path: root/core/java/android/app/AssistStructure.java

/*
 * Copyright (C) 2015 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 android.app;

import android.content.ComponentName;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Typeface;
import android.os.Binder;
import android.os.Bundle;
import android.os.IBinder;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.PooledStringReader;
import android.os.PooledStringWriter;
import android.os.RemoteException;
import android.os.SystemClock;
import android.text.TextPaint;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.view.ViewAssistStructure;
import android.view.ViewRootImpl;
import android.view.WindowManager;
import android.view.WindowManagerGlobal;

import java.util.ArrayList;

/**
 * Assist data automatically created by the platform's implementation
 * of {@link Activity#onProvideAssistData}.
 */
final public class AssistStructure implements Parcelable {
    static final String TAG = "AssistStructure";

    /**
     * @hide
     * Key name this data structure is stored in the Bundle generated by
     * {@link Activity#onProvideAssistData}.
     */
    public static final String ASSIST_KEY = "android:assist_structure";

    boolean mHaveData;

    ComponentName mActivityComponent;

    final ArrayList<WindowNode> mWindowNodes = new ArrayList<>();

    final ArrayList<ViewNodeBuilder> mPendingAsyncChildren = new ArrayList<>();

    SendChannel mSendChannel;
    IBinder mReceiveChannel;

    Rect mTmpRect = new Rect();

    static final int TRANSACTION_XFER = Binder.FIRST_CALL_TRANSACTION+1;
    static final String DESCRIPTOR = "android.app.AssistStructure";

    final class SendChannel extends Binder {
        @Override protected boolean onTransact(int code, Parcel data, Parcel reply, int flags)
                throws RemoteException {
            if (code == TRANSACTION_XFER) {
                data.enforceInterface(DESCRIPTOR);
                writeContentToParcel(reply, Parcelable.PARCELABLE_WRITE_RETURN_VALUE);
                return true;
            } else {
                return super.onTransact(code, data, reply, flags);
            }
        }
    }

    final static class ViewNodeText {
        CharSequence mText;
        int mTextSelectionStart;
        int mTextSelectionEnd;
        int mTextColor;
        int mTextBackgroundColor;
        float mTextSize;
        int mTextStyle;
        String mHint;

        ViewNodeText() {
        }

        ViewNodeText(Parcel in) {
            mText = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(in);
            mTextSelectionStart = in.readInt();
            mTextSelectionEnd = in.readInt();
            mTextColor = in.readInt();
            mTextBackgroundColor = in.readInt();
            mTextSize = in.readFloat();
            mTextStyle = in.readInt();
            mHint = in.readString();
        }

        void writeToParcel(Parcel out) {
            TextUtils.writeToParcel(mText, out, 0);
            out.writeInt(mTextSelectionStart);
            out.writeInt(mTextSelectionEnd);
            out.writeInt(mTextColor);
            out.writeInt(mTextBackgroundColor);
            out.writeFloat(mTextSize);
            out.writeInt(mTextStyle);
            out.writeString(mHint);
        }
    }

    /**
     * Describes a window in the assist data.
     */
    static public class WindowNode {
        final int mX;
        final int mY;
        final int mWidth;
        final int mHeight;
        final CharSequence mTitle;
        final ViewNode mRoot;

        WindowNode(AssistStructure assist, ViewRootImpl root) {
            View view = root.getView();
            Rect rect = new Rect();
            view.getBoundsOnScreen(rect);
            mX = rect.left - view.getLeft();
            mY = rect.top - view.getTop();
            mWidth = rect.width();
            mHeight = rect.height();
            mTitle = root.getTitle();
            mRoot = new ViewNode();
            ViewNodeBuilder builder = new ViewNodeBuilder(assist, mRoot, false);
            if ((root.getWindowFlags()&WindowManager.LayoutParams.FLAG_SECURE) != 0) {
                // This is a secure window, so it doesn't want a screenshot, and that
                // means we should also not copy out its view hierarchy.
                view.onProvideStructure(builder);
                builder.setAssistBlocked(true);
                return;
            }
            view.dispatchProvideStructure(builder);
        }

