On Tue, Nov 25, 2008 at 02:01:02PM +0800, sunyinan wrote:
>    As for a fast scaler, I think there must be two for-loops to 
> extract the pixels from lines and columns. So from this, it is hard to be 
> faster.
>
Hi sunyinan,

well, the referenced bmpfast.cxx does speed things up, e.g. by
taking one scanline at a time. But you won't get orders of magnitude
with this, that's true.

>    So I think scaling image when decoding is an acceptable way even
> it slows down the inserting speed. What do you think about it? 
>
I don't like that, at least not if it's done unconditionally. Better
make that an option, and better still, do both - keep the original
file, and have a low-res "preview" bitmap along with it, maybe even
stored on disk.
 
>   Another question is that GDI+ is used to "slide show" the presentatio
> while GDI to the  presentation. As we all know, GDI+ is slower than GDI
> ( if DrawImage method is repleased by bitblt, the speed is more fast than 
> now). So, why don't we also use GDI for "Slide show"?
> 
Because GDI doesn't do antialiasing. But feel free to replace the
DrawImage call with a GDI method, the difference in quality is
usually not too big for pictures.

Cheers,

-- Thorsten

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