More efficient way of creating CssColor instances?

[markww]

Hi,

I need to do some drawing on a <canvas> element, is there any better way of creating fill styles on the fly? Currently I have to do this:

    public void drawFoo(Context2d context, int r, int g, int b, int a) {

        CssColor clr = CssColor.make("rgba(" + r + "," + g + "," + b + "," a + ")");

        context.setFillStyle(clr);

        context.fillRect(10, 10, 10, 10);

    }

so every time my drawFoo() method is called, I need to create a new CssColor instance to handle the red,green,blue,alpha components passed in. I don't know how efficient it is for CssColor.make() to parse the string, also ignoring that a string object needs to be constructed in the first place each time too.

Is there any better way of creating different colors on the fly like this?

Thanks

[Joseph Lust]

You could cache those color objects of course or just declare them as static where they are used (assuming they don't often change). That being said, are you experiencing latencies right now with your current approach?

Sincerely,

Joseph

[Thomas Broyer]

CssColor does not parse the string, it only wraps it. FYI, CssColor.make(r, g, b) simply calls  CssColor.make("rgb(" + r + ", " + g + ", " + b + ")").

The wrapping is a no-op once compiled to JS, leaving only the String concatenation.

If you were doing the same in pure JS, you'd still have to build that string to assign it to the context's fillStyle: http://dev.w3.org/html5/2dcontext/#fill-and-stroke-styles

So no, there's no better way of doing it, because there's no other way.

[Joseph Lust]

By better way I was referring to a case where these values are not known completely at compile time but defined dynamically at run time. In such a case, not all permutations would be preconcatentated at compile time. If the implementer found themselves wanting to speed this up they could stash the commonly used color strings (i.e. if animating a repeating color ramp) rather than making them over and over. That being said, the gains would be minimal.

Sincerely,

Joseph