My project is JSF+PRIMEFACES+JPA and i want to draw rectangles in a jsf web page (XHTML) .
that draw need to be showen after i click on a button based on a list of rectangle that already existe in the managed bean .
its possible to do that just with JSF and primefaces ? or i need to introduce javascript or something else ?
Update 1 :
i fount that richfaces have paint2d option . It'is possible to use just this functionnality from richfaces in my project ?
I think that you want this:
<!doctype html>
<html>
<head>
<title>Example</title>
<meta charset='utf-8' />
</head>
<body>
<input type="button" value="Click Me" onclick="changeColor()" />
<canvas id='example'>Somewhat</canvas>
<script>
var changeColor = function(){
var colors = ['red' ,'green','blue','yellow','brown','azure','gold'];
var example = document.getElementById("example"),
context = example.getContext('2d');
example.height = 480;
example.width = 640;
context.beginPath();
context.rect(188, 50, 200, 100);
context.fillStyle = colors[parseInt(Math.random()*colors.length)];
context.fill();
context.lineWidth = 7;
context.strokeStyle = 'black';
context.stroke();
}
</script>
</body>
</html>
Since the 5.1.8 elite release (or the 5.2-SNAPSHOT), Primefaces has the diagram component. It can create images you have above, so maybe that is something you cab use
I know that in js one must use canvas. Here simpliest example:
You can write javascript handler to capture click event and then invoke code that image a rectangle
<!doctype html>
<html>
<head>
<title>pathExample</title>
<meta charset='utf-8' />
</head>
<body>
<canvas id='example'>Обновите браузер</canvas>
<script>
var example = document.getElementById("example"),
context = example.getContext('2d');
example.height = 480;
example.width = 640;
context.beginPath();
context.rect(188, 50, 200, 100);
context.fillStyle = 'red';
context.fill();
context.lineWidth = 7;
context.strokeStyle = 'black';
context.stroke();
</script>
</body>
</html>
Related
I have two canvases. I'd like to draw a green circle on the first canvas when clicking on it and a red circle when clicking on the other canvas.
The code below works only for the first canvas. I'd like to know how I can pull off my original idea.
HTML:
<!DOCTYPE html>
<html>
<head>
*** Import jQuery + Paper.js ***
</head>
<body>
<canvas id='firstCanvas'></canvas>
<canvas id='secondCanvas'></canvas
</body>
</html>
JS:
$(document).ready(function() {
paper.install(window);
paper.setup(document.getElementById('firstCanvas'));
var tool = new Tool();
tool.onMouseDown = function(event) {
var c = Shape.Circle(event.point.x, event.point.y, 20);
c.fillColor = 'green';
};
paper.view.draw();
});
Thank you in advance.
With kind regards,
You could use PaperScope, and activate each scope with scope.activate() then draw in the activated scope.
It's in the paper.js docs here http://paperjs.org/reference/paperscope/
In my console I get the error: "Uncaught TypeError: Cannot read property 'getContext' of null"
and I just can't find the error I've made... or what I've done wrong.
So maybe you can help me find it?
Please help :)
enter code here
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var cW = canvas.width = 1000;
var cH = canvas.height = 500;
var particleAmount = 10;
var particles = [];
for(var i=0;i<particleAmount;i++) {
particles.push(new particle());
}
function particle() {
this.x = (Math.random() * (cW-(40*2))) + 40;
this.y = (Math.random() * (cH-(40*2))) + 40;
this.xv = Math.random()*20-10;
this.yv = Math.random()*20-10;
}
function draw () {
ctx.fillStyle = "black";
ctx.fillRect(0,0,cW,cH);
for(var ii=0;ii<particles.length;ii++){
var p = particles[ii];
ctx.fillStyle = "red";
ctx.beginPath();
ctx.arc(p.x,p.y,40,Math.PI*2,false);
ctx.fill();
}
}
setInterval(draw,30);
The error basically means that the HTML and the JavaScript code aren't cooperating properly, or simply that you haven't loaded the script correctly.
