So basically, I'm loading and inserting html to a div element on my homepage. It all works well except that I've realised my regular href link just won't work. When I hover the URL appears on the bottom of Chrome as usual, but when I click, nothing happens.
For what I've seen, it seems like click events might not work properly on dynamically added elements?
The issue is, I've only seen jQuery solutions for this, and, frankly, I'm not even sure if this is the issue at all.
Any ideas?
PS: http://jsfiddle.net/8hz1Lubr/
// -------------------------- get the elements ----------------------- //
const deskbar = document.querySelector('#deskbar');
const screen = document.querySelector('#desktop');
const menuLink = document.querySelector('#primaryNav');
const tabsList = document.querySelector('#tabsList');
const clock = document.getElementById('theTime');
const desktop = document.querySelector('#contentarea');
// -------------------------- create events -------------------------- //
screen.addEventListener('click', toggleMenu);
tabsList.addEventListener('click', activateTab);
menuLink.addEventListener('click', openWindow);
menuLink.addEventListener('click', generateTab);
// -------------------------- open windows --------------------------- //
function openWindow(e) {
let windows = document.querySelectorAll('.window');
let openWindows = [];
windows.forEach(function(theWindow){
openWindows.push(theWindow.getAttribute('data-window'));
});
if(e.target.classList.contains('menuLink') && !openWindows.includes(e.target.getAttribute('data-link'))) {
let newWindow =`<div class="window" id="${e.target.getAttribute('data-link')}" data-window="${e.target.getAttribute('data-link')}">
<header class="header"></header>
<span class="close"></span>
<div class="headerContent">
${e.target.innerText}
<span class="minimize"></span>
</div>
<article>
<div class="content"></div>
</article>
</div>`;
desktop.insertAdjacentHTML('afterbegin', newWindow);
fetchPage(e.target.href, e.target.getAttribute('data-link'));
}
windows = document.querySelectorAll('.window');
// create add event listener for each new window
windows.forEach(function(theWindow){
theWindow.addEventListener('click', closeWindow);
theWindow.addEventListener('click', closeTab);
if(window.matchMedia("(min-width: 960px)").matches) {
theWindow.getElementsByClassName('headerContent')[0].onmousedown = function(event) {
let shiftX = event.clientX - theWindow.getBoundingClientRect().left;
let shiftY = event.clientY - theWindow.getBoundingClientRect().top;
deactivateAllWindows();
theWindow.classList.add('activeWindow');
theWindow.style.position = 'absolute';
theWindow.style.zIndex = 15;
desktop.append(theWindow);
moveAt(event.pageX, event.pageY);
// centers the ball at (pageX, pageY) coordinates
function moveAt(pageX, pageY) {
theWindow.style.left = pageX - shiftX + 'px';
theWindow.style.top = pageY - shiftY + 'px';
}
function onMouseMove(event) {
moveAt(event.pageX, event.pageY);
}
// move the window on mousemove
document.addEventListener('mousemove', onMouseMove);
// drop the window, remove unneeded handlers
theWindow.onmouseup = function() {
document.removeEventListener('mousemove', onMouseMove);
theWindow.onmouseup = null;
};
};
theWindow.ondragstart = function() {
return false;
};
}
});
e.preventDefault();
}
// -------------------------- fetch html content --------------------- //
function fetchPage(url, attribute) {
let windows = document.querySelectorAll('.window');
fetch(url)
.then(function(response) {
return response.text();
})
.then(function(body) {
windows.forEach(function(theWindow) {
theWindow.style.zIndex = 14;
theWindow.classList.remove('activeWindow');
});
windows.forEach(function(theWindow) {
if(theWindow.getAttribute('data-window') == attribute) {
if(window.matchMedia("(min-width: 960px)").matches) {
let randomHeight = Math.floor(Math.random() * (40 - 20 + 1)) + 20;
let randomWidth = Math.floor(Math.random() * (40 - 20 + 1)) + 20;
theWindow.style.zIndex = 15;
theWindow.style.top = randomHeight + '%';
theWindow.style.left = randomWidth + '%';
setTimeout(function(){
theWindow.style.opacity = 1;
}, 125);
}
theWindow.classList.add('activeWindow');
let content = theWindow.querySelector('.content');
content.innerHTML = body;
}
});
});
}
Related
I have a function that craeates divs with a circle.
