Add checked state to MaterialButton

PiperOrigin-RevId: 234214200

Author: gsajith

lib/java/com/google/android/material/button/MaterialButton.java

@@ -49,6 +49,8 @@
 import androidx.appcompat.widget.AppCompatButton;
 import android.util.AttributeSet;
 import android.util.Log;
+import android.view.accessibility.AccessibilityNodeInfo;
+import android.widget.Checkable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 
@@ -88,7 +90,20 @@
  * <p>Specify the radius of all four corners of the button using the {@link R.attr#cornerRadius
  * app:cornerRadius} attribute.
  */
-public class MaterialButton extends AppCompatButton {
+public class MaterialButton extends AppCompatButton implements Checkable {
+
+  /** Interface definition for a callback to be invoked when the button checked state changes. */
+  public interface OnCheckedChangeListener {
+    /**
+     * Called when the checked state of a MaterialButton has changed.
+     *
+     * @param button The MaterialButton whose state has changed.
+     * @param isChecked The new checked state of MaterialButton.
+     */
+    void onCheckedChanged(MaterialButton button, boolean isChecked);
+  }
+
+  private static final int[] CHECKED_STATE_SET = {android.R.attr.state_checked};
 
   /**
    * Gravity used to position the icon at the start of the view.
@@ -123,6 +138,9 @@ public class MaterialButton extends AppCompatButton {
   private Drawable icon;
   @Px private int iconSize;
   @Px private int iconLeft;
+  private boolean checked = false;
+  private boolean broadcasting = false;
+  @Nullable private OnCheckedChangeListener onCheckedChangeListener;
 
   @IconGravity private int iconGravity;
 
@@ -168,6 +186,14 @@ public MaterialButton(Context context, AttributeSet attrs, int defStyleAttr) {
     updateIcon();
   }
 
+  @Override
+  public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
+    super.onInitializeAccessibilityNodeInfo(info);
+    info.setClassName(MaterialButton.class.getName());
+    info.setCheckable(isCheckable());
+    info.setClickable(isClickable());
+  }
+
   /**
    * This should be accessed via {@link
    * androidx.core.view.ViewCompat#setBackgroundTintList(android.view.View, ColorStateList)}
@@ -748,6 +774,84 @@ public int getIconGravity() {
   public void setIconGravity(@IconGravity int iconGravity) {
     this.iconGravity = iconGravity;
   }
+  
+  @Override
+  protected int[] onCreateDrawableState(int extraSpace) {
+    final int[] drawableState = super.onCreateDrawableState(extraSpace + 1);
+    if (isChecked()) {
+      mergeDrawableStates(drawableState, CHECKED_STATE_SET);
+    }
+
+    return drawableState;
+  }
+
+  /**
+   * Register a callback to be invoked when the checked state of this MaterialButton changes.
+   *
+   * @param listener the callback to call on checked state change
+   */
+  public void setOnCheckedChangeListener(@Nullable OnCheckedChangeListener listener) {
+    onCheckedChangeListener = listener;
+  }
+
+  @Override
+  public void setChecked(boolean checked) {
+    if (isCheckable() && isEnabled() && this.checked != checked) {
+      this.checked = checked;
+      refreshDrawableState();
+
+      // Avoid infinite recursions if setChecked() is called from a listener
+      if (broadcasting) {
+        return;
+      }
+
+      broadcasting = true;
+      if (onCheckedChangeListener != null) {
+        onCheckedChangeListener.onCheckedChanged(this, this.checked);
+      }
+
+      broadcasting = false;
+    }
+  }
+
+  @Override
+  public boolean isChecked() {
+    return checked;
+  }
+
+  @Override
+  public void toggle() {
+    setChecked(!checked);
+  }
+
+  @Override
+  public boolean performClick() {
+    toggle();
+
+    return super.performClick();
+  }
+
+  /**
+   * Returns whether this MaterialButton is checkable.
+   *
+   * @see #setCheckable(boolean)
+   * @attr ref com.google.android.material.R.styleable#MaterialButton_android_checkable
+   */
+  public boolean isCheckable() {
+    return materialButtonHelper != null && materialButtonHelper.isCheckable();
+  }
+
+  /**
+   * Sets whether this MaterialButton is checkable.
+   *
+   * @param checkable Whether this button is checkable.
+   * @attr ref com.google.android.material.R.styleable#MaterialButton_android_checkable
+   */
+  public void setCheckable(boolean checkable) {
+    if (isUsingOriginalBackground()) {
+      materialButtonHelper.setCheckable(checkable);
+    }
+  }
 
