Animation in javascript and HTML - javascript

I'm trying to create an animation in javascript.
I created a canvas
<canvas id = "animation" width="1130" height="222"></canvas>
and what I want to do, is to add 3 images (+1 more which is the background), and during each second I want to have 1 image shown and the other 2 hidden.
What I have now is:
var canvas = document.getElementById('animation');
context = canvas.getContext('2d');
background = new Image();
background.src = 'images/background.png';
background.onload = function(){
context.drawImage(background, 0, 0);
}
var image1 = new Image();
image1.src = 'images/image1.png';
image1.onload = function(){
context.drawImage(image1, 895, 61);
}
var image2 = new Image();
image2.src = 'images/image2.png';
image2.onload = function(){
context.drawImage(image2, 895, 61);
}
var image3 = new Image();
image3.src = 'images/image3.png';
image3.onload = function(){
context.drawImage(image3, 895, 61);
}
image1.style.visibility = "visible";
image2.style.visibility = "hidden";
image3.style.visibility = "hidden";
setTimeout(function(){
image1.style.visibility = "hidden";
image2.style.visibility = "visible";
image3.style.visibility = "hidden";
}, 1000);
setTimeout(function(){
image1.style.visibility = "hidden";
image3.style.visibility = "visible";
image2.style.visibility = "hidden";
}, 2000);
setTimeout(function(){
image3.style.visibility = "hidden";
image1.style.visibility = "visible";
image2.style.visibility = "hidden";
}, 3000);
however it does not work. All of them appear on the screen

You are trying to mix two different things here: canvas and CSS.
The canvas works like (surprise!) a canvas: that means that once you draw something there it will stay there until you draw something else over it. Therefore, changing the css of the images on memory will have no effect.
You have two alternatives: the DOM route, just insert the images in the DOM without the canvas and you will be able to change their style, or the Canvas route, calling to context.drawImage INSIDE various setTimeout, so you draw a new image each second.

Related

EaselJS Picture scaling blurred out

Importing a picture to EaselJS with Bitmap:
var stage;
$(document).ready(function(){
var gameCanvas = document.getElementById("game");
stage = new createjs.Stage(gameCanvas);
loadPics();
function loadPics() {
let image = new Image();
image.src = "assets/img/island1.png";
image.onload = loadPic;
}
function loadPic(event) {
let bitmap = new createjs.Bitmap(event.target);
bitmap.scaleX = 1;
bitmap.scaleY = 1;
bitmap.image.width = gameCanvas.width;
stage.addChild(bitmap);
stage.update();
}
});
It doesn't matter if I export the picture from photoshop with 400x400 or 200x200
The picture is still all over the canvas.
If i scale it down
bitmap.scaleX = 0.2;
bitmap.scaleY = 0.2;
It becomes extremely blurred
Anyone knows a fix?
Canvas output can get pixelated if scaled with CSS
Make sure you're not adjusting canvas size in CSS but directly on the canvas element via either HTML or JS, otherwise canvas output can get distorted.
var stage;
$(document).ready(function(){
var gameCanvas = document.getElementById("game"),
windowWidth = $(window).width(),
windowHeight = $(window).height();
$(gameCanvas).width(windowWidth+'px');
$(gameCanvas).height(windowHeight+'px');
stage = new createjs.Stage(gameCanvas);
loadPics();
function loadPics() {
let image = new Image();
image.src = "assets/img/island1.png";
image.onload = loadPic;
}
function loadPic(event) {
let bitmap = new createjs.Bitmap(event.target);
bitmap.scaleX = 1;
bitmap.scaleY = 1;
bitmap.image.width = gameCanvas.width;
stage.addChild(bitmap);
stage.update();
}
});