Now they are all created and appear at the beginning of the page and go further in order.
Next, I need each circle to appear in a random place. I did this.
Now I need all of them to move randomly across the entire page, I have difficulties with this.
Here is an example of how everything works for one element that is already on the page.
https://jsfiddle.net/quej8wko/
But when I add this code, all my created circles don't move.
I get an error:
"message": "Uncaught TypeError: Cannot set properties of null (setting 'willChange')",
This is probably due to the fact that initially there are no circles on the page. How can I connect the code so that all created circles move?
//creating circles
var widthHeight = 40; // <-- circle width
var margin = 20; // <-- margin - is it necessary ?
var delta = widthHeight + margin;
function createDiv(id, color) {
let div = document.createElement('div');
var currentTop = 0;
var documentHeight = document.documentElement.clientHeight;
var documentWidth = document.documentElement.clientWidth;
div.setAttribute('class', id);
if (color === undefined) {
let colors = ['#35def2', '#35f242', '#b2f235', '#f2ad35', '#f24735', '#3554f2', '#8535f2', '#eb35f2', '#f2359b', '#f23547'];
div.style.backgroundColor = colors[Math.floor(Math.random() * colors.length)];
}
else {
div.style.backgroundColor = color;
}
div.classList.add("circle");
div.classList.add("animation");
// Get the random positions minus the delta
currentTop = Math.floor(Math.random() * documentHeight) - delta;
currentLeft = Math.floor(Math.random() * documentWidth) - delta;
// Keep the positions between -20px and the current positions
var limitedTop = Math.max(margin * -1, currentTop);
var limitedLeft = Math.max(margin * -1, currentLeft);
div.style.top = limitedTop + "px";
div.style.left = limitedLeft + "px";
document.body.appendChild(div);
}
let i = 0;
const oneSecond = 1000;
setInterval(() => {
i += 1;
createDiv(`circle${i}`)
}, oneSecond);
//move circles
function RandomObjectMover(obj, container) {
this.$object = obj;
this.$container = container;
this.container_is_window = container === window;
this.pixels_per_second = 250;
this.current_position = { x: 0, y: 0 };
this.is_running = false;
}
// Set the speed of movement in Pixels per Second.
RandomObjectMover.prototype.setSpeed = function(pxPerSec) {
this.pixels_per_second = pxPerSec;
}
RandomObjectMover.prototype._getContainerDimensions = function() {
if (this.$container === window) {
return { 'height' : this.$container.innerHeight, 'width' : this.$container.innerWidth };
} else {
return { 'height' : this.$container.clientHeight, 'width' : this.$container.clientWidth };
}
}
RandomObjectMover.prototype._generateNewPosition = function() {
// Get container dimensions minus div size
var containerSize = this._getContainerDimensions();
var availableHeight = containerSize.height - this.$object.clientHeight;
var availableWidth = containerSize.width - this.$object.clientHeight;
// Pick a random place in the space
var y = Math.floor(Math.random() * availableHeight);
var x = Math.floor(Math.random() * availableWidth);
return { x: x, y: y };
}
RandomObjectMover.prototype._calcDelta = function(a, b) {
var dx = a.x - b.x;
var dy = a.y - b.y;
var dist = Math.sqrt( dx*dx + dy*dy );
return dist;
}
RandomObjectMover.prototype._moveOnce = function() {
// Pick a new spot on the page
var next = this._generateNewPosition();
// How far do we have to move?
var delta = this._calcDelta(this.current_position, next);
// Speed of this transition, rounded to 2DP
var speed = Math.round((delta / this.pixels_per_second) * 100) / 100;
//console.log(this.current_position, next, delta, speed);
this.$object.style.transition='transform '+speed+'s linear';
this.$object.style.transform='translate3d('+next.x+'px, '+next.y+'px, 0)';
// Save this new position ready for the next call.
