ODF specification regarding multistop/-color gradients

[Armin Le Grand]

Hi,

checked that ODF1.2 has svg:linearGradient (16.40.2) and 
svg:radialGradient (16.40.3) with all needed child elements, so this 
would work.

Also checked that draw:gradient (16.40.1) has only the known elements 
for the current gradients - thus enhancing the current ones with adding 
multistop colors seems difficult, hmmm.

Next question is how to use these backwards-compatible - need to think 
about this, but the gradient itself is identified using an ID-String 
(aka 'Name') in the file format, so we could e.g. have a current and a 
svg one with the same name, prefer the svg one. In that way the older 
offices would - at least - load a two-color gradient which hopefully 
looks somewhat similar...

Anyways, SVG and current ones will geometrically look different, also 
only two types in svg. This means we need somewhere new UI and 
Interactions (did I mention that we have interactive controls in the 
EditView to edit the current gradients?) and probably more (adapt to 
other FileFormats...)

Just my 2ct...

Regards,
ALG


Am 10.09.2016 um 11:11 schrieb Heiko Tietze:
> Hello all,
>
> the LibreOffice conference gave me the chance to present some ideas regarding Draw and shapes in general. One of the most wanted features is the multistop gradient. Today we can define gradients between two colors, either linear, radial, or whatever. It would be nice to have a) non-linear multistop gradients, for example to illustrate a sundown with a small red and a larger yellow section, and b) a gradient over more than two colors, e.g. in order to add blue sky to the sundown.
>
> Since Calligra offers multicolor gradients, Armin and me checked how it is saved (the rendering is build-in right now). And it turns out that they hack SVG into the ODF. For the (predefined) rainbow-like gradient the style.xml looks like this:
>
> <svg:linearGradient draw:name="gradient1" svg:spreadMethod="pad" svg:x1="0.000000%" svg:x2="100.000000%" svg:y1="0.000000%" svg:y2="100.000000%">
> <svg:stop svg:offset="0" svg:stop-color="#ff0000"/><svg:stop svg:offset="0.183575" svg:stop-color="#ffe100"/><svg:stop svg:offset="0.347826" svg:stop-color="#00ff00"/><svg:stop svg:offset="0.516908" svg:stop-color="#00ffff"/><svg:stop svg:offset="0.68599" svg:stop-color="#0000ff"/><svg:stop svg:offset="0.845411" svg:stop-color="#ff00fb"/><svg:stop svg:offset="1" svg:stop-color="#ff0004"/>
> </svg:linearGradient>
>
> As an UX evangelist I don't care too much about the implementation and have rather the workflow and interactions in mind. Ideally the multi-gradient works with all features, and not as another type next to linear, radial etc. (There might be a problem that result in this sub-optimal solution).
>    
> And finally we have to take interoperability into account as well as the conformity to the ODF specs (no idea if and how it is defined).
>    
> So how do we make multistop/multicolor gradients possible?
>    
> Cheers,
> Heiko
>
> PS: Suggestions on how to implement this feature in the UI are existing.

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ALG (PGP Key: EE1C 4B3F E751 D8BC C485 DEC1 3C59 F953 D81C F4A2)