Fading a loaded image into Canvas with drawImage

This question about crossfading images already gave an answer to the crossfading solution in Canvas. I am trying to do the same thing, only difference is that i am trying to fade images that are loaded on runtime.
The images are loaded propperly but no fade is visible. Is this not working because of the loaded images? Thanks.
HTML
<div id="wrapper">
<canvas id="bg1"></canvas>
<canvas id="bg2"></canvas>
</div>
JS
var toggle = true;
var canvas = document.getElementById('bg1');
canvas.width = $(document).width();
canvas.height = $(document).height();
var ctx = canvas.getContext('2d');
var canvas2 = document.getElementById('bg2');
canvas2.width = $(document).width();
canvas2.height = $(document).height();
var ctx2 = canvas2.getContext('2d');
var image = new Image();
image.src = 'download1.jpg';
var image2 = new Image();
image2.src = 'download2.jpg';
image.onload = function() {
ctx.drawImage(image, 0, 0, 200, 100);
ctx2.drawImage(image2, 0, 0, 200, 100);
};
$('#wrapper').click(function () {
if (toggle)
{
$('#bg2').fadeIn();
$('#bg1').fadeOut();
}
else
{
$('#bg1').fadeIn();
$('#bg2').fadeOut();
}
toggle = !toggle;
});
Yep, you need to give your images time to load.
But also, jQuery cannot do fadeIn/fadeout on a canvas element so you will have to do that manually.
Demo: http://jsfiddle.net/m1erickson/zw9S4/
Code:
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
$("#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();
});
}); // end $(function(){});
</script>
</head>
<body>
<button id="fade">Fade to next Image</button><br>
<canvas id="canvas" width=204 height=204></canvas><br>
</body>
</html>
Try to fade in/out the images directly on the canvas instead of fading in and out the canvas elements (or there is not really any point using the canvas as you could use image elements instead).
First, of course, wait for the images to load:
var isBusy = false, /// for fade loop
count = 2; /// number of images to load
image = new Image();
image2 = new Image();
/// setup load handler
image.onload = image2.onload = handleLoad;
image.src = 'download1.jpg';
image2.src = 'download2.jpg';
function handleLoad() {
count--;
if (count === 0) {
/// when loaded draw a single image onto canvas
ctx.drawImage(image, 0, 0, ctx.canvas.width, ctx.canvas.height);
}
};
Now we can change the click handler a little bit around and use canvas only to do the fade in of the next image:
$('#wrapper').click(function () {
var img, /// current image to fade in
opacity = 0; /// current globalAlpha of canvas
/// if we're in a fade exit until done
if (isBusy) return;
isBusy = true;
/// what image to use
img = toggle ? image2 : image;
/// fade in
(function fadeIn() {
/// set alpha
ctx.globalAlpha = opacity;
/// draw image with current alpha
ctx.drawImage(img, 0, 0, ctx.canvas.width, ctx.canvas.height);
/// increase alpha to 1, then exit resetting isBusy flag
opacity += 0.02;
if (opacity < 1)
requestAnimationFrame(fadeIn);
else
isBusy = false;
})();
toggle = !toggle;
});
Online demo
Hope this helps.

Canvas to data url not working properly

I have a function that takes an img-element and returns a data url. This works like 7/10 times and returns a blank image 3/10 times. I view the created data url through my browser(chrome) and use the same images so I know that this function is returning broken images. Can anyone spot why?
function imgToDataURL(img) {
var canvas = document.createElement('canvas');
canvas.width = img.naturalWidth;
canvas.height = img.naturalHeight;
var c = canvas.getContext('2d');
c.drawImage(img, 0, 0);
dataurl = canvas.toDataURL();
return dataurl;
}
$(function() {
img = new Image();
img.crossOrigin = '';
img.onload = function() {
newimg = new Image();
newimg.onload = function() {
document.body.appendChild(newimg);
}
newimg.src = imgToDataURL(img);
}
img.src = 'https://somedomain.s3.amazonaws.com/someimg.png';
});
This example works most of the time but sometimes ends with a large white rectangle instead of the image.
You have to wait for images to load before drawing them using .drawImage function.
Only after the image is loaded by the browser you can call your imgToDataURL function.
Something like this:
var image_sources = ["img1.png", "img2.png", "..."];
for(var i=0; i<image_sources.length; i++) {
var new_img = document.createElement("img");
new_img.onload = function() {
imgToDataURL(this);
};
new_img.src = image_sources[i];
}