this.current_position = next;
};
RandomObjectMover.prototype.start = function() {
if (this.is_running) {
return;
}
// Make sure our object has the right css set
this.$object.willChange = 'transform';
this.$object.pointerEvents = 'auto';
this.boundEvent = this._moveOnce.bind(this)
// Bind callback to keep things moving
this.$object.addEventListener('transitionend', this.boundEvent);
// Start it moving
this._moveOnce();
this.is_running = true;
}
RandomObjectMover.prototype.stop = function() {
if (!this.is_running) {
return;
}
this.$object.removeEventListener('transitionend', this.boundEvent);
this.is_running = false;
}
// Init it
var x = new RandomObjectMover(document.querySelector(".circle"), window);
// Start it off
x.start();
.circle {
clip-path: circle(50%);
height: 40px;
width: 40px;
margin: 20px;
position: absolute;
}
I have modified the snippet which works as you expected.
There was a mistake where you were initializing and creating the object instance only once and none of the div elements that you created inside the setInterval function never got Instantiated.
I think you are just starting out with JavaScript with this sample project.
Below are few suggestions:
Learn to debug the code. You should be using dev tools by making use of debugger statement where it takes you to the source code to analyze the variable scope and stack during the runtime. console.log also helps in few situations.
I could see a lot of confusing naming convention (You have named the create div parameter as id but creating a div class using that id)
Try using ES6 features (class syntax is really good when writing OOP in JS although it's just a syntactic sugar for prototype)
//creating circles
var widthHeight = 40; // <-- circle width
var margin = 20; // <-- margin - is it necessary ?
var delta = widthHeight + margin;
function createAndInitializeDivObject(id, color) {
let div = document.createElement('div');
var currentTop = 0;
var documentHeight = document.documentElement.clientHeight;
var documentWidth = document.documentElement.clientWidth;
div.setAttribute('class', id);
if (color === undefined) {
let colors = ['#35def2', '#35f242', '#b2f235', '#f2ad35', '#f24735', '#3554f2', '#8535f2', '#eb35f2', '#f2359b', '#f23547'];
div.style.backgroundColor = colors[Math.floor(Math.random() * colors.length)];
}
else {
div.style.backgroundColor = color;
}
div.classList.add("circle");
div.classList.add("animation");
// Get the random positions minus the delta
currentTop = Math.floor(Math.random() * documentHeight) - delta;
currentLeft = Math.floor(Math.random() * documentWidth) - delta;
// Keep the positions between -20px and the current positions
var limitedTop = Math.max(margin * -1, currentTop);
var limitedLeft = Math.max(margin * -1, currentLeft);
div.style.top = limitedTop + "px";
div.style.left = limitedLeft + "px";
document.body.appendChild(div);
var x = new RandomObjectMover(document.querySelector(`.${id}`), window);
x.start();
}
let i = 0;
const oneSecond = 1000;
setInterval(() => {
i += 1;
createAndInitializeDivObject(`circle${i}`)
}, oneSecond);
//move circles
function RandomObjectMover(obj, container) {
this.$object = obj;
this.$container = container;
this.container_is_window = container === window;
this.pixels_per_second = 250;
this.current_position = { x: 0, y: 0 };
this.is_running = false;
}
// Set the speed of movement in Pixels per Second.
RandomObjectMover.prototype.setSpeed = function(pxPerSec) {
this.pixels_per_second = pxPerSec;
}
RandomObjectMover.prototype._getContainerDimensions = function() {
if (this.$container === window) {
return { 'height' : this.$container.innerHeight, 'width' : this.$container.innerWidth };
} else {
return { 'height' : this.$container.clientHeight, 'width' : this.$container.clientWidth };
}
}
RandomObjectMover.prototype._generateNewPosition = function() {
// Get container dimensions minus div size
var containerSize = this._getContainerDimensions();
var availableHeight = containerSize.height - this.$object.clientHeight;
var availableWidth = containerSize.width - this.$object.clientHeight;
// Pick a random place in the space
var y = Math.floor(Math.random() * availableHeight);
var x = Math.floor(Math.random() * availableWidth);
return { x: x, y: y };
}
RandomObjectMover.prototype._calcDelta = function(a, b) {
var dx = a.x - b.x;
var dy = a.y - b.y;
var dist = Math.sqrt( dx*dx + dy*dy );
return dist;
}
RandomObjectMover.prototype._moveOnce = function() {
// Pick a new spot on the page
var next = this._generateNewPosition();
// How far do we have to move?
