src/com/android/launcher3/util/ViewCapture.java - platform/packages/apps/Launcher3 - Git at Google

 /*
  * Copyright (C) 2022 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.launcher3.util;

 import static com.android.launcher3.util.Executors.MAIN_EXECUTOR;
 import static com.android.launcher3.util.Executors.UI_HELPER_EXECUTOR;
 import static com.android.launcher3.util.Executors.createAndStartNewLooper;

 import static java.util.stream.Collectors.toList;

 import android.content.Context;
 import android.content.res.Resources;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
 import android.os.Process;
 import android.os.Trace;
 import android.text.TextUtils;
 import android.util.Base64;
 import android.util.Base64OutputStream;
 import android.util.Log;
 import android.util.Pair;
 import android.util.SparseArray;
 import android.view.View;
 import android.view.View.OnAttachStateChangeListener;
 import android.view.ViewGroup;
 import android.view.ViewTreeObserver.OnDrawListener;
 import android.view.Window;

 import androidx.annotation.UiThread;
 import androidx.annotation.WorkerThread;

 import com.android.launcher3.config.FeatureFlags;
 import com.android.launcher3.view.ViewCaptureData.ExportedData;
 import com.android.launcher3.view.ViewCaptureData.FrameData;
 import com.android.launcher3.view.ViewCaptureData.ViewNode;

 import java.io.FileDescriptor;
 import java.io.FileOutputStream;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Future;
 import java.util.zip.GZIPOutputStream;

 /**
  * Utility class for capturing view data every frame
  */
 public class ViewCapture {

     private static final String TAG = "ViewCapture";

     // Number of frames to keep in memory
     private static final int MEMORY_SIZE = 2000;
     // Initial size of the reference pool. This is at least be 5 * total number of views in
     // Launcher. This allows the first free frames avoid object allocation during view capture.
     private static final int INIT_POOL_SIZE = 300;

     public static final MainThreadInitializedObject<ViewCapture> INSTANCE =
             new MainThreadInitializedObject<>(ViewCapture::new);

     private final List<WindowListener> mListeners = new ArrayList<>();

     private final Context mContext;
     private final LooperExecutor mExecutor;

     // Pool used for capturing view tree on the UI thread.
     private ViewRef mPool = new ViewRef();

     private ViewCapture(Context context) {
         mContext = context;
         if (FeatureFlags.CONTINUOUS_VIEW_TREE_CAPTURE.get()) {
             Looper looper = createAndStartNewLooper("ViewCapture",
                     Process.THREAD_PRIORITY_FOREGROUND);
             mExecutor = new LooperExecutor(looper);
             mExecutor.execute(this::initPool);
         } else {
             mExecutor = UI_HELPER_EXECUTOR;
         }
     }

     @UiThread
     private void addToPool(ViewRef start, ViewRef end) {
         end.next = mPool;
         mPool = start;
     }

     @WorkerThread
     private void initPool() {
         ViewRef start = new ViewRef();
         ViewRef current = start;

         for (int i = 0; i < INIT_POOL_SIZE; i++) {
             current.next = new ViewRef();
             current = current.next;
         }

         ViewRef finalCurrent = current;
         MAIN_EXECUTOR.execute(() -> addToPool(start, finalCurrent));
     }

     /**
      * Attaches the ViewCapture to the provided window and returns a handle to detach the listener
      */
     public SafeCloseable startCapture(Window window) {
         String title = window.getAttributes().getTitle().toString();
         String name = TextUtils.isEmpty(title) ? window.toString() : title;
         return startCapture(window.getDecorView(), name);
     }

     /**
      * Attaches the ViewCapture to the provided window and returns a handle to detach the listener
      */
     public SafeCloseable startCapture(View view, String name) {
         if (!FeatureFlags.CONTINUOUS_VIEW_TREE_CAPTURE.get()) {
             return () -> { };
         }

