LatinIME/java/src/com/android/inputmethod/keyboard/KeyboardView.java

/*
 * Copyright (C) 2010 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.inputmethod.keyboard;

import com.android.inputmethod.latin.LatinImeLogger;
import com.android.inputmethod.latin.R;
import com.android.inputmethod.latin.SubtypeSwitcher;

import android.content.Context;
import android.content.pm.PackageManager;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.graphics.PorterDuff;
import android.graphics.Rect;
import android.graphics.Region.Op;
import android.graphics.Typeface;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.GestureDetector;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.view.WindowManager;
import android.widget.PopupWindow;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.WeakHashMap;

/**
 * A view that renders a virtual {@link Keyboard}. It handles rendering of keys and detecting key
 * presses and touch movements.
 *
 * @attr ref R.styleable#KeyboardView_keyBackground
 * @attr ref R.styleable#KeyboardView_keyPreviewLayout
 * @attr ref R.styleable#KeyboardView_keyPreviewOffset
 * @attr ref R.styleable#KeyboardView_labelTextSize
 * @attr ref R.styleable#KeyboardView_keyTextSize
 * @attr ref R.styleable#KeyboardView_keyTextColor
 * @attr ref R.styleable#KeyboardView_verticalCorrection
 * @attr ref R.styleable#KeyboardView_popupLayout
 */
public class KeyboardView extends View implements PointerTracker.UIProxy {
    private static final String TAG = "KeyboardView";
    private static final boolean DEBUG = false;
    private static final boolean DEBUG_SHOW_ALIGN = false;
    private static final boolean DEBUG_KEYBOARD_GRID = false;

    private static final boolean ENABLE_CAPSLOCK_BY_LONGPRESS = false;
    private static final boolean ENABLE_CAPSLOCK_BY_DOUBLETAP = true;

    public static final int COLOR_SCHEME_WHITE = 0;
    public static final int COLOR_SCHEME_BLACK = 1;

    public static final int NOT_A_TOUCH_COORDINATE = -1;

    // Timing constants
    private final int mKeyRepeatInterval;

    // Miscellaneous constants
    private static final int[] LONG_PRESSABLE_STATE_SET = { android.R.attr.state_long_pressable };
    private static final int HINT_ICON_VERTICAL_ADJUSTMENT_PIXEL = -1;

    // XML attribute
    private int mKeyLetterSize;
    private int mKeyTextColor;
    private int mKeyTextColorDisabled;
    private Typeface mKeyLetterStyle = Typeface.DEFAULT;
    private int mLabelTextSize;
    private int mColorScheme = COLOR_SCHEME_WHITE;
    private int mShadowColor;
    private float mShadowRadius;
    private Drawable mKeyBackground;
    private float mBackgroundDimAmount;
    private float mKeyHysteresisDistance;
    private float mVerticalCorrection;
    private int mPreviewOffset;
    private int mPreviewHeight;
    private int mPopupLayout;

    // Main keyboard
    private Keyboard mKeyboard;
    private Key[] mKeys;

    // Key preview popup
    private boolean mInForeground;
    private TextView mPreviewText;
    private PopupWindow mPreviewPopup;
    private int mPreviewTextSizeLarge;
    private int[] mOffsetInWindow;
    private int mOldPreviewKeyIndex = KeyDetector.NOT_A_KEY;
    private boolean mShowPreview = true;
    private boolean mShowTouchPoints = true;
    private int mPopupPreviewOffsetX;
    private int mPopupPreviewOffsetY;
    private int mWindowY;
    private int mPopupPreviewDisplayedY;
    private final int mDelayBeforePreview;
    private final int mDelayAfterPreview;

    // Popup mini keyboard
    private PopupWindow mMiniKeyboardPopup;
    private KeyboardView mMiniKeyboard;
    private View mMiniKeyboardParent;
    private final WeakHashMap<Key, View> mMiniKeyboardCache = new WeakHashMap<Key, View>();
    private int mMiniKeyboardOriginX;
    private int mMiniKeyboardOriginY;
    private long mMiniKeyboardPopupTime;
    private int[] mWindowOffset;
    private final float mMiniKeyboardSlideAllowance;
    private int mMiniKeyboardTrackerId;

    /** Listener for {@link KeyboardActionListener}. */
    private KeyboardActionListener mKeyboardActionListener;

    private final ArrayList<PointerTracker> mPointerTrackers = new ArrayList<PointerTracker>();

    // TODO: Let the PointerTracker class manage this pointer queue
    private final PointerTrackerQueue mPointerQueue = new PointerTrackerQueue();

    private final boolean mHasDistinctMultitouch;
    private int mOldPointerCount = 1;

    protected KeyDetector mKeyDetector = new ProximityKeyDetector();

    // Swipe gesture detector
    private GestureDetector mGestureDetector;
    private final SwipeTracker mSwipeTracker = new SwipeTracker();
    private final int mSwipeThreshold;
    private final boolean mDisambiguateSwipe;

    // Drawing
    /** Whether the keyboard bitmap needs to be redrawn before it's blitted. **/
    private boolean mDrawPending;
    /** The dirty region in the keyboard bitmap */
    private final Rect mDirtyRect = new Rect();
    /** The keyboard bitmap for faster updates */
    private Bitmap mBuffer;
    /** Notes if the keyboard just changed, so that we could possibly reallocate the mBuffer. */
    private boolean mKeyboardChanged;
    private Key mInvalidatedKey;
    /** The canvas for the above mutable keyboard bitmap */
    private Canvas mCanvas;
    private final Paint mPaint;
    private final Rect mPadding;
    private final Rect mClipRegion = new Rect(0, 0, 0, 0);
    // This map caches key label text height in pixel as value and key label text size as map key.
    private final HashMap<Integer, Integer> mTextHeightCache = new HashMap<Integer, Integer>();
    // Distance from horizontal center of the key, proportional to key label text height and width.
    private final float KEY_LABEL_VERTICAL_ADJUSTMENT_FACTOR_CENTER = 0.45f;
    private final float KEY_LABEL_VERTICAL_PADDING_FACTOR = 1.60f;
    private final String KEY_LABEL_REFERENCE_CHAR = "H";
    private final int KEY_LABEL_OPTION_ALIGN_LEFT = 1;
    private final int KEY_LABEL_OPTION_ALIGN_RIGHT = 2;
    private final int KEY_LABEL_OPTION_ALIGN_BOTTOM = 8;
    private final int KEY_LABEL_OPTION_FONT_NORMAL = 16;
    private final int mKeyLabelHorizontalPadding;

    private final UIHandler mHandler = new UIHandler();

    class UIHandler extends Handler {
        private static final int MSG_POPUP_PREVIEW = 1;
        private static final int MSG_DISMISS_PREVIEW = 2;
        private static final int MSG_REPEAT_KEY = 3;
        private static final int MSG_LONGPRESS_KEY = 4;
        private static final int MSG_LONGPRESS_SHIFT_KEY = 5;

        private boolean mInKeyRepeat;

