ConstraintRadioGroup

ConstraintRadioGroup.java

/*
 * Copyright (C) 2019 Sam Lu
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//code style "fix" from Selvin
//documentation/usage and original source https://github.com/samlu/ConstraintRadioGroup

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CompoundButton;
import android.widget.RadioButton;

import androidx.annotation.IdRes;
import androidx.constraintlayout.widget.ConstraintHelper;
import androidx.constraintlayout.widget.ConstraintLayout;

import java.util.ArrayList;

public class ConstraintRadioGroup extends ConstraintHelper {

    private final ArrayList<RadioButton> mRadioButtons = new ArrayList<>();
    private boolean mSkipCheckingViewsRecursively = false;
    private int mCurrentSelectedViewId = -1;
    private int mSelectedViewIdBeforePreLayout = -1;
    private OnCheckedChangeListener mListenerOnCheckedChange;
    private final CompoundButton.OnCheckedChangeListener mListenerRadioButton = (buttonView, isChecked) -> {
        if (mSkipCheckingViewsRecursively)
            return;

        if (mCurrentSelectedViewId != -1) {
            // uncheck the checked button
            mSkipCheckingViewsRecursively = true;
            for (RadioButton v : mRadioButtons) {
                if (v.getId() == mCurrentSelectedViewId) {
                    v.setChecked(false);
                    break;
                }
            }
            mSkipCheckingViewsRecursively = false;
        }

        setCurrentSelectedViewId(buttonView.getId());
    };

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

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

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

    @Override
    protected void init(AttributeSet attrs) {
        super.init(attrs);
        mUseViewMeasure = false;
    }

    @Override
    public void updatePreLayout(ConstraintLayout container) {
        super.updatePreLayout(container);

        for (int i = 0; i < mCount; i++) {
            int nId = mIds[i];
            View v = container.getViewById(nId);
            if (v instanceof RadioButton) {
                mRadioButtons.add((RadioButton) v);
                ((RadioButton) v).setOnCheckedChangeListener(mListenerRadioButton);
            }
        }

        if (mSelectedViewIdBeforePreLayout != -1)
            check(mSelectedViewIdBeforePreLayout);
    }

    @Override
    public void updatePostLayout(ConstraintLayout container) {
        ViewGroup.LayoutParams params = getLayoutParams();
        params.width = 0;
        params.height = 0;
        super.updatePostLayout(container);
    }

    public void setEnabled(boolean enabled) {

    }

    public void check(int radioButtonId) {
        final boolean isBeforePreLayout = mRadioButtons.isEmpty();
        mSelectedViewIdBeforePreLayout = (isBeforePreLayout ? radioButtonId : -1);

        boolean found = false;
        mSkipCheckingViewsRecursively = true;
        for (RadioButton v : mRadioButtons) {
            if (v.getId() == radioButtonId) {
                v.setChecked(true);
                found = true;
            } else
                v.setChecked(false);
        }
        mSkipCheckingViewsRecursively = false;

        if (!isBeforePreLayout)
            setCurrentSelectedViewId(found ? radioButtonId : -1);
    }

    public void setOnCheckedChangeListener(OnCheckedChangeListener listener) {
        mListenerOnCheckedChange = listener;
    }

    private void setCurrentSelectedViewId(@IdRes int radioButtonId) {
        if (mCurrentSelectedViewId != radioButtonId) {
            mCurrentSelectedViewId = radioButtonId;

            if (mListenerOnCheckedChange != null)
                mListenerOnCheckedChange.onCheckedChanged(this, radioButtonId);
        }
    }

    public interface OnCheckedChangeListener {
        void onCheckedChanged(ConstraintRadioGroup group, @IdRes int checkedId);
    }
}