How do I erase an image on html5 canvas

I have a html5 canvas where you can erase the blur on top of an image. I would like to replace the blur with another image. I would like the end result to be once you erase the top image the bottom image will appear below it. I have been using an easeljs demo as a template.
http://www.createjs.com/#!/EaselJS/demos/alphamask
I feel like what I need to edit is in the html page script but it might be much deeper than that.
(Full code can be viewed here)
HTML
<canvas id="testCanvas" width="960" height="400"></canvas>
JavaScript
var stage;
var isDrawing;
var drawingCanvas;
var oldPt;
var oldMidPt;
var displayCanvas;
var image;
var bitmap;
var maskFilter;
var cursor;
var text;
var blur;
function init() {
if (window.top != window) {
document.getElementById("header").style.display = "none";
}
document.getElementById("loader").className = "loader";
image = new Image();
image.onload = handleComplete;
image.src = "images/summer.jpg";
stage = new createjs.Stage("testCanvas");
text = new createjs.Text("Loading...", "20px Arial", "#999999");
text.set({x:stage.canvas.width/2, y:stage.canvas.height-80});
text.textAlign = "center";
}
function handleComplete() {
document.getElementById("loader").className = "";
createjs.Touch.enable(stage);
stage.enableMouseOver();
stage.addEventListener("stagemousedown", handleMouseDown);
stage.addEventListener("stagemouseup", handleMouseUp);
stage.addEventListener("stagemousemove", handleMouseMove);
drawingCanvas = new createjs.Shape();
bitmap = new createjs.Bitmap(image);
blur = new createjs.Bitmap(image);
blur.filters = [new createjs.BoxBlurFilter(15,15,2)];
blur.cache(0,0,960,400);
blur.alpha = .5;
text.text = "Click and Drag to Reveal the Image.";
stage.addChild(blur, text, bitmap);
updateCacheImage(false);
cursor = new createjs.Shape(new createjs.Graphics().beginFill("#FFFFFF").drawCircle(0,0,20));
cursor.cursor = "pointer";
stage.addChild(cursor);
}
function handleMouseDown(event) {
oldPt = new createjs.Point(stage.mouseX, stage.mouseY);
oldMidPt = oldPt;
isDrawing = true;
}
function handleMouseMove(event) {
cursor.x = stage.mouseX;
cursor.y = stage.mouseY;
if (!isDrawing) {
stage.update();
return;
}
var midPoint = new createjs.Point(oldPt.x + stage.mouseX>>1, oldPt.y+stage.mouseY>>1);
drawingCanvas.graphics.setStrokeStyle(40, "round", "round")
.beginStroke("rgba(0,0,0,0.15)")
.moveTo(midPoint.x, midPoint.y)
.curveTo(oldPt.x, oldPt.y, oldMidPt.x, oldMidPt.y);
oldPt.x = stage.mouseX;
oldPt.y = stage.mouseY;
oldMidPt.x = midPoint.x;
oldMidPt.y = midPoint.y;
updateCacheImage(true);
}
function handleMouseUp(event) {
updateCacheImage(true);
isDrawing = false;
}
function updateCacheImage(update) {
if (update) {
drawingCanvas.updateCache(0, 0, image.width, image.height);
} else {
drawingCanvas.cache(0, 0, image.width, image.height);
}
maskFilter = new createjs.AlphaMaskFilter(drawingCanvas.cacheCanvas);
bitmap.filters = [maskFilter];
if (update) {
bitmap.updateCache(0, 0, image.width, image.height);
} else {
bitmap.cache(0, 0, image.width, image.height);
}
stage.update();
}
If you simply want to replace the blur-image, you have to change the following parts:
Add this after the loading of the first image:
image.src = "images/summer.jpg";
// add new part
image2 = new Image();
image2.onload = handleComplete;
image2.src = "images/your_newImage.jpg";
In the handleComplete() you now wait for 2 images to be loaded, so you add this:
function handleComplete() {
loaded++; // and initialize this variable in the very top with: var loaded = 0;
if ( window.loaded < 2 ) return;
//... other stull
and finally you change the following lines:
// old
blur = new createjs.Bitmap(image);
blur.filters = [new createjs.BoxBlurFilter(15,15,2)];
blur.cache(0,0,960,400);
blur.alpha = .5;
// new
blur = new createjs.Bitmap(image2);
This should now replace the blurred image with your desired image, it's not the best way, but it should get you there. I recommend you to start with some tutorial if you are planing to do more "deeper" stuff ;)
a common, though kinda janky, way is to re-size your canvas real quick. so changing your <canvas> elements width and height attributes. This will erase everything in your canvas.
Once that is done, reset it back to what you want it to be right away, and redraw the bottom image.
As I said this method is kinda sketchy but it does get the job done.

