MaterialButtonToggleGroup.java

/*
 * Copyright (C) 2019 The Android Open Source Project
 *
 * 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.
 */

package com.google.android.material.button;

import com.google.android.material.R;

import static com.google.android.material.theme.overlay.MaterialThemeOverlay.wrap;

import android.content.Context;
import android.content.res.TypedArray;
import android.text.TextUtils.TruncateAt;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.LinearLayout;
import android.widget.RadioButton;
import android.widget.ToggleButton;
import androidx.annotation.BoolRes;
import androidx.annotation.IdRes;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.view.AccessibilityDelegateCompat;
import androidx.core.view.ViewCompat;
import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;
import androidx.core.view.accessibility.AccessibilityNodeInfoCompat.CollectionInfoCompat;
import androidx.core.view.accessibility.AccessibilityNodeInfoCompat.CollectionItemInfoCompat;
import com.google.android.material.internal.ThemeEnforcement;
import com.google.android.material.shape.AbsoluteCornerSize;
import com.google.android.material.shape.StateListCornerSize;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

/**
 * A common container for a set of related, toggleable {@link MaterialButton}s. The {@link
 * MaterialButton}s in this group will be shown on a single line.
 *
 * <p>This layout currently only supports child views of type {@link MaterialButton}. Buttons can be
 * added to this view group via XML, as follows:
 *
 * <pre>
 * &lt;com.google.android.material.button.MaterialButtonToggleGroup
 *     xmlns:android="http://schemas.android.com/apk/res/android"
 *     android:id="@+id/toggle_button_group"
 *     android:layout_width="wrap_content"
 *     android:layout_height="wrap_content"&gt;
 *
 *     &lt;com.google.android.material.button.MaterialButton
 *         style="?attr/materialButtonOutlinedStyle"
 *         android:layout_width="wrap_content"
 *         android:layout_height="wrap_content"
 *         android:text="@string/button_label_private"/&gt;
 *     &lt;com.google.android.material.button.MaterialButton
 *         style="?attr/materialButtonOutlinedStyle"
 *         android:layout_width="wrap_content"
 *         android:layout_height="wrap_content"
 *         android:text="@string/button_label_team"/&gt;
 *     &lt;com.google.android.material.button.MaterialButton
 *         style="?attr/materialButtonOutlinedStyle"
 *         android:layout_width="wrap_content"
 *         android:layout_height="wrap_content"
 *         android:text="@string/button_label_everyone"/&gt;
 *     &lt;com.google.android.material.button.MaterialButton
 *         style="?attr/materialButtonOutlinedStyle"
 *         android:layout_width="wrap_content"
 *         android:layout_height="wrap_content"
 *         android:text="@string/button_label_custom"/&gt;
 *
 * &lt;/com.google.android.material.button.MaterialButtonToggleGroup&gt;
 * </pre>
 *
 * <p>Buttons can also be added to this view group programmatically via the {@link #addView(View)}
 * methods.
 *
 * <p>Note: Styling must applied to each child button individually. It is recommended to use the
 * {@code materialButtonOutlinedStyle} attribute for all child buttons. {@code
 * materialButtonOutlinedStyle} will most closely match the Material Design guidelines for this
 * component, and supports the checked state for child buttons.
 *
 * <p>Any {@link MaterialButton}s added to this view group are automatically marked as {@code
 * checkable}, and by default multiple buttons within the same group can be checked. To enforce that
 * only one button can be checked at a time, set the {@code app:singleSelection} attribute to {@code
 * true} on the MaterialButtonToggleGroup or call {@link #setSingleSelection(boolean)
 * setSingleSelection(true)}.
 *
 * <p>MaterialButtonToggleGroup is a {@link LinearLayout}. Using {@code
 * android:layout_width="MATCH_PARENT"} and removing {@code android:insetBottom} {@code
 * android:insetTop} on the children is recommended if using {@code VERTICAL}.
 *
 * <p>In order to cohesively group multiple buttons together, MaterialButtonToggleGroup overrides
 * the start and end margins of any children added to this layout such that child buttons are placed
 * directly adjacent to one another.
 *
 * <p>MaterialButtonToggleGroup also overrides any {@code shapeAppearance}, {@code
 * shapeAppearanceOverlay}, or {@code cornerRadius} attribute set on MaterialButton children such
 * that only the left-most corners of the first child and the right-most corners of the last child
 * retain their shape appearance or corner size.
 *
 * <p>For more information, see the <a
 * href="https://github.com/material-components/material-components-android/blob/master/docs/components/Button.md">component
 * developer guidance</a> and <a href="https://material.io/components/buttons/overview">design
 * guidelines</a>.
 */
public class MaterialButtonToggleGroup extends MaterialButtonGroup {

