That 1 pixel border of the clipping shape at ClipViews

[pork]

You know what I mean? That wrong border pixels at ClipViews. Why is it hard to fix this in the rendering? Is it trying to anti-alias, but the clipped shape can't be used for the anti-aliasing, because it's clipped as a bitmap? But it should be used. It's on the top, and the way it's clipped looks wrong.

My workaround is either doing a clip on an invisible duplicate and scaling this up a little bit, or exporting at 800% or so and then downscaling.

But it would be cool if it was rendered correctly in the first place.

[mwenz]

Got a sample document to demonstrate the issue?

[pork]

yep

clipviewborder.xar

[pork]

yep

clipviewborder.xar

I tested around and found out, it has nothing to do with bitmaps. In fact, when creating the result with boolean operations, it looks the same.

And then when recreating xara behaviour with SVG like that:

<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
    <clipPath id="cut-off-bottom">
      <circle cx="100" cy="100" r="100" />
    </clipPath>
  </defs>

  <circle cx="100" cy="100" r="100" style="fill:#0000ff" />
  <circle cx="50" cy="50" r="50" style="fill:#ffffff" clip-path="url(#cut-off-bottom)" />
</svg>

again the same (rendered in firefox)



So my conecptual problem is, the shapes do their antialiasing too early. The blue shape does AA on the white background, and that goes somehow to outside. And when I draw on top of it, the new AA pixels won't cover, they just mix. All vector graphics renderers work like that? there's no cool magic thingie to prevent the pixel border?

[Christine Farrelly]

I have to wonder why you are clipping this? Just subtract the white ellipse from the pink one.

[pork]

I have to wonder why you are clipping this? Just subtract the white ellipse from the pink one.

sorry, there's a post waiting for moderation, don't know why

i rewrite that post in short words: found out, it's nothing to do with bitmaps, it's the way the shapes are antialiased each on top of others, the AA pixels probably mix, and the renderer probably can't "know" that on top new AA pixels will come that actually would have to be opaque and not mixed with stuff beneath

tried it with boolean ops, and tried svg with firefox (mimicing xara ClipViews) and the result is always the same

ok, my example .xar was bad because it's no drawing where u need a clipview. but it was just to demostrate what happens with clipviews.

thanks for the response maybe my earlier post will be unblocked somewhen

ps: actually there should be an alternative renderer that does not antialias (mix) pixels with pixels that are already antialiasing-pixels themselves. i know that's a big task for folks who have the worlds fastest renderer (kinda), but i know you can do it

[theinonen]

Just switch the antialiasing off by decreasing rendering quality when saving.

Antialiasing has to be done simply by downscaling the image afterwards.

[pork]

Just switch the antialiasing off by decreasing rendering quality when saving.

Antialiasing has to be done simply by downscaling the image afterwards.

weird, i knew the antialiasing can be switched off and the border is caused by it, but i actually forgot to switch it off when doing the supersampling.

and i was speculating that in theory the developers could go the root of the problem / wysiwyg solution. but it's time to become realistic again.

anyway, you're right & thanks : )

[gwpriester]

I approved your moderated post. It was probably moderated because of the script.

I agree with Christine. Unless you are trying to make a point, just subtract the shape from the crescent.

[pork]

I approved your moderated post. It was probably moderated because of the script.

I agree with Christine. Unless you are trying to make a point, just subtract the shape from the crescent.

Thanks for approving the post and for the replies. : )

Sorry, the .xar should just show the problematic border pixels. The actual problem is, when you clip a group that has a transparent area in it, then you would want to see the shape beneath too, and then you can't subtract from it. In other words: i might want to use a ClipView, and it's not rendering that nice. And even when you do it without ClipViews, the problem isn't them, it's the shape borders on top of other shape borders. Put a dark shape somewhere, create another more light shape on top of it, let both share some border and it won't be what you would expect. It will be what is to be expected from the "early pixel blending" way of anti-aliasing. This is probably the same in Illustrator and Corel, but I haven't tried yet. Just wanted to say that it's something that might be improved.