var delta = this._calcDelta(this.current_position, next);
// Speed of this transition, rounded to 2DP
var speed = Math.round((delta / this.pixels_per_second) * 100) / 100;
//console.log(this.current_position, next, delta, speed);
this.$object.style.transition='transform '+speed+'s linear';
this.$object.style.transform='translate3d('+next.x+'px, '+next.y+'px, 0)';
// Save this new position ready for the next call.
this.current_position = next;
};
RandomObjectMover.prototype.start = function() {
if (this.is_running) {
return;
}
// Make sure our object has the right css set
this.$object.willChange = 'transform';
this.$object.pointerEvents = 'auto';
this.boundEvent = this._moveOnce.bind(this)
// Bind callback to keep things moving
this.$object.addEventListener('transitionend', this.boundEvent);
// Start it moving
this._moveOnce();
this.is_running = true;
}
RandomObjectMover.prototype.stop = function() {
if (!this.is_running) {
return;
}
this.$object.removeEventListener('transitionend', this.boundEvent);
this.is_running = false;
}
// Init it
var x = new RandomObjectMover(document.querySelector(".circle"), window);
// Start it off
x.start();
.circle {
width: 35px;
height: 35px;
border-radius: 35px;
background-color: #ffffff;
border: 3px solid purple;
position: absolute;
}
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="style.css">
</head>
<body>
<div class="circle"></div>
<script src="app.js"></script>
</body>
</html>
I have a function that adds random images to my divs that disappear over time and create a mouse trail. My issue is: there are double images.
I'd like to add something that checks if the background url is already located on the page and if that's the case, skips to the next in the array and check it again until until it comes across one that is not there. So like a loop that refreshes every time a 'trail' is being created.
Maybe I am asking for something that won't work? What if all the images are already on the page? I don't really have an answer for it and I also don't have an idea how to solve that problem yet.
For now I tried adding a counter that checks the usedImages and counts them, but it seems to have flaws and I am unsure where to look or how to fix it. Does anyone have any tips on how to do this? Is it even possible?
My fiddle
var bgImages = new Array(
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2019/05/schraegluftbild-1024x725.jpg",
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2019/05/pikto-608x1024.jpg",
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2019/05/Jettenhausen-EG-Grundriss-913x1024.jpg",
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2019/05/lageplan-945x1024.jpg",
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2019/05/Jettenhausen-EG-Grundriss-913x1024.jpg",
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2019/05/Jettenhauser-Esch-Modell-2-1024x768.jpg",
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2019/07/DSCN3481-1024x768.jpg",
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2019/07/zoom-in-3_ASTOC-1024x683.jpg",
"https://www.studiourbanestrategien.com/wordpress/wp-content/uploads/2016/07/IMG_1345-1024x768.jpg"
);
const numberOfImages = 10;
const timesPerSecond = .1;
var usedImages = {};
var usedImagesCount = 0;
function preloadImages(images) {
for (i = 0; i < images.length; i++) {
let l = document.createElement('link')
l.rel = 'preload'
l.as = 'image'
l.href = images[i]
document.head.appendChild(l);
}
}
function animate(e) {
var image = document.createElement('div');
image.classList.add('trail');
var sizew = 200;
var sizeh = 200;
image.style.transition = '3s ease';
image.style.position = 'fixed';
image.style.top = e.pageY - sizeh / 2 + 'px';
image.style.left = e.pageX - sizew / 2 + 'px';
image.style.width = sizew + 'px';
image.style.height = sizeh + 'px';
var random = Math.floor(Math.random() * (bgImages.length));
if (!usedImages[random]) {
image.style.backgroundImage = "url(" + bgImages[random] + ")";
usedImages[random] = true;