         WindowListener listener = new WindowListener(view, name);
         mExecutor.execute(() -> MAIN_EXECUTOR.execute(listener::attachToRoot));
         mListeners.add(listener);
         return () -> {
             mListeners.remove(listener);
             listener.destroy();
         };
     }

     /**
      * Dumps all the active view captures
      */
     public void dump(PrintWriter writer, FileDescriptor out) {
         if (!FeatureFlags.CONTINUOUS_VIEW_TREE_CAPTURE.get()) {
             return;
         }
         ViewIdProvider idProvider = new ViewIdProvider(mContext.getResources());

         // Collect all the tasks first so that all the tasks are posted on the executor
         List<Pair<String, Future<ExportedData>>> tasks = mListeners.stream()
                 .map(l -> Pair.create(l.name, mExecutor.submit(() -> l.dumpToProto(idProvider))))
                 .collect(toList());

         tasks.forEach(pair -> {
             writer.println();
             writer.println(" ContinuousViewCapture:");
             writer.println(" window " + pair.first + ":");
             writer.println("  pkg:" + mContext.getPackageName());
             writer.print("  data:");
             writer.flush();
             try (OutputStream os = new FileOutputStream(out)) {
                 ExportedData data = pair.second.get();
                 OutputStream encodedOS = new GZIPOutputStream(new Base64OutputStream(os,
                         Base64.NO_CLOSE | Base64.NO_PADDING | Base64.NO_WRAP));
                 data.writeTo(encodedOS);
                 encodedOS.close();
                 os.flush();
             } catch (Exception e) {
                 Log.e(TAG, "Error capturing proto", e);
             }
             writer.println();
             writer.println("--end--");
         });
     }

     private class WindowListener implements OnDrawListener {

         private final View mRoot;
         public final String name;

         private final Handler mHandler;
         private final ViewRef mViewRef = new ViewRef();

         private int mFrameIndexBg = -1;
         private final long[] mFrameTimesBg = new long[MEMORY_SIZE];
         private final ViewPropertyRef[] mNodesBg = new ViewPropertyRef[MEMORY_SIZE];

         private boolean mDestroyed = false;

         WindowListener(View view, String name) {
             mRoot = view;
             this.name = name;
             mHandler = new Handler(mExecutor.getLooper(), this::captureViewPropertiesBg);
         }

         @Override
         public void onDraw() {
             Trace.beginSection("view_capture");
             captureViewTree(mRoot, mViewRef);
             Message m = Message.obtain(mHandler);
             m.obj = mViewRef.next;
             mHandler.sendMessage(m);
             Trace.endSection();
         }

         /**
          * Captures the View property on the background thread, and transfer all the ViewRef objects
          * back to the pool
          */
         @WorkerThread
         private boolean captureViewPropertiesBg(Message msg) {
             ViewRef start = (ViewRef) msg.obj;
             long time = msg.getWhen();
             if (start == null) {
                 return false;
             }
             mFrameIndexBg++;
             if (mFrameIndexBg >= MEMORY_SIZE) {
                 mFrameIndexBg = 0;
             }
             mFrameTimesBg[mFrameIndexBg] = time;

             ViewPropertyRef recycle = mNodesBg[mFrameIndexBg];

             ViewPropertyRef result = null;
             ViewPropertyRef resultEnd = null;

             ViewRef current = start;
             ViewRef last = start;
             while (current != null) {
                 ViewPropertyRef propertyRef = recycle;
                 if (propertyRef == null) {
                     propertyRef = new ViewPropertyRef();
                 } else {
                     recycle = recycle.next;
                     propertyRef.next = null;
                 }

                 propertyRef.transfer(current);
                 last = current;
                 current = current.next;

                 if (result == null) {
                     result = propertyRef;
                     resultEnd = result;
                 } else {
                     resultEnd.next = propertyRef;
                     resultEnd = propertyRef;
                 }
             }
             mNodesBg[mFrameIndexBg] = result;
             ViewRef end = last;
             MAIN_EXECUTOR.execute(() -> addToPool(start, end));
             return true;
         }

