.requestPointerLock();
} else if (timeout <= 0) {
addErrorMessage('Unable to establish pointer lock.');
clearTimeout(interval);
} else {
timeout -= 50;
}
}, 50);
}
This function repeatedly checks if full screen mode is established. When it is, it initiate pointer lock. If fullscreen mode can't be determined after 2 s, it times out.
I haven't done any testing in IE.
<!DOCTYPE HTML>
<html lang="en-US">
<head>
<style>
</style>
</head>
<body>
<p id="msgs">Click 'Full screen' button below to go full screen. <br>
Click the left mouse button to draw a red circle. <br>
Click any other mouse button to draw a cyan circle. <br>
Press the 'Esc' key to exit full screen.</p>
<div id="canvas_container">
<canvas id="canvas"> </canvas>
</div>
<br>
<button id='fullscreen_button'>Full screen</button>
</body>
<script>
// Display constants
var CANVAS_BG_COLOR = 'rgb(75, 75, 75)';
var LEFT_CLICK_COLOR = 'rgb(255, 150, 150)';
var OTHER_CLICK_COLOR = 'rgb(150, 255, 255)';
var CURSOR_COLOR = 'rgb(200, 200, 200)';
var CANVAS_SCALING_FACTOR = 4; // Ratio between screen dimension and canvas dimension before going full-screen
// Store mouse position
var mouseX, mouseY;
// Setup onscreen canvas, smaller than the screen by a factor of CANVAS_SCALING_FACTOR
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
canvas.width = screen.width/CANVAS_SCALING_FACTOR;
canvas.height = screen.height/CANVAS_SCALING_FACTOR;
// Create an offscreen canvas that's the same as the size of the screen
var offscreenCanvas = document.createElement('canvas');
var offscreenCtx = offscreenCanvas.getContext('2d');
offscreenCanvas.width = screen.width;
offscreenCanvas.height = screen.height;
var canvasContainer = document.getElementById('canvas_container');
// Radius of the circle drawn and of the circle cursor
var circleRadius = 12;
var cursorRadius = circleRadius/CANVAS_SCALING_FACTOR
offscreenCtx.drawCircle = ctx.drawCircle = function (x, y, color, radius) {
this.fillStyle = color;
this.beginPath();
this.arc(x, y, radius, 0, 2*Math.PI, true);
this.fill();
}
offscreenCtx.clearCanvas = function() {
this.fillStyle = CANVAS_BG_COLOR;
this.fillRect(0, 0, this.canvas.width, this.canvas.height);
}
ctx.update = function() {
// Copy the offscreen canvas, scaling down if not in full-screen mode
this.drawImage(offscreenCanvas, 0, 0, offscreenCanvas.width, offscreenCanvas.height,
0, 0, canvas.width, canvas.height);
// Draw the cursor
this.drawCircle(mouseX, mouseY, CURSOR_COLOR, cursorRadius);
}
function pointerLockActive() {
return document.pointerLockElement===canvasContainer || document.mozPointerLockElement === canvasContainer;
}
// Perform initial canvas setup
offscreenCtx.clearCanvas();
ctx.update();
// Setup pointerlock and fullscreen API functions for cross-browser support
function addErrorMessage(msg) {
document.getElementById('msgs').innerHTML += ('<br><font color="red">' + msg + '</font>');
}
canvasContainer.requestPointerLock = canvasContainer.requestPointerLock || canvasContainer.mozRequestPointerLock;
canvasContainer.requestFullscreen = canvasContainer.webkitRequestFullscreen || canvasContainer.mozRequestFullScreen || canvasContainer.msRequestFullscreen
if (!canvasContainer.requestPointerLock) addErrorMessage('Error: Pointer lock not available');
if (!canvasContainer.requestFullscreen) addErrorMessage('Error: Full screen mode not available');
canvasContainer.addEventListener('mousemove', function(e) {
if (pointerLockActive()) {
// If in pointer lock, then cursor positions need to be updated manually;
// Normal cursor positions (e.g. e.clientX and e.clientY) don't get updated in pointer lock
mouseX += e.movementX, mouseY += e.movementY;
// Prevent the mouse from moving off-screen
mouseX = Math.min(Math.max(0, mouseX), canvas.width);
mouseY = Math.min(Math.max(0, mouseY), canvas.height);
} else {
// If pointer lock is inactive, then mouse position is just position relative to canvas offset
mouseX = (e.pageX - canvas.offsetLeft)
mouseY = (e.pageY - canvas.offsetTop)
}
ctx.update(); // Update the onscreen canvas
}, false);
// Handle entering and exiting pointer lock; pointer lock status is yoked to full screen status; both are entered and exited at the same time
document.addEventListener('pointerlockchange', function(e) {
if (!pointerLockActive()) {
console.log('Pointer lock deactivated');
canvas.width /= CANVAS_SCALING_FACTOR;
canvas.height /= CANVAS_SCALING_FACTOR
cursorRadius /= CANVAS_SCALING_FACTOR;
} else {
console.log('Pointer lock activated')
canvas.width *= CANVAS_SCALING_FACTOR;
canvas.height *= CANVAS_SCALING_FACTOR;
cursorRadius *= CANVAS_SCALING_FACTOR;
// Set the initial mouse position to be the middle of the canvas
mouseX = screen.width/2, mouseY = screen.height/2;
}
// Update the onscreen canvas
ctx.update();
});
document.getElementById('fullscreen_button').onclick = function(e) {
// When button is clicked, enter both full screen and pointer lock
canvasContainer.requestFullscreen();
var timeout = 2000;
var interval = window.setInterval(function() {
if (document.mozFullScreenElement !== null) {
window.clearInterval(interval);
canvasContainer.requestPointerLock();
} else if (timeout <= 0) {
addErrorMessage('Unable to establish pointer lock.');
clearTimeout(interval);
} else {
timeout -= 50;
}
}, 50);
}
canvasContainer.onclick = function(e) {
console.log('canvasContainer clicked');
if (pointerLockActive())
// If pointer lock is active, then use the mouseX and mouseY positions that are manually updated by the mousemove event handler
var cursorX = mouseX, cursorY = mouseY;
else
// Otherwise use the mouse positions passed in the event object
// If not in full screen mode, the cursor position has to be scaled up, because the mouse position is relative to the onscreen canvas, but we're drawing on the offscreen canvas, which is larger by a factor of fullscreenScale
var cursorX = (e.pageX - canvas.offsetLeft)*CANVAS_SCALING_FACTOR, cursorY = (e.pageY - canvas.offsetTop)*CANVAS_SCALING_FACTOR;
// If the left mouse button is clicked (e.which===1), draw a circle of one color
// If any other mouse button is clicked, draw a circle of another color
var color = e.which === 1 ? LEFT_CLICK_COLOR : OTHER_CLICK_COLOR;
offscreenCtx.drawCircle(cursorX, cursorY, color, circleRadius);
ctx.update();
};
// Detect canvas right-click events. Prevent default behavior (e.g. context menu display) and pass on to the onclick handler to do the rest of the work
canvasContainer.oncontextmenu = function(e) {
e.preventDefault();
this.onclick(e);
}
canvas.onclick = function() {
console.log('canvas clicked');
}
document.onclick = function() {
console.log('document clicked');
}
</script>
</html>

