Re: [MiNT] Menu redraw

[Eero Tamminen <oak@helsinkinet.fi>]

Hi,

On sunnuntai 24 maaliskuu 2013, Ole wrote:
>  The app suffers the same problem like the AES - it can't blit some
>  backup-buffer because the content may changed, or was never fully shown
>  (maybe overlapped by an other window, or whatever).
>  And there are no offscreen bitmaps with standard VDI ;)

Browsers typically do their own rendering, to be able to position
things (text etc) accurately without OS overhead.  And they use
their own buffers from which all drawing is done.

Drawing being done from the HTML itself would be too slow when user
is scrolling the page [1].  That's why browsers use intermediate
buffer/tiles into which the engine renders the page, and where
the frontend blits it from.

If engine cannot render content fast enough, frontend generates some
kind checkerboard pattern & scroll indicator which let user to see
that page is indeed scrolling.


	- Eero

[1] Window updates are needed at screen refresh rate, typically 60Hz,
    for scolling to be smooth, whereas www-page content, even with video,
    needs to be updated much less frequently.