XnView does not paste alpha channel data into clipboard

[btakacs]

XnView does not copy the alpha channel data to clipboard. In case of an image with palette it does not copy the information which is the transparent colour of the palette.

For experimenting I copied the same transparent image into XnView itself:


Using XnView 2.0.4 on Windows 7
Image is transparent png with colour palette (transparent colour is on the index 0)

Steps to reproduce:
- Open an image with transparent colour
- Select a part of it then Ctrl + C
- Ctrl + Shift + V into XnView

[xnview]

could you send me the file used?

[btakacs]

Dear Pierre

Here is the file I used for that test:

But you can easily create an image like this in XnView:
- take an image that has a big volume of the same colour
- Image > Convert to colours
- Image > Edit palette > (Select colour) (Enable transparency) (Ok)

Then (to reproduce the issue):
- Ctrl+ C
- Ctrl + Shift + V

Regards:
Bence

[xnview]

Ok, 'Import from clipboard' doesn't use alpha channel, but if you use Ctrl+C/Ctrl+V, XnView use it

[btakacs]

What do you mean? If you repeat the steps above you loose transparency of the background.
Is that the desired behaviour?
If not: Could it be fixed?

Please check with the given picture.

Update: If the transparent colour is the index 0 then the Ctrl+V works. But the if the transparent is other than the index 0 or I use Ctrl+Shift+V then the issue persists.

[xnview]

If not: Could it be fixed?

yes it's a bug of 'import clipboard'

[btakacs]

According to my understanding the problem is with exporting to clipboard, not with importing from clipboard.

AFAIK this kind of the images are displayed wrong in all applications if we use the image exported from XnView and imported to the different kinds of applications.

[xnview]

No If you copy/paste the alpha channel is not lost
But there is a lot of problem with alpha channel support in windows

[btakacs]

Ok, you are the expert. The only thing I want to tell: if I export this kind of images into any other application in Windows then the transparency is lost. But if I open them from the file system everything is ok.

For me it's happening with images that has color palette with a non-zero index transparent color.

But there is a lot of problem with alpha channel support in windows

Do you mean that it is basically a windows bug but you might create a workaround for it?

[xnview]

Sorry about my misunderstanding, it's not alpha channel, but RIGHT there is a problem with 8bits picture + transparency index, the clipboard doesn't support transparency index (i don't know how to use it)... I need to check...