How to align absolutely positioned element to center?

css html5-canvas
PaulLing picture PaulLing · Oct 11, 2011 · Viewed 151.3k times · Source

I am trying to stack two canvas together and make it a double layers canvas.

I've saw an example here:

<div style="position: relative;">
 <canvas id="layer1" width="100" height="100" 
   style="position: absolute; left: 0; top: 0; z-index: 0;"></canvas>
 <canvas id="layer2" width="100" height="100" 
   style="position: absolute; left: 0; top: 0; z-index: 1;"></canvas>
</div>

But i would like to set both of the canvas align at the center of the screen. If i set the value of left as a constant, while I change the orientation of the screen (as I'm doing aps on iPad) the canvas won't remain at the middle of the screen like how it act in 

<div align="center">

Can anyone help, please?

Answer

Andrew picture Andrew · Sep 22, 2013

If you set both left and right to zero, and left and right margins to auto you can center an absolutely positioned element.

position:absolute;
left:0;
right:0;
margin-left:auto;
margin-right:auto;

Related questions

How to show a running progress bar while page is loading

I want to show a running progress bar while my page is loading like here, in my page. I used a simple loading image in my example, but I want to convert it in a running progress bar. Here is …

Read More
HTML5 Canvas Resize (Downscale) Image High Quality?

I use html5 canvas elements to resize images im my browser. It turns out that the quality is very low. I found this: Disable Interpolation when Scaling a <canvas> but it does not help to increase the quality. …

Read More
Changing three.js background to transparent or other color

I've been trying to change what seems to be the default background color of my canvas from black to transparent / any other color - but no luck. My HTML: <canvas id="canvasColor"> My CSS: <style type="text/…

Read More