Colour Selector Alpha 0 ->255

WIndows 10 Pro

20.09.13 64 Bit

In the properties of a text or colour block, click the colour button.
Select a colour and OK
Colour as expected.
Click the colour button.
Set the Alpha channel to some value - e.g. 32 and OK
Transparent colour as expected.
Click the colour button.
Set the Alpha channel to 0 and OK
Transparency is #FF (no transparency)
Click the colour button.
Alpha channel shows now shows 255.

image

Looks like the bounds check is checking the alpha value and deciding 0 is out of range, so sets it to FF.

Work around exists - set the colour preset to default.

1 Like

Bien vu, je le reproduis sur Mac OSX 10.11.6

Good point, I reproduce it on Mac OSX 10.11.6

There is by design an algorithm to protect the user and people providing support. When starting with transparent and changing the color, the user typically forgets (or does not know about) changing the alpha value as well. As a result, people get frustrated and report that they changed the color, but it is not working! So, the algorithm is: if the user changed the color but the alpha is 0, then set the alpha to 255. The bug here is that this color change test is not ignoring the alpha component. It should only be comparing the RGB values.

Thanks for the explanation.

I found this trying out something, I was trying to add a semi transparent background to an area of the screen.
I was undoing a change I had made and expected setting Alpha to zero to work.

So unlikely to happen in practice, because as you explained, most users would be changing from transparent to colour, where you would want alpha changing.

Thinking ahead, I would probably save some presets for this kind of thing.

This is fixed for the next version 19.10 or 19.11

There already is a preset for transparent labeled “default” in a few different languages other than English, but I did save one called “Transparent”, the other yellow preset I saved a long time ago. Clicking on “(defaults)” does bring back the transparent color.
shotcut_2020-09-15_17-03-27

Even though the color doesn’t change to transparent, you can still enter Alpha of 1 and it’s not even noticeable.

1 Like

Presets can be useful.
I found you can name presets with a prefix, so your favourites are at the top - #MyPreset or _MyPreset.
It is also possible to open the directory where they are saved should you want to back them up or share them.

I went to the folder for colour presets and renamed the (defaults) file.
Opened ShotCut and my renamed one was there.
It had also recreated the (defaults) preset.