In Java script I am changing the height and width of the HTML5 canvas. It works in Mozila, Chrome, opera and safari, But it is not working in IE9. Can any body tell me what I am doing wrong, do I need to set any property?
Thanks in advance
UPDATE:-
HTML:-
<body onload="Load();">
<canvas id="myCanvas" width="500" height="300"></canvas>
</body>
Javascript:-
function Load(){
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext('2d');
img=new Image();
img.src= "data:image/bmp;base64,"+respObj.respData; //Adding bmp image header
img.onload = function(){
canvas.width = 300;
canvas.height = 500;
context.clearRect(0, 0, canvas.width, canvas.height);
context.drawImage(img,0,0,canvas.width, canvas.height);
}
}
CSS:-
.canvas{
height: auto;
width: auto;
margin : 0px 35px;
border:1px solid black;
position: relative;
}
Try the following code. It is working in IE9, Firefox, Chrome :
<!DOCTYPE html>
<html>
<style language="css/text">
.canvas{
height: auto;
width: auto;
margin : 0px 35px;
border:1px solid black;
position: relative;
}
</style>
<body onload="Load();">
<canvas id="myCanvas" width="500" height="300"></canvas>
<input type="button" onClick="change()"/>
</body>
<script>
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext('2d');
function Load(){
img=new Image();
//img.src= "data:image/bmp;base64,"+respObj.respData; //Adding bmp image header
canvas.width = 300;
canvas.height = 500;
context.fillStyle="#FF0000";
context.fillRect(0, 0, canvas.width, canvas.height);
//context.drawImage(img,0,0,canvas.width, canvas.height);
}
function change() {
canvas.width = 100;
canvas.height = 100;
context.fillStyle="#FF0000";
context.fillRect(0, 0, canvas.width, canvas.height);
}
</script>
</html>
I found the issue with my canvas. It was the issue with style. I have removed the height and width setting from the style script. Because of it, the canvas height and width was overriding to its default values i.e. 150 and 300 as height and width respectively.
Related
I have the following html file:
<canvas id="myCanvas" width="1440" height="800" style="border:0px solid #d3d3d3;"></canvas>
<body style="background-color:#FF0000;">
<script>
var canvas = document.getElementById('myCanvas')
let ctx = canvas.getContext('2d')
ctx.beginPath()
ctx.fillStyle = "#00FF00"
ctx.fillRect(0, 0, 2400, 2000) // background
ctx.stroke()
</script>
which produces a page that looks like this:
Notice that the canvas begins slightly below and to the right of the top left corner. How can I place it exactly at the top left corner?
Add margin: 0; padding: 0; to the body and it will place the canvas to the top-left.
Use position position:absolute; top: 0; left: 0;.
<canvas id="myCanvas" width="1440" height="800" style="border:0px solid #d3d3d3;position:absolute; top: 0; left: 0;"></canvas>
<body style="background-color:#FF0000;">
<script>
var canvas = document.getElementById('myCanvas')
let ctx = canvas.getContext('2d')
ctx.beginPath()
ctx.fillStyle = "#00FF00"
ctx.fillRect(0, 0, 2400, 2000) // background
ctx.stroke()
</script>
Try this on your css
*{
padding:0;
margin:0;
}
body{
background:#00FF00;
}
canvas{
position: absolute;
top: 0;
left: 0;
}
I'm trying out canvas for the first time. After creating a circle I want to be able to change the position of the center of this circle at the click of a button. But I am unable to figure how to do so. Can someone suggest a method for it?
#button{
height: 25px;
width:125px;
border: 1px solid black;
text-align: center;
cursor: pointer;
}
<html>
<head></head>
<body>
<div id="button" onclick="changePosition()">Click here</div>
<canvas id="testCanvas" width="500px" height="500px"></canvas>
<script type="text/javascript">
var canvas = document.getElementById("testCanvas");
var a = canvas.getContext("2d");
a.fillStyle = "#b22222";
a.beginPath();
a.arc(100,100,25,0,2*Math.PI);
a.fill();
function changePosition(){
//what do I put here??
