On Monday, November 12, 2012 3:22:47 PM UTC+1, markww wrote:
>
> 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?
>
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.
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