canvas default size
Finnnn, you are right.
From html5 specification,http://www.w3.org/TR/2012/WD-html5-author-20120329/the-canvas-element.html#the-canvas-element
The canvas element has two attributes to control the size of the coordinate space: width and height.
These attributes, when specified, must have values that are valid non-negative integers.
The width attribute defaults to 300, and the height attribute defaults to 150.
Arrange your layout such that there is a div and that div's only job is to dictate and be the size you want the canvas to be.
var canvas = document.createElement('canvas');canvas.width = div.clientWidth;canvas.height = div.clientHeight;Then add the canvas to the div.