How do I load a local image using JS?

I want to load two separate images in my script. I've accomplished it using:
<img src="iphone4.png" id="img1">
<img src="screenshot.png" id="img2">
<script>
window.onload = function () {
var img1 = document.getElementById('img1');
var img2 = document.getElementById('img2');
</script>
Problem here though is that the images should not be visible on the page but are when loaded using markup. I simply want to load them through the script without first having to add them in the markup. I realize this is an extremely trivial problem, but searching for a solution has given me nothing.
I tried this approach:
window.onload = function () {
var img1 = "iphone4.png";
var img2 = "screenshot.png";
But this did not work.
Can someone with some common JS sense please give me some input on this issue.
EDIT :
So this is how the markup/JS looks now, the images are still displayed and the final merge of the images won't show. The error I get is:
IndexSizeError: Index or size is negative or greater than the allowed amount
[Stanna vid fel]
var image1 = context.getImageData(0, 0, width, height);
And this is the syntax:
<body>
<img src="" id="img1">
<img src="" id="img2">
<p>Blended image<br><canvas id="canvas"></canvas></p>
<script>
window.onload = function () {
var img1 = document.getElementById('img1');
var img2 = document.getElementById('img2');
img1.src = "iphone4.png";
img2.src = "screenshot.png";
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var width = img1.width;
var height = img1.height;
canvas.width = width;
canvas.height = height;
var pixels = 4 * width * height;
context.drawImage(img1, 0, 0);
var image1 = context.getImageData(0, 0, width, height);
var imageData1 = image1.data;
context.drawImage(img2, 73, 265);
var image2 = context.getImageData(0, 0, width, height);
var imageData2 = image2.data;
while (pixels--) {
imageData1[pixels] = imageData1[pixels] * 0 + imageData2[pixels] * 1;
}
image1.data = imageData1;
context.putImageData(image1, 0, 0);
};
</script>
You can create an Image without having the actual tag in the markup:
var img = new Image();
img.src = 'iphone4.png';
//use img however you want
Hope this helps.
window.onload = function () {
var img1 = new Image();
var img2 = new Image();
//EDIT2 you can hide img, or simply not add them to the DOM...
img1.style.display = "none";
img2.style.display = "none";
img1.src = "iphone4.png";
img2.src = "screenshot.png";
EDIT: DO NOT DO THAT and your images won't be displayed
document.body.append(img1);
OR
document.getElementById("myID").append(img2);
"What I'm doing is merging two images using JS"
Your problem is probably due to the fact that you are trying to draw images that have not been loaded yet. To circumvent this issue, you could create the images dynamically and set their src attribute to start loading the image and listen to the image's load event to know when they are fully loaded so that you can perform the merge safely.
I have not tested the code, but it should give you the idea.
var images = [
'iphone4.png',
'screenshot.png'
],
len = images.length,
i = 0,
loadedCount = 0,
img;
for (; i < len; i++) {
img = document.createElement('img');
//listener has to be added before setting the src attribute in case the image is cached
img.addEventListener('load', imgLoadHandler);
img.src = images[i];
images[i] = img;
}
function mergeImages() {
var img1 = images[0],
img2 = images[1];
//do the merging stuff
}
function imgLoadHandler() {
if (++loadedCount === len) {
mergeImages();
}
}
There is a way with HTML5, but it would still require the user to have dropped the file into a drop target or use a box.
Using the File API you can read files, and potentially decode them.
Actually reading the file blob and displaying it locally may be tricky though. You may be able to use the FileReader.readAsDataURL method to set the content as a data: URL for the image tag.
example:
$('#f').on('change', function(ev) {
var f = ev.target.files[0];
var fr = new FileReader();
fr.onload = function(ev2) {
console.dir(ev2);
$('#i').attr('src', ev2.target.result);
};
fr.readAsDataURL(f);
});​
see the working fiddle here :
http://jsfiddle.net/alnitak/Qszjg/
using jquery:
$('#my_image').attr('src','image.jpg');
using javasript:
document.getElementById("my_image").src="image.jpg";
just check path to your image
Write the below code in head block
<script>
window.onload = function () {
document.getElementById("img1").src="iphone4.png";
document.getElementById("img2").src="screenshot.png";
}
</script>
This will work
Thanks

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