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case MSG_POPUP_PREVIEW:
                    showKey(msg.arg1, (PointerTracker)msg.obj);
                    break;
                case MSG_DISMISS_PREVIEW:
                    mPreviewPopup.dismiss();
                    break;
                case MSG_REPEAT_KEY: {
                    final PointerTracker tracker = (PointerTracker)msg.obj;
                    tracker.repeatKey(msg.arg1);
                    startKeyRepeatTimer(mKeyRepeatInterval, msg.arg1, tracker);
                    break;
                }
                case MSG_LONGPRESS_KEY: {
                    final PointerTracker tracker = (PointerTracker)msg.obj;
                    openPopupIfRequired(msg.arg1, tracker);
                    break;
                }
                case MSG_LONGPRESS_SHIFT_KEY: {
                    final PointerTracker tracker = (PointerTracker)msg.obj;
                    onLongPressShiftKey(tracker);
                    break;
                }
            }
        }

        public void popupPreview(long delay, int keyIndex, PointerTracker tracker) {
            removeMessages(MSG_POPUP_PREVIEW);
            if (mPreviewPopup.isShowing() && mPreviewText.getVisibility() == VISIBLE) {
                // Show right away, if it's already visible and finger is moving around
                showKey(keyIndex, tracker);
            } else {
                sendMessageDelayed(obtainMessage(MSG_POPUP_PREVIEW, keyIndex, 0, tracker),
                        delay);
            }
        }

        public void cancelPopupPreview() {
            removeMessages(MSG_POPUP_PREVIEW);
        }

        public void dismissPreview(long delay) {
            if (mPreviewPopup.isShowing()) {
                sendMessageDelayed(obtainMessage(MSG_DISMISS_PREVIEW), delay);
            }
        }

        public void cancelDismissPreview() {
            removeMessages(MSG_DISMISS_PREVIEW);
        }

        public void startKeyRepeatTimer(long delay, int keyIndex, PointerTracker tracker) {
            mInKeyRepeat = true;
            sendMessageDelayed(obtainMessage(MSG_REPEAT_KEY, keyIndex, 0, tracker), delay);
        }

        public void cancelKeyRepeatTimer() {
            mInKeyRepeat = false;
            removeMessages(MSG_REPEAT_KEY);
        }

        public boolean isInKeyRepeat() {
            return mInKeyRepeat;
        }

        public void startLongPressTimer(long delay, int keyIndex, PointerTracker tracker) {
            cancelLongPressTimers();
            sendMessageDelayed(obtainMessage(MSG_LONGPRESS_KEY, keyIndex, 0, tracker), delay);
        }

        public void startLongPressShiftTimer(long delay, int keyIndex, PointerTracker tracker) {
            cancelLongPressTimers();
            if (ENABLE_CAPSLOCK_BY_LONGPRESS) {
                sendMessageDelayed(
                        obtainMessage(MSG_LONGPRESS_SHIFT_KEY, keyIndex, 0, tracker), delay);
            }
        }

        public void cancelLongPressTimers() {
            removeMessages(MSG_LONGPRESS_KEY);
            removeMessages(MSG_LONGPRESS_SHIFT_KEY);
        }

        public void cancelKeyTimers() {
            cancelKeyRepeatTimer();
            cancelLongPressTimers();
        }

        public void cancelAllMessages() {
            cancelKeyTimers();
            cancelPopupPreview();
            cancelDismissPreview();
        }
    }

    public KeyboardView(Context context, AttributeSet attrs) {
        this(context, attrs, R.attr.keyboardViewStyle);
    }

    public KeyboardView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        TypedArray a = context.obtainStyledAttributes(
                attrs, R.styleable.KeyboardView, defStyle, R.style.KeyboardView);
        LayoutInflater inflate =
                (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        int previewLayout = 0;
        int keyTextSize = 0;

        int n = a.getIndexCount();

        for (int i = 0; i < n; i++) {
            int attr = a.getIndex(i);

            switch (attr) {
            case R.styleable.KeyboardView_keyBackground:
                mKeyBackground = a.getDrawable(attr);
                break;
            case R.styleable.KeyboardView_keyHysteresisDistance:
                mKeyHysteresisDistance = a.getDimensionPixelOffset(attr, 0);
                break;
            case R.styleable.KeyboardView_verticalCorrection:
                mVerticalCorrection = a.getDimensionPixelOffset(attr, 0);
                break;
            case R.styleable.KeyboardView_keyPreviewLayout:
                previewLayout = a.getResourceId(attr, 0);
                break;
            case R.styleable.KeyboardView_keyPreviewOffset:
                mPreviewOffset = a.getDimensionPixelOffset(attr, 0);
                break;
            case R.styleable.KeyboardView_keyPreviewHeight:
                mPreviewHeight = a.getDimensionPixelSize(attr, 80);
                break;
            case R.styleable.KeyboardView_keyLetterSize:
                mKeyLetterSize = a.getDimensionPixelSize(attr, 18);
                break;
            case R.styleable.KeyboardView_keyTextColor:
                mKeyTextColor = a.getColor(attr, 0xFF000000);
                break;
            case R.styleable.KeyboardView_keyTextColorDisabled:
                mKeyTextColorDisabled = a.getColor(attr, 0xFF000000);
                break;
            case R.styleable.KeyboardView_labelTextSize:
                mLabelTextSize = a.getDimensionPixelSize(attr, 14);
                break;
            case R.styleable.KeyboardView_popupLayout:
                mPopupLayout = a.getResourceId(attr, 0);
                break;
            case R.styleable.KeyboardView_shadowColor:
                mShadowColor = a.getColor(attr, 0);
                break;
            case R.styleable.KeyboardView_shadowRadius:
                mShadowRadius = a.getFloat(attr, 0f);
                break;
            // TODO: Use Theme (android.R.styleable.Theme_backgroundDimAmount)
            case R.styleable.KeyboardView_backgroundDimAmount:
                mBackgroundDimAmount = a.getFloat(attr, 0.5f);
                break;
            case R.styleable.KeyboardView_keyLetterStyle:
                mKeyLetterStyle = Typeface.defaultFromStyle(a.getInt(attr, Typeface.NORMAL));
                break;
            case R.styleable.KeyboardView_colorScheme:
                mColorScheme = a.getInt(attr, COLOR_SCHEME_WHITE);
                break;
            }
        }

        final Resources res = getResources();

        mPreviewPopup = new PopupWindow(context);
        if (previewLayout != 0) {
            mPreviewText = (TextView) inflate.inflate(previewLayout, null);
            mPreviewTextSizeLarge = (int) res.getDimension(R.dimen.key_preview_text_size_large);
            mPreviewPopup.setContentView(mPreviewText);
            mPreviewPopup.setBackgroundDrawable(null);
        } else {
            mShowPreview = false;
        }
        mPreviewPopup.setTouchable(false);
        mPreviewPopup.setAnimationStyle(R.style.KeyPreviewAnimation);
        mDelayBeforePreview = res.getInteger(R.integer.config_delay_before_preview);
        mDelayAfterPreview = res.getInteger(R.integer.config_delay_after_preview);
        mKeyLabelHorizontalPadding = (int)res.getDimension(
                R.dimen.key_label_horizontal_alignment_padding);

        mMiniKeyboardParent = this;
        mMiniKeyboardPopup = new PopupWindow(context);
        mMiniKeyboardPopup.setBackgroundDrawable(null);
        mMiniKeyboardPopup.setAnimationStyle(R.style.MiniKeyboardAnimation);

        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setTextSize(keyTextSize);
        mPaint.setTextAlign(Align.CENTER);
        mPaint.setAlpha(255);

        mPadding = new Rect(0, 0, 0, 0);
        mKeyBackground.getPadding(mPadding);

        mSwipeThreshold = (int) (500 * res.getDisplayMetrics().density);
        // TODO: Refer frameworks/base/core/res/res/values/config.xml
        mDisambiguateSwipe = res.getBoolean(R.bool.config_swipeDisambiguation);
        mMiniKeyboardSlideAllowance = res.getDimension(R.dimen.mini_keyboard_slide_allowance);