usedImagesCount++;
if (usedImagesCount === bgImages.length) {
usedImagesCount = 0;
usedImages = {};
}
} else {
animate(e);
}
console.log(usedImages);
console.log(usedImagesCount);
image.style.backgroundSize = 'cover';
image.style.pointerEvents = 'none';
image.style.zIndex = 1;
document.body.appendChild(image);
//opacity and blur animations
window.setTimeout(function() {
image.style.opacity = 0;
image.style.filter = 'blur(20px)';
}, 40);
window.setTimeout(function() {
document.body.removeChild(image);
}, 2100);
};
window.onload = function() {
preloadImages(bgImages);
var wait = false;
window.addEventListener('mousemove', function(e) {
if (!wait) {
wait = true;
setTimeout(() => {
wait = false
}, timesPerSecond * 800);
animate(e);
}
});
};
I want to create cross on the position of the cursor on click and then fade out
but It's working only when I wait for a moment after I click and I don't know why
here`s the code
body = document.querySelector('body');
function Crossing(e) {
this.newCross = document.createElement('i');
this.newCross.className = 'fas fa-times';
this.newCross.style.position = 'absolute';
this.newCross.style.left = e.clientX - 10 + 'px';
this.newCross.style.top = e.clientY - 14 + 'px';
this.newCross.style.fontSize = '30px';
this.newCross.style.opacity = '100%';
this.newCross.style.transition = 'all 1s ease-out';
body.appendChild(this.newCross);
this.timeout1 = setTimeout(() => this.newCross.style.opacity = '0%', 1);
this.timeout2 = setTimeout(() => this.newCross.remove(), 1000);
}
window.addEventListener('click', () => {
new Crossing(e);
});
This is just part of the actual code but only this part has something to do with creating icon
I'm working on the project where I need to do some kind of screen calibration.
This calibration works in the way that when the plus button is pressed "credit card" is zoomed in and when the minus button is pressed it is zoomed out for 0.5mm.
Everything works fine but when button is clicked "credit card" is just zoomed in or zoomed out for 0.5mm, so I need to keep clicking to change zoom further. I want zoom to be constant when mouse key is pressed and to stop zooming when released.
There is my JavaScript code:
var c = document.querySelector('.card'),
m = document.querySelector('.m'),
p = document.querySelector('.p'),
s = document.querySelector('.s'),
r = document.querySelector('.r'),
w = c.style.width = '54mm';
m.addEventListener('click', function() {
w = c.style.width = parseFloat(w) - 0.5 + 'mm';
});
p.addEventListener('click', function() {
w = c.style.width = parseFloat(w) + 0.5 + 'mm';
});
s.addEventListener('click', function() {
r.innerHTML = 54 / parseFloat(w);
});
You can look at JSFiddle to see the code that I'm using now. Can somebody help me with the integration of this function in the existing code?
You need to setup event listeners a little bit different. This is my solution - I belive it's quite clear:
var c = document.querySelector('.card'),
m = document.querySelector('.m'),
p = document.querySelector('.p'),
s = document.querySelector('.s'),
r = document.querySelector('.r'),
w = c.style.width = '54mm';
var min = false;
var max = false;
m.addEventListener('mousedown', function(event) {
min = true;
});
m.addEventListener('mouseup', function(event) {
min = false;
});
p.addEventListener('mousedown', function() {
max = true;
});
p.addEventListener('mouseup', function() {
max = false;
});
s.addEventListener('click', function() {
r.innerHTML = 54 / parseFloat(w);
});
setInterval(function() {
if(min) {
w = c.style.width = parseFloat(w) - 0.5 + 'mm';
}
}, 100);
setInterval(function() {
if(max) {
w = c.style.width = parseFloat(w) + 0.5 + 'mm';
}
},100);
We're working with the HTML5 canvas, displaying lots of images at one time.
This is working pretty well but recently we've had a problem with chrome.
When drawing images on to a canvas you seem to reach a certain point where the performance degrades very quickly.
It's not a slow effect, it seems that you go right from 60fps to 2-4fps.