  /**
   * Interface definition for a callback to be invoked when a {@link MaterialButton} is checked or
   * unchecked in this group.
   */
  public interface OnButtonCheckedListener {
    /**
     * Called when a {@link MaterialButton} in this group is checked or unchecked.
     *
     * @param group The group in which the MaterialButton's checked state was changed
     * @param checkedId The unique identifier of the MaterialButton whose check state changed
     * @param isChecked Whether the MaterialButton is currently checked
     */
    void onButtonChecked(MaterialButtonToggleGroup group, @IdRes int checkedId, boolean isChecked);
  }

  private static final String LOG_TAG = "MButtonToggleGroup";
  private static final int DEF_STYLE_RES =
      R.style.Widget_MaterialComponents_MaterialButtonToggleGroup;
  private final LinkedHashSet<OnButtonCheckedListener> onButtonCheckedListeners =
      new LinkedHashSet<>();

  private boolean skipCheckedStateTracker = false;
  private boolean singleSelection;
  private boolean selectionRequired;

  @IdRes private final int defaultCheckId;
  private Set<Integer> checkedIds = new HashSet<>();

  public MaterialButtonToggleGroup(@NonNull Context context) {
    this(context, null);
  }

  public MaterialButtonToggleGroup(@NonNull Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, R.attr.materialButtonToggleGroupStyle);
  }

  public MaterialButtonToggleGroup(
      @NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(wrap(context, attrs, defStyleAttr, DEF_STYLE_RES), attrs, defStyleAttr);
    // Ensure we are using the correctly themed context rather than the context that was passed in.
    context = getContext();
    TypedArray attributes =
        ThemeEnforcement.obtainStyledAttributes(
            context, attrs, R.styleable.MaterialButtonToggleGroup, defStyleAttr, DEF_STYLE_RES);

    setSingleSelection(
        attributes.getBoolean(R.styleable.MaterialButtonToggleGroup_singleSelection, false));
    defaultCheckId =
        attributes.getResourceId(R.styleable.MaterialButtonToggleGroup_checkedButton, View.NO_ID);
    selectionRequired =
        attributes.getBoolean(R.styleable.MaterialButtonToggleGroup_selectionRequired, false);

    // If inner corner size is not specified in button group, set it to 0 as default.
    if (innerCornerSize == null) {
      innerCornerSize = StateListCornerSize.create(new AbsoluteCornerSize(0));
    }

    setEnabled(attributes.getBoolean(R.styleable.MaterialButtonToggleGroup_android_enabled, true));
    attributes.recycle();

    setImportantForAccessibility(View.IMPORTANT_FOR_ACCESSIBILITY_YES);
  }

  @Override
  protected void onFinishInflate() {
    super.onFinishInflate();
    if (defaultCheckId != View.NO_ID) {
      updateCheckedIds(Collections.singleton(defaultCheckId));
    }
  }

  /**
   * This override prohibits Views other than {@link MaterialButton} to be added. It also makes
   * updates to the add button shape and margins.
   */
  @Override
  public void addView(@NonNull View child, int index, @NonNull ViewGroup.LayoutParams params) {
    if (!(child instanceof MaterialButton)) {
      Log.e(LOG_TAG, "Child views must be of type MaterialButton.");
      return;
    }

    super.addView(child, index, params);
    MaterialButton buttonChild = (MaterialButton) child;

