Re: [platform-dev] most performant way to paint a (platform-specific) pi

[Christoph Läubrich <laeubi@xxxxxxxxxxxxxx>]

Hi Nick,

currently I don't have any measures and just trying to collect some 
information. My use case is to integrate a software OpenGL render (jGL) 
and for that I need to store the rendered pixels somewhere and of course 
later I need to paint them.

I just wondering if I could short-circuit some of the steps 
(imagedata>image>gc) and maybe write directly inside some kind of 
direct-buffer.

For example if I look at

org.eclipse.swt.graphics.Image.init(ImageData) for GTK there seem to 
happen some more action than simply keeping a reference to the image 
data, e.g. a scale factor is computed, copy of data is involved, color 
transformation and so on are performed.

Maybe as you mention it does not matter, on the other hand the faster 
the better here (maybe) this also is a bit depending on the effort to 
make this happen here of course but I'd like to investigate a bit if I 
should take some internals into account before starting to implement the 
actual thing.


Am 20.04.21 um 19:19 schrieb Nick Edgar:
> Hi Christoph,
>
> That approach is generally the recommended way to paint images 
> <https://www.eclipse.org/articles/Article-SWT-images/graphics-resources.html> in 
> SWT. Painting of a pre-created Image should be as fast as the OS allows.
> Have you measured the times involved? Which phase do you need to speed up:
>
>  1. creating ImageData,
>  2. creating Image from ImageData, or
>  3. painting Image?
>
> If 1, see if you can directly manipulate the ImageData’s data, or using 
> setPixels 
> <https://github.com/eclipse/eclipse.platform.swt/blob/eae1f39bbc4fdd01ac0416927ed3fa2d50ec9a9f/bundles/org.eclipse.swt/Eclipse%20SWT/common/org/eclipse/swt/graphics/ImageData.java#L1307>.
> If 2, check which image format you’re using — it may not map directly to 
> the native display, and thus be expensive to convert.
> If 3, I’d be surprised, but it would be good to know details and the 
> times for 1,2,3.
>
> Best, Nick
> On Apr 19, 2021, 5:20 AM -0400, Christoph Läubrich 
> <laeubi@xxxxxxxxxxxxxx>, wrote:
> > I have a pixel-buffer and like it o be painted in the most performant
> > way onto a SWT Canvas.
> >
> > Current approach is to convert this into an ImageData, create an image
> > and then paint it inside PaintListener to the GC.
> >
> > Is there a way to avoid this intermediate steps? I won't mind if I need
> > to provide platform-specific implementations if it is possible to gain
> > performance here.
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