Here's some reproduction code:
// Helpers
// https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Math/random
function getRandomInt(min, max) { return Math.floor(Math.random() * (max - min + 1)) + min; }
// http://www.paulirish.com/2011/requestanimationframe-for-smart-animating/
window.requestAnimFrame = (function () { return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || function (callback) { window.setTimeout(callback, 1000 / 60); }; })();
// https://github.com/mrdoob/stats.js
var Stats = function () { var e = Date.now(), t = e; var n = 0, r = Infinity, i = 0; var s = 0, o = Infinity, u = 0; var a = 0, f = 0; var l = document.createElement("div"); l.id = "stats"; l.addEventListener("mousedown", function (e) { e.preventDefault(); y(++f % 2) }, false); l.style.cssText = "width:80px;opacity:0.9;cursor:pointer"; var c = document.createElement("div"); c.id = "fps"; c.style.cssText = "padding:0 0 3px 3px;text-align:left;background-color:#002"; l.appendChild(c); var h = document.createElement("div"); h.id = "fpsText"; h.style.cssText = "color:#0ff;font-family:Helvetica,Arial,sans-serif;font-size:9px;font-weight:bold;line-height:15px"; h.innerHTML = "FPS"; c.appendChild(h); var p = document.createElement("div"); p.id = "fpsGraph"; p.style.cssText = "position:relative;width:74px;height:30px;background-color:#0ff"; c.appendChild(p); while (p.children.length < 74) { var d = document.createElement("span"); d.style.cssText = "width:1px;height:30px;float:left;background-color:#113"; p.appendChild(d) } var v = document.createElement("div"); v.id = "ms"; v.style.cssText = "padding:0 0 3px 3px;text-align:left;background-color:#020;display:none"; l.appendChild(v); var m = document.createElement("div"); m.id = "msText"; m.style.cssText = "color:#0f0;font-family:Helvetica,Arial,sans-serif;font-size:9px;font-weight:bold;line-height:15px"; m.innerHTML = "MS"; v.appendChild(m); var g = document.createElement("div"); g.id = "msGraph"; g.style.cssText = "position:relative;width:74px;height:30px;background-color:#0f0"; v.appendChild(g); while (g.children.length < 74) { var d = document.createElement("span"); d.style.cssText = "width:1px;height:30px;float:left;background-color:#131"; g.appendChild(d) } var y = function (e) { f = e; switch (f) { case 0: c.style.display = "block"; v.style.display = "none"; break; case 1: c.style.display = "none"; v.style.display = "block"; break } }; var b = function (e, t) { var n = e.appendChild(e.firstChild); n.style.height = t + "px" }; return { REVISION: 11, domElement: l, setMode: y, begin: function () { e = Date.now() }, end: function () { var f = Date.now(); n = f - e; r = Math.min(r, n); i = Math.max(i, n); m.textContent = n + " MS (" + r + "-" + i + ")"; b(g, Math.min(30, 30 - n / 200 * 30)); a++; if (f > t + 1e3) { s = Math.round(a * 1e3 / (f - t)); o = Math.min(o, s); u = Math.max(u, s); h.textContent = s + " FPS (" + o + "-" + u + ")"; b(p, Math.min(30, 30 - s / 100 * 30)); t = f; a = 0 } return f }, update: function () { e = this.end() } } }
// Firefox events suck
function getOffsetXY(eventArgs) { return { X: eventArgs.offsetX == undefined ? eventArgs.layerX : eventArgs.offsetX, Y: eventArgs.offsetY == undefined ? eventArgs.layerY : eventArgs.offsetY }; }
function getWheelDelta(eventArgs) { if (!eventArgs) eventArgs = event; var w = eventArgs.wheelDelta; var d = eventArgs.detail; if (d) { if (w) { return w / d / 40 * d > 0 ? 1 : -1; } else { return -d / 3; } } else { return w / 120; } }
// Reproduction Code
var stats = new Stats();
document.body.appendChild(stats.domElement);
var masterCanvas = document.getElementById('canvas');
var masterContext = masterCanvas.getContext('2d');
var viewOffsetX = 0;
var viewOffsetY = 0;
var viewScaleFactor = 1;
var viewMinScaleFactor = 0.1;
var viewMaxScaleFactor = 10;
var mouseWheelSensitivity = 10; //Fudge Factor
var isMouseDown = false;
var lastMouseCoords = null;
var imageDimensionPixelCount = 25;
var paddingPixelCount = 2;
var canvasDimensionImageCount = 50;
