Submit a bug report

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2019-11-01 19:18:54

Is there a way to submit a bug report for Pixelmator?
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2019-11-01 19:52:34

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2019-11-01 21:22:23

Thanks st3f.

Actually, I saw a previous post from you on transparency and masking which is where my potential bug lies. Perhaps you could resolve the mystery as to if this is a bug or was done intentionally.

The situation arises when you have top layer (call it X) that has some transparency and a bottom layer (call it Y) that also has some transparency and you then place X on top of Y and "Create Clipping Mask" with X and Y. This can lead to four different combinations of these two layers of which one combination seems be a bug (or at least a bad design choice). Let me go through the four combinations.

1 - Opaque bit in X on top of opaque bit in Y. What you see is X.
2 - Transparent bit in X on top of transparent bit in Y. What you see is transparency through both layers.
3 - Opaque bit in X on top of transparent bit in Y. What you see is transparency through both layers.
4 - And finally the problem case - transparent bit in X on top of opaque bit in Y. What you see is Y. This makes no sense to me. They are mixing the purpose of layer Y to be both for clipping but also for its image content. I would think it should just be transparent as well.
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2019-11-02 04:12:27

Hi Rumboogy.
I don't think that's a bug. Opacity masks and clipping masks work slightly differently and you have highlighted the difference. I think of an opacity mask as a pair of scissors that cut out part of an image and a clipping mask as a piece of cardboard that I have already cut out and want to add paint to. In the first the opacity mask defines transparency and nothing else. In the second, any transparency in the upper layer of the clipping mask will show through to the cardboard/base layer of the clipping mask pair. The analogy breaks down a bit as you can't do partial transparency with a pair of scissors but hopefully you get the idea.
If you're not familiar with opacity masks, they're quick and easy to use. They're not as flexible as clipping masks because the mask has to be a bitmap (although you can use a shape or piece of text as source) but they are more compact as the image layer and the mask share a single entry in the layers panel. If you want to use your existing file to create an opacity mask:
1. Release any clipping mask currently in effect.
2. Select the bottom layer in the layers panel and use Edit > Load Selection to create a selection based on the opacity information (quick sneaky shortcut, Cmd-click on the image of the layer in the layers panel).
3. Right-click on the top layer in the layer panel and select Add Mask. A mask will be created in the shape of the selection.
4. Hide the lower layer (or delete it if you really don't need it any more).
Hope this helps.
- Stef.