        WindowNode(Parcel in, PooledStringReader preader) {
            mX = in.readInt();
            mY = in.readInt();
            mWidth = in.readInt();
            mHeight = in.readInt();
            mTitle = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(in);
            mRoot = new ViewNode(in, preader);
        }

        void writeToParcel(Parcel out, PooledStringWriter pwriter) {
            out.writeInt(mX);
            out.writeInt(mY);
            out.writeInt(mWidth);
            out.writeInt(mHeight);
            TextUtils.writeToParcel(mTitle, out, 0);
            mRoot.writeToParcel(out, pwriter);
        }

        public int getLeft() {
            return mX;
        }

        public int getTop() {
            return mY;
        }

        public int getWidth() {
            return mWidth;
        }

        public int getHeight() {
            return mHeight;
        }

        public CharSequence getTitle() {
            return mTitle;
        }

        public ViewNode getRootViewNode() {
            return mRoot;
        }
    }

    /**
     * Describes a single view in the assist data.
     */
    static public class ViewNode {
        /**
         * Magic value for text color that has not been defined, which is very unlikely
         * to be confused with a real text color.
         */
        public static final int TEXT_COLOR_UNDEFINED = 1;

        public static final int TEXT_STYLE_BOLD = 1<<0;
        public static final int TEXT_STYLE_ITALIC = 1<<1;
        public static final int TEXT_STYLE_UNDERLINE = 1<<2;
        public static final int TEXT_STYLE_STRIKE_THRU = 1<<3;

        int mId;
        String mIdPackage;
        String mIdType;
        String mIdEntry;
        int mX;
        int mY;
        int mScrollX;
        int mScrollY;
        int mWidth;
        int mHeight;

        static final int FLAGS_DISABLED = 0x00000001;
        static final int FLAGS_VISIBILITY_MASK = View.VISIBLE|View.INVISIBLE|View.GONE;
        static final int FLAGS_FOCUSABLE = 0x00000010;
        static final int FLAGS_FOCUSED = 0x00000020;
        static final int FLAGS_ACCESSIBILITY_FOCUSED = 0x04000000;
        static final int FLAGS_SELECTED = 0x00000040;
        static final int FLAGS_ASSIST_BLOCKED = 0x00000080;
        static final int FLAGS_ACTIVATED = 0x40000000;
        static final int FLAGS_CHECKABLE = 0x00000100;
        static final int FLAGS_CHECKED = 0x00000200;
        static final int FLAGS_CLICKABLE = 0x00004000;
        static final int FLAGS_LONG_CLICKABLE = 0x00200000;
        static final int FLAGS_STYLUS_BUTTON_PRESSABLE = 0x00400000;

        int mFlags;

        String mClassName;
        CharSequence mContentDescription;

        ViewNodeText mText;
        Bundle mExtras;

        ViewNode[] mChildren;

        ViewNode() {
        }

        ViewNode(Parcel in, PooledStringReader preader) {
            mId = in.readInt();
            if (mId != 0) {
                mIdEntry = preader.readString();
                if (mIdEntry != null) {
                    mIdType = preader.readString();
                    mIdPackage = preader.readString();
                } else {
                    mIdPackage = mIdType = null;
                }
            } else {
                mIdPackage = mIdType = mIdEntry = null;
            }
            mX = in.readInt();
            mY = in.readInt();
            mScrollX = in.readInt();
            mScrollY = in.readInt();
            mWidth = in.readInt();
            mHeight = in.readInt();
            mFlags = in.readInt();
            mClassName = preader.readString();
            mContentDescription = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(in);
            if (in.readInt() != 0) {
                mText = new ViewNodeText(in);
            } else {
                mText = null;
            }
            mExtras = in.readBundle();
            final int NCHILDREN = in.readInt();
            if (NCHILDREN > 0) {
                mChildren = new ViewNode[NCHILDREN];
                for (int i=0; i<NCHILDREN; i++) {
                    mChildren[i] = new ViewNode(in, preader);
                }
            } else {
                mChildren = null;
            }
        }

        void writeToParcel(Parcel out, PooledStringWriter pwriter) {
            out.writeInt(mId);
            if (mId != 0) {
                pwriter.writeString(mIdEntry);
                if (mIdEntry != null) {
                    pwriter.writeString(mIdType);
                    pwriter.writeString(mIdPackage);
                }
            }
            out.writeInt(mX);
            out.writeInt(mY);
            out.writeInt(mScrollX);
            out.writeInt(mScrollY);
            out.writeInt(mWidth);
            out.writeInt(mHeight);
            out.writeInt(mFlags);
            pwriter.writeString(mClassName);
            TextUtils.writeToParcel(mContentDescription, out, 0);
            if (mText != null) {
                out.writeInt(1);
                mText.writeToParcel(out);
            } else {
                out.writeInt(0);
            }
            out.writeBundle(mExtras);
            if (mChildren != null) {
                final int NCHILDREN = mChildren.length;
                out.writeInt(NCHILDREN);
                for (int i=0; i<NCHILDREN; i++) {
                    mChildren[i].writeToParcel(out, pwriter);
                }
            } else {
                out.writeInt(0);
            }
        }