var totalImageCount = Math.pow(canvasDimensionImageCount, 2);
var images = null;
function init() {
images = createLocalImages(totalImageCount, imageDimensionPixelCount);
initInteraction();
renderLoop();
}
function initInteraction() {
var handleMouseDown = function (eventArgs) {
isMouseDown = true;
var offsetXY = getOffsetXY(eventArgs);
lastMouseCoords = [
offsetXY.X,
offsetXY.Y
];
};
var handleMouseUp = function (eventArgs) {
isMouseDown = false;
lastMouseCoords = null;
}
var handleMouseMove = function (eventArgs) {
if (isMouseDown) {
var offsetXY = getOffsetXY(eventArgs);
var panX = offsetXY.X - lastMouseCoords[0];
var panY = offsetXY.Y - lastMouseCoords[1];
pan(panX, panY);
lastMouseCoords = [
offsetXY.X,
offsetXY.Y
];
}
};
var handleMouseWheel = function (eventArgs) {
var mouseX = eventArgs.pageX - masterCanvas.offsetLeft;
var mouseY = eventArgs.pageY - masterCanvas.offsetTop;
var zoom = 1 + (getWheelDelta(eventArgs) / mouseWheelSensitivity);
zoomAboutPoint(mouseX, mouseY, zoom);
if (eventArgs.preventDefault !== undefined) {
eventArgs.preventDefault();
} else {
return false;
}
}
masterCanvas.addEventListener("mousedown", handleMouseDown, false);
masterCanvas.addEventListener("mouseup", handleMouseUp, false);
masterCanvas.addEventListener("mousemove", handleMouseMove, false);
masterCanvas.addEventListener("mousewheel", handleMouseWheel, false);
masterCanvas.addEventListener("DOMMouseScroll", handleMouseWheel, false);
}
function pan(panX, panY) {
masterContext.translate(panX / viewScaleFactor, panY / viewScaleFactor);
viewOffsetX -= panX / viewScaleFactor;
viewOffsetY -= panY / viewScaleFactor;
}
function zoomAboutPoint(zoomX, zoomY, zoomFactor) {
var newCanvasScale = viewScaleFactor * zoomFactor;
if (newCanvasScale < viewMinScaleFactor) {
zoomFactor = viewMinScaleFactor / viewScaleFactor;
} else if (newCanvasScale > viewMaxScaleFactor) {
zoomFactor = viewMaxScaleFactor / viewScaleFactor;
}
masterContext.translate(viewOffsetX, viewOffsetY);
masterContext.scale(zoomFactor, zoomFactor);
viewOffsetX = ((zoomX / viewScaleFactor) + viewOffsetX) - (zoomX / (viewScaleFactor * zoomFactor));
viewOffsetY = ((zoomY / viewScaleFactor) + viewOffsetY) - (zoomY / (viewScaleFactor * zoomFactor));
viewScaleFactor *= zoomFactor;
masterContext.translate(-viewOffsetX, -viewOffsetY);
}
function renderLoop() {
clearCanvas();
renderCanvas();
stats.update();
requestAnimFrame(renderLoop);
}
function clearCanvas() {
masterContext.clearRect(viewOffsetX, viewOffsetY, masterCanvas.width / viewScaleFactor, masterCanvas.height / viewScaleFactor);
}
function renderCanvas() {
for (var imageY = 0; imageY < canvasDimensionImageCount; imageY++) {
for (var imageX = 0; imageX < canvasDimensionImageCount; imageX++) {
var x = imageX * (imageDimensionPixelCount + paddingPixelCount);
var y = imageY * (imageDimensionPixelCount + paddingPixelCount);
var imageIndex = (imageY * canvasDimensionImageCount) + imageX;
var image = images[imageIndex];
masterContext.drawImage(image, x, y, imageDimensionPixelCount, imageDimensionPixelCount);
}
}
}
function createLocalImages(imageCount, imageDimension) {
var tempCanvas = document.createElement('canvas');
tempCanvas.width = imageDimension;
tempCanvas.height = imageDimension;
var tempContext = tempCanvas.getContext('2d');
var images = new Array();
for (var imageIndex = 0; imageIndex < imageCount; imageIndex++) {
tempContext.clearRect(0, 0, imageDimension, imageDimension);
tempContext.fillStyle = "rgb(" + getRandomInt(0, 255) + ", " + getRandomInt(0, 255) + ", " + getRandomInt(0, 255) + ")";
tempContext.fillRect(0, 0, imageDimension, imageDimension);
var image = new Image();
image.src = tempCanvas.toDataURL('image/png');
images.push(image);
}
return images;
}
// Get this party started
init();
And a jsfiddle link for your interactive pleasure:
http://jsfiddle.net/BtyL6/14/
This is drawing 50px x 50px images in a 50 x 50 (2500) grid on the canvas. I've also quickly tried with 25px x 25px and 50 x 50 (2500) images.