        GestureDetector.SimpleOnGestureListener listener =
                new GestureDetector.SimpleOnGestureListener() {
            private boolean mProcessingDoubleTapEvent = false;

            @Override
            public boolean onFling(MotionEvent me1, MotionEvent me2, float velocityX,
                    float velocityY) {
                final float absX = Math.abs(velocityX);
                final float absY = Math.abs(velocityY);
                float deltaX = me2.getX() - me1.getX();
                float deltaY = me2.getY() - me1.getY();
                int travelX = getWidth() / 2; // Half the keyboard width
                int travelY = getHeight() / 2; // Half the keyboard height
                mSwipeTracker.computeCurrentVelocity(1000);
                final float endingVelocityX = mSwipeTracker.getXVelocity();
                final float endingVelocityY = mSwipeTracker.getYVelocity();
                if (velocityX > mSwipeThreshold && absY < absX && deltaX > travelX) {
                    if (mDisambiguateSwipe && endingVelocityX >= velocityX / 4) {
                        swipeRight();
                        return true;
                    }
                } else if (velocityX < -mSwipeThreshold && absY < absX && deltaX < -travelX) {
                    if (mDisambiguateSwipe && endingVelocityX <= velocityX / 4) {
                        swipeLeft();
                        return true;
                    }
                } else if (velocityY < -mSwipeThreshold && absX < absY && deltaY < -travelY) {
                    if (mDisambiguateSwipe && endingVelocityY <= velocityY / 4) {
                        swipeUp();
                        return true;
                    }
                } else if (velocityY > mSwipeThreshold && absX < absY / 2 && deltaY > travelY) {
                    if (mDisambiguateSwipe && endingVelocityY >= velocityY / 4) {
                        swipeDown();
                        return true;
                    }
                }
                return false;
            }

            @Override
            public boolean onDoubleTap(MotionEvent e) {
                if (ENABLE_CAPSLOCK_BY_DOUBLETAP && mKeyboard instanceof LatinKeyboard
                        && ((LatinKeyboard) mKeyboard).isAlphaKeyboard()) {
                    final int pointerIndex = e.getActionIndex();
                    final int id = e.getPointerId(pointerIndex);
                    final PointerTracker tracker = getPointerTracker(id);
                    if (tracker.isOnShiftKey((int)e.getX(), (int)e.getY())) {
                        onDoubleTapShiftKey(tracker);
                        mProcessingDoubleTapEvent = true;
                        return true;
                    }
                }
                mProcessingDoubleTapEvent = false;
                return false;
            }

            @Override
            public boolean onDoubleTapEvent(MotionEvent e) {
                return mProcessingDoubleTapEvent;
            }
        };

        final boolean ignoreMultitouch = true;
        mGestureDetector = new GestureDetector(getContext(), listener, null, ignoreMultitouch);
        mGestureDetector.setIsLongpressEnabled(false);

        mHasDistinctMultitouch = context.getPackageManager()
                .hasSystemFeature(PackageManager.FEATURE_TOUCHSCREEN_MULTITOUCH_DISTINCT);
        mKeyRepeatInterval = res.getInteger(R.integer.config_key_repeat_interval);
    }

    public void setOnKeyboardActionListener(KeyboardActionListener listener) {
        mKeyboardActionListener = listener;
        for (PointerTracker tracker : mPointerTrackers) {
            tracker.setOnKeyboardActionListener(listener);
        }
    }

    /**
     * Returns the {@link KeyboardActionListener} object.
     * @return the listener attached to this keyboard
     */
    protected KeyboardActionListener getOnKeyboardActionListener() {
        return mKeyboardActionListener;
    }

    /**
     * Attaches a keyboard to this view. The keyboard can be switched at any time and the
     * view will re-layout itself to accommodate the keyboard.
     * @see Keyboard
     * @see #getKeyboard()
     * @param keyboard the keyboard to display in this view
     */
    public void setKeyboard(Keyboard keyboard) {
        if (mKeyboard != null) {
            dismissKeyPreview();
        }
        // Remove any pending messages, except dismissing preview
        mHandler.cancelKeyTimers();
        mHandler.cancelPopupPreview();
        mKeyboard = keyboard;
        LatinImeLogger.onSetKeyboard(keyboard);
        mKeys = mKeyDetector.setKeyboard(keyboard, -getPaddingLeft(),
                -getPaddingTop() + mVerticalCorrection);
        for (PointerTracker tracker : mPointerTrackers) {
            tracker.setKeyboard(keyboard, mKeys, mKeyHysteresisDistance);
        }
        requestLayout();
        // Hint to reallocate the buffer if the size changed
        mKeyboardChanged = true;
        invalidateAllKeys();
        computeProximityThreshold(keyboard, mKeys);
        mMiniKeyboardCache.clear();
    }

    /**
     * Returns the current keyboard being displayed by this view.
     * @return the currently attached keyboard
     * @see #setKeyboard(Keyboard)
     */
    public Keyboard getKeyboard() {
        return mKeyboard;
    }

    /**
     * Return whether the device has distinct multi-touch panel.
     * @return true if the device has distinct multi-touch panel.
     */
    @Override
    public boolean hasDistinctMultitouch() {
        return mHasDistinctMultitouch;
    }

    /**
     * Enables or disables the key feedback popup. This is a popup that shows a magnified
     * version of the depressed key. By default the preview is enabled.
     * @param previewEnabled whether or not to enable the key feedback popup
     * @see #isPreviewEnabled()
     */
    public void setPreviewEnabled(boolean previewEnabled) {
        mShowPreview = previewEnabled;
    }

    /**
     * Returns the enabled state of the key feedback popup.
     * @return whether or not the key feedback popup is enabled
     * @see #setPreviewEnabled(boolean)
     */
    public boolean isPreviewEnabled() {
        return mShowPreview;
    }

    public int getColorScheme() {
        return mColorScheme;
    }

    public void setPopupParent(View v) {
        mMiniKeyboardParent = v;
    }

    public void setPopupOffset(int x, int y) {
        mPopupPreviewOffsetX = x;
        mPopupPreviewOffsetY = y;
        mPreviewPopup.dismiss();
    }

    /**
     * When enabled, calls to {@link KeyboardActionListener#onKey} will include key
     * codes for adjacent keys.  When disabled, only the primary key code will be
     * reported.
     * @param enabled whether or not the proximity correction is enabled
     */
    public void setProximityCorrectionEnabled(boolean enabled) {
        mKeyDetector.setProximityCorrectionEnabled(enabled);
    }

    /**
     * Returns true if proximity correction is enabled.
     */
    public boolean isProximityCorrectionEnabled() {
        return mKeyDetector.isProximityCorrectionEnabled();
    }

    protected CharSequence adjustCase(CharSequence label) {
        if (mKeyboard.isShiftedOrShiftLocked() && label != null && label.length() < 3
                && Character.isLowerCase(label.charAt(0))) {
            return label.toString().toUpperCase();
        }
        return label;
    }

    @Override
    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // Round up a little
        if (mKeyboard == null) {
            setMeasuredDimension(
                    getPaddingLeft() + getPaddingRight(), getPaddingTop() + getPaddingBottom());
        } else {
            int width = mKeyboard.getMinWidth() + getPaddingLeft() + getPaddingRight();
            if (MeasureSpec.getSize(widthMeasureSpec) < width + 10) {
                width = MeasureSpec.getSize(widthMeasureSpec);
            }
            setMeasuredDimension(
                    width, mKeyboard.getHeight() + getPaddingTop() + getPaddingBottom());
        }
    }