This worked for me to handle rightClick after pointer was locked.
const onMouseDown = (evt) => {
switch (evt.which) {
case 1: return handleLeftClick();
case 3: return handleRightClick();
}
};
document.body.addEventListener('mousedown', onMouseDown, true);

html canvas - issue with moving image

I am learning html canvas and below is my html code.
<!DOCTYPE html>
<html>
<head>
<script language="javascript">
function moveImage(x) {
var context = document.getElementById('myCanvas').getContext("2d");
var img = new Image();
img.onload = function () {
context.drawImage(img, x, 259);
}
img.src = "flower.jpg";
}
function startDrawing() {
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
context.beginPath();
context.moveTo(50, 300);
context.lineTo(950, 300);
context.stroke();
var x=50;
setInterval(function() {
x = x+20;
moveImage(x);
}, 1000);
}
</script>
</head>
<body onload="startDrawing()">
<canvas id="myCanvas" width="1000" height="1000">
</body>
</html>
Please find the below output from this code:
How can I remove the traces of 'older frames' (of the flower), as you could see lots of flowers while it is moving from left to right in the screen shot ? Please help the code changes required.
Thanks.

The problem is you aren't clearing the canvas before drawing on it again. You can clear it using clearRect.
setInterval(function() {
// Clear the canvas
context.clearRect(0, 0, canvas.width, canvas.height);
x += 20;
moveImage(x);
}, 1000);
Keep in mind that this will clear the entire canvas. If you're rendering anything else, you'll want to redraw it after the clear.

