Im trying to do a composite operation on layers using KineticJS.
Everything works fine in Chrome, but nothing shows for firefox, or IE10
The code runs through without any errors.
You can see the issue here:
http://clients.lilodesign.com/Lilo/Kinetic/
Chrome you should see a circle with a partial bit of the standard MS Blue Trees image showing through. In Firefox and IE10 you just get a blank screen.
You can view the code by viewing the source. Its all in-line and a very simple example to show the issue.
If you remove the following line:
ctx.globalCompositeOperation = "destination-atop";
Then you see the blue trees image with the ellipse on top of it as expected in all three browsers, so the code does "work".
Has anyone else experienced this and found a workaround?
I have searched and tried a couple of suggested solutions such as:
shape intersection with KineticJS
But all these still only seem to work in Chrome.
Any help or pointers would be appreciated.
Thanks
Tyrone.
We used to be able to cheat by grabbing the context of a layer, but now it’s unreliable (as you’ve discovered).
You can still get verrrrry hacky and do it like this: : http://jsfiddle.net/m1erickson/6fTQU/
But don’t ! (Even this hack doesn’t actually work on images with transparent pixels).
Instead, do it the official way by creating a Kinetic custom Shape Object.
Kinetic Shape gives you an official canvas and context to work with.
As a result, the globalCompositeOperation works fine (reliably!).
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/LtxEe/
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Prototype</title>
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.5.1.min.js"></script>
<style>
body{ background-color: ivory; }
#container{
border:solid 1px #ccc;
margin-top: 10px;
width:300px;
height:300px;
}
</style>
<script>
$(function(){
var stage = new Kinetic.Stage({
container: 'container',
width: 300,
height: 300
});
var layer = new Kinetic.Layer();
stage.add(layer);
var img=new Image();
img.onload=function(){
buildLayer(img);
}
img.src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/KoolAidMan.png";
function buildLayer(img){
var myShape=new Kinetic.Shape({
drawFunc:function(canvas){
var ctx=canvas.getContext();
ctx.beginPath();
ctx.drawImage(img,0,0);
ctx.globalCompositeOperation="destination-atop";
ctx.arc(150,150,60,0,Math.PI*2,false);
ctx.closePath();
ctx.fill();
canvas.fillStroke(this);
},
x:0,
y:0,
width:img.width,
height:img.height
});
layer.add(myShape);
layer.draw();
}
}); // end $(function(){});
</script>
</head>
<body>
<div id="container"></div>
</body>
</html>
Related
am making a Createjs and html5 project in which I am drawing a shape(Red circle), when I click over the circle it gives alert. It works fine on all desktops and android phones. Except when I open this in a windows phone it works fine on the normal screen but when I zoom the screen it loses it working, an alert is shown when I click anywhere on the screen(maybe where the co-ordinates of the shape resides) but not when I click over the shape(Circle),,
Your help is appreciated
my demo.html
<!DOCTYPE html>
<html>
<head><title></title>
<script type="text/javascript" src="createjs-2013.12.12.min.js"></script>
<script type="text/javascript" src="jquery-1.11.0.min.js"></script>
<script type="text/javascript">
function init() {
var stage = new createjs.Stage("demoCanvas");
var circle = new createjs.Shape();
createjs.Touch.enable(stage);
circle.graphics.beginFill("red").drawCircle(0, 0, 50);
circle.x = 100;
circle.y = 100;
circle.addEventListener("click", function(evt) { /*$("span#log").text(circle.x);*/ alert('clicked'); });
stage.addChild(circle);
stage.update();
}
</script>
</head>
<body onLoad="init();">
<span id="log"></span>
<br>
<canvas id="demoCanvas" width="500" height="300">
alternate content
</canvas>
</body>
</html>..
Here's the project
Not sure if this is relevant as haven't looked at sample code, but I think createjs.Touch.enable works on Stage instances rather than DisplayObjects
See here
I do alot of Research over this topic, and at the end i came to this point that this the
BUG in IE11 . Hope Microsoft helps to solve this.
I'm also curious to know if this is a best practice.
