How to center canvas javascript?
Question
I'm having trouble trying to figure out how to center the canvas in the page. The canvas's code is in a javascript file. Here's the html for the page.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Game Tut</title>
</head>
<body>
<script src="game.js"></script>
</body>
</html>
I've tried something like this in the javascript file.
var canvas = document.createElement("canvas");
canvas.width = 800;
canvas.height = 600;
canvas.tabindex = 0;
canvas.style = "position: absolute; top: 50px; left: 50px; border:2px solid blue"
document.addEventListener('keydown', doKeyDown, true);
var ctx = canvas.getContext("2d");
document.body.appendChild(canvas);
For some reason the blue border or the positioning don't seem to show up in Google Chrome.
3 answers
solution1
2 2013-11-12 05:06:38
var canvas = document.getElementsByName("canvas")[0];
var style = canvas.style;
style.marginLeft = "auto";
style.marginRight = "auto";
var parentStyle = canvas.parentElement.style;
parentStyle.textAlign = "center";
parentStyle.width = "100%";
OR
canvas.style = "position:absolute; left: 50%; width: 400px; margin-left: -200px;";
solution2
2 2013-11-12 05:14:21
Try this:
var canvas = document.createElement("canvas");
canvas.width = 800;
canvas.height = 600;
canvas.tabindex = 0;
canvas.setAttribute('style', "position: absolute; left: 50%;margin-left:-400px; top: 50%;margin-top:-300px; border:2px solid blue");
var ctx = canvas.getContext("2d");
document.body.appendChild(canvas);
document.addEventListener('keydown', doKeyDown, true);
solution3
2 2018-07-25 02:00:26
Try this
the code below made the canvas center
canvas.style = "position: absolute; top: 0px; left: 0px; right: 0px; bottom: 0px; margin: auto; border:2px solid blue";
By the way
document.addEventListener('keydown', doKeyDown, true);
I posted your code but chrome showed the 'doKeyDown' function is undefined so maybe you need to fix this error then your canvas will show correctly.
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