Change Magnification Mode Settings UI

To support new settings UI, we change the UI from scrollview
to listview to simplify UI initialization.

Bug: 182118397
Test: atest MagnificationSettingsFragmentTest
      and manual test.
Change-Id: Ib65dc139ba54f2281e5cb7e2dc55b3574ad2c733

src/com/android/settings/widget/CheckableRelativeLayout.java

@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2021 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.widget;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.accessibility.AccessibilityEvent;
+import android.view.accessibility.AccessibilityNodeInfo;
+import android.widget.Checkable;
+import android.widget.RelativeLayout;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+/**
+ * A RelativeLayout which implements {@link Checkable}. With this implementation, it could be used
+ * in the list item layout for {@link android.widget.AbsListView} to change UI after item click.
+ * Its checked state would be propagated to the checkable child.
+ *
+ * <p>
+ * To support accessibility, the state description is from the checkable view and is
+ * changed with {@link #setChecked(boolean)}. We make the checkable child unclickable, unfocusable
+ * and non-important for accessibility, so that the announcement wouldn't include
+ * the checkable view.
+ * <
+ */
+public class CheckableRelativeLayout extends RelativeLayout implements Checkable {
+
+    private Checkable mCheckable;
+    private View mCheckableChild;
+    private boolean mChecked;
+
+    public CheckableRelativeLayout(Context context) {
+        super(context);
+    }
+
+    public CheckableRelativeLayout(Context context, @Nullable AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    @Override
+    protected void onFinishInflate() {
+        mCheckableChild = findFirstCheckableView(this);
+        if (mCheckableChild != null) {
+            mCheckableChild.setClickable(false);
+            mCheckableChild.setFocusable(false);
+            mCheckableChild.setImportantForAccessibility(IMPORTANT_FOR_ACCESSIBILITY_NO);
+            mCheckable = (Checkable) mCheckableChild;
+            mCheckable.setChecked(isChecked());
+            setStateDescriptionIfNeeded();
+        }
+        super.onFinishInflate();
+    }
+
+    @Nullable
+    private static View findFirstCheckableView(@NonNull ViewGroup viewGroup) {
+        final int childCount = viewGroup.getChildCount();
+        for (int i = 0; i < childCount; i++) {
+            final View child = viewGroup.getChildAt(i);
+            if (child instanceof Checkable) {
+                return child;
+            }
+            if (child instanceof ViewGroup) {
+                findFirstCheckableView((ViewGroup) child);
+            }
+        }
+        return  null;
+    }
+
+    @Override
+    public void setChecked(boolean checked) {
+        if (mChecked != checked) {
+            mChecked = checked;
+            if (mCheckable != null) {
+                mCheckable.setChecked(checked);
+            }
+        }
+        setStateDescriptionIfNeeded();
+        notifyViewAccessibilityStateChangedIfNeeded(
+                AccessibilityEvent.CONTENT_CHANGE_TYPE_UNDEFINED);
+    }
+
+    private void setStateDescriptionIfNeeded() {
+        if (mCheckableChild == null) {
+            return;
+        }
+        setStateDescription(mCheckableChild.getStateDescription());
+    }
+
+    @Override
+    public boolean isChecked() {
+        return mChecked;
+    }
+
+    @Override
+    public void toggle() {
+        setChecked(!mChecked);
+    }
+
+    @Override
+    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
+        super.onInitializeAccessibilityEvent(event);
+        event.setChecked(mChecked);
+    }
+
+    @Override
+    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
+        super.onInitializeAccessibilityNodeInfo(info);
+        info.setChecked(mChecked);
+    }
+}