I load a sprite map:
canvas = $('#GameCanvas')[0];
context = canvas.getContext('2d');
// load sprite map
spriteMap = new Image();
spriteMap.src = "resources/spritemap.png";
Now I've loaded my sprites, I want to draw them on the screen. I can do so by using context.drawImage(..) but:
I don't know if this is the best way, instead of just extracting each image I want and storing them separately eg. var playerCharacter = [cut the image out of the sprite map]
I want to colorise the images. If I pull out a 'white' sprite, I may then want to colorise it red, green, etc. I don't know how to do this yet, but it will probably require creating a new colorised Image so I'd have to pull it out of the spritemap anyway. I don't want to be recolorising constantly.
Any idea the best way of doing this?
Performance using sprites
Phrogz has some useful FPS tests for CSS vs Canvas here: Efficiency of <canvas> and <div>s They are live tests so you can run them in the environments you want to test.
Recoloring sprites
If you want to quickly take your white sprite and create red, green and blue sprites from it, you can use globalCompositeOperation=”source-in” to do that with very little work. Just use an image editor to create a cutout of the part of the image you want to recolor. Then use the code below to automatically create different colored sprites. I did the mask below in Photoshop using the magic want tool – 2 minutes tops!
Original Fish + Mask = Green Fish
Of course, you can create any color you want...even patterns instead of solid colors!
Here’s code. You will probably have to create your own image and mask because of CORS – stupid CORS !!
<!doctype html>
<html>
<head>
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
canvas{border:1px solid red;}
#wrapper{ position:relative;}
#overlay,#base{ position:absolute; top:0; left:0;}
</style>
<script>
$(function(){
var canvas=document.getElementById("overlay");
var ctx=canvas.getContext("2d");
var img=new Image();
img.onload=function(){
ctx.drawImage(img,0,0,img.width,img.height,0,0,overlay.width,overlay.height);
}
img.src="http://dl.dropbox.com/u/139992952/stackoverflow/fish%20overlay.png";
function draw(red,green,blue) {
ctx.save();
ctx.globalCompositeOperation = 'source-in';
ctx.fillStyle="rgb("+red+","+green+","+blue+")";
ctx.beginPath();
ctx.rect(0,0,overlay.width,overlay.height);
ctx.fill();
ctx.restore();
}
$("#red").click(function(){ draw(255,0,0); });
$("#green").click(function(){ draw(0,255,0); });
$("#blue").click(function(){ draw(0,0,255); });
});
</script>
</head>
<body>
<button id="red">Red Fish</button>
<button id="green">Green Fish</button>
<button id="blue">Blue Fish</button>
<div id="wrapper">
<img id="base" src="http://dl.dropbox.com/u/139992952/stackoverflow/fish.png" width=350 height=250>
<canvas id="overlay" width=350 height=250></canvas>
</div>
</body>
</html>
Googled this a lot and didn't get any useful hint/solution.
I have this simple html page including some CSS styles, jQuery, jQuery-ui and obviously Fabric.js; on document.ready I launch an ajax call and render something on the canvas. Until now everything seems fine but when a I need to catch some mouse events I get nothing. This behaviour is shown only on Chrome (current version 25.0.1364.97); everything works fine on Firefox or Internet Explorer (v. 9).
Here's some of the js code:
$(document).ready(function() {
//setup canvas etc.
eCanvas = new fabric.Canvas('EViewport', {
backgroundColor: 'rgba(255, 50, 50, .3)',
selection: true,
selectionColor: 'blue',
selectionLineWidth: 2
});
EViewport = $("#CanvasContainer");
viewW = EViewport.width();
viewH = EViewport.height();
eCanvas.setWidth(viewW);
eCanvas.setHeight(viewH);
eCanvas.observe('object:selected', function(options) {
if (options.target) {
console.log('an object was selected! ', options.target.type);
}
});
eCanvas.observe('mouse:down', function() {
console.log('mouse click! ');
});
eCanvas.on('mouse:down', function() {
console.log('mouse click! ');
});
eCanvas.on('mousedown', function() {
console.log('mouse click! ');
});
//... render some rectangles and stuff...
});
And here's the html structure (notice that Eviewport.js file contains previously pasted code):
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="baseCss/jquery-ui.css" type="text/css">
<script type="text/javascript" src="baseJs/jquery.js"></script>
<script type="text/javascript" src="baseJs/jquery-ui.js"></script>
<script type="text/javascript" src="Eviewport.js"></script>
<link type="text/css" rel="stylesheet" href="Eviewport.css">
<script type="text/javascript" src="baseJs/Fabric.js"></script>
</head>
<body>
<div id="MainContainer">
<div id="CanvasContainer">
<canvas id="EViewport">
Canvas is not supported
</canvas>
</div>
</div>
</body>
</html>
Selection features don't work with chrome either while they work on IE and Firefox.
