Add a collapsible checkbox preference for deletion helper.

This adds a custom preference group which has both a checkbox
and collapse/expand behavior. This is intended to be used in
the deletion helper for apps deletion and downloads folder
deletion.

This patch implements the apps deletion integration.

Bug: 28769691
Change-Id: I9fb28a1baa4067841742b5dbeaf2083728c16144

src/com/android/settings/CollapsibleCheckboxPreferenceGroup.java

@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2016 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.android.settings;
+
+import android.content.Context;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceGroup;
+import android.support.v7.preference.PreferenceViewHolder;
+import android.util.AttributeSet;
+
+import android.util.Log;
+import android.util.TypedValue;
+import android.view.View;
+import android.widget.Checkable;
+import android.widget.TextView;
+
+import java.util.LinkedHashMap;
+
+/**
+ * CollapsibleCheckboxPreferenceGroup is a preference group that can be expanded or collapsed and
+ * also has a checkbox.
+ */
+public class CollapsibleCheckboxPreferenceGroup extends PreferenceGroup implements
+        View.OnClickListener {
+    private boolean mCollapsed;
+    private boolean mChecked;
+
+    public CollapsibleCheckboxPreferenceGroup(Context context) {
+        this(context, null);
+    }
+
+    public CollapsibleCheckboxPreferenceGroup(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        setWidgetLayoutResource(com.android.settings.R.layout.preference_widget_checkbox);
+    }
+
+    @Override
+    public void onBindViewHolder(PreferenceViewHolder holder) {
+        super.onBindViewHolder(holder);
+        View checkbox = holder.findViewById(com.android.internal.R.id.checkbox);
+        if (checkbox != null && checkbox instanceof Checkable) {
+            ((Checkable) checkbox).setChecked(mChecked);
+            checkbox.setClickable(true);
+            checkbox.setFocusable(true);
+            checkbox.setOnClickListener(this);
+        }
+
+        final TextView titleView = (TextView) holder.findViewById(android.R.id.title);
+        if (titleView != null) {
+            Context context = getContext();
+            TypedValue value = new TypedValue();
+            context.getTheme().resolveAttribute(android.R.attr.colorAccent, value, true);
+            titleView.setTextColor(context.getColor(value.resourceId));
+        }
+    }
+
+    @Override
+    public boolean addPreference(Preference p) {
+        super.addPreference(p);
+        p.setVisible(!isCollapsed());
+        return true;
+    }
+
+    // The preference click handler.
+    @Override
+    protected void onClick() {
+        super.onClick();
+        setCollapse(!isCollapsed());
+    }
+
+    // The checkbox view click handler.
+    @Override
+    public void onClick(View v) {
+        setChecked(!isChecked());
+    }
+
+    /**
+     * Return if the view is collapsed.
+     */
+    public boolean isCollapsed() {
+        return mCollapsed;
+    }
+
+    /**
+     * Returns the checked state of the preference.
+     */
+    public boolean isChecked() {
+        return mChecked;
+    }
+
+    /**
+     * Sets the checked state and notifies listeners of the state change.
+     */
+    public void setChecked(boolean checked) {
+        if (mChecked != checked) {
+            mChecked = checked;
+
+            callChangeListener(checked);
+            notifyDependencyChange(shouldDisableDependents());
+            notifyChanged();
+        }
+    }
+
+    private void setCollapse(boolean isCollapsed) {
+        if (mCollapsed == isCollapsed) {
+            return;
+        }
+
+        mCollapsed = isCollapsed;
+        if (isCollapsed) {
+            hideDropdownPreferences();
+        } else {
+            showDropdownPreferences();
+        }
+    }
+
+    private void showDropdownPreferences() {
+        setAllPreferencesVisibility(true);
+        setIcon(R.drawable.ic_keyboard_arrow_down_black_32);
+    }
+
+    private void hideDropdownPreferences() {
+        setAllPreferencesVisibility(false);
+        setIcon(R.drawable.ic_keyboard_arrow_up_black_32);
+    }
+
+    private void setAllPreferencesVisibility(boolean visible) {
+        for (int i = 0; i < getPreferenceCount(); i++) {
+            Preference p = getPreference(i);
+            p.setVisible(visible);
+        }
+    }
+}