        public int getId() {
            return mId;
        }

        public String getIdPackage() {
            return mIdPackage;
        }

        public String getIdType() {
            return mIdType;
        }

        public String getIdEntry() {
            return mIdEntry;
        }

        public int getLeft() {
            return mX;
        }

        public int getTop() {
            return mY;
        }

        public int getScrollX() {
            return mScrollX;
        }

        public int getScrollY() {
            return mScrollY;
        }

        public int getWidth() {
            return mWidth;
        }

        public int getHeight() {
            return mHeight;
        }

        public int getVisibility() {
            return mFlags&ViewNode.FLAGS_VISIBILITY_MASK;
        }

        public boolean isAssistBlocked() {
            return (mFlags&ViewNode.FLAGS_ASSIST_BLOCKED) == 0;
        }

        public boolean isEnabled() {
            return (mFlags&ViewNode.FLAGS_DISABLED) == 0;
        }

        public boolean isClickable() {
            return (mFlags&ViewNode.FLAGS_CLICKABLE) != 0;
        }

        public boolean isFocusable() {
            return (mFlags&ViewNode.FLAGS_FOCUSABLE) != 0;
        }

        public boolean isFocused() {
            return (mFlags&ViewNode.FLAGS_FOCUSED) != 0;
        }

        public boolean isAccessibilityFocused() {
            return (mFlags&ViewNode.FLAGS_ACCESSIBILITY_FOCUSED) != 0;
        }

        public boolean isCheckable() {
            return (mFlags&ViewNode.FLAGS_CHECKABLE) != 0;
        }

        public boolean isChecked() {
            return (mFlags&ViewNode.FLAGS_CHECKED) != 0;
        }

        public boolean isSelected() {
            return (mFlags&ViewNode.FLAGS_SELECTED) != 0;
        }

        public boolean isActivated() {
            return (mFlags&ViewNode.FLAGS_ACTIVATED) != 0;
        }

        public boolean isLongClickable() {
            return (mFlags&ViewNode.FLAGS_LONG_CLICKABLE) != 0;
        }

        public boolean isStylusButtonPressable() {
            return (mFlags&ViewNode.FLAGS_STYLUS_BUTTON_PRESSABLE) != 0;
        }

        public String getClassName() {
            return mClassName;
        }

        public CharSequence getContentDescription() {
            return mContentDescription;
        }

        public CharSequence getText() {
            return mText != null ? mText.mText : null;
        }

        public int getTextSelectionStart() {
            return mText != null ? mText.mTextSelectionStart : -1;
        }

        public int getTextSelectionEnd() {
            return mText != null ? mText.mTextSelectionEnd : -1;
        }

        public int getTextColor() {
            return mText != null ? mText.mTextColor : TEXT_COLOR_UNDEFINED;
        }

        public int getTextBackgroundColor() {
            return mText != null ? mText.mTextBackgroundColor : TEXT_COLOR_UNDEFINED;
        }

        public float getTextSize() {
            return mText != null ? mText.mTextSize : 0;
        }

        public int getTextStyle() {
            return mText != null ? mText.mTextStyle : 0;
        }

        public String getHint() {
            return mText != null ? mText.mHint : null;
        }

        public Bundle getExtras() {
            return mExtras;
        }

        public int getChildCount() {
            return mChildren != null ? mChildren.length : 0;
        }

        public ViewNode getChildAt(int index) {
            return mChildren[index];
        }
    }

    static class ViewNodeBuilder extends ViewAssistStructure {
        final AssistStructure mAssist;
        final ViewNode mNode;
        final boolean mAsync;

        ViewNodeBuilder(AssistStructure assist, ViewNode node, boolean async) {
            mAssist = assist;
            mNode = node;
            mAsync = async;
        }

        @Override
        public void setId(int id, String packageName, String typeName, String entryName) {
            mNode.mId = id;
            mNode.mIdPackage = packageName;
            mNode.mIdType = typeName;
            mNode.mIdEntry = entryName;
        }

