[softwarelist] Re: OvPro and pictures -- Artworks
- From: Martin Wuerthner <public@xxxxxxxxxxxxxxx>
- To: davidpilling@xxxxxxxxxxxxx
- Date: Mon, 27 Feb 2012 19:52:31 +0100
In message <cA1yWFBBV3SPFwEi@xxxxxxxxxxxxxxxxxxx>
David Pilling <flist@xxxxxxxxxxxxxxxxxxx> wrote:
> Old fashioned sprites come in 45, 90 and 180dpi fixed resolutions.
> The new ones that came in with the RISC PC have the potential for
> variable resolution. Not sure if anyone uses that or if software would
> be happy with odd values.
I do not think RISC OS itself would be happy with odd values. One
reason is that you can redirect output to a sprite, and all rendering
routines make use of screen Eigen factors, which are only defined for
resolutions that are of the form R=180/(2^Eig) with an integral
Eig>=0. So, the only accepted dpi values are 22 (meaning 22.5), 45, 90
and 180, and 180 is only fully supported on RISC OS 5.
>>Curious Q: if the sprite arrives wrapped in an Artworks file instead
>>of a drawfile, does OPro also see the resolution info? What's the
>>mechanism involved?
> Yes if a sprite came in an ArtWorks file the resolution info would be
> preserved. The mechanism is that a vector file (Draw or AW) says "this
> bitmap is 6 inches by 4 inches".
Yes, the size is known to OvationPro, but in contrast to a Draw file,
OvationPro cannot see the sprite inside the ArtWorks file.
> All is obvious after that, because you know how many pixels, and you
> know the linear dimensions, so you can calculate the resolution in dots
> per inch.
Not so obvious, I am afraid, since OvationPro has no way of finding
out the pixel size of the sprite.
Martin
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