         void attachToRoot() {
             if (mRoot.isAttachedToWindow()) {
                 mRoot.getViewTreeObserver().addOnDrawListener(this);
             } else {
                 mRoot.addOnAttachStateChangeListener(new OnAttachStateChangeListener() {
                     @Override
                     public void onViewAttachedToWindow(View v) {
                         if (!mDestroyed) {
                             mRoot.getViewTreeObserver().addOnDrawListener(WindowListener.this);
                         }
                         mRoot.removeOnAttachStateChangeListener(this);
                     }

                     @Override
                     public void onViewDetachedFromWindow(View v) { }
                 });
             }
         }

         void destroy() {
             mRoot.getViewTreeObserver().removeOnDrawListener(this);
             mDestroyed = true;
         }

         @WorkerThread
         private ExportedData dumpToProto(ViewIdProvider idProvider) {
             ExportedData.Builder dataBuilder = ExportedData.newBuilder();
             ArrayList<Class> classList = new ArrayList<>();

             int size = (mNodesBg[MEMORY_SIZE - 1] == null) ? mFrameIndexBg + 1 : MEMORY_SIZE;
             for (int i = size - 1; i >= 0; i--) {
                 int index = (MEMORY_SIZE + mFrameIndexBg - i) % MEMORY_SIZE;
                 ViewNode.Builder nodeBuilder = ViewNode.newBuilder();
                 mNodesBg[index].toProto(idProvider, classList, nodeBuilder);
                 dataBuilder.addFrameData(FrameData.newBuilder()
                         .setNode(nodeBuilder)
                         .setTimestamp(mFrameTimesBg[index]));
             }
             return dataBuilder
                     .addAllClassname(classList.stream().map(Class::getName).collect(toList()))
                     .build();
         }

         private ViewRef captureViewTree(View view, ViewRef start) {
             ViewRef ref;
             if (mPool != null) {
                 ref = mPool;
                 mPool = mPool.next;
                 ref.next = null;
             } else {
                 ref = new ViewRef();
             }
             ref.view = view;
             start.next = ref;
             if (view instanceof ViewGroup) {
                 ViewRef result = ref;
                 ViewGroup parent = (ViewGroup) view;
                 int childCount = ref.childCount = parent.getChildCount();
                 for (int i = 0; i < childCount; i++) {
                     result = captureViewTree(parent.getChildAt(i), result);
                 }
                 return result;
             } else {
                 ref.childCount = 0;
                 return ref;
             }
         }
     }

     private static class ViewPropertyRef {
         // We store reference in memory to avoid generating and storing too many strings
         public Class clazz;
         public int hashCode;
         public int childCount = 0;

         public int id;
         public int left, top, right, bottom;
         public int scrollX, scrollY;

         public float translateX, translateY;
         public float scaleX, scaleY;
         public float alpha;
         public float elevation;

         public int visibility;
         public boolean willNotDraw;
         public boolean clipChildren;

         public ViewPropertyRef next;

         public void transfer(ViewRef viewRef) {
             childCount = viewRef.childCount;

             View view = viewRef.view;
             viewRef.view = null;

             clazz = view.getClass();
             hashCode = view.hashCode();
             id = view.getId();
             left = view.getLeft();
             top = view.getTop();
             right = view.getRight();
             bottom = view.getBottom();
             scrollX = view.getScrollX();
             scrollY = view.getScrollY();

             translateX = view.getTranslationX();
             translateY = view.getTranslationY();
             scaleX = view.getScaleX();
             scaleY = view.getScaleY();
             alpha = view.getAlpha();

             visibility = view.getVisibility();
             willNotDraw = view.willNotDraw();
             elevation = view.getElevation();
         }