    // Sets sensible default values and an internal checked change listener for this child
    setupButtonChild(buttonChild);

    // Update button group's checked states
    checkInternal(buttonChild.getId(), buttonChild.isChecked());

    ViewCompat.setAccessibilityDelegate(
        buttonChild,
        new AccessibilityDelegateCompat() {
          @Override
          public void onInitializeAccessibilityNodeInfo(
              View host, @NonNull AccessibilityNodeInfoCompat info) {
            super.onInitializeAccessibilityNodeInfo(host, info);
            info.setCollectionItemInfo(
                CollectionItemInfoCompat.obtain(
                    /* rowIndex= */ 0,
                    /* rowSpan= */ 1,
                    /* columnIndex= */ getIndexWithinVisibleButtons(host),
                    /* columnSpan= */ 1,
                    /* heading= */ false,
                    /* selected= */ ((MaterialButton) host).isChecked()));
          }
        });
  }

  @Override
  public void onInitializeAccessibilityNodeInfo(@NonNull AccessibilityNodeInfo info) {
    super.onInitializeAccessibilityNodeInfo(info);
    AccessibilityNodeInfoCompat infoCompat = AccessibilityNodeInfoCompat.wrap(info);
    infoCompat.setCollectionInfo(
        CollectionInfoCompat.obtain(
            /* rowCount= */ 1,
            /* columnCount= */ getVisibleButtonCount(),
            /* hierarchical= */ false,
            /* selectionMode= */ isSingleSelection()
                ? CollectionInfoCompat.SELECTION_MODE_SINGLE
                : CollectionInfoCompat.SELECTION_MODE_MULTIPLE));
  }

  /**
   * Sets the {@link MaterialButton} whose id is passed in to the checked state. If this
   * MaterialButtonToggleGroup is in {@link #isSingleSelection() single selection mode}, then all
   * other MaterialButtons in this group will be unchecked. Otherwise, other MaterialButtons will
   * retain their checked state.
   *
   * @param id View ID of {@link MaterialButton} to set checked
   * @see #uncheck(int)
   * @see #clearChecked()
   * @see #getCheckedButtonIds()
   * @see #getCheckedButtonId()
   */
  public void check(@IdRes int id) {
    checkInternal(id, true);
  }

  /**
   * Sets the {@link MaterialButton} whose id is passed in to the unchecked state.
   *
   * @param id View ID of {@link MaterialButton} to set unchecked
   * @see #check(int)
   * @see #clearChecked()
   * @see #getCheckedButtonIds()
   * @see #getCheckedButtonId()
   */
  public void uncheck(@IdRes int id) {
    checkInternal(id, false);
  }

  /**
   * Clears the selections. When the selections are cleared, no {@link MaterialButton} in this group
   * is checked and {@link #getCheckedButtonIds()} returns an empty list.
   *
   * @see #check(int)
   * @see #uncheck(int)
   * @see #getCheckedButtonIds()
   * @see #getCheckedButtonId()
   */
  public void clearChecked() {
    updateCheckedIds(new HashSet<Integer>());
  }

  /**
   * When in {@link #isSingleSelection() single selection mode}, returns the identifier of the
   * selected button in this group. Upon empty selection, the returned value is {@link View#NO_ID}.
   * If not in single selection mode, the return value is {@link View#NO_ID}.
   *
   * @return The unique id of the selected {@link MaterialButton} in this group in {@link
   *     #isSingleSelection() single selection mode}. When not in {@link #isSingleSelection() single
   *     selection mode}, returns {@link View#NO_ID}.
   * @see #check(int)
   * @see #uncheck(int)
   * @see #clearChecked()
   * @see #getCheckedButtonIds()
   * @attr ref R.styleable#MaterialButtonToggleGroup_checkedButton
   */
  @IdRes
  public int getCheckedButtonId() {
    return singleSelection && !checkedIds.isEmpty() ? checkedIds.iterator().next() : View.NO_ID;
  }