    /**
     * Compute the most common key width and use it as proximity key detection threshold.
     * @param keyboard
     * @param keys
     */
    private void computeProximityThreshold(Keyboard keyboard, Key[] keys) {
        if (keyboard == null || keys == null || keys.length == 0) return;
        final HashMap<Integer, Integer> histogram = new HashMap<Integer, Integer>();
        int maxCount = 0;
        int mostCommonWidth = 0;
        for (Key key : keys) {
            final Integer width = key.mWidth + key.mGap;
            Integer count = histogram.get(width);
            if (count == null)
                count = 0;
            histogram.put(width, ++count);
            if (count > maxCount) {
                maxCount = count;
                mostCommonWidth = width;
            }
        }
        mKeyDetector.setProximityThreshold(mostCommonWidth);
    }

    @Override
    public void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        // Release the buffer, if any and it will be reallocated on the next draw
        mBuffer = null;
    }

    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mDrawPending || mBuffer == null || mKeyboardChanged) {
            onBufferDraw();
        }
        canvas.drawBitmap(mBuffer, 0, 0, null);
    }

    @SuppressWarnings("unused")
    private void onBufferDraw() {
        if (mBuffer == null || mKeyboardChanged) {
            if (mBuffer == null || mKeyboardChanged &&
                    (mBuffer.getWidth() != getWidth() || mBuffer.getHeight() != getHeight())) {
                // Make sure our bitmap is at least 1x1
                final int width = Math.max(1, getWidth());
                final int height = Math.max(1, getHeight());
                mBuffer = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
                mCanvas = new Canvas(mBuffer);
            }
            invalidateAllKeys();
            mKeyboardChanged = false;
        }
        final Canvas canvas = mCanvas;
        canvas.clipRect(mDirtyRect, Op.REPLACE);

        if (mKeyboard == null) return;

        final Paint paint = mPaint;
        final Drawable keyBackground = mKeyBackground;
        final Rect clipRegion = mClipRegion;
        final Rect padding = mPadding;
        final int kbdPaddingLeft = getPaddingLeft();
        final int kbdPaddingTop = getPaddingTop();
        final Key[] keys = mKeys;
        final Key invalidKey = mInvalidatedKey;
        final boolean isManualTemporaryUpperCase = mKeyboard.isManualTemporaryUpperCase();

        boolean drawSingleKey = false;
        if (invalidKey != null && canvas.getClipBounds(clipRegion)) {
            // TODO we should use Rect.inset and Rect.contains here.
            // Is clipRegion completely contained within the invalidated key?
            if (invalidKey.mX + kbdPaddingLeft - 1 <= clipRegion.left &&
                    invalidKey.mY + kbdPaddingTop - 1 <= clipRegion.top &&
                    invalidKey.mX + invalidKey.mWidth + kbdPaddingLeft + 1 >= clipRegion.right &&
                    invalidKey.mY + invalidKey.mHeight + kbdPaddingTop + 1 >= clipRegion.bottom) {
                drawSingleKey = true;
            }
        }
        canvas.drawColor(0x00000000, PorterDuff.Mode.CLEAR);
        final int keyCount = keys.length;
        for (int i = 0; i < keyCount; i++) {
            final Key key = keys[i];
            if (drawSingleKey && invalidKey != key) {
                continue;
            }
            int[] drawableState = key.getCurrentDrawableState();
            keyBackground.setState(drawableState);

            // Switch the character to uppercase if shift is pressed
            String label = key.mLabel == null? null : adjustCase(key.mLabel).toString();

            final Rect bounds = keyBackground.getBounds();
            if (key.mWidth != bounds.right || key.mHeight != bounds.bottom) {
                keyBackground.setBounds(0, 0, key.mWidth, key.mHeight);
            }
            canvas.translate(key.mX + kbdPaddingLeft, key.mY + kbdPaddingTop);
            keyBackground.draw(canvas);

            final int rowHeight = padding.top + key.mHeight;
            // Draw key label
            if (label != null) {
                // For characters, use large font. For labels like "Done", use small font.
                final int labelSize = getLabelSizeAndSetPaint(label, key, paint);
                final int labelCharHeight = getLabelCharHeight(labelSize, paint);

                // Vertical label text alignment.
                final float baseline;
                if ((key.mLabelOption & KEY_LABEL_OPTION_ALIGN_BOTTOM) != 0) {
                    baseline = key.mHeight -
                            + labelCharHeight * KEY_LABEL_VERTICAL_PADDING_FACTOR;
                    if (DEBUG_SHOW_ALIGN)
                        drawHorizontalLine(canvas, (int)baseline, key.mWidth, 0xc0008000,
                                new Paint());
                } else { // Align center
                    final float centerY = (key.mHeight + padding.top - padding.bottom) / 2;
                    baseline = centerY
                            + labelCharHeight * KEY_LABEL_VERTICAL_ADJUSTMENT_FACTOR_CENTER;
                    if (DEBUG_SHOW_ALIGN)
                        drawHorizontalLine(canvas, (int)baseline, key.mWidth, 0xc0008000,
                                new Paint());
                }
                // Horizontal label text alignment
                final int positionX;
                if ((key.mLabelOption & KEY_LABEL_OPTION_ALIGN_LEFT) != 0) {
                    positionX = mKeyLabelHorizontalPadding + padding.left;
                    paint.setTextAlign(Align.LEFT);
                    if (DEBUG_SHOW_ALIGN)
                        drawVerticalLine(canvas, positionX, rowHeight, 0xc0800080, new Paint());
                } else if ((key.mLabelOption & KEY_LABEL_OPTION_ALIGN_RIGHT) != 0) {
                    positionX = key.mWidth - mKeyLabelHorizontalPadding - padding.right;
                    paint.setTextAlign(Align.RIGHT);
                    if (DEBUG_SHOW_ALIGN)
                        drawVerticalLine(canvas, positionX, rowHeight, 0xc0808000, new Paint());
                } else {
                    positionX = (key.mWidth + padding.left - padding.right) / 2;
                    paint.setTextAlign(Align.CENTER);
                    if (DEBUG_SHOW_ALIGN && label.length() > 1)
                        drawVerticalLine(canvas, positionX, rowHeight, 0xc0008080, new Paint());
                }
                if (key.mManualTemporaryUpperCaseHintIcon != null && isManualTemporaryUpperCase) {
                    paint.setColor(mKeyTextColorDisabled);
                } else {
                    paint.setColor(mKeyTextColor);
                }
                // Set a drop shadow for the text
                paint.setShadowLayer(mShadowRadius, 0, 0, mShadowColor);
                canvas.drawText(label, positionX, baseline, paint);
                // Turn off drop shadow
                paint.setShadowLayer(0, 0, 0, 0);
            }
            // Draw key icon
            final Drawable icon = key.getIcon();
            if (key.mLabel == null && icon != null) {
                final int drawableWidth = icon.getIntrinsicWidth();
                final int drawableHeight = icon.getIntrinsicHeight();
                final int drawableX;
                final int drawableY = (
                        key.mHeight + padding.top - padding.bottom - drawableHeight) / 2;
                if ((key.mLabelOption & KEY_LABEL_OPTION_ALIGN_LEFT) != 0) {
                    drawableX = padding.left + mKeyLabelHorizontalPadding;
                    if (DEBUG_SHOW_ALIGN)
                        drawVerticalLine(canvas, drawableX, rowHeight, 0xc0800080, new Paint());
                } else if ((key.mLabelOption & KEY_LABEL_OPTION_ALIGN_RIGHT) != 0) {
                    drawableX = key.mWidth - padding.right - mKeyLabelHorizontalPadding
                            - drawableWidth;
                    if (DEBUG_SHOW_ALIGN)
                        drawVerticalLine(canvas, drawableX + drawableWidth, rowHeight,
                                0xc0808000, new Paint());
                } else { // Align center
                    drawableX = (key.mWidth + padding.left - padding.right - drawableWidth) / 2;
                    if (DEBUG_SHOW_ALIGN)
                        drawVerticalLine(canvas, drawableX + drawableWidth / 2, rowHeight,
                                0xc0008080, new Paint());
                }
                drawIcon(canvas, icon, drawableX, drawableY, drawableWidth, drawableHeight);
                if (DEBUG_SHOW_ALIGN)
                    drawRectangle(canvas, drawableX, drawableY, drawableWidth, drawableHeight,
                            0x80c00000, new Paint());
            }
            if (key.mHintIcon != null) {
                final int drawableWidth = key.mWidth;
                final int drawableHeight = key.mHeight;
                final int drawableX = 0;
                final int drawableY = HINT_ICON_VERTICAL_ADJUSTMENT_PIXEL;
                Drawable hintIcon = (isManualTemporaryUpperCase
                        && key.mManualTemporaryUpperCaseHintIcon != null)
                        ? key.mManualTemporaryUpperCaseHintIcon : key.mHintIcon;
                drawIcon(canvas, hintIcon, drawableX, drawableY, drawableWidth, drawableHeight);
                if (DEBUG_SHOW_ALIGN)
                    drawRectangle(canvas, drawableX, drawableY, drawableWidth, drawableHeight,
                            0x80c0c000, new Paint());
            }
            canvas.translate(-key.mX - kbdPaddingLeft, -key.mY - kbdPaddingTop);
        }

