Change RippleEffect Color back to it's Styled original value

Question

I have an Android project where I'm changing the color of the Ripple effect that happens in one of my views using the following approach

Although it's working, I do need to reset this color back to it's default value, based on my style. Bellow I'll show my Style file, and I'd love to have a way to set the RippleDrawable back to it's default color.

<style name="AppTheme" parent="Theme.MaterialComponents.Light.DarkActionBar">
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="editTextColor">@android:color/white</item>
    <item name="font">@font/roboto_regular</item>

    <item name="colorControlNormal">@android:color/white</item>
    <item name="android:scrollbarThumbVertical">@drawable/nice_scrollbar</item>

    <item name="android:textColor">@color/darkGrey</item>
    <item name="android:editTextColor">@android:color/black</item>

    <item name="android:textColorHighlight">@color/colorPrimary</item>
    <item name="android:colorBackground">@color/darkerWhite</item>
    <item name="android:windowBackground">@color/darkerWhite</item>

    <item name="windowNoTitle">true</item>
    <item name="android:windowNoTitle">true</item>
</style>

As it can be noticed, I'm using MaterialComponents.

Below you'll find the current method I'm using to change color and also force the ripple effect on the view at a given x/y:

private void forceRippleAnimation(View view, int x, int y) {
    Drawable background = view.getBackground();
    if (Build.VERSION.SDK_INT >= 21 && background instanceof RippleDrawable) {
        RippleDrawable rippleDrawable = (RippleDrawable) background;
        rippleDrawable.setHotspot(x, y);
        rippleDrawable.setColor(new ColorStateList(
            new int[][]{
                new int[]{}
            },
            new int[]{
                getContext().getResources().getColor(R.color.rippleColor)
            }
        ));
        rippleDrawable.setState(new int[]{android.R.attr.state_pressed, android.R.attr.state_enabled});

        Handler handler = new Handler();
        handler.postDelayed(new Runnable(){
            @Override public void run(){
                rippleDrawable.setState(view.getDrawableState());
            }
        }, 650);
    }
}

Please show how you change the color - there are at least two useful answers to the linked question and I've no idea which one looked most promising in your eyes. — Bö macht Blau, Jan 29 '19 at 19:58
Hello @0X0nosugar, I just edited my question with the description of how I'm forcing the ripple effect. A possible way would be finding the initial ColorStateList from the RippleDrawable, but there's no getColorStateList, neither a way to find the default value... — Marcelo Petrucelli, Jan 30 '19 at 10:20

Bö macht Blau · Accepted Answer · 2019-02-08T19:07:29.300

Instead of trying to reverse the changes made to the original background RippleDrawable, you can keep it and apply the changes to a copy:

Let the Activity have two Drawable fields:

private RippleDrawable customRippleDrawable;
private RippleDrawable backgroundFromXml;

Create a copy of the given background and set it as the new background:

Drawable background = view.getBackground();
if (Build.VERSION.SDK_INT >= 21 && background instanceof RippleDrawable) {
    backgroundFromXml = (RippleDrawable) background;
    customRippleDrawable = (RippleDrawable) background.getConstantState().newDrawable().mutate();
    customRippleDrawable.setHotspot(x, y);
    customRippleDrawable.setColor(new ColorStateList(
            new int[][]{
                new int[]{}
            },
            new int[]{
                MainActivity.this.getResources().getColor(R.color.rippleColor)
            }
    ));
    customRippleDrawable.setState(new int[]{android.R.attr.state_pressed, android.R.attr.state_enabled});
    view.setBackground(customRippleDrawable);
}

Since backgroundFromXml is a field, you can access it later on to reset the background to its original value:

view.setBackground(backgroundFromXml);

What does mutate() do?

All Drawables generated from one drawable resource share a common state. This helps saving resources (e.g. memory) and so will improve the performance of an android application.

Normally, if you apply for example a ColorFilter to a Drawable generated from a certain drawable resource, you will notice the effect everywhere in your app where this specific drawable resource is used.

Calling mutate() on a Drawable tells the runtime that this Drawable should have its own state. If you apply any changes afterwards, the other Drawables wil remain unchanged.

See also the documentation on mutate()

I found another solution that doesn't work over ripples. But I may chose your answer the correct answer for what I asked. Could you further explain how .mutate() works? Seems like getResources().getColor(R.color.rippleColor) may be a way of getting this color, but I was unable to make it working. I always got a crash trying this out. — Marcelo Petrucelli, Feb 05 '19 at 10:38
I'm sorry, one more question, where in your code you consider copying the background? I see that you get it from the view, mutates it and apply a new colorstate to it. After that you set again this same background to the view. Why would this reset the color? And where do you copy this background (all I see is the reference being picked up and changed, being reset to the view afterwards)? — Marcelo Petrucelli, Feb 07 '19 at 10:23
@MarceloPetrucelli - there are two `Drawable`s in my example. One is created based on the other. I use one of them (*customRippleDrawable*) to show the changed ripple and the other one (*backgroundFromXml*) to show the normal ripple. — Bö macht Blau, Feb 08 '19 at 19:10

Change RippleEffect Color back to it's Styled original value

1 Answers1