Extending Preference classes in Android Lollipop = losing animation

Question

Just for extending CheckBoxPreference or SwitchPreference on Android Lollipop, the widget (the checkbox or the switch) won't have animation anymore.

I'd like to extend SwitchPreference to force api < 21 to use SwitchCompat instead of the default one they are using (which is obviously wrong).

I am using the new AppCompatPreferenceActivity with appcompat-v7:22.1.1 but that doesn't seem to affect the switches.

The thing is that with just extending those classes, without adding any custom layout or widget resource layout, the animation is gone.

I know I can write two instances of my preference.xml (on inside values-v21) and it will work... But I'd like to know why is this happening and if somebody knows a solution without having two preference.xml.

Code example:

public class SwitchPreference extends android.preference.SwitchPreference {

    public SwitchPreference(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public SwitchPreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    public SwitchPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SwitchPreference(Context context) {
        super(context);
    }
}

This or the same for CheckBoxPreference and then using:

<com.my.package.SwitchPreference />

Will make the animation in a Lollipop device to be gone.

--

Another thing I tried for the SwitchPreference (that I can with CheckBoxPreference) is to give a layout with the default id but @android:id/switchWidgetis not public while @android:id/checkbox is. I also know I can use a <CheckBoxPreference /> and give a widget layout that is in fact a SwitchCompat, but I'd like to avoid that (confusing the names).

Thorn

Did you find a solution? – Whipstall

No, I did not. Actually, I have a library for material preferences before Lollipop: github.com/ferrannp/material-preferences and the only bug it has is this one: github.com/ferrannp/material-preferences/issues/9 – Thorn

code.google.com/p/android/issues/detail?id=85392 is relevant. – Salesgirl

There's a good answer here that worked for me. – Exhilarant

Answer 1

It seems I found a fix for your issue.

Extensive Explanation

In SwitchCompat, when toggling the the switch, it tests a few functions before playing the animation: getWindowToken() != null && ViewCompat.isLaidOut(this) && isShown().

Full method:

@Override
public void setChecked(boolean checked) {
    super.setChecked(checked);
    // Calling the super method may result in setChecked() getting called
    // recursively with a different value, so load the REAL value...
    checked = isChecked();
    if (getWindowToken() != null && ViewCompat.isLaidOut(this) && isShown()) {
        animateThumbToCheckedState(checked);
    } else {
        // Immediately move the thumb to the new position.
        cancelPositionAnimator();
        setThumbPosition(checked ? 1 : 0);
    }
}

By using a custom view extending SwitchCompat, I found out, that isShown() always returns false, because the at third iteration of the while, parent == null.

public boolean isShown() {
    View current = this;
    //noinspection ConstantConditions
    do {
        if ((current.mViewFlags & VISIBILITY_MASK) != VISIBLE) {
            return false;
        }
        ViewParent parent = current.mParent;
        if (parent == null) {
            return false; // We are not attached to the view root
        }
        if (!(parent instanceof View)) {
            return true;
        }
        current = (View) parent;
    } while (current != null);

    return false;
}

Interestingly, the third parent is the second attribute passed to getView(View convertView, ViewGroup parent) in Preference, means the PreferenceGroupAdapter didn't get a parent passed to its own getView(). Why this happens exactly and why this happens only for custom preference classes, I don't know.

For my testing purposes, I used the CheckBoxPreference with a SwitchCompat as widgetLayout, and I also didn't see animations.

Fix

Now to the fix: simply make your own view extending SwitchCompat, and override your isShown() like this:

@Override
public boolean isShown() {
    return getVisibility() == VISIBLE;
}

Use this SwitchView for your widgetLayout style, and animations work again :D

Styles:

<style name="AppTheme" parent="Theme.AppCompat.NoActionBar">
    …
    <item name="android:checkBoxPreferenceStyle">@style/Preference.SwitchView</item>
    …
</style>

<style name="Preference.SwitchView">
    <item name="android:widgetLayout">@layout/preference_switch_view</item>
</style>

Widget layout:

<de.Maxr1998.example.preference.SwitchView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/checkbox"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@null"
    android:clickable="false"
    android:focusable="false" />

Chapiter

This sounds promising! However, I did try it in my lib (github.com/ferrannp/material-preferences) and I didn't get it to work (no animation still on pre-Lollipop). Do you have maybe a working repo? . By the way, I don't get animation on pre-Lollipop neither on a Switch or on a Checkbox. – Thorn

Animation works on Lollipop and before. I don't have set up a repo for this, it's only the code listed here anyway. Btw, this solution has a bug as well, since the animation gets played sometimes while scrolling through the list. Additionally, the switch's thumb is sometimes on the wrong side, though showing the correct color.. – Chapiter

Answer 2

Sometimes Extending from a Class is not the best solution. To avoid loosing the animations you could instead Compose it, I meant creating a Class where you have a SwitchPreference field variable and apply the new logic to it. It's like a wrapper. This worked for me.

Muniments

Answer 3

i manage to fix it like this and animations is working before it was going to the state directly without animation:

FIX:

CustomSwitchCompat.class

public class CustomSwitchCompat extends SwitchCompat {

    public CustomSwitchCompat(Context context) {
        super(context);
    }

    public CustomSwitchCompat(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public CustomSwitchCompat(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean isShown() {
        return getVisibility() == VISIBLE;
    }

}

In your layout do this: preference_switch_layout.xml

<com.example.CustomSwitchCompat
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@android:id/checkbox"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@null"
    android:clickable="false"
    android:focusable="false"
    app:switchMinWidth="55dp"/>

and in your preference.xml do this:

<CheckBoxPreference
   android:defaultValue="false"
   android:key=""
   android:widgetLayout="@layout/preference_switch_layout"
   android:summary=""
   android:title="" />

Chiachiack

Answer 4

I was having this issue, when I was using custom layout (app:layout) for SwitchPreference. At first, switch animation was triggered, but after a little scrolling it stopped and switch was jumping without animation. I tried every solution from stackoverflow, but nothing helped.

After debugging of SwitchCompat.setChecked method I found out that this condition is failing:

    public void setChecked(boolean checked) {
        ...

        if (getWindowToken() != null && ViewCompat.isLaidOut(this)) {
            animateThumbToCheckedState(checked);
        } else {
            // Immediately move the thumb to the new position.
            cancelPositionAnimator();
            setThumbPosition(checked ? 1 : 0);
        }
    }

Concretely ViewCompat.isLaidOut(this) returned false. I guess this is a bug either in View or Preference (or subclasses). Anyway, I was able to fix this with little hack.

I created a subclass of SwitchCompat and did override setChecked method, where I call requestLayout() and in onNextLayout I call SwitchCompat's setChecked method. This guarantees that isLaidOut condition is true when changing checked state.

Full code of custom SwitchCompat:

class SwitchCompatFix @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = androidx.appcompat.R.attr.switchStyle,
): SwitchCompat(context, attrs, defStyleAttr) {

    override fun setChecked(checked: Boolean) {
        doOnNextLayout {
            post { super.setChecked(checked) }
        }
        requestLayout()
    }
}

Cherian

Answer 5

public class SwitchPreference extends android.preference.SwitchPreference {

public SwitchPreference(Context context) {
    this(context, null);
}

public SwitchPreference(Context context, AttributeSet attrs) {
    this(context, attrs, android.R.attr.checkBoxPreferenceStyle);
}

public SwitchPreference(Context context, AttributeSet attrs, int defStyleAttr) {
    this(context, attrs, defStyleAttr, 0);
}

public SwitchPreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    super(context, attrs, defStyleAttr, defStyleRes);

    try {
        Field canRecycleLayoutField = Preference.class.getDeclaredField("mCanRecycleLayout");
        canRecycleLayoutField.setAccessible(true);
        canRecycleLayoutField.setBoolean(this, true);
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
}

Gurolinick

Hi, can you elaborate on this? I tried and I am getting a java.lang.NoSuchFieldException: mCanRecycleLayout error. – Thorn