         /**
          * Converts the data to the proto representation and returns the next property ref
          * at the end of the iteration.
          * @return
          */
         public ViewPropertyRef toProto(ViewIdProvider idProvider, ArrayList<Class> classList,
                 ViewNode.Builder outBuilder) {
             int classnameIndex = classList.indexOf(clazz);
             if (classnameIndex < 0) {
                 classnameIndex = classList.size();
                 classList.add(clazz);
             }
             outBuilder
                     .setClassnameIndex(classnameIndex)
                     .setHashcode(hashCode)
                     .setId(idProvider.getName(id))
                     .setLeft(left)
                     .setTop(top)
                     .setWidth(right - left)
                     .setHeight(bottom - top)
                     .setTranslationX(translateX)
                     .setTranslationY(translateY)
                     .setScaleX(scaleX)
                     .setScaleY(scaleY)
                     .setAlpha(alpha)
                     .setVisibility(visibility)
                     .setWillNotDraw(willNotDraw)
                     .setElevation(elevation)
                     .setClipChildren(clipChildren);

             ViewPropertyRef result = next;
             for (int i = 0; (i < childCount) && (result != null); i++) {
                 ViewNode.Builder childBuilder = ViewNode.newBuilder();
                 result = result.toProto(idProvider, classList, childBuilder);
                 outBuilder.addChildren(childBuilder);
             }
             return result;
         }
     }

     private static class ViewRef {
         public View view;
         public int childCount = 0;
         public ViewRef next;
     }

     private static final class ViewIdProvider {

         private final SparseArray<String> mNames = new SparseArray<>();
         private final Resources mRes;

         ViewIdProvider(Resources res) {
             mRes = res;
         }

         String getName(int id) {
             String name = mNames.get(id);
             if (name == null) {
                 if (id >= 0) {
                     try {
                         name = mRes.getResourceTypeName(id) + '/' + mRes.getResourceEntryName(id);
                     } catch (Resources.NotFoundException e) {
                         name = "id/" + "0x" + Integer.toHexString(id).toUpperCase();
                     }
                 } else {
                     name = "NO_ID";
                 }
                 mNames.put(id, name);
             }
             return name;
         }
     }
 }
	/*
	* Copyright (C) 2022 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.launcher3.util;

	import static com.android.launcher3.util.Executors.MAIN_EXECUTOR;
	import static com.android.launcher3.util.Executors.UI_HELPER_EXECUTOR;
	import static com.android.launcher3.util.Executors.createAndStartNewLooper;

	import static java.util.stream.Collectors.toList;

	import android.content.Context;
	import android.content.res.Resources;
	import android.os.Handler;
	import android.os.Looper;
	import android.os.Message;
	import android.os.Process;
	import android.os.Trace;
	import android.text.TextUtils;
	import android.util.Base64;
	import android.util.Base64OutputStream;
	import android.util.Log;
	import android.util.Pair;
	import android.util.SparseArray;
	import android.view.View;
	import android.view.View.OnAttachStateChangeListener;
	import android.view.ViewGroup;
	import android.view.ViewTreeObserver.OnDrawListener;
	import android.view.Window;

	import androidx.annotation.UiThread;
	import androidx.annotation.WorkerThread;

	import com.android.launcher3.config.FeatureFlags;
	import com.android.launcher3.view.ViewCaptureData.ExportedData;
	import com.android.launcher3.view.ViewCaptureData.FrameData;
	import com.android.launcher3.view.ViewCaptureData.ViewNode;

	import java.io.FileDescriptor;
	import java.io.FileOutputStream;
	import java.io.OutputStream;
	import java.io.PrintWriter;
	import java.util.ArrayList;
	import java.util.List;
	import java.util.concurrent.Future;
	import java.util.zip.GZIPOutputStream;

	/**
	* Utility class for capturing view data every frame
	*/
	public class ViewCapture {

	private static final String TAG = "ViewCapture";