I tried many things (as you can see I tried changing canvas.observe with canvas.on), changed jQuery and jQueryui versions but nothing changed.
Using developer tools on Google Chrome doesn't show much.
There's no z-index on html elements given by CSS, and I tried disabling different js and CSS but that didn't solve the problem.
I noticed that the problem shows also shows on the demo page of Fabric.js (just tried http://fabricjs.com/stickman/); render works, effects also but no mouse events or selection working.
Is this a bug?
Ok, finally found what's not working.
I have a Wacom device attached and looks like latest Chrome version sets a flag about "touch enabled device" and that's breaking my code.
A simple solution can be changing chrome flags (chrome://flags/)
Related posts:
https://github.com/kangax/fabric.js/issues/450
I tried to create rectangle in canvas, i am bit confused with coordinate system of canvas
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>jQuery UI Dialog - Modal form</title>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<style>
body{
background-color: #231F20;
}
#ribbonid{
width:90px;
height: 90px;
}
</style>
</head>
<body>
<canvas id='ribbonid' > </canvas>
<script>
$(document).ready(function(){
var $ribbonid = $('#ribbonid');
// get the canvas element using the DOM
var canvas = document.getElementById('ribbonid');
// Make sure we don't execute when canvas isn't supported
if (canvas.getContext){
// use getContext to use the canvas for drawing
var cts = canvas.getContext('2d');
cts.fillStyle = '#f7911e';
cts.beginPath();
cts.moveTo(0, 0);
cts.lineTo(90, 0);
cts.lineTo(90, 90);
cts.lineTo(0, 90);
cts.lineTo(0, 0);
cts.fill();
cts.closePath();
}
});
</script>
</body>
</html>
http://jsfiddle.net/bkf2e/
i am aware of canvas.rect function, but i need to create some different shape for me.
I created rectangle of size (90,90)(square), but it is creating full square.
I know it may be my simple mistake, but can you please help me on that.
you need to set the size of your canvas using the width and height attributes, if you use css to size it then it will scale the default size rather than becoming the size you want, which is why it was distorted like that.
I've updated your jsfiddle with the attributes set and you'll see that it's now square.
solved problem,
it was silly mistake of width and height attribute
<canvas id='ribbonid' width='90' height='90' > </canvas>
I heard that drawing abilities will be supported by Web 2.0
Tried to find something in Internet about, nothing really clear. Could you please point me into something that allows (or will allow in future) to draw in HTML?
For example: I want to have ability draw few hexagons in different color on the page.
Thanks.
P.S. Sorry if question is a little bit "stupid", but I can't make it more smart.
A quick exemple of what you want to do:
<html>
<head>
<title>Hexagon canvas tutorial</title>
<script type="text/javascript">
function draw(){
//first let's get canvas HTML Element to draw something on it
var canvas = document.getElementById('tutorial');
//then let's see if the browser supports canvas element
if (canvas.getContext){
var ctx = canvas.getContext('2d');
//Pick Hexagon color, this one will be blue
ctx.fillStyle = "rgb(0, 0, 255)";
//let's start a path
ctx.beginPath();
//move cursor to position x=10 and y=60, and move it around to create an hexagon
ctx.moveTo(10,60);
ctx.lineTo(40,100);
ctx.lineTo(80,100);
ctx.lineTo(110,60);
ctx.lineTo(80,20);
ctx.lineTo(40,20);
//fill it and you got your first Hexagon
ctx.fill();
//This one will be green, but we will draw it like the first one
ctx.fillStyle = "rgb(0, 255, 0)";
ctx.beginPath();
ctx.moveTo(110,160);
ctx.lineTo(140,200);
ctx.lineTo(180,200);
ctx.lineTo(210,160);
ctx.lineTo(180,120);
ctx.lineTo(140,120);
ctx.fill();
}
}
</script>
<style type="text/css">
canvas { border: 1px solid black; }
</style>
</head>
<body onload="draw();">
<canvas id="tutorial" width="300" height="300"></canvas>
</body>
</html>
What you're talking about is most likely the HTML5 Canvas element
I suspect you've been hearing about the Canvas Element. You can get started with it here: http://en.wikipedia.org/wiki/Canvas_element
Good luck!