Moves all x and y coordinates so that anti-aliasing will be kept to a minimum. This solves the problem where single pixel lines becomes 'blurry' by making sure that they are drawn at right position.

aliased.canvas.js

// Canvas Rendering Fix
//

if (window.CanvasRenderingContext2D) {
	var arc = CanvasRenderingContext2D.prototype.arc,
		arcTo = CanvasRenderingContext2D.prototype.arcTo,
		bezierCurveTo = CanvasRenderingContext2D.prototype.bezierCurveTo,
		clearRect = CanvasRenderingContext2D.prototype.clearRect,
		fillRect = CanvasRenderingContext2D.prototype.fillRect,
		lineTo = CanvasRenderingContext2D.prototype.lineTo,
		moveTo = CanvasRenderingContext2D.prototype.moveTo,
		rect = CanvasRenderingContext2D.prototype.rect,
		strokeRect = CanvasRenderingContext2D.prototype.strokeRect;

	function f(value) {
		return Math.round(value) + 0.5;
	}

	CanvasRenderingContext2D.prototype.arc = function (x, y, radius, startAngle, endAngle, anticlockwise) {
		return arc.call(this, f(x), f(y), radius, startAngle, endAngle, anticlockwise);
	};

	CanvasRenderingContext2D.prototype.arcTo = function (x1, y1, x2, y2, radius) {
		return arcTo.call(this, f(x1), f(y1), f(x2), f(y2), radius);
	};

	CanvasRenderingContext2D.prototype.bezierCurveTo = function (cp1x, cp1y, cp2x, cp2y, x, y) {
		return bezierCurveTo.call(this, f(cp1x), f(cp1y), f(cp2x), f(cp2y), f(x), f(y));
	};

	CanvasRenderingContext2D.prototype.clearRect = function (x, y, w, h) {
		return clearRect.call(this, f(x), f(y), w, h);
	};

	CanvasRenderingContext2D.prototype.fillRect = function (x, y, w, h) {
		return fillRect.call(this, f(x), f(y), w, h);
	};

	CanvasRenderingContext2D.prototype.lineTo = function (x, y) {
		return lineTo.call(this, f(x), f(y));
	};

	CanvasRenderingContext2D.prototype.moveTo = function (x, y) {
		return moveTo.call(this, f(x), f(y));
	};

	CanvasRenderingContext2D.prototype.rect = function (x, y, w, h) {
		return rect.call(this, f(x), f(y), w, h);
	};

	CanvasRenderingContext2D.prototype.strokeRect = function (x, y, w, h) {
		return strokeRect.call(this, f(x), f(y), w, h);
	};
}