	// Number of frames to keep in memory
	private static final int MEMORY_SIZE = 2000;
	// Initial size of the reference pool. This is at least be 5 * total number of views in
	// Launcher. This allows the first free frames avoid object allocation during view capture.
	private static final int INIT_POOL_SIZE = 300;

	public static final MainThreadInitializedObject<ViewCapture> INSTANCE =
	new MainThreadInitializedObject<>(ViewCapture::new);

	private final List<WindowListener> mListeners = new ArrayList<>();

	private final Context mContext;
	private final LooperExecutor mExecutor;

	// Pool used for capturing view tree on the UI thread.
	private ViewRef mPool = new ViewRef();

	private ViewCapture(Context context) {
	mContext = context;
	if (FeatureFlags.CONTINUOUS_VIEW_TREE_CAPTURE.get()) {
	Looper looper = createAndStartNewLooper("ViewCapture",
	Process.THREAD_PRIORITY_FOREGROUND);
	mExecutor = new LooperExecutor(looper);
	mExecutor.execute(this::initPool);
	} else {
	mExecutor = UI_HELPER_EXECUTOR;
	}
	}

	@UiThread
	private void addToPool(ViewRef start, ViewRef end) {
	end.next = mPool;
	mPool = start;
	}

	@WorkerThread
	private void initPool() {
	ViewRef start = new ViewRef();
	ViewRef current = start;

	for (int i = 0; i < INIT_POOL_SIZE; i++) {
	current.next = new ViewRef();
	current = current.next;
	}

	ViewRef finalCurrent = current;
	MAIN_EXECUTOR.execute(() -> addToPool(start, finalCurrent));
	}

	/**
	* Attaches the ViewCapture to the provided window and returns a handle to detach the listener
	*/
	public SafeCloseable startCapture(Window window) {
	String title = window.getAttributes().getTitle().toString();
	String name = TextUtils.isEmpty(title) ? window.toString() : title;
	return startCapture(window.getDecorView(), name);
	}

	/**
	* Attaches the ViewCapture to the provided window and returns a handle to detach the listener
	*/
	public SafeCloseable startCapture(View view, String name) {
	if (!FeatureFlags.CONTINUOUS_VIEW_TREE_CAPTURE.get()) {
	return () -> { };
	}

	WindowListener listener = new WindowListener(view, name);
	mExecutor.execute(() -> MAIN_EXECUTOR.execute(listener::attachToRoot));
	mListeners.add(listener);
	return () -> {
	mListeners.remove(listener);
	listener.destroy();
	};
	}

	/**
	* Dumps all the active view captures
	*/
	public void dump(PrintWriter writer, FileDescriptor out) {
	if (!FeatureFlags.CONTINUOUS_VIEW_TREE_CAPTURE.get()) {
	return;
	}
	ViewIdProvider idProvider = new ViewIdProvider(mContext.getResources());

	// Collect all the tasks first so that all the tasks are posted on the executor
	List<Pair<String, Future<ExportedData>>> tasks = mListeners.stream()
	.map(l -> Pair.create(l.name, mExecutor.submit(() -> l.dumpToProto(idProvider))))
	.collect(toList());

	tasks.forEach(pair -> {
	writer.println();
	writer.println(" ContinuousViewCapture:");
	writer.println(" window " + pair.first + ":");
	writer.println(" pkg:" + mContext.getPackageName());
	writer.print(" data:");
	writer.flush();
	try (OutputStream os = new FileOutputStream(out)) {
	ExportedData data = pair.second.get();
	OutputStream encodedOS = new GZIPOutputStream(new Base64OutputStream(os,
	Base64.NO_CLOSE \| Base64.NO_PADDING \| Base64.NO_WRAP));
	data.writeTo(encodedOS);
	encodedOS.close();
	os.flush();
	} catch (Exception e) {
	Log.e(TAG, "Error capturing proto", e);
	}
	writer.println();
	writer.println("--end--");
	});
	}

	private class WindowListener implements OnDrawListener {

	private final View mRoot;
	public final String name;

	private final Handler mHandler;
	private final ViewRef mViewRef = new ViewRef();

	private int mFrameIndexBg = -1;
	private final long[] mFrameTimesBg = new long[MEMORY_SIZE];
	private final ViewPropertyRef[] mNodesBg = new ViewPropertyRef[MEMORY_SIZE];

	private boolean mDestroyed = false;