        if (DEBUG_KEYBOARD_GRID) {
            Paint p = new Paint();
            p.setStyle(Paint.Style.STROKE);
            p.setStrokeWidth(1.0f);
            p.setColor(0x800000c0);
            int cw = (mKeyboard.getMinWidth() + mKeyboard.GRID_WIDTH - 1) / mKeyboard.GRID_WIDTH;
            int ch = (mKeyboard.getHeight() + mKeyboard.GRID_HEIGHT - 1) / mKeyboard.GRID_HEIGHT;
            for (int i = 0; i <= mKeyboard.GRID_WIDTH; i++)
                canvas.drawLine(i * cw, 0, i * cw, ch * mKeyboard.GRID_HEIGHT, p);
            for (int i = 0; i <= mKeyboard.GRID_HEIGHT; i++)
                canvas.drawLine(0, i * ch, cw * mKeyboard.GRID_WIDTH, i * ch, p);
        }

        mInvalidatedKey = null;
        // Overlay a dark rectangle to dim the keyboard
        if (mMiniKeyboard != null) {
            paint.setColor((int) (mBackgroundDimAmount * 0xFF) << 24);
            canvas.drawRect(0, 0, getWidth(), getHeight(), paint);
        }

        if (DEBUG) {
            if (mShowTouchPoints) {
                for (PointerTracker tracker : mPointerTrackers) {
                    int startX = tracker.getStartX();
                    int startY = tracker.getStartY();
                    int lastX = tracker.getLastX();
                    int lastY = tracker.getLastY();
                    paint.setAlpha(128);
                    paint.setColor(0xFFFF0000);
                    canvas.drawCircle(startX, startY, 3, paint);
                    canvas.drawLine(startX, startY, lastX, lastY, paint);
                    paint.setColor(0xFF0000FF);
                    canvas.drawCircle(lastX, lastY, 3, paint);
                    paint.setColor(0xFF00FF00);
                    canvas.drawCircle((startX + lastX) / 2, (startY + lastY) / 2, 2, paint);
                }
            }
        }

        mDrawPending = false;
        mDirtyRect.setEmpty();
    }

    private int getLabelSizeAndSetPaint(CharSequence label, Key key, Paint paint) {
        // For characters, use large font. For labels like "Done", use small font.
        final int labelSize;
        final Typeface labelStyle;
        if (label.length() > 1 && key.mCodes.length < 2) {
            labelSize = mLabelTextSize;
            if ((key.mLabelOption & KEY_LABEL_OPTION_FONT_NORMAL) != 0) {
                labelStyle = Typeface.DEFAULT;
            } else {
                labelStyle = Typeface.DEFAULT_BOLD;
            }
        } else {
            labelSize = mKeyLetterSize;
            labelStyle = mKeyLetterStyle;
        }
        paint.setTextSize(labelSize);
        paint.setTypeface(labelStyle);
        return labelSize;
    }

    private int getLabelCharHeight(int labelSize, Paint paint) {
        Integer labelHeightValue = mTextHeightCache.get(labelSize);
        final int labelCharHeight;
        if (labelHeightValue != null) {
            labelCharHeight = labelHeightValue;
        } else {
            Rect textBounds = new Rect();
            paint.getTextBounds(KEY_LABEL_REFERENCE_CHAR, 0, 1, textBounds);
            labelCharHeight = textBounds.height();
            mTextHeightCache.put(labelSize, labelCharHeight);
        }
        return labelCharHeight;
    }

    private static void drawIcon(Canvas canvas, Drawable icon, int x, int y, int width,
            int height) {
        canvas.translate(x, y);
        icon.setBounds(0, 0, width, height);
        icon.draw(canvas);
        canvas.translate(-x, -y);
    }

    private static void drawHorizontalLine(Canvas canvas, int y, int w, int color, Paint paint) {
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(1.0f);
        paint.setColor(color);
        canvas.drawLine(0, y, w, y, paint);
    }

    private static void drawVerticalLine(Canvas canvas, int x, int h, int color, Paint paint) {
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(1.0f);
        paint.setColor(color);
        canvas.drawLine(x, 0, x, h, paint);
    }

    private static void drawRectangle(Canvas canvas, int x, int y, int w, int h, int color,
            Paint paint) {
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(1.0f);
        paint.setColor(color);
        canvas.translate(x, y);
        canvas.drawRect(0, 0, w, h, paint);
        canvas.translate(-x, -y);
    }

    public void setForeground(boolean foreground) {
        mInForeground = foreground;
    }

    // TODO: clean up this method.
    private void dismissKeyPreview() {
        for (PointerTracker tracker : mPointerTrackers)
            tracker.releaseKey();
        showPreview(KeyDetector.NOT_A_KEY, null);
    }

    @Override
    public void showPreview(int keyIndex, PointerTracker tracker) {
        int oldKeyIndex = mOldPreviewKeyIndex;
        mOldPreviewKeyIndex = keyIndex;
        // We should re-draw popup preview when 1) we need to hide the preview, 2) we will show
        // the space key preview and 3) pointer moves off the space key to other letter key, we
        // should hide the preview of the previous key.
        @SuppressWarnings("unused")
        final boolean hidePreviewOrShowSpaceKeyPreview = (tracker == null)
                || (SubtypeSwitcher.USE_SPACEBAR_LANGUAGE_SWITCHER
                        && SubtypeSwitcher.getInstance().needsToDisplayLanguage()
                        && (tracker.isSpaceKey(keyIndex) || tracker.isSpaceKey(oldKeyIndex)));
        // If key changed and preview is on or the key is space (language switch is enabled)
        if (oldKeyIndex != keyIndex && (mShowPreview || (hidePreviewOrShowSpaceKeyPreview))) {
            if (keyIndex == KeyDetector.NOT_A_KEY) {
                mHandler.cancelPopupPreview();
                mHandler.dismissPreview(mDelayAfterPreview);
            } else if (tracker != null) {
                mHandler.popupPreview(mDelayBeforePreview, keyIndex, tracker);
            }
        }
    }