}
</script>
</body>
</html>
You need to redraw the scene. Create a function that resets the canvas and then draws the circle
var canvas = document.getElementById("testCanvas");
var ctx = canvas.getContext("2d");
var circlePos = {
left: 100,
top: 100,
}
function renderCircle( circlePos ) {
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = "#b22222";
ctx.beginPath();
ctx.arc(circlePos.left, circlePos.top, 25, 0, 2 * Math.PI);
ctx.fill();
}
function changePosition() {
circlePos.left += 10;
if ( circlePos.left > canvas.width ) {
circlePos.left = 0;
}
renderCircle( circlePos );
}
changePosition();
#button {
height: 25px;
width: 125px;
border: 1px solid black;
text-align: center;
cursor: pointer;
}
<button onclick="changePosition()">Click here</button>
<canvas id="testCanvas" width="500" height="200"></canvas>
An HTML canvas element can be automatically resized by the dynamics of a HTML page: Maybe because its style properties are set to a percentage value, or maybe because it is inside a flex container.
Thereby the content of the canvas gets resized as well: Because of the interpolation the canvas content looks blurred (loss of resolution).
In order to keep the resolution to the maximum, one must render the canvas content based on the current pixel size of the element.
This fiddle shows how this can be done with the help of the function getComputedStyle: https://jsfiddle.net/fx98gmu2/1/
setInterval(function() {
var computed = getComputedStyle(canvas);
var w = parseInt(computed.getPropertyValue("width"), 10);
var h = parseInt(computed.getPropertyValue("height"), 10);
canvas.width = w;
canvas.height = h;
// re-rendering of canvas content...
}, 2000); // intentionally long to see the effect
With a setTimeout function I'm updating the width and height of the canvas to the computed values of these properties.
As the fiddle shows, this works only when increasing the size of the window. Whenever the window size gets decreased, the canvas (item of the flexbox) stays fixed.
Set its flex-basis to 0, allow it to shrink with flex-shrink, and don't force any minimum width:
#canvas {
flex: 1 1 0;
min-width: 0;
}
var canvas = document.getElementById("canvas"),
ctx = canvas.getContext("2d");
setInterval(function() {
var computed = getComputedStyle(canvas),
w = parseInt(computed.width, 10),
h = parseInt(computed.height, 10);
canvas.width = w;
canvas.height = h;
ctx.clearRect(0, 0, w, h);
ctx.beginPath();
ctx.arc(w/2, h/2, h/2, 0, Math.PI*2, true);
ctx.stroke();
}, 2000); // intentionally long to see the effect
#container {
border: 1px solid blue;
width: 100%;
display: flex;
}
#canvas {
border: 1px solid red;
flex: 1 1 0;
min-width: 0;
height: 150px;
}
<div id="container">
<canvas id="canvas"></canvas>
<div>something else...</div>
</div>
You need to place the canvas into a container with overflow:hidden and set canvas dimensions to dimensions of that container:
window.setTimeout( function() {
var div = $("div");
div.find("canvas").attr( { width:div.width(), height:div.height()} );
})
canvas { background:gold; display:block; }
div { width:50%; height:50%; border:1px solid; overflow:hidden; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div>
<canvas width="200" height="100" />
</div>
I managed to put together a dynamically resizing HTML5 Canvas but it has issues. For instance, it only scales the height, not the width too. My canvas has width of 900px and height of 850px. Another issue is that it enlarges the canvas too, way beyond it's defined width and height.
What am I doing wrong?
