Thanks Leonard,
GradientPaint is a pretty terrible way of doing it though. I have long,
complicated paths made up of thousands of curveTo() commands. Say I want
one end of one of these paths to be RGB(255, 0, 0) and the other end to be
RGB(0, 0, 0).
That means I have to:
- Construct many GradientPaints - using some heuristic to decide when
the curvature of the path is "straight" enough for the color change along
the curve to be approximated by a linear gradient for that section.
- Split up the path into a segment per GradientPaint. This makes the PDF
far bigger than it otherwise would be.
What would be simpler is to just specify a colour per "vertex" on the paths
(i.e. curveTo(x, y, color)), and have the PDF renderer interpolate between
these colours when it draws. It's odd that a vector format doesn't support
this since the whole point is to parametrise the information needed to
render the vector image - in my case I'm forced to artificially quantize
the information to get a poor approximation of the desired result.
On Thu, Feb 23, 2012 at 11:35 PM, Leonard Rosenthol <[email protected]>wrote:
> I can’t speak to Java2D, but a linear gradient is indeed the correct way
> to do this with PDF. ****
>
> ** **
>
> And performance is certainly going to related to the rendering system – of
> which Acrobat/Reader do just fine J.****
>
> ** **
>
> Leonard****
>
> ** **
>
> *From:* Jarrod Smith [mailto:[email protected]]
> *Sent:* Thursday, February 23, 2012 4:24 AM
> *To:* [email protected]
> *Subject:* [iText-questions] How to smoothly interpolate color along a
> path?****
>
> ** **
>
> I'm from a 3D rendering background where this is trivial to do, but I
> can't find how to do this in iText (or Java2D for that matter):****
>
> ** **
>
> Say I have points A, B and colors cA, cB.****
>
> ** **
>
> The points are joined together by a curveTo() command. I want the colors
> to smoothly interpolate between each point. i.e. point A is color cA, point
> B is color cB, and the color of the line between A and B linearly
> interpolates between cA and cB.****
>
> ** **
>
> I've tried stroking with a gradient fill but for my purposes it is far too
> slow, and also produces inaccurate results since I am actually joining up
> thousands of these curve segments into long continuous curves.****
>
> ** **
>
> It seems like good 'ole point to point linear color interpolation isn't
> supported in either Java2D or iText?****
>
> ** **
>
> Thanks for any help,****
>
> Jarrod****
>
>
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iText(R) is a registered trademark of 1T3XT BVBA.
Many questions posted to this list can (and will) be answered with a reference
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Please check the keywords list before you ask for examples:
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