    // TODO Must fix popup preview on xlarge layout
    private void showKey(final int keyIndex, PointerTracker tracker) {
        Key key = tracker.getKey(keyIndex);
        // If keyIndex is invalid or IME is already closed, we must not show key preview.
        // Trying to show preview PopupWindow while root window is closed causes
        // WindowManager.BadTokenException.
        if (key == null || !mInForeground)
            return;
        // What we show as preview should match what we show on key top in onBufferDraw(). 
        if (key.mLabel != null) {
            // TODO Should take care of temporaryShiftLabel here.
            mPreviewText.setCompoundDrawables(null, null, null, null);
            mPreviewText.setText(adjustCase(tracker.getPreviewText(key)));
            if (key.mLabel.length() > 1 && key.mCodes.length < 2) {
                mPreviewText.setTextSize(TypedValue.COMPLEX_UNIT_PX, mKeyLetterSize);
                mPreviewText.setTypeface(Typeface.DEFAULT_BOLD);
            } else {
                mPreviewText.setTextSize(TypedValue.COMPLEX_UNIT_PX, mPreviewTextSizeLarge);
                mPreviewText.setTypeface(mKeyLetterStyle);
            }
        } else {
            final Drawable previewIcon = key.getPreviewIcon();
            mPreviewText.setCompoundDrawables(null, null, null,
                   previewIcon != null ? previewIcon : key.getIcon());
            mPreviewText.setText(null);
        }
        mPreviewText.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),
                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
        int popupWidth = Math.max(mPreviewText.getMeasuredWidth(), key.mWidth
                + mPreviewText.getPaddingLeft() + mPreviewText.getPaddingRight());
        final int popupHeight = mPreviewHeight;
        LayoutParams lp = mPreviewText.getLayoutParams();
        if (lp != null) {
            lp.width = popupWidth;
            lp.height = popupHeight;
        }

        int popupPreviewX = key.mX - (popupWidth - key.mWidth) / 2;
        int popupPreviewY = key.mY - popupHeight + mPreviewOffset;

        mHandler.cancelDismissPreview();
        if (mOffsetInWindow == null) {
            mOffsetInWindow = new int[2];
            getLocationInWindow(mOffsetInWindow);
            mOffsetInWindow[0] += mPopupPreviewOffsetX; // Offset may be zero
            mOffsetInWindow[1] += mPopupPreviewOffsetY; // Offset may be zero
            int[] windowLocation = new int[2];
            getLocationOnScreen(windowLocation);
            mWindowY = windowLocation[1];
        }
        // Set the preview background state
        mPreviewText.getBackground().setState(
                key.mPopupCharacters != null ? LONG_PRESSABLE_STATE_SET : EMPTY_STATE_SET);
        popupPreviewX += mOffsetInWindow[0];
        popupPreviewY += mOffsetInWindow[1];

        // If the popup cannot be shown above the key, put it on the side
        if (popupPreviewY + mWindowY < 0) {
            // If the key you're pressing is on the left side of the keyboard, show the popup on
            // the right, offset by enough to see at least one key to the left/right.
            if (key.mX + key.mWidth <= getWidth() / 2) {
                popupPreviewX += (int) (key.mWidth * 2.5);
            } else {
                popupPreviewX -= (int) (key.mWidth * 2.5);
            }
            popupPreviewY += popupHeight;
        }

        try {
            if (mPreviewPopup.isShowing()) {
                mPreviewPopup.update(popupPreviewX, popupPreviewY, popupWidth, popupHeight);
            } else {
                mPreviewPopup.setWidth(popupWidth);
                mPreviewPopup.setHeight(popupHeight);
                mPreviewPopup.showAtLocation(mMiniKeyboardParent, Gravity.NO_GRAVITY,
                        popupPreviewX, popupPreviewY);
            }
        } catch (WindowManager.BadTokenException e) {
            // Swallow the exception which will be happened when IME is already closed.
            Log.w(TAG, "LatinIME is already closed when tried showing key preview.");
        }
        // Record popup preview position to display mini-keyboard later at the same positon
        mPopupPreviewDisplayedY = popupPreviewY;
        mPreviewText.setVisibility(VISIBLE);
    }

    /**
     * Requests a redraw of the entire keyboard. Calling {@link #invalidate} is not sufficient
     * because the keyboard renders the keys to an off-screen buffer and an invalidate() only
     * draws the cached buffer.
     * @see #invalidateKey(Key)
     */
    public void invalidateAllKeys() {
        mDirtyRect.union(0, 0, getWidth(), getHeight());
        mDrawPending = true;
        invalidate();
    }

    /**
     * Invalidates a key so that it will be redrawn on the next repaint. Use this method if only
     * one key is changing it's content. Any changes that affect the position or size of the key
     * may not be honored.
     * @param key key in the attached {@link Keyboard}.
     * @see #invalidateAllKeys
     */
    @Override
    public void invalidateKey(Key key) {
        if (key == null)
            return;
        mInvalidatedKey = key;
        // TODO we should clean up this and record key's region to use in onBufferDraw.
        mDirtyRect.union(key.mX + getPaddingLeft(), key.mY + getPaddingTop(),
                key.mX + key.mWidth + getPaddingLeft(), key.mY + key.mHeight + getPaddingTop());
        onBufferDraw();
        invalidate(key.mX + getPaddingLeft(), key.mY + getPaddingTop(),
                key.mX + key.mWidth + getPaddingLeft(), key.mY + key.mHeight + getPaddingTop());
    }

    private boolean openPopupIfRequired(int keyIndex, PointerTracker tracker) {
        // Check if we have a popup layout specified first.
        if (mPopupLayout == 0) {
            return false;
        }

        Key popupKey = tracker.getKey(keyIndex);
        if (popupKey == null)
            return false;
        boolean result = onLongPress(popupKey);
        if (result) {
            dismissKeyPreview();
            mMiniKeyboardTrackerId = tracker.mPointerId;
            // Mark this tracker "already processed" and remove it from the pointer queue
            tracker.setAlreadyProcessed();
            mPointerQueue.remove(tracker);
        }
        return result;
    }

    private void onLongPressShiftKey(PointerTracker tracker) {
        tracker.setAlreadyProcessed();
        mPointerQueue.remove(tracker);
        mKeyboardActionListener.onKey(Keyboard.CODE_CAPSLOCK, null, 0, 0);
    }

    private void onDoubleTapShiftKey(@SuppressWarnings("unused") PointerTracker tracker) {
        // When shift key is double tapped, the first tap is correctly processed as usual tap. And
        // the second tap is treated as this double tap event, so that we need not mark tracker
        // calling setAlreadyProcessed() nor remove the tracker from mPointerQueueueue.
        mKeyboardActionListener.onKey(Keyboard.CODE_CAPSLOCK, null, 0, 0);
    }

    private View inflateMiniKeyboardContainer(Key popupKey) {
        int popupKeyboardResId = mKeyboard.getPopupKeyboardResId();
        LayoutInflater inflater = (LayoutInflater)getContext().getSystemService(
                Context.LAYOUT_INFLATER_SERVICE);
        View container = inflater.inflate(mPopupLayout, null);
        if (container == null)
            throw new NullPointerException();