Here's what I tried so far:
var canvas, stage, exportRoot;
function init() {
createjs.MotionGuidePlugin.install();
canvas = document.getElementById("canvas");
exportRoot = new lib.Hat_finale();
stage = new createjs.Stage(canvas);
stage.addChild(exportRoot);
stage.update();
createjs.Ticker.setFPS(24);
createjs.Ticker.addEventListener("tick", stage);
}
function resize() {
var height = window.innerHeight;
var ratio = canvas.width / canvas.height;
var width = height * ratio;
canvas.style.width = width + 'px';
canvas.style.height = height + 'px';
}
window.addEventListener('load', resize, false);
window.addEventListener('resize', resize, false);
#container {
margin: 0 auto;
max-width: 900px;
max-height: 850px;
}
<div id="container">
<canvas id="canvas" width="900" height="850" style="background-color:#ffffff"></canvas>
</div>
UPDATE:
If I try what #havex said, changing the attributes like so: canvas.width = width; and canvas.height = height; instead of canvas.style.width = width+'px'; and canvas.style.height = height+'px'; what I get is a resizable box BUT NOT the animation. See picture for reference :
I can't explain why that is happening because it's 4:30 in the morning and I haven't slept yet, but change these and it should work (you can remove the borders):
HTML
<div id="container">
<canvas id="canvas" style="background-color:#ffffff"></canvas>
</div>
CSS
#container{
margin:0 auto;
width:900px;
height:850px;
border: 1px solid black;
}
canvas { width: 900px; height: 850px; border: 1px solid red; }
http://jsfiddle.net/Ln5z1zab/
Hello I am lilbit new to Javascript and Jquery.
i want to move earth(image) around sun(image) but i dont want to use any jQuery-plugin.
I have tried few Option but it is not working.
So If there is anyway(i guess it is) then plz answer.
Thanks in Advance
<html>
<head>
<style type="text/css">
body {
background-color: ivory;
}
canvas {
position:absolute;
left:15%;
top:5%;
margin-left:center;
margin-top:center;
background-color:black;
border:1px solid red;
}
#Aditya{
position:relative;
top:25%;
left:20%;
}
</style>
<script type="text/javascript" src="js/Jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
var canvas = document.getElementById("icanvas");
var ctx = canvas.getContext("2d");
var radianAngle = 0;
var cx = 400;
var cy = 400;
var radius = 230;
var img = document.getElementById("myearth");
img.height="5px";
img.width="5px";
img.onload = start;
function start() {
animate();
}
function animate() {
requestAnimationFrame(animate);
// Drawing code goes here
radianAngle +=Math.PI / 120;
ctx.clearRect(0, 0, canvas.width, canvas.height);
// draw the image rotated around the circumference
ctx.save();
ctx.translate(cx, cy);
ctx.rotate(radianAngle);
ctx.drawImage(img, radius - img.width / 2, -img.height/2);
ctx.restore();
}
});
</script>
</head>
<body>
<canvas id="icanvas" width="800px" height="800px">
<img src="earth.jpg" alt="earth" id="myearth" width="50%" height="50%"></img>
<img src="sun.jpg" alt="Sun" id="Aditya"></img>
</canvas>
</canvas>
</body>
sorry for delay to upload code.only earth is moving into canvas.dont know how to put sun in center.
Thank you all to showing interest.But i finally did it.perhaps you would like to see.
<html>
<head>
<style type="text/css">
body {
background-color: ivory;
}
canvas {
position:absolute;
left:15%;
top:5%;
margin-left:center;
margin-top:center;
background-color:black;
border:1px solid red;
}
.sunimg{
position:absolute;
left:40%;
top:40%;
}
</style>
<script type="text/javascript" src="js/Jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$("#Aditya").addClass("sunimg");
var canvas = document.getElementById("icanvas");
var ctx = canvas.getContext("2d");
var radianAngle = 0;
var cx = 400;
var cy = 400;
var radius = 230;
var img = document.getElementById("myearth");
img.height="5px";
img.width="5px";
img.onload = start;
function start() {
animate();
}
function animate() {
requestAnimationFrame(animate);
// Drawing code goes here
radianAngle +=Math.PI / 120;
ctx.clearRect(0, 0, canvas.width, canvas.height);
// draw the image rotated around the circumference
ctx.save();
ctx.translate(cx, cy);
ctx.rotate(radianAngle);
ctx.drawImage(img, radius - img.width / 2, -img.height/2);
ctx.restore();
}
});
</script>
</head>
<body>
<canvas id="icanvas" width="800px" height="800px">
<img src="earth.jpg" alt="earth" id="myearth" width="50%" height="50%"></img>
</canvas>
<img src="sun.jpg" alt="Sun" id="Aditya"></img>
</body>