We have other local examples that deal with bigger images and larger numbers of images and the other browser start to struggle with these at higher values.
As a quick test I jacked up the code in the js fiddle to 100px x 100px and 100 x 100 (10000) images and that was still running at 16fps when fully zoomed out. (Note: I had to lower the viewMinScaleFactor to 0.01 to fit it all in when zoomed out.)
Chrome on the other hand seems to hit some kind of limit and the FPS drops from 60 to 2-4.
Here's some info about what we've tried and the results:
We've tried using setinterval rather than requestAnimationFrame.
If you load 10 images and draw them 250 times each rather than 2500 images drawn once each then the problem goes away. This seems to indicate that chrome is hitting some kind of limit/trigger as to how much data it's storing about the rendering.
We have culling (not rendering images outside of the visual range) in our more complex examples and while this helps it's not a solution as we need to be able to show all the images at once.
We have the images only being rendered if there have been changes in our local code, against this helps (when nothing changes, obviously) but it isn't a full solution because the canvas should be interactive.
In the example code we're creating the images using a canvas, but the code can also be run hitting a web service to provide the images and the same behaviour (slowness) will be seen.
We've found it very hard to even search for this issue, most results are from a couple of years ago and woefully out of date.
If any more information would be useful then please ask!
EDIT: Changed js fiddle URL to reflect the same code as in the question. The code itself didn't actually change, just the formatting. But I want to be consistent.
EDIT: Updated jsfiddle and and code with css to prevent selection and call requestAnim after the render loop is done.
In Canary this code freezes it on my computer. As to why this happens in Chrome the simple answer is that it uses a different implementation than f.ex. FF. In-depth detail I don't know, but there is obviously room for optimizing the implementation in this area.
I can give some tip however on how you can optimize the given code to make it run in Chrome as well :-)
There are several things here:
You are storing each block of colors as images. This seem to have a huge performance impact on Canary / Chrome.
You are calling requestAnimationFrame at the beginning of the loop
You are clearing and rendering even if there are no changes
Try to (addressing the points):
If you only need solid blocks of colors, draw them directly using fillRect() instead and keep the color indexes in an array (instead of images). Even if you draw them to an off-screen canvas you will only have to do one draw to main canvas instead of multiple image draw operations.
Move requestAnimationFrame to the end of the code block to avoid stacking.
Use dirty flag to prevent unnecessary rendering:
I modified the code a bit - I modified it to use solid colors to demonstrate where the performance impact is in Chrome / Canary.
I set a dirty flag in global scope as true (to render the initial scene) which is set to true each time the mouse move occur:
//global
var isDirty = true;
//mouse move handler
var handleMouseMove = function (eventArgs) {
// other code
isDirty = true;
// other code
};
//render loop
function renderLoop() {
if (isDirty) {
clearCanvas();
renderCanvas();
}
stats.update();
requestAnimFrame(renderLoop);
}
//in renderCanvas at the end:
function renderCanvas() {
// other code
isDirty = false;
}
You will of course need to check for caveats for the isDirty flag elsewhere and also introduce more criteria if it's cleared at the wrong moment. I would store the old position of the mouse and only (in the mouse move) if it changed set the dirty flag - I didn't modify this part though.
As you can see you will be able to run this in Chrome and in FF at a higher FPS.
I also assume (I didn't test) that you can optimize the clearCanvas() function by only drawing the padding/gaps instead of clearing the whole canvas. But that need to be tested.
Added a CSS-rule to prevent the canvas to be selected when using the mouse:
For further optimizing in cases such as this, which is event driven, you don't actually need an animation loop at all. You can just call the redraw when the coords or mouse-wheel changes.
Modification:
http://jsfiddle.net/BtyL6/10/
This was a legitimate bug in chrome.
https://code.google.com/p/chromium/issues/detail?id=247912
It has now been fixed and should be in a chrome mainline release soon.