	WindowListener(View view, String name) {
	mRoot = view;
	this.name = name;
	mHandler = new Handler(mExecutor.getLooper(), this::captureViewPropertiesBg);
	}

	@Override
	public void onDraw() {
	Trace.beginSection("view_capture");
	captureViewTree(mRoot, mViewRef);
	Message m = Message.obtain(mHandler);
	m.obj = mViewRef.next;
	mHandler.sendMessage(m);
	Trace.endSection();
	}

	/**
	* Captures the View property on the background thread, and transfer all the ViewRef objects
	* back to the pool
	*/
	@WorkerThread
	private boolean captureViewPropertiesBg(Message msg) {
	ViewRef start = (ViewRef) msg.obj;
	long time = msg.getWhen();
	if (start == null) {
	return false;
	}
	mFrameIndexBg++;
	if (mFrameIndexBg >= MEMORY_SIZE) {
	mFrameIndexBg = 0;
	}
	mFrameTimesBg[mFrameIndexBg] = time;

	ViewPropertyRef recycle = mNodesBg[mFrameIndexBg];

	ViewPropertyRef result = null;
	ViewPropertyRef resultEnd = null;

	ViewRef current = start;
	ViewRef last = start;
	while (current != null) {
	ViewPropertyRef propertyRef = recycle;
	if (propertyRef == null) {
	propertyRef = new ViewPropertyRef();
	} else {
	recycle = recycle.next;
	propertyRef.next = null;
	}

	propertyRef.transfer(current);
	last = current;
	current = current.next;

	if (result == null) {
	result = propertyRef;
	resultEnd = result;
	} else {
	resultEnd.next = propertyRef;
	resultEnd = propertyRef;
	}
	}
	mNodesBg[mFrameIndexBg] = result;
	ViewRef end = last;
	MAIN_EXECUTOR.execute(() -> addToPool(start, end));
	return true;
	}

	void attachToRoot() {
	if (mRoot.isAttachedToWindow()) {
	mRoot.getViewTreeObserver().addOnDrawListener(this);
	} else {
	mRoot.addOnAttachStateChangeListener(new OnAttachStateChangeListener() {
	@Override
	public void onViewAttachedToWindow(View v) {
	if (!mDestroyed) {
	mRoot.getViewTreeObserver().addOnDrawListener(WindowListener.this);
	}
	mRoot.removeOnAttachStateChangeListener(this);
	}

	@Override
	public void onViewDetachedFromWindow(View v) { }
	});
	}
	}

	void destroy() {
	mRoot.getViewTreeObserver().removeOnDrawListener(this);
	mDestroyed = true;
	}

	@WorkerThread
	private ExportedData dumpToProto(ViewIdProvider idProvider) {
	ExportedData.Builder dataBuilder = ExportedData.newBuilder();
	ArrayList<Class> classList = new ArrayList<>();

	int size = (mNodesBg[MEMORY_SIZE - 1] == null) ? mFrameIndexBg + 1 : MEMORY_SIZE;
	for (int i = size - 1; i >= 0; i--) {
	int index = (MEMORY_SIZE + mFrameIndexBg - i) % MEMORY_SIZE;
	ViewNode.Builder nodeBuilder = ViewNode.newBuilder();
	mNodesBg[index].toProto(idProvider, classList, nodeBuilder);
	dataBuilder.addFrameData(FrameData.newBuilder()
	.setNode(nodeBuilder)
	.setTimestamp(mFrameTimesBg[index]));
	}
	return dataBuilder
	.addAllClassname(classList.stream().map(Class::getName).collect(toList()))
	.build();
	}