Try this:
function init() {
// Run your javascript code here
}
// Run the 'init' function when the DOM content is loaded
document.addEventListener("DOMContentLoaded", init, false);
Hope this helps.
The answer is in the comments just after the question! Someone else also posted it as an answer a bit below, but all credits to: #elclanrs
"Right, so the canvas doesn't exist yet. Load the script after the canvas element. – elclanrs Sep 13 '14 at 22:43"
I think you put the script tag above of the canvas tag please put it after the canvas tag.
Put the scripts file after the canvas. That means put down your script before the body tag.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>HTML5 Canvas</title>
<link rel="shortcut icon" href="assets/1.png">
<link rel="stylesheet" href="assets/canvas.css">
</head>
<body>
<div class="container">
<h2>Canvas</h2>
<canvas id="myCanvas" width="400" height="300">
</canvas> <!-- End Canvas -->
</div> <!-- End Container -->
<script src="canvas.js"></script>
</body>
</html>
Try to declare the canvas element before the script tag. It worked fine for me.
Writing a simple script to have two buttons. One button animates a "painting" feature where rectangles follow the cursor around the canvas. The other button would display a rectangle that follows the canvas but doesn't leave a trail like the other. I have the buttons linked to do different functions. Right now the follow button doesn't work, it does clear the canvas but it still allows you to paint. It seems that the paint function is still running after I hit the follow button. Any help is appreciated.
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>Canvas</title>
</head>
<body>
<input type="button" value="Paint" onclick="isPaint()">
<input type="button" value="Follow" onclick="isFollow()">
<canvas id="myCanvas" width="500" height="500"></canvas>
<script>
function isPaint(){
var canvas = document.getElementById('myCanvas');
var ctx = canvas.getContext('2d');
//change draw color
ctx.fillStyle = "#FF0000";
ctx.clearRect(0,0,500,500);
canvas.addEventListener("mousemove", function(event) {
ctx.fillRect(event.x,event.y,10,10);
})
}
function isFollow(){
var canvas = document.getElementById('myCanvas');
var ctx = canvas.getContext('2d');
//change draw color
ctx.fillStyle = "#FF0000";
ctx.clearRect(0,0,500,500);
}
</script>
</body>
</html>
Work for me : http://jsfiddle.net/XF7m4/1/
Using document.getElementById("paint").onclick= function (){
PS :And think to remove the mousemouse listener ;)
To achieve what you are trying to do you will need to enhance your code a little more.
The main idea is to bind the mousemove event only once and clear the canvas if it is to behave like a follow.
Try using the following code:
<!doctype html>
<html>
<head>
<meta charset="UTF-8" />
<title>Canvas</title>
</head>
<body>
<input type="button" value="Paint" onclick="CanvasPainter.paint()" />
<input type="button" value="Follow" onclick="CanvasPainter.follow()" />
<canvas id="myCanvas" width="500" height="500"></canvas>
<script type="text/javascript">
(function () {
var canvas = document.getElementById('myCanvas');
var ctx = canvas.getContext('2d');
//change draw color
ctx.fillStyle = "#FF0000";
var CanvasPainter = {
isPaint: false,
isFollow: false,
paint: function () {
this.isPaint = true;
this.isFollow = false;
return;
},
follow: function () {
this.isPaint = false;
this.isFollow = true;
return;
}
};
window.CanvasPainter = CanvasPainter;
canvas.addEventListener("mousemove", function (event) {
if (CanvasPainter.isPaint || CanvasPainter.isFollow) {
if (CanvasPainter.isFollow) {
// Clear canvas on every mousemove if it is a follow
ctx.clearRect(0, 0, 500, 500);
}
ctx.fillRect(event.x, event.y, 10, 10);
}
return;
});
return;
})();
</script>
</body>
</html>
Hope this helps!
Your isPaint() function is adding an event listener for "mousemove" to the canvas, but it isn't getting removed in the isFollow() function. If you remove your listener in the isFollow() function this should fix your problem.