  /**
   * Returns the identifiers of the selected {@link MaterialButton}s in this group. Upon empty
   * selection, the returned value is an empty list.
   *
   * @return The unique IDs of the selected {@link MaterialButton}s in this group. When in {@link
   *     #isSingleSelection() single selection mode}, returns a list with a single ID. When no
   *     {@link MaterialButton}s are selected, returns an empty list.
   * @see #check(int)
   * @see #uncheck(int)
   * @see #clearChecked()
   * @see #getCheckedButtonId()
   */
  @NonNull
  public List<Integer> getCheckedButtonIds() {
    List<Integer> orderedCheckedIds = new ArrayList<>();
    for (int i = 0; i < getChildCount(); i++) {
      int childId = getChildButton(i).getId();
      if (checkedIds.contains(childId)) {
        orderedCheckedIds.add(childId);
      }
    }

    return orderedCheckedIds;
  }

  /**
   * Add a listener that will be invoked when the check state of a {@link MaterialButton} in this
   * group changes. See {@link OnButtonCheckedListener}.
   *
   * <p>Components that add a listener should take care to remove it when finished via {@link
   * #removeOnButtonCheckedListener(OnButtonCheckedListener)}.
   *
   * @param listener listener to add
   */
  public void addOnButtonCheckedListener(@NonNull OnButtonCheckedListener listener) {
    onButtonCheckedListeners.add(listener);
  }

  /**
   * Remove a listener that was previously added via {@link
   * #addOnButtonCheckedListener(OnButtonCheckedListener)}.
   *
   * @param listener listener to remove
   */
  public void removeOnButtonCheckedListener(@NonNull OnButtonCheckedListener listener) {
    onButtonCheckedListeners.remove(listener);
  }

  /** Remove all previously added {@link OnButtonCheckedListener}s. */
  public void clearOnButtonCheckedListeners() {
    onButtonCheckedListeners.clear();
  }

  /**
   * Returns whether this group only allows a single button to be checked.
   *
   * @return whether this group only allows a single button to be checked
   * @attr ref R.styleable#MaterialButtonToggleGroup_singleSelection
   */
  public boolean isSingleSelection() {
    return singleSelection;
  }

  /**
   * Sets whether this group only allows a single button to be checked.
   *
   * <p>Calling this method results in all the buttons in this group to become unchecked.
   *
   * @param singleSelection whether this group only allows a single button to be checked
   * @attr ref R.styleable#MaterialButtonToggleGroup_singleSelection
   */
  public void setSingleSelection(boolean singleSelection) {
    if (this.singleSelection != singleSelection) {
      this.singleSelection = singleSelection;
      clearChecked();
    }
    updateChildrenA11yClassName();
  }

  private void updateChildrenA11yClassName() {
    String className = getChildrenA11yClassName();
    for (int i = 0; i < getChildCount(); i++) {
      getChildButton(i).setA11yClassName(className);
    }
  }

  @NonNull
  private String getChildrenA11yClassName() {
    return singleSelection ? RadioButton.class.getName() : ToggleButton.class.getName();
  }

  /**
   * Sets whether we prevent all child buttons from being deselected.
   *
   * @attr ref R.styleable#MaterialButtonToggleGroup_selectionRequired
   */
  public void setSelectionRequired(boolean selectionRequired) {
    this.selectionRequired = selectionRequired;
  }

  /**
   * Returns whether we prevent all child buttons from being deselected.
   *
   * @attr ref R.styleable#MaterialButtonToggleGroup_selectionRequired
   */
  public boolean isSelectionRequired() {
    return selectionRequired;
  }