        @Override
        public void setDimens(int left, int top, int scrollX, int scrollY, int width, int height) {
            mNode.mX = left;
            mNode.mY = top;
            mNode.mScrollX = scrollX;
            mNode.mScrollY = scrollY;
            mNode.mWidth = width;
            mNode.mHeight = height;
        }

        @Override
        public void setVisibility(int visibility) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_VISIBILITY_MASK) | visibility;
        }

        @Override
        public void setAssistBlocked(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_ASSIST_BLOCKED)
                    | (state ? 0 : ViewNode.FLAGS_ASSIST_BLOCKED);
        }

        @Override
        public void setEnabled(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_DISABLED)
                    | (state ? 0 : ViewNode.FLAGS_DISABLED);
        }

        @Override
        public void setClickable(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_CLICKABLE)
                    | (state ? ViewNode.FLAGS_CLICKABLE : 0);
        }

        @Override
        public void setLongClickable(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_LONG_CLICKABLE)
                    | (state ? ViewNode.FLAGS_LONG_CLICKABLE : 0);
        }

        @Override
        public void setStylusButtonPressable(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_STYLUS_BUTTON_PRESSABLE)
                    | (state ? ViewNode.FLAGS_STYLUS_BUTTON_PRESSABLE : 0);
        }

        @Override
        public void setFocusable(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_FOCUSABLE)
                    | (state ? ViewNode.FLAGS_FOCUSABLE : 0);
        }

        @Override
        public void setFocused(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_FOCUSED)
                    | (state ? ViewNode.FLAGS_FOCUSED : 0);
        }

        @Override
        public void setAccessibilityFocused(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_ACCESSIBILITY_FOCUSED)
                    | (state ? ViewNode.FLAGS_ACCESSIBILITY_FOCUSED : 0);
        }

        @Override
        public void setCheckable(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_CHECKABLE)
                    | (state ? ViewNode.FLAGS_CHECKABLE : 0);
        }

        @Override
        public void setChecked(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_CHECKED)
                    | (state ? ViewNode.FLAGS_CHECKED : 0);
        }

        @Override
        public void setSelected(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_SELECTED)
                    | (state ? ViewNode.FLAGS_SELECTED : 0);
        }

        @Override
        public void setActivated(boolean state) {
            mNode.mFlags = (mNode.mFlags&~ViewNode.FLAGS_ACTIVATED)
                    | (state ? ViewNode.FLAGS_ACTIVATED : 0);
        }

        @Override
        public void setClassName(String className) {
            mNode.mClassName = className;
        }

        @Override
        public void setContentDescription(CharSequence contentDescription) {
            mNode.mContentDescription = contentDescription;
        }

        private final ViewNodeText getNodeText() {
            if (mNode.mText != null) {
                return mNode.mText;
            }
            mNode.mText = new ViewNodeText();
            return mNode.mText;
        }

        @Override
        public void setText(CharSequence text) {
            ViewNodeText t = getNodeText();
            t.mText = text;
            t.mTextSelectionStart = t.mTextSelectionEnd = -1;
        }

        @Override
        public void setText(CharSequence text, int selectionStart, int selectionEnd) {
            ViewNodeText t = getNodeText();
            t.mText = text;
            t.mTextSelectionStart = selectionStart;
            t.mTextSelectionEnd = selectionEnd;
        }

        @Override
        public void setTextStyle(float size, int fgColor, int bgColor, int style) {
            ViewNodeText t = getNodeText();
            t.mTextColor = fgColor;
            t.mTextBackgroundColor = bgColor;
            t.mTextSize = size;
            t.mTextStyle = style;
        }

        @Override
        public void setHint(CharSequence hint) {
            getNodeText().mHint = hint != null ? hint.toString() : null;
        }

        @Override
        public CharSequence getText() {
            return mNode.mText != null ? mNode.mText.mText : null;
        }

        @Override
        public int getTextSelectionStart() {
            return mNode.mText != null ? mNode.mText.mTextSelectionStart : -1;
        }

        @Override
        public int getTextSelectionEnd() {
            return mNode.mText != null ? mNode.mText.mTextSelectionEnd : -1;
        }

        @Override
        public CharSequence getHint() {
            return mNode.mText != null ? mNode.mText.mHint : null;
        }

