kotlin - 以编程方式为视图设置 aplha

Question

I want to change alpha value of my views programmatically , it can easily be set via xml and it works fine , the value is between 0 to 1 and if I set it 0.5 in xml it semi transparent the view in my xml layout .

but how can I set it in kotlin ?

I've tried this code but it doesn't work at all :

ln.alpha = 0.5f

i've also tried to set value by integer ,someone said that it gets the value between 0 to 255 but when I set it , it shows me an error that the value is <=1

how can I dos o ?

Answer 1

There are two types of alpha you can set

1. Alpha on View

Sets the opacity of the view to a value from 0 to 1, where 0 means the view is completely transparent and 1 means the view is completely opaque.

view.alpha = 0.5f

2. Alpha on Drawable

Specify an alpha value for the drawable. 0 means fully transparent, and 255 means fully opaque.

view.background.alpha = 128

Answer 2

Use this:

open fun setAlpha(alpha: Float): Unit

Example:

view.setAlpha(0.6f);

Read more at: https://developer.android.com/reference/kotlin/android/view/View.html#setAlpha(kotlin.Float)

Answer 3

use this one

  views.setAlpha(0.5f); // for 50%  

and if it is not worked use this one

views.getBackground().setAlpha(128);// for 50% and 256 for 100%