Re: Where to look for performance issues

On 3 August 2012 13:32, Neil Hodgson <nyamatongwe <at> me.com> wrote:
> Matthew Brush:
>
>
> The only drawback I can see is that the
> squiggles are no longer anti-aliased as they were with the
> MoveTo()/LineTo() stuff.
>
>
>    This should really be a new indicator type so that the current
> antialiased drawing can be used when it is fast enough. One problem with the
> bitmap code is that for OS X HiDPI mode, it will be displaying 2x2 pixel
> blocks instead of using the full resolution.

Sorry can't test with that platform.

>
>    For maximum intensity, the bitmap should be aligned to the pixel grid
> (and INDIC_DOTBOX should be fixed to do this) since text and thus the
> rectangle may be located at fractional pixels. This is done by rounding the
> rectangle to pixels: rcSquiggle.left = int(rc.left + 0.5); ...
>
>    Approximate antialiasing can still be done with the bitmap and this can
> make it look heavier although its a question of taste as to the best
> settings. Here are three versions: the original and with heavy and light
> antialiasing. http://www.scintilla.org/Squiggles.png
>

Tried your code below in Geany and the performance is only marginally
slower than the un-antialiased version:

UnAA:   ~48ms for re-draw
Below: ~52ms for re-draw
Original: ~320ms for re-draw

(thats showing C++ code with about 9 80 character lines with indic
squiggle (of the 50 on screen), a not unreasonable scenario when
compiling)

Since This pseudo AA version is nearly as fast as non-AA and looks (to
me) as good as the original it seems like a good approach.

Cheers
Lex

>    In the following code, the three alpha values can be modified to change
> antialiasing and thus visibility. Choosing alphaSide2 to be double alphaSide
> keeps the line weight even although other choices may work.
>
> PRectangle rcSquiggle = rc;
> rcSquiggle.left = int(rc.left + 0.5);
> rcSquiggle.right = int(rc.right + 0.5);
>
> int width = Platform::Minimum(4000, rcSquiggle.right - rcSquiggle.left);
> RGBAImage image(width, 3, 1.0, 0);
> enum { alphaFull = 0xff, alphaSide = 0x1f, alphaSide2=0x3f };
> for (int x = 0; x < width; x++) {
> switch (x%4) {
> case 0:
> image.SetPixel(x, 2, fore, alphaFull);
> image.SetPixel(x, 1, fore, alphaSide2);
> break;
> case 1:
> image.SetPixel(x, 1, fore, alphaFull);
> image.SetPixel(x, 0, fore, alphaSide);
> image.SetPixel(x, 2, fore, alphaSide);
> break;
> case 2:
> image.SetPixel(x, 0, fore, alphaFull);
> image.SetPixel(x, 1, fore, alphaSide2);
> break;
> default: // 3
> image.SetPixel(x, 1, fore, alphaFull);
> image.SetPixel(x, 2, fore, alphaSide);
> image.SetPixel(x, 0, fore, alphaSide);
> }
> }
> surface->DrawRGBAImage(rcSquiggle, image.GetWidth(), image.GetHeight(),
> image.Pixels());
>
>    Neil
>
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