  /**
   * Sets whether this group only allows a single button to be checked.
   *
   * <p>Calling this method results in all the buttons in this group to become unchecked.
   *
   * @param id boolean resource ID of whether this group only allows a single button to be checked
   * @attr ref R.styleable#MaterialButtonToggleGroup_singleSelection
   */
  public void setSingleSelection(@BoolRes int id) {
    setSingleSelection(getResources().getBoolean(id));
  }

  private void setCheckedStateForView(@IdRes int viewId, boolean checked) {
    View checkedView = findViewById(viewId);
    if (checkedView instanceof MaterialButton) {
      skipCheckedStateTracker = true;
      ((MaterialButton) checkedView).setChecked(checked);
      skipCheckedStateTracker = false;
    }
  }

  private boolean isChildVisible(int i) {
    View child = getChildAt(i);
    return child.getVisibility() != View.GONE;
  }

  private int getVisibleButtonCount() {
    int count = 0;
    for (int i = 0; i < getChildCount(); i++) {
      if (this.getChildAt(i) instanceof MaterialButton && isChildVisible(i)) {
        count++;
      }
    }
    return count;
  }

  private int getIndexWithinVisibleButtons(@Nullable View child) {
    if (!(child instanceof MaterialButton)) {
      return -1;
    }
    int index = 0;
    for (int i = 0; i < getChildCount(); i++) {
      if (this.getChildAt(i) == child) {
        return index;
      }
      if (this.getChildAt(i) instanceof MaterialButton && isChildVisible(i)) {
        index++;
      }
    }
    return -1;
  }

  private void checkInternal(@IdRes int buttonId, boolean checked) {
    if (buttonId == View.NO_ID) {
      Log.e(LOG_TAG, "Button ID is not valid: " + buttonId);
      return;
    }
    Set<Integer> checkedIds = new HashSet<>(this.checkedIds);
    if (checked && !checkedIds.contains(buttonId)) {
      if (singleSelection && !checkedIds.isEmpty()) {
        checkedIds.clear();
      }
      checkedIds.add(buttonId);
    } else if (!checked && checkedIds.contains(buttonId)) {
      // Do not uncheck button if no selection remains when selection is required.
      if (!selectionRequired || checkedIds.size() > 1) {
        checkedIds.remove(buttonId);
      }
    } else {
      // No state change, do nothing
      return;
    }
    updateCheckedIds(checkedIds);
  }

  private void updateCheckedIds(Set<Integer> checkedIds) {
    Set<Integer> previousCheckedIds = this.checkedIds;
    this.checkedIds = new HashSet<>(checkedIds);
    for (int i = 0; i < getChildCount(); i++) {
      int buttonId = getChildButton(i).getId();
      setCheckedStateForView(buttonId, checkedIds.contains(buttonId));
      if (previousCheckedIds.contains(buttonId) != checkedIds.contains(buttonId)) {
        dispatchOnButtonChecked(buttonId, checkedIds.contains(buttonId));
      }
    }
    invalidate();
  }

  private void dispatchOnButtonChecked(@IdRes int buttonId, boolean checked) {
    for (OnButtonCheckedListener listener : onButtonCheckedListeners) {
      listener.onButtonChecked(this, buttonId, checked);
    }
  }

  /**
   * Sets sensible default values for {@link MaterialButton} child of this group, set child to
   * {@code checkable}, and set internal checked change listener for this child.
   *
   * @param buttonChild {@link MaterialButton} child to set up to be added to this {@link
   *     MaterialButtonToggleGroup}
   */
  private void setupButtonChild(@NonNull MaterialButton buttonChild) {
    buttonChild.setMaxLines(1);
    buttonChild.setEllipsize(TruncateAt.END);
    buttonChild.setCheckable(true);
    buttonChild.setA11yClassName(getChildrenA11yClassName());

    // Enables surface layer drawing for semi-opaque strokes
    buttonChild.setShouldDrawSurfaceColorStroke(true);
  }

  void onButtonCheckedStateChanged(@NonNull MaterialButton button, boolean isChecked) {
    // Checked state change is triggered by the button group, do not update checked ids again.
    if (skipCheckedStateTracker) {
      return;
    }
    checkInternal(button.getId(), isChecked);
  }
}