        @Override
        public Bundle getExtras() {
            if (mNode.mExtras != null) {
                return mNode.mExtras;
            }
            mNode.mExtras = new Bundle();
            return mNode.mExtras;
        }

        @Override
        public boolean hasExtras() {
            return mNode.mExtras != null;
        }

        @Override
        public void setChildCount(int num) {
            mNode.mChildren = new ViewNode[num];
        }

        @Override
        public int getChildCount() {
            return mNode.mChildren != null ? mNode.mChildren.length : 0;
        }

        @Override
        public ViewAssistStructure newChild(int index) {
            ViewNode node = new ViewNode();
            mNode.mChildren[index] = node;
            return new ViewNodeBuilder(mAssist, node, false);
        }

        @Override
        public ViewAssistStructure asyncNewChild(int index) {
            synchronized (mAssist) {
                ViewNode node = new ViewNode();
                mNode.mChildren[index] = node;
                ViewNodeBuilder builder = new ViewNodeBuilder(mAssist, node, true);
                mAssist.mPendingAsyncChildren.add(builder);
                return builder;
            }
        }

        @Override
        public void asyncCommit() {
            synchronized (mAssist) {
                if (!mAsync) {
                    throw new IllegalStateException("Child " + this
                            + " was not created with ViewAssistStructure.asyncNewChild");
                }
                if (!mAssist.mPendingAsyncChildren.remove(this)) {
                    throw new IllegalStateException("Child " + this + " already committed");
                }
                mAssist.notifyAll();
            }
        }

        @Override
        public Rect getTempRect() {
            return mAssist.mTmpRect;
        }
    }

    AssistStructure(Activity activity) {
        mHaveData = true;
        mActivityComponent = activity.getComponentName();
        ArrayList<ViewRootImpl> views = WindowManagerGlobal.getInstance().getRootViews(
                activity.getActivityToken());
        for (int i=0; i<views.size(); i++) {
            ViewRootImpl root = views.get(i);
            mWindowNodes.add(new WindowNode(this, root));
        }
    }

    AssistStructure() {
        mHaveData = true;
        mActivityComponent = null;
    }

    AssistStructure(Parcel in) {
        mReceiveChannel = in.readStrongBinder();
    }

    /** @hide */
    public void dump() {
        Log.i(TAG, "Activity: " + mActivityComponent.flattenToShortString());
        final int N = getWindowNodeCount();
        for (int i=0; i<N; i++) {
            WindowNode node = getWindowNodeAt(i);
            Log.i(TAG, "Window #" + i + " [" + node.getLeft() + "," + node.getTop()
                    + " " + node.getWidth() + "x" + node.getHeight() + "]" + " " + node.getTitle());
            dump("  ", node.getRootViewNode());
        }
    }

    void dump(String prefix, ViewNode node) {
        Log.i(TAG, prefix + "View [" + node.getLeft() + "," + node.getTop()
                + " " + node.getWidth() + "x" + node.getHeight() + "]" + " " + node.getClassName());
        int id = node.getId();
        if (id != 0) {
            StringBuilder sb = new StringBuilder();
            sb.append(prefix); sb.append("  ID: #"); sb.append(Integer.toHexString(id));
            String entry = node.getIdEntry();
            if (entry != null) {
                String type = node.getIdType();
                String pkg = node.getIdPackage();
                sb.append(" "); sb.append(pkg); sb.append(":"); sb.append(type);
                sb.append("/"); sb.append(entry);
            }
            Log.i(TAG, sb.toString());
        }
        int scrollX = node.getScrollX();
        int scrollY = node.getScrollY();
        if (scrollX != 0 || scrollY != 0) {
            Log.i(TAG, prefix + "  Scroll: " + scrollX + "," + scrollY);
        }
        CharSequence contentDescription = node.getContentDescription();
        if (contentDescription != null) {
            Log.i(TAG, prefix + "  Content description: " + contentDescription);
        }
        CharSequence text = node.getText();
        if (text != null) {
            Log.i(TAG, prefix + "  Text (sel " + node.getTextSelectionStart() + "-"
                    + node.getTextSelectionEnd() + "): " + text);
            Log.i(TAG, prefix + "  Text size: " + node.getTextSize() + " , style: #"
                    + node.getTextStyle());
            Log.i(TAG, prefix + "  Text color fg: #" + Integer.toHexString(node.getTextColor())
                    + ", bg: #" + Integer.toHexString(node.getTextBackgroundColor()));
        }
        String hint = node.getHint();
        if (hint != null) {
            Log.i(TAG, prefix + "  Hint: " + hint);
        }
        Bundle extras = node.getExtras();
        if (extras != null) {
            Log.i(TAG, prefix + "  Extras: " + extras);
        }
        final int NCHILDREN = node.getChildCount();
        if (NCHILDREN > 0) {
            Log.i(TAG, prefix + "  Children:");
            String cprefix = prefix + "    ";
            for (int i=0; i<NCHILDREN; i++) {
                ViewNode cnode = node.getChildAt(i);
                dump(cprefix, cnode);
            }
        }
    }

