Reuse frame state arrays

[fredj]

Reuse the extent and viewHints arrays from the previous frameState to reduce the number of temporary array

[tschaub]

I'm not opposed to this. But do you see any problem with just returning this.hints_?

[fredj]

Not sure about this; frameState.viewHints is updated in (at least) the animation functions

[tschaub]

Ok, I agree we can't reuse the same hints array everywhere. Though I think it is a pity that view hints are specific to a frame instead of a view.

If I ever get around to changing how animation works (so view properties are properly animated and we could finally have a "side-by-side" example that looks nice), then I think we won't need the extra code here.

[fredj]

Thanks for the reminder, #5234

[tschaub]

This looks like a good idea to me. I didn't check where else view.getHints() is called, but I wonder if we could just pass around a single array instead of adding the opt_hints arg.

I'm also curious to learn if you are profiling to help identify places where garbage collection can be reduced. Or if you are just identifying optimization opportunities like this by looking through the code.

[fredj]

I'm also curious to learn if you are profiling to help identify places where garbage collection can be reduced. Or if you are just identifying optimization opportunities like this by looking through the code.

It was very manual; I've added breakpoints in size.js, extent.js, ... where the optional value is not provided. For example with :

ol.size.buffer = function(size, buffer, opt_size) {
 ...
};

I've added a conditional breakpoint if opt_size == undefined.

[tschaub]

Thanks for the extra detail @fredj. This looks good to merge.

[fredj]

Thanks for the review