Set Alpha/Opacity of Layout

Question

Is it possible to set and get the Alpha/Opacity of a Layout and all it's child views? I'm not talking about the background. Say a collection of Video Controls like Play, Pause and Progressbar in a Relative Layout.

I can use animation to fade in and out but wanted to know if there was a direct method I could use.

score 60 · Accepted Answer · edited May 06 '11 at 15:51

60

You can set the alpha on the layout and it's children (or any other view for that matter) using AlphaAnimation with 0 duration and setFillAfter option.

Example:

AlphaAnimation alpha = new AlphaAnimation(0.5F, 0.5F);
alpha.setDuration(0); // Make animation instant
alpha.setFillAfter(true); // Tell it to persist after the animation ends
// And then on your layout
yourLayout.startAnimation(alpha);

You can use one animation for multiple components to save memory. And do reset() to use again, or clearAnimation() to drop alpha.

Though it looks crude and hacked it's actually a good way to set alpha on set ov views that doesn't take much memory or processor time.

Not sure about getting current alpha value though.

edited May 06 '11 at 15:51

Thierry Roy

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answered Jan 27 '11 at 09:33

Alex Orlov

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Thanks. I was using animation but I was setting the object visibility to gone once the animation had completed instead of using the setFillAfter method. – Tsuma-Shifu Jan 28 '11 at 10:23
It seems to break the animations (if run during the animation). Any fix for this? – Sufian Apr 29 '13 at 07:18
As a workaround, I used a semi-transparent image set as background of a `View`. – Sufian Apr 29 '13 at 08:19

score 15 · Answer 2 · edited May 23 '17 at 12:32

Here is a method that works across all versions (thanks to @AlexOrlov):

@SuppressLint("NewApi")
public static void setAlpha(View view, float alpha)
{
    if (Build.VERSION.SDK_INT < 11)
    {
        final AlphaAnimation animation = new AlphaAnimation(alpha, alpha);
        animation.setDuration(0);
        animation.setFillAfter(true);
        view.startAnimation(animation);
    }
    else view.setAlpha(alpha);
}

Clearly, for API less than 11 if you can you should create a custom view that calls Canvas.saveLayerAlpha() before drawing its children (thanks to @RomainGuy).

Use: ViewCompat.setAlpha(View, float). – TomerBu Dec 13 '15 at 09:40 — TomerBu, Dec 13 '15 at 09:40

score 6 · Answer 3 · answered Jan 27 '11 at 10:18

6

Alex's solution works but another way is to create a custom view that calls Canvas.saveLayerAlpha() before drawing its children. Note that in Android 3.0 there is a new View.setAlpha() API :)

answered Jan 27 '11 at 10:18

Romain Guy

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Thanks, looking forward to the setAlpha method. Something I'm more use to from other languages. – Tsuma-Shifu Jan 28 '11 at 10:24

score 3 · Answer 4 · edited Dec 29 '14 at 09:11

3

Now you can use ViewCompat.setAlpha(View, float) for this action.

edited Dec 29 '14 at 09:11

Pang

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answered Nov 28 '14 at 12:54

Firstborn

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Quote from doc: "*Prior to API 11 this will have no effect.*" – Pang Dec 29 '14 at 09:17
there is No such method. I have set minimum api set to 11.But it has ViewCompat.getAlpha(anyView) method – Xar-e-ahmer Khan Oct 16 '15 at 12:05

score 0 · Answer 5 · answered Feb 08 '16 at 12:43

0

Sorry for my answer but if you want the alpha you can use the ViewCompat Class

ViewCompat.setAlpha(View view, float alpha)

ViewCompat is in the appcompat v4

answered Feb 08 '16 at 12:43

vincent091

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Set Alpha/Opacity of Layout

5 Answers5

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