You need to re-render the frame. Here's some code from an incomplete game I wrote:
var main = function () {
var now = Date.now(),
delta = now - then;
update(delta / 1000);
render();
then = now;
// Request to do this again ASAP
requestAnimationFrame(main);
};
GitHub repo code
My render function contains the context.drawImg() work (getting properly re-rendered), and that's similar to your moveImage function.
Edit: A little explanation. The image traces are previous renderings of the your image at each updated position. Without the frame itself being reset, each move of the image is preserved on the screen, giving the appearance of a trail of images.

html5 canvas drawing: fast motion with mouse cancels line before it hits the edge of the canvas

The app works fine so far except if the line is drawn really fast and leaves the edge of the canvas, the line is then not drawn to the edge of the canvas. There is a part missing from it.
I'm trying to fix the issue with:
canvasVar.addEventListener ('mouseout', clearPathIfMouseCursorLeavesCanvasFunc);
and
function clearPathIfMouseCursorLeavesCanvasFunc(e){
contextVar.beginPath(); // clears the path so buttonpresses dont connect the line
mouseButtonHeld = false;
I've tried some things like adding a settimeout(); but nothing worked so far. I don't know what causes this and I've been searching if someone else had this problem and a fix for it, but every canvas drawing app I've come across has the same issues.
It's very important that the line is drawn to the edge and that the users mouse motion is recognized, not just a line to the last coordinates where the mouse left the canvas.
It's been days now that I'm stuck with this problem. Help is really appreciated!
Whole Code:
// Varibale declaration
var canvasVar = document.getElementById('canvasHtmlElement');
var contextVar = canvasVar.getContext('2d');
var pointRadiusVar = 0.5;
var mouseButtonHeld = false;
var pointsArrPosition = 0;
//Arrays
var pointsArr = [];
// Varibale declration end
//canvas setup
canvasVar.width = window.innerWidth;
canvasVar.height = window.innerHeight;
//canvas setup end
//resize fix
window.onresize = function() {
var tempImageVar = contextVar.getImageData(0, 0, canvasVar.width, canvasVar.height);
canvasVar.width = window.innerWidth;
canvasVar.height = window.innerHeight;
contextVar.putImageData(tempImageVar, 0, 0);
}
//resize fix end
//functions
// Objects
function pointObject() {
this.x = 0;
this.y = 0;
this.fill = '#444444';
}
function addFilledCircleFunc(x, y) {
//alert('works1');
var filledCircle = new pointObject;
filledCircle.x = x;
filledCircle.y = y;
pointsArr.push(filledCircle);
contextVar.lineWidth = 10; //pointRadiusVar * 2; // Line Width
contextVar.lineTo(pointsArr[pointsArrPosition].x, pointsArr[pointsArrPosition].y);
contextVar.stroke();
//contextVar.beginPath();
contextVar.fillRect(filledCircle.x, filledCircle.y, 1, 1);
//contextVar.arc(filledCircle.x, filledCircle.y, pointRadiusVar, 0, Math.PI * 2);
//contextVar.fill();
//contextVar.lineWidth = 0.5;
//contextVar.stroke();
//contextVar.beginPath();
pointsArrPosition++;
//contextVar.moveTo(pointsArr[pointsArrPosition].x, pointsArr[pointsArrPosition].y);
//alert(pointsArr[0].x);
}
//Objects end
// create circle on mouse clicked point while mousebutton is held
var addPointToCanvasVar = function(e) {
if (mouseButtonHeld) {
//alert('addpointfunc');
addFilledCircleFunc(e.clientX, e.clientY);
}
};
// MAKE SURE that lines work when drawn over the edge of the canvas
function clearPathIfMouseCursorLeavesCanvasFunc(e) {
contextVar.beginPath(); // clears the path so buttonpresses dont connect the line
mouseButtonHeld = false;
}
// end
// mouse Up/Down functions
var mouseDownVar = function(e) {
//alert("mouseDown");
addPointToCanvasVar(e); // add point on first click, not just when mousebutton is held
mouseButtonHeld = true;
}
var mouseUpVar = function() {
//alert("mouseUp");
mouseButtonHeld = false;
contextVar.beginPath(); // clears the path so buttonpresses dont connect the line
}
// mouse Up/Down Switch end
//functions end
//listeners
canvasVar.addEventListener('mousemove', addPointToCanvasVar);
canvasVar.addEventListener('mouseup', mouseUpVar);
canvasVar.addEventListener('mousedown', mouseDownVar);
canvasVar.addEventListener('mouseout', clearPathIfMouseCursorLeavesCanvasFunc);
//listeners end
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>Confident Drawing</title>
</head>
<body style="margin: 0">
<canvas id="canvasHtmlElement" style="display: block;">
Your Browser does not support Canvas! Please update to a newer version.
</canvas>
<script src="main_0.06.js"></script>
</body>
</html>
If you don't get what I mean: Run the snippet and draw a line as fast as you can while exiting the canvas.

