Set transparency on color before export

[Insane_Fox]

If I make some Black-white art I use groups and layers and use white color for "delete" black layers. In the end I want set all white color in image to transparent but without expose that "deleted" black parts. Is it posible? Using Add, Subtract, Intersect... is option only for easy parts, I cant make it with groups and coplicated arts. Set transparency in document seting will make only transparent backroud, white color stay white.

[NotMyFault]

Hi, this depends.

Do you export as bitmap format like png, jpeg, tiff?

• merge visible, copy layer, create new layer from clipboard. Use blend range to make white transparent.
• You can achieve the same effect non-destructively with help of channels mixer and levels adjustment, using the alpha channel.
• you could use a layer with blend mode erase to delete areas

Do you export as vector format e.g. svg?

• please upload an example file. To keep the layers in vector form, you may need to change colors from white to transparent in original layers.

But my first question would be why not using transparent colors in the first place? 
You could prepare such color changes by using color tags for layers, using global colors, or using styles. Al these can be selected / changed easily afterwards, affecting all layers who share that tag/style/global color.

Again, uploading an example file (saved with history) will make it much easier for us to understand what you want and provide possible solutions 

[Insane_Fox]

@NotMyFault

This is what I want get but everithing white will be transparent. I give white color to circle and set circle layer first so white color cover black lines from second layer. If I set transparency colour instead white, I will see lines from second layers.

transparency.afdesign

[NotMyFault]

Is that what you want?
 

• grouped all layers
• blend range of group adjusted to make white transparent (curve in source panel)

 

transparency2.afdesign

[NotMyFault]

A better way to stay 100% vector:

• Duplikate biggest ellipse (remove nested layers)
• Convert to curves
• select ellipse and lower layer in layer stack
• Geometry>subtract
• the set fill to transparent for all layers

 

transparency3.afdesign

[Insane_Fox]

@NotMyFault Yea, its that what I want. Im not home now, I dont know what you do in first way, I dont know this options, I will test it when I will come home. I know substract option. I use it. But substract is problem if I make more complicated arts. Sometimes I dont know how it will be in final. You cant substract groupes. You have to gelete group. I might want to  move circle in future. If you substract it, you cant move.

[NotMyFault]

10 minutes ago, Insane_Fox said:

Yea, its that what I want. Im not home now, I dont know what you do in first way, I dont know this options, I will test it when I will come home. I know substract option. I use it. But substract is problem if I make more complicated arts. Sometimes I dont know how it will be in final. You cant substract groupes. You have to gelete group. Meybe I can want move circle in future. If you substract it, you cant move.

You can use compound shapes, these stay fully editable, but they have other restrictions.

Again, the big questions is still unanswered: Do you need the result export file in bitmap (png, jpeg, tiff) or vector format (svg)?

Bitmap formats allow many more tricks like blend mode erase, blend ranges etc. which help you to continue with your workflow style, and convert everything from white to transparent as final step before export.

If you need vector export, you need to work with the more limited options and create "clean" vector shapes, mainly Geometric functions, or compounds. In SVG, to my knowledge there is no way to "cover" any area which a transparent layer on top. The result would always be rasterized. This limitation is more from Affinity's capabilities, the svg format gained more flexible options, but I'm no expert regarding svg.