Android：如何指定一个不透明度 <layer-list> ？

Question

I want my LayerList to have an opacity of 80 so I wrote:

<layer-list
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:opacity="80">

But I get:

Error: Integer types not allowed (at 'opacity' with value '80')

How can I specify the opacity?

Answer 1

android:opacity supports only translucent|opaque|transparent values in layer-list.

By the way what is your requirement?

Updated-Answer: To set opacity/less-visible as 80%, you need to set to your view

android:alpha="0.8"

Answer 2

To give a translucent effect, say 50% opacity, use:

Drawable d = new ColorDrawable(Color.BLACK);
d.setAlpha(130);
mDialog.getWindow().setBackgroundDrawable(d);

'130' can be changed (0-255) to acheive desired opacity.

Answer 3

I think the question asks about setting the opacity of individual items inside a <layer-list> , and not the whole image programmatically.

If you know the color already, Use a combine hex RGBA code, for eg :

<solid android:color="#80FF0000" />

Sets the color to red (0xFF0000) with 0x80 opacity.

Same thing applies to few other items. eg stroke

<stroke android:color="#6000FF00" android:width="20dp" />

This creates a 20dp thick green stroke of 0x60 opacity.

Futher, if you want to do it pro grammatically, ie modify the alpha of a specific item and not the whole drawable, use a new resource id (android:id="@+id/...") for the item and access it . I haven't happened to verify this part though.