My question is why does drawScreen have to be located where it is and cannot be moved outside of the method. It is like a method inside a method. I think that this is where I am still weak on JavaScript because there seems times when method, like this one, should be able to be moved outside of where it is as long as it can be called from some point inside of the script.
Question: Why does the drawScreen() method have to be located where it is in the code?
Code Here:
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Chapter 1 Example 6 Canvas Sub Dom Example </title>
<script src="modernizr.js"></script>
<script type="text/javascript">
window.addEventListener("load", eventWindowLoaded, false);
var Debugger = function () { };
Debugger.log = function (message) {
try {
console.log(message);
} catch (exception) {
return;
}
}
function eventWindowLoaded () {
canvasApp();
}
function canvasSupport () {
return Modernizr.canvas;
}
function canvasApp () {
if (!canvasSupport()) {
return;
}
var theCanvas = document.getElementById("canvasOne");
var context = theCanvas.getContext("2d");
Debugger.log("Drawing Canvas");
**function drawScreen() {
//background
context.fillStyle = "#ffffaa";
context.fillRect(0, 0, 500, 300);
//text
context.fillStyle = "#000000";
context.font = "20px Sans-Serif";
context.textBaseline = "top";
context.fillText ("Hello World!", 195, 80 );
//image
var helloWorldImage = new Image();
helloWorldImage.onload = function () {
context.drawImage(helloWorldImage, 155, 110);
}
helloWorldImage.src = "helloworld.gif";
//box
context.strokeStyle = "#000000";
context.strokeRect(5, 5, 490, 290);
}**
drawScreen();
}
</script>
</head>
<body>
<div style="position: absolute; top: 50px; left: 50px;">
<canvas id="canvasOne" width="500" height="300">
<div>A yellow background with an image and text on top
<ol>
<li>The text says "Hello World"</li>
<li>The image is of the planet earth.</li>
</ol>
</div>
</canvas>
</div>
</body>
</html>
JavaScript has lexical scope, so it inherits the scope of outer functions (scope is dependant on where functions are located in source code).
In order to move it out, you'd need to either pass it the data it needs (context) or make it available via some other means.
This simple Canvas script creates a rectangle with a border and text. It works in Chrome and FireFox. But the text does not work in Internet Explorer 7.0. I have included excanvas.js; for this reason the rectangle and border show up in IE 7. However, the text is not showing up in IE 7. I want to know if it is possible to get this simple script to work in IE 7 and 8?
<!DOCTYPE html>
<html lang="en">
<head>
<link href = "style.css" type = "text/css" rel = "stylesheet" />
<script src="js/excanvas.js" type="text/javascript"></script>
<script type="text/javascript">
function addBox(){
var c = document.getElementById("myCanvas");
context=c.getContext("2d");
//Inner rectangle with shadow
context.fillStyle = 'red';
context.shadowColor="brown";
context.shadowBlur = 20;
context.fillRect(402,227,96.5,48.5);
context.shadowColor = null;
context.shadowBlur = null;
//Outer Rectangle
context.lineWidth = '5';
context.strokeStyle='green';
context.strokeRect(400,225,100,50); //draws just the edges of a rectangle
//font
context.font = '17px Arial';
context.textBaseline = 'top';
context.fillStyle = 'black';
context.fillText ('hello', 433, 243);
}
</script>
</head>
<body onload="addBox()">
<canvas id="myCanvas" width="900" height="500">Your browser does not support the canvas element.</canvas> <br />
<script type="text/javascript">
c = document.getElementById("myCanvas");
cxt4=c.getContext("2d");
resetCanvas();
</script>
</body>
</html>
I just tried this on mine and had the same results. Then I found that I was using an earlier revision of excanvas. Ran the code again with this version and it worked in IE8. Haven't tested on IE7 but with some luck it will work.
Steve
The fillText is working when i changed excanvas.js file
http://canvas-text.googlecode.com/svn-history/r48/trunk/excanvas.js