Re: [linux-audio-dev] Re: Which widgets?

From: Jussi Laako <jussi.laako@email-addr-hidden>
Date: Mon Feb 27 2006 - 01:16:17 EET

On Sun, 2006-02-26 at 20:38 +0100, Albert Graef wrote:
> Canvases give you much more than just rendering. They also manage the
> graphical objects that you created and, if anything changes, rerendering
> the changed parts happens automatically.

That's usually bad and undesirable for any real time graphics rendering,
like audio UIs often are. For example with proper interfaces I can now
get full screen scrolling spectrogram at 50-100 fps without huge CPU

> Moreover, they let you inspect
> the object model of the rendered graphic. Does Cairo do that for you?

Well, Gtk+ uses Cairo nowadays anyway... Coordinate transformations,
etc. make it reasonable to also get proper printer output.

> OpenGL can do something like this with its display lists, but that's a
> very low-level abstraction compared to what canvas widgets offer.

Probably you could create proper canvas implementation on top of
Cairo/OpenGL, but most of the current implementations I've seen are dead
slow. I'm not sure if GnomeCanvas or some other implementation has been
converted to Cairo yet...

        - Jussi
Received on Mon Feb 27 04:15:08 2006

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