The reason the line ends prematurely near the edge when you quickly draw a line across the edge is because the last mousemove event fired when the mouse was still in the canvas and just short of the edge, and the very next mousemove event fired after your mouse left the canvas. To fix that problem, simply draw your line from the last recorded mouse position in the canvas to the one outside of the canvas as soon as the mouseout event fires.
You can add a new global variable mousePosition and initialize it to {x:0,y:0}. Every time mousemove fires (whenever you call addPointToCanvasVar), record the e.clientX and e.clientY to your mousePosition. Then when mouseout fires (whenever you call clearPathIfMouseCursorLeavesCanvasFunc), draw the rest of the line from mousePosition to the current e.clientX and e.clientY position. This will complete the line to the end of the canvas edge.

Calling several functions using JavaScript's window.onload attribute

I have the following code in the index.html page of my site, which when the page loads, draws a number of images to the HTML5 canvas:
window.onload = function(){
var sources = {};
sources[0] = document.getElementById("building").src,
sources[1] = document.getElementById("chair").src,
sources[2] = document.getElementById("drink").src,
sources[3] = document.getElementById("food").src,
sources[4] = document.getElementById("fridge").src,
sources[5] = document.getElementById("land").src,
sources[6] = document.getElementById("money").src,
sources[7] = document.getElementById("oven").src,
sources[8] = document.getElementById("table").src,
sources[9] = document.getElementById("van").src,
sources[10] = document.getElementById("burger").src,
sources[11] = document.getElementById("chips").src,
sources[12] = document.getElementById("drink").src,
sources[13] = document.getElementById("franchiseFee").src,
sources[14] = document.getElementById("wages").src,
sources[15] = document.getElementById("admin").src,
sources[16] = document.getElementById("cleaners").src,
sources[17] = document.getElementById("electricity").src,
sources[18] = document.getElementById("insurance").src,
sources[19] = document.getElementById("manager").src,
sources[20] = document.getElementById("rates").src,
sources[21] = document.getElementById("training").src,
sources[22] = document.getElementById("water").src,
sources[23] = document.getElementById("burger").src,
sources[24] = document.getElementById("chips").src,
sources[25] = document.getElementById("drink").src,
sources[26] = document.getElementById("creditors").src,
sources[27] = document.getElementById("electricity").src,
sources[28] = document.getElementById("food").src,
sources[29] = document.getElementById("hirePurchase").src,
sources[30] = document.getElementById("loan").src,
sources[31] = document.getElementById("overdraft").src,
sources[32] = document.getElementById("payeTax").src,
sources[33] = document.getElementById("tax").src
loadImages(sources, drawImage);
};
Sources is the array that I'm using to hold the images in JavaScript so that they can be drawn to the canvas once they've been loaded from a hidden section in my HTML.
This function currently works exactly as it's intended- it has a call to the loadImages function, which loads the images from a hidden section in the HTML into the JavaScript array, and calls the drawImage function on each of the images in the array.
But I also have another function that I want to be called with the window.onload:
The function I want to add to window.onload is this:
function drawGameElements(){
/* Draw a line for the 'score bar'. */
context.moveTo(0, 25);
context.lineTo(1000, 25);
context.stroke();
/* Draw current level/ total levels on the left, and current score on the right. */
context.font = "11pt Calibri"; /* Text font & size */
context.strokeStyle = "black"; /* Font colour */
context.strokeText(currentLevel + "/" + totalLevels, 10, 15);
context.strokeText(currentScore, 950, 15);
}
I tried adding a call to the function just below the loadImages(sources, drawImage); line in window.onload = function(){};
So that I now have:
window.onload = function(){
...
loadImages(sources, drawImage);
drawGameElements();
};
Although this partially works, in that it draws the line across the top of the canvas for the 'score bar' and writes "1/3" for the levels on the left hand side of the canvas just above the line, for some reason it doesn't draw the current score on the right hand side.
Also, as soon as I click on one of the images that's been drawn to the canvas, to drag and drop it around the canvas, the 'score bar' then disappears from the canvas completely.
Does anyone know why this is? How can I get the score bar to remain visible throughout the duration of the game, no matter what else happens on the canvas? Also, how can I get the currentScore variable to be displayed?

I would instead use a callback inside of loadImages to call drawGameElements. That way drawGameElements only runs after loadImages is finished. It sounds like you've created a race condition with your two functions.

If I where you, I would create the score bar outside of the canvas. Set its position to absolute and let it hover above the canvas at the desired location. That way you can just access it as HTML elements and do not need to worry about redrawing.
The major advantage of using HTML elements for these displays is that you don't need to redraw them, for example after moving the images around on the canvas. You also don't have to worry about how to refresh the values (on a canvas, just painting new values over the old ones will not be enough). This way you can just store the values in HTML elements and go wild on the canvas, knowing the score will always stay on top.