        KeyboardView miniKeyboard =
                (KeyboardView)container.findViewById(R.id.KeyboardView);
        miniKeyboard.setOnKeyboardActionListener(new KeyboardActionListener() {
            @Override
            public void onKey(int primaryCode, int[] keyCodes, int x, int y) {
                mKeyboardActionListener.onKey(primaryCode, keyCodes, x, y);
                dismissPopupKeyboard();
            }

            @Override
            public void onText(CharSequence text) {
                mKeyboardActionListener.onText(text);
                dismissPopupKeyboard();
            }

            @Override
            public void onCancel() {
                dismissPopupKeyboard();
            }

            @Override
            public void swipeLeft() {
                // Nothing to do.
            }
            @Override
            public void swipeRight() {
                // Nothing to do.
            }
            @Override
            public void swipeUp() {
                // Nothing to do.
            }
            @Override
            public void swipeDown() {
                // Nothing to do.
            }
            @Override
            public void onPress(int primaryCode) {
                mKeyboardActionListener.onPress(primaryCode);
            }
            @Override
            public void onRelease(int primaryCode) {
                mKeyboardActionListener.onRelease(primaryCode);
            }
        });
        // Override default ProximityKeyDetector.
        miniKeyboard.mKeyDetector = new MiniKeyboardKeyDetector(mMiniKeyboardSlideAllowance);
        // Remove gesture detector on mini-keyboard
        miniKeyboard.mGestureDetector = null;

        Keyboard keyboard = new MiniKeyboardBuilder(getContext(), popupKeyboardResId, popupKey)
                .build();
        miniKeyboard.setKeyboard(keyboard);
        miniKeyboard.setPopupParent(this);

        container.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),
                MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));

        return container;
    }

    private static boolean isOneRowKeys(List<Key> keys) {
        if (keys.size() == 0) return false;
        final int edgeFlags = keys.get(0).mEdgeFlags;
        // HACK: The first key of mini keyboard which was inflated from xml and has multiple rows,
        // does not have both top and bottom edge flags on at the same time.  On the other hand,
        // the first key of mini keyboard that was created with popupCharacters must have both top
        // and bottom edge flags on.
        // When you want to use one row mini-keyboard from xml file, make sure that the row has
        // both top and bottom edge flags set.
        return (edgeFlags & Keyboard.EDGE_TOP) != 0
                && (edgeFlags & Keyboard.EDGE_BOTTOM) != 0;
    }

    /**
     * Called when a key is long pressed. By default this will open any popup keyboard associated
     * with this key through the attributes popupLayout and popupCharacters.
     * @param popupKey the key that was long pressed
     * @return true if the long press is handled, false otherwise. Subclasses should call the
     * method on the base class if the subclass doesn't wish to handle the call.
     */
    protected boolean onLongPress(Key popupKey) {
        if (popupKey.mPopupCharacters == null)
            return false;

        View container = mMiniKeyboardCache.get(popupKey);
        if (container == null) {
            container = inflateMiniKeyboardContainer(popupKey);
            mMiniKeyboardCache.put(popupKey, container);
        }
        mMiniKeyboard = (KeyboardView)container.findViewById(R.id.KeyboardView);
        if (mWindowOffset == null) {
            mWindowOffset = new int[2];
            getLocationInWindow(mWindowOffset);
        }

        // Get width of a key in the mini popup keyboard = "miniKeyWidth".
        // On the other hand, "popupKey.width" is width of the pressed key on the main keyboard.
        // We adjust the position of mini popup keyboard with the edge key in it:
        //  a) When we have the leftmost key in popup keyboard directly above the pressed key
        //     Right edges of both keys should be aligned for consistent default selection
        //  b) When we have the rightmost key in popup keyboard directly above the pressed key
        //     Left edges of both keys should be aligned for consistent default selection
        final List<Key> miniKeys = mMiniKeyboard.getKeyboard().getKeys();
        final int miniKeyWidth = miniKeys.size() > 0 ? miniKeys.get(0).mWidth : 0;

        // HACK: Have the leftmost number in the popup characters right above the key
        boolean isNumberAtLeftmost =
                hasMultiplePopupChars(popupKey) && isNumberAtLeftmostPopupChar(popupKey);
        int popupX = popupKey.mX + mWindowOffset[0];
        popupX += getPaddingLeft();
        if (isNumberAtLeftmost) {
            popupX += popupKey.mWidth - miniKeyWidth;  // adjustment for a) described above
            popupX -= container.getPaddingLeft();
        } else {
            popupX += miniKeyWidth;  // adjustment for b) described above
            popupX -= container.getMeasuredWidth();
            popupX += container.getPaddingRight();
        }
        int popupY = popupKey.mY + mWindowOffset[1];
        popupY += getPaddingTop();
        popupY -= container.getMeasuredHeight();
        popupY += container.getPaddingBottom();
        final int x = popupX;
        final int y = mShowPreview && isOneRowKeys(miniKeys) ? mPopupPreviewDisplayedY : popupY;

        int adjustedX = x;
        if (x < 0) {
            adjustedX = 0;
        } else if (x > (getMeasuredWidth() - container.getMeasuredWidth())) {
            adjustedX = getMeasuredWidth() - container.getMeasuredWidth();
        }
        mMiniKeyboardOriginX = adjustedX + container.getPaddingLeft() - mWindowOffset[0];
        mMiniKeyboardOriginY = y + container.getPaddingTop() - mWindowOffset[1];
        mMiniKeyboard.setPopupOffset(adjustedX, y);
        Keyboard baseMiniKeyboard = mMiniKeyboard.getKeyboard();
        if (baseMiniKeyboard != null && baseMiniKeyboard.setShifted(mKeyboard == null
                ? false : mKeyboard.isShiftedOrShiftLocked())) {
            mMiniKeyboard.invalidateAllKeys();
        }
        // Mini keyboard needs no pop-up key preview displayed.
        mMiniKeyboard.setPreviewEnabled(false);
        mMiniKeyboardPopup.setContentView(container);
        mMiniKeyboardPopup.setWidth(container.getMeasuredWidth());
        mMiniKeyboardPopup.setHeight(container.getMeasuredHeight());
        mMiniKeyboardPopup.showAtLocation(this, Gravity.NO_GRAVITY, x, y);

        // Inject down event on the key to mini keyboard.
        long eventTime = SystemClock.uptimeMillis();
        mMiniKeyboardPopupTime = eventTime;
        MotionEvent downEvent = generateMiniKeyboardMotionEvent(MotionEvent.ACTION_DOWN, popupKey.mX
                + popupKey.mWidth / 2, popupKey.mY + popupKey.mHeight / 2, eventTime);
        mMiniKeyboard.onTouchEvent(downEvent);
        downEvent.recycle();

        invalidateAllKeys();
        return true;
    }

    private static boolean hasMultiplePopupChars(Key key) {
        if (key.mPopupCharacters != null && key.mPopupCharacters.length > 1) {
            return true;
        }
        return false;
    }

    private static boolean isNumberAtLeftmostPopupChar(Key key) {
        if (key.mPopupCharacters != null && isAsciiDigit(key.mPopupCharacters[0].charAt(0))) {
            return true;
        }
        return false;
    }

    private static boolean isAsciiDigit(char c) {
        return (c < 0x80) && Character.isDigit(c);
    }

    private MotionEvent generateMiniKeyboardMotionEvent(int action, int x, int y, long eventTime) {
        return MotionEvent.obtain(mMiniKeyboardPopupTime, eventTime, action,
                    x - mMiniKeyboardOriginX, y - mMiniKeyboardOriginY, 0);
    }

    private PointerTracker getPointerTracker(final int id) {
        final ArrayList<PointerTracker> pointers = mPointerTrackers;
        final Key[] keys = mKeys;
        final KeyboardActionListener listener = mKeyboardActionListener;