   private boolean isUsingOriginalBackground() {
     return materialButtonHelper != null && !materialButtonHelper.isBackgroundOverwritten();

lib/java/com/google/android/material/button/MaterialButtonHelper.java

@@ -65,6 +65,7 @@ class MaterialButtonHelper {
   private boolean shouldDrawSurfaceColorStroke = false;
   private boolean backgroundOverwritten = false;
   private boolean cornerRadiusSet = false;
+  private boolean checkable;
   private LayerDrawable rippleDrawable;
 
   MaterialButtonHelper(MaterialButton button, ShapeAppearanceModel shapeAppearanceModel) {
@@ -102,6 +103,7 @@ void loadFromAttributes(TypedArray attributes) {
         MaterialResources.getColorStateList(
             materialButton.getContext(), attributes, R.styleable.MaterialButton_rippleColor);
 
+    checkable = attributes.getBoolean(R.styleable.MaterialButton_android_checkable, false);
     int elevation = attributes.getDimensionPixelSize(R.styleable.MaterialButton_elevation, 0);
 
     // Store padding before setting background, since background overwrites padding values
@@ -384,6 +386,14 @@ MaterialShapeDrawable getMaterialShapeDrawable() {
     return getMaterialShapeDrawable(false);
   }
 
+  void setCheckable(boolean checkable) {
+    this.checkable = checkable;
+  }
+
+  boolean isCheckable() {
+    return checkable;
+  }
+
   @Nullable
   private MaterialShapeDrawable getSurfaceColorStrokeDrawable() {
     return getMaterialShapeDrawable(true);

lib/java/com/google/android/material/button/res/color/mtrl_btn_stroke_color_selector.xml

@@ -16,5 +16,6 @@
 -->
 
 <selector xmlns:android="http://schemas.android.com/apk/res/android">
-  <item android:alpha="0.12" android:color="?attr/colorOnSurface"/>
+  <item android:alpha="0.24" android:color="?attr/colorPrimary" android:state_checked="true"/>
+  <item android:alpha="0.12" android:color="?attr/colorOnSurface" android:state_checked="false"/>
 </selector>

lib/java/com/google/android/material/button/res/color/mtrl_btn_text_btn_bg_color_selector.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+    Copyright 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.
+-->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+  <item android:alpha="0.12" android:color="?attr/colorPrimary" android:state_checked="true"/>
+  <item android:color="@android:color/transparent" android:state_checked="false"/>
+</selector>

lib/java/com/google/android/material/button/res/values/attrs.xml

@@ -24,6 +24,8 @@
   <attr name="materialButtonOutlinedStyle" format="reference"/>
 
   <declare-styleable name="MaterialButton">
+    <!-- Whether the button can be checked. -->
+    <attr name="android:checkable"/>
     <attr name="android:insetLeft"/>
     <attr name="android:insetRight"/>
     <attr name="android:insetTop"/>

lib/java/com/google/android/material/button/res/values/styles.xml

@@ -60,7 +60,7 @@
     <item name="android:paddingRight">@dimen/mtrl_btn_text_btn_padding_right</item>
     <item name="iconTint">@color/mtrl_text_btn_text_color_selector</item>
     <item name="iconPadding">@dimen/mtrl_btn_text_btn_icon_padding</item>
-    <item name="backgroundTint">@android:color/transparent</item>
+    <item name="backgroundTint">@color/mtrl_btn_text_btn_bg_color_selector</item>
     <item name="rippleColor">@color/mtrl_btn_text_btn_ripple_color</item>
   </style>