    /**
     * @hide
     * Retrieve the framework-generated AssistStructure that is stored within
     * the Bundle filled in by {@link Activity#onProvideAssistData}.
     */
    public static AssistStructure getAssistStructure(Bundle assistBundle) {
        return assistBundle.getParcelable(ASSIST_KEY);
    }

    public ComponentName getActivityComponent() {
        ensureData();
        return mActivityComponent;
    }

    /**
     * Return the number of window contents that have been collected in this assist data.
     */
    public int getWindowNodeCount() {
        ensureData();
        return mWindowNodes.size();
    }

    /**
     * Return one of the windows in the assist data.
     * @param index Which window to retrieve, may be 0 to {@link #getWindowNodeCount()}-1.
     */
    public WindowNode getWindowNodeAt(int index) {
        ensureData();
        return mWindowNodes.get(index);
    }

    public int describeContents() {
        return 0;
    }

    /** @hide */
    public void ensureData() {
        if (mHaveData) {
            return;
        }
        mHaveData = true;
        Parcel data = Parcel.obtain();
        Parcel reply = Parcel.obtain();
        data.writeInterfaceToken(DESCRIPTOR);
        try {
            mReceiveChannel.transact(TRANSACTION_XFER, data, reply, 0);
        } catch (RemoteException e) {
            Log.w(TAG, "Failure reading AssistStructure data", e);
            return;
        }
        readContentFromParcel(reply);
        data.recycle();
        reply.recycle();
    }

    void writeContentToParcel(Parcel out, int flags) {
        // First make sure all content has been created.
        boolean skipStructure = false;
        synchronized (this) {
            long endTime = SystemClock.uptimeMillis() + 5000;
            long now;
            while (mPendingAsyncChildren.size() > 0 && (now=SystemClock.uptimeMillis()) < endTime) {
                try {
                    wait(endTime-now);
                } catch (InterruptedException e) {
                }
            }
            if (mPendingAsyncChildren.size() > 0) {
                // We waited too long, assume none of the assist structure is valid.
                skipStructure = true;
            }
        }
        int start = out.dataPosition();
        PooledStringWriter pwriter = new PooledStringWriter(out);
        ComponentName.writeToParcel(mActivityComponent, out);
        final int N = skipStructure ? 0 : mWindowNodes.size();
        out.writeInt(N);
        for (int i=0; i<N; i++) {
            mWindowNodes.get(i).writeToParcel(out, pwriter);
        }
        pwriter.finish();
        Log.i(TAG, "Flattened assist data: " + (out.dataPosition() - start) + " bytes");
    }

    void readContentFromParcel(Parcel in) {
        PooledStringReader preader = new PooledStringReader(in);
        mActivityComponent = ComponentName.readFromParcel(in);
        final int N = in.readInt();
        for (int i=0; i<N; i++) {
            mWindowNodes.add(new WindowNode(in, preader));
        }
        //dump();
    }

    public void writeToParcel(Parcel out, int flags) {
        if (mHaveData) {
            // This object holds its data.  We want to write a send channel that the
            // other side can use to retrieve that data.
            if (mSendChannel == null) {
                mSendChannel = new SendChannel();
            }
            out.writeStrongBinder(mSendChannel);
        } else {
            // This object doesn't hold its data, so just propagate along its receive channel.
            out.writeStrongBinder(mReceiveChannel);
        }
    }

    public static final Parcelable.Creator<AssistStructure> CREATOR
            = new Parcelable.Creator<AssistStructure>() {
        public AssistStructure createFromParcel(Parcel in) {
            return new AssistStructure(in);
        }

        public AssistStructure[] newArray(int size) {
            return new AssistStructure[size];
        }
    };
}