        // Create pointer trackers until we can get 'id+1'-th tracker, if needed.
        for (int i = pointers.size(); i <= id; i++) {
            final PointerTracker tracker =
                new PointerTracker(i, mHandler, mKeyDetector, this, getResources());
            if (keys != null)
                tracker.setKeyboard(mKeyboard, keys, mKeyHysteresisDistance);
            if (listener != null)
                tracker.setOnKeyboardActionListener(listener);
            pointers.add(tracker);
        }

        return pointers.get(id);
    }

    public int getPointerCount() {
        return mOldPointerCount;
    }

    @Override
    public boolean onTouchEvent(MotionEvent me) {
        final int action = me.getActionMasked();
        final int pointerCount = me.getPointerCount();
        final int oldPointerCount = mOldPointerCount;
        mOldPointerCount = pointerCount;

        // TODO: cleanup this code into a multi-touch to single-touch event converter class?
        // If the device does not have distinct multi-touch support panel, ignore all multi-touch
        // events except a transition from/to single-touch.
        if (!mHasDistinctMultitouch && pointerCount > 1 && oldPointerCount > 1) {
            return true;
        }

        // Track the last few movements to look for spurious swipes.
        mSwipeTracker.addMovement(me);

        // Gesture detector must be enabled only when mini-keyboard is not on the screen.
        if (mMiniKeyboard == null
                && mGestureDetector != null && mGestureDetector.onTouchEvent(me)) {
            dismissKeyPreview();
            mHandler.cancelKeyTimers();
            return true;
        }

        final long eventTime = me.getEventTime();
        final int index = me.getActionIndex();
        final int id = me.getPointerId(index);
        final int x = (int)me.getX(index);
        final int y = (int)me.getY(index);

        // Needs to be called after the gesture detector gets a turn, as it may have
        // displayed the mini keyboard
        if (mMiniKeyboard != null) {
            final int miniKeyboardPointerIndex = me.findPointerIndex(mMiniKeyboardTrackerId);
            if (miniKeyboardPointerIndex >= 0 && miniKeyboardPointerIndex < pointerCount) {
                final int miniKeyboardX = (int)me.getX(miniKeyboardPointerIndex);
                final int miniKeyboardY = (int)me.getY(miniKeyboardPointerIndex);
                MotionEvent translated = generateMiniKeyboardMotionEvent(action,
                        miniKeyboardX, miniKeyboardY, eventTime);
                mMiniKeyboard.onTouchEvent(translated);
                translated.recycle();
            }
            return true;
        }

        if (mHandler.isInKeyRepeat()) {
            // It will keep being in the key repeating mode while the key is being pressed.
            if (action == MotionEvent.ACTION_MOVE) {
                return true;
            }
            final PointerTracker tracker = getPointerTracker(id);
            // Key repeating timer will be canceled if 2 or more keys are in action, and current
            // event (UP or DOWN) is non-modifier key.
            if (pointerCount > 1 && !tracker.isModifier()) {
                mHandler.cancelKeyRepeatTimer();
            }
            // Up event will pass through.
        }

        // TODO: cleanup this code into a multi-touch to single-touch event converter class?
        // Translate mutli-touch event to single-touch events on the device that has no distinct
        // multi-touch panel.
        if (!mHasDistinctMultitouch) {
            // Use only main (id=0) pointer tracker.
            PointerTracker tracker = getPointerTracker(0);
            if (pointerCount == 1 && oldPointerCount == 2) {
                // Multi-touch to single touch transition.
                // Send a down event for the latest pointer.
                tracker.onDownEvent(x, y, eventTime);
            } else if (pointerCount == 2 && oldPointerCount == 1) {
                // Single-touch to multi-touch transition.
                // Send an up event for the last pointer.
                tracker.onUpEvent(tracker.getLastX(), tracker.getLastY(), eventTime);
            } else if (pointerCount == 1 && oldPointerCount == 1) {
                tracker.onTouchEvent(action, x, y, eventTime);
            } else {
                Log.w(TAG, "Unknown touch panel behavior: pointer count is " + pointerCount
                        + " (old " + oldPointerCount + ")");
            }
            return true;
        }

        if (action == MotionEvent.ACTION_MOVE) {
            for (int i = 0; i < pointerCount; i++) {
                PointerTracker tracker = getPointerTracker(me.getPointerId(i));
                tracker.onMoveEvent((int)me.getX(i), (int)me.getY(i), eventTime);
            }
        } else {
            PointerTracker tracker = getPointerTracker(id);
            switch (action) {
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_POINTER_DOWN:
                onDownEvent(tracker, x, y, eventTime);
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_POINTER_UP:
                onUpEvent(tracker, x, y, eventTime);
                break;
            case MotionEvent.ACTION_CANCEL:
                onCancelEvent(tracker, x, y, eventTime);
                break;
            }
        }

        return true;
    }

    private void onDownEvent(PointerTracker tracker, int x, int y, long eventTime) {
        if (tracker.isOnModifierKey(x, y)) {
            // Before processing a down event of modifier key, all pointers already being tracked
            // should be released.
            mPointerQueue.releaseAllPointersExcept(null, eventTime);
        }
        tracker.onDownEvent(x, y, eventTime);
        mPointerQueue.add(tracker);
    }

    private void onUpEvent(PointerTracker tracker, int x, int y, long eventTime) {
        if (tracker.isModifier()) {
            // Before processing an up event of modifier key, all pointers already being tracked
            // should be released.
            mPointerQueue.releaseAllPointersExcept(tracker, eventTime);
        } else {
            int index = mPointerQueue.lastIndexOf(tracker);
            if (index >= 0) {
                mPointerQueue.releaseAllPointersOlderThan(tracker, eventTime);
            } else {
                Log.w(TAG, "onUpEvent: corresponding down event not found for pointer "
                        + tracker.mPointerId);
            }
        }
        tracker.onUpEvent(x, y, eventTime);
        mPointerQueue.remove(tracker);
    }

    private void onCancelEvent(PointerTracker tracker, int x, int y, long eventTime) {
        tracker.onCancelEvent(x, y, eventTime);
        mPointerQueue.remove(tracker);
    }

    protected void swipeRight() {
        mKeyboardActionListener.swipeRight();
    }

    protected void swipeLeft() {
        mKeyboardActionListener.swipeLeft();
    }

    protected void swipeUp() {
        mKeyboardActionListener.swipeUp();
    }

    protected void swipeDown() {
        mKeyboardActionListener.swipeDown();
    }

    public void closing() {
        mPreviewPopup.dismiss();
        mHandler.cancelAllMessages();

        dismissPopupKeyboard();
        mBuffer = null;
        mCanvas = null;
        mMiniKeyboardCache.clear();
    }

    @Override
    public void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        closing();
    }

    private void dismissPopupKeyboard() {
        if (mMiniKeyboardPopup.isShowing()) {
            mMiniKeyboardPopup.dismiss();
            mMiniKeyboard = null;
            mMiniKeyboardOriginX = 0;
            mMiniKeyboardOriginY = 0;
            invalidateAllKeys();
        }
    }

    public boolean handleBack() {
        if (mMiniKeyboardPopup.isShowing()) {
            dismissPopupKeyboard();
            return true;
        }
        return false;
    }
}