Re: [question/testing] SoundFileView improvements

Thanks for the suggestions, Scott.

In further working on this, I came to realize that:
- we can stick to short_int, since:
- we can't set the data after loading a soundfile, so setting min/max
values from the soundfile would fix representation of float soundfiles
- I'd add maxValue parameter to the allocate and setData methods, to
provide that control to the user when plotting data from the language


> 1. p.drawLine( x + i, min, x + i, max );
>     p.drawLine( x + i, minRMS[i], x + i, maxRMS[i] );
> These might be faster if they were a 1px wide fillRect.
>
Maybe I'll try these later in my branch.

2. compositionMode of the pen should be QPainter::CompositionMode_Source
>
Will try...


> 3. p.setClipping(true); p.setClipRect( x, -halfChH, x+width, chHeight );
> I believe it would be cheaper to guarantee the ranges of our values either
> when we calculate in displayData, or inline in our inner loop.
>
Yeah, I'll remove this clipping. I'll need to ensure data range in
displayData anyway and my whole point is to be able to draw values outside
this range.


> 4. Drawing vertical lines is bad for cache coherence and eliminates
> possibilities for vectorization. It MIGHT be worth experimenting with
> rotating the pixmap 90 degrees and drawing that way (so we have horizontal
> scanlines), and then rotating back to the correct orientation when we do
> drawPixmap, in hopes that Qt has either optimized the 90 degree rotation
> case or vectorized horizontal line drawing.
>
I'm not sure I'll get to trying this... but it's an interesting concept.

Anyway, I'll keep working on this and will probably submit a PR once it's
in a working state.

Marcin