	private ViewRef captureViewTree(View view, ViewRef start) {
	ViewRef ref;
	if (mPool != null) {
	ref = mPool;
	mPool = mPool.next;
	ref.next = null;
	} else {
	ref = new ViewRef();
	}
	ref.view = view;
	start.next = ref;
	if (view instanceof ViewGroup) {
	ViewRef result = ref;
	ViewGroup parent = (ViewGroup) view;
	int childCount = ref.childCount = parent.getChildCount();
	for (int i = 0; i < childCount; i++) {
	result = captureViewTree(parent.getChildAt(i), result);
	}
	return result;
	} else {
	ref.childCount = 0;
	return ref;
	}
	}
	}

	private static class ViewPropertyRef {
	// We store reference in memory to avoid generating and storing too many strings
	public Class clazz;
	public int hashCode;
	public int childCount = 0;

	public int id;
	public int left, top, right, bottom;
	public int scrollX, scrollY;

	public float translateX, translateY;
	public float scaleX, scaleY;
	public float alpha;
	public float elevation;

	public int visibility;
	public boolean willNotDraw;
	public boolean clipChildren;

	public ViewPropertyRef next;

	public void transfer(ViewRef viewRef) {
	childCount = viewRef.childCount;

	View view = viewRef.view;
	viewRef.view = null;

	clazz = view.getClass();
	hashCode = view.hashCode();
	id = view.getId();
	left = view.getLeft();
	top = view.getTop();
	right = view.getRight();
	bottom = view.getBottom();
	scrollX = view.getScrollX();
	scrollY = view.getScrollY();

	translateX = view.getTranslationX();
	translateY = view.getTranslationY();
	scaleX = view.getScaleX();
	scaleY = view.getScaleY();
	alpha = view.getAlpha();

	visibility = view.getVisibility();
	willNotDraw = view.willNotDraw();
	elevation = view.getElevation();
	}

	/**
	* Converts the data to the proto representation and returns the next property ref
	* at the end of the iteration.
	* @return
	*/
	public ViewPropertyRef toProto(ViewIdProvider idProvider, ArrayList<Class> classList,
	ViewNode.Builder outBuilder) {
	int classnameIndex = classList.indexOf(clazz);
	if (classnameIndex < 0) {
	classnameIndex = classList.size();
	classList.add(clazz);
	}
	outBuilder
	.setClassnameIndex(classnameIndex)
	.setHashcode(hashCode)
	.setId(idProvider.getName(id))
	.setLeft(left)
	.setTop(top)
	.setWidth(right - left)
	.setHeight(bottom - top)
	.setTranslationX(translateX)
	.setTranslationY(translateY)
	.setScaleX(scaleX)
	.setScaleY(scaleY)
	.setAlpha(alpha)
	.setVisibility(visibility)
	.setWillNotDraw(willNotDraw)
	.setElevation(elevation)
	.setClipChildren(clipChildren);

	ViewPropertyRef result = next;
	for (int i = 0; (i < childCount) && (result != null); i++) {
	ViewNode.Builder childBuilder = ViewNode.newBuilder();
	result = result.toProto(idProvider, classList, childBuilder);
	outBuilder.addChildren(childBuilder);
	}
	return result;
	}
	}

	private static class ViewRef {
	public View view;
	public int childCount = 0;
	public ViewRef next;
	}

	private static final class ViewIdProvider {

	private final SparseArray<String> mNames = new SparseArray<>();
	private final Resources mRes;

	ViewIdProvider(Resources res) {
	mRes = res;
	}

	String getName(int id) {
	String name = mNames.get(id);
	if (name == null) {
	if (id >= 0) {
	try {
	name = mRes.getResourceTypeName(id) + '/' + mRes.getResourceEntryName(id);
	} catch (Resources.NotFoundException e) {
	name = "id/" + "0x" + Integer.toHexString(id).toUpperCase();
	}
	} else {
	name = "NO_ID";
	}
	mNames.put(id, name);
	}
	return name;
	}
	}
	}