CounterView to support localization of grouping character.

CounterView.java

/*
 * Copyright (C) 2014 Twitter Inc. 
 *
 * 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.
 */


import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

import java.util.ArrayList;
import java.util.concurrent.TimeUnit;

/**
 * Usage: http://edisonwang.com/blog/vine-loop-counter-view 
 * @author ewang (@wew)
 */
public class CounterView extends View implements Runnable {

    private static final String TAG = "CounterView";

    private static final int FRAME_DELAY = 20; // 1000 / 20 = 50 fps
    private static final int DIGIT_SPACING_X = 3; // px between text
    private static final int DIGIT_SPACING_Y = 3; // px between text

    private static final int ANIMATION_DURATION_MAX = (int) TimeUnit.NANOSECONDS.convert(150, TimeUnit.MILLISECONDS);
    private static final int ANIMATION_DURATION_MIN = (int) TimeUnit.NANOSECONDS.convert(20, TimeUnit.MILLISECONDS);

    private static final String K_SEPARATOR =  String.valueOf(new DecimalFormat().getDecimalFormatSymbols().getGroupingSeparator());
    private static final int K_INDEX = 10;
    private static final boolean NO_ANIMATE_TO_NEXT_NUMBER = false;

    private final Paint mPaint;
    private long mKnownCount;
    private double mVelocityPerMS;
    private int mLastDigitCount;
    private long mKnownCountRefreshTime;
    private long mDrawingCount;
    private Rect[] mBounds;
    private int mMaxTextWidth;
    private int mMaxTextHeight;
    private final ArrayList<DigitAnimation> mDigitAnimations = new ArrayList<>();
    private String mLastPrint;
    private long mExtraCount;
    private AnimationMode mAnimationMode = new AnimationMode(false, false, true);
    private long mMinAnimationSeparation;
    private long mLastAnimationTime;
    private volatile boolean mCanAnimate;
    private final int[] mLOCK = new int[0];
    private long mMaxAnimationSeparation;
    private boolean mIsPaused;

    public void setAnimationMode(AnimationMode animationMode) {
        mAnimationMode = animationMode;
    }

    public void setMinAnimationSeparation(long minAnimationSeparation) {
        mMinAnimationSeparation = minAnimationSeparation;
    }

    public void setMaxAnimationSeparation(long maxAnimationSeparation) {
        mMaxAnimationSeparation = maxAnimationSeparation;
    }

    public void incrementExtraCount(int n) {
        adjustExtraCount(mExtraCount + n);
    }

    public static class AnimationMode {
        public final boolean continuousAnimation;
        public final boolean pedometerAnimation;
        public final boolean alphaAnimation;

        public AnimationMode(boolean continuousAnimation, boolean pedometerAnimation, boolean alphaAnimation) {
            this.continuousAnimation = continuousAnimation;
            this.pedometerAnimation = pedometerAnimation;
            this.alphaAnimation = alphaAnimation;
        }
    }

    //Holds the state for individual digits. 
    public class DigitAnimation {
        public final int mIndexFromRight;
        private final double mDivider;
        private final double mNextDivider;
        public long mAnimationDuration;
        public long mAnimationStartTime;
        public long mAnimatingCount;
        public boolean mIsAnimating;
        public int mDrawingDigit;
        public int mCurrentAnimatingToDigit;

        public DigitAnimation(int indexFromRight, double velocityPerMS, long drawingCount) {
            mIndexFromRight = indexFromRight;
            mDivider = Math.pow(10, mIndexFromRight);
            mNextDivider = Math.pow(10, mIndexFromRight + 1);
            if (mIndexFromRight > 0) {
                mDrawingDigit = (int) (((drawingCount / mDivider) % 10));
            } else {
                mDrawingDigit = (int) (drawingCount % 10);
            }
            mAnimatingCount = drawingCount;
            if (velocityPerMS > 0) {
                if (mAnimationMode.continuousAnimation) {
                    if (mIndexFromRight > 0) {
                        mAnimationDuration = (long) (1 / (velocityPerMS / (10 * mIndexFromRight)));
                    } else {
                        mAnimationDuration = (long) (1 / velocityPerMS);
                    }
                } else {
                    mAnimationDuration = Integer.MAX_VALUE;
                }
            } else {
                mAnimationDuration = Integer.MAX_VALUE;
            }
            mAnimationDuration = TimeUnit.NANOSECONDS.convert(mAnimationDuration, TimeUnit.MILLISECONDS);
            mAnimationDuration = Math.min(mAnimationDuration, ANIMATION_DURATION_MAX);
            mAnimationDuration = Math.max(mAnimationDuration, ANIMATION_DURATION_MIN);
        }

        public boolean invalidate(long currentTime, long currentCount, boolean shouldAnimate) {
            int currentRealDigit = mDrawingDigit;
            if (mIsAnimating) {
                if ((currentTime - mAnimationStartTime) > mAnimationDuration) {
                    if (mIndexFromRight > 0) {
                        currentRealDigit = (int) ((mAnimatingCount / mDivider) % 10);
                    } else {
                        currentRealDigit = (int) (mAnimatingCount % 10);
                    }
                    if (mAnimationMode.pedometerAnimation) {
                        mDrawingDigit = (mDrawingDigit + 1) % 10;
                    } else {
                        mDrawingDigit = mCurrentAnimatingToDigit;
                    }
                    mIsAnimating = false;
                }
            }
            boolean shouldAnimateNext = false;
            if (shouldAnimate || currentRealDigit != mDrawingDigit) {
                if (!mIsAnimating) {
                    mIsAnimating = true;
                    mAnimationStartTime = System.nanoTime();
                    int currentRest = (int) ((mAnimatingCount / mNextDivider));
                    int nextRest = (int) ((currentCount / mNextDivider) );
                    shouldAnimateNext = currentRest != nextRest;
                    mAnimatingCount = currentCount;
                    if (mAnimationMode.pedometerAnimation) {
                        mCurrentAnimatingToDigit = (mDrawingDigit + 1) % 10;
                    } else {
                        if (mIndexFromRight > 0) {
                            mCurrentAnimatingToDigit = (int) ((mAnimatingCount / mDivider) % 10);
                        } else {
                            mCurrentAnimatingToDigit = (int) (mAnimatingCount % 10);
                        }
                    }
                }
            }
            return shouldAnimateNext;
        }
    }

    public CounterView(Context context) {
        super(context);
        mPaint = init();
        updateTextSizes();
    }

    private Paint init() {
        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.LINEAR_TEXT_FLAG);
        mBounds = new Rect[] {
                new Rect(),
                new Rect(),
                new Rect(),
                new Rect(),
                new Rect(),
                new Rect(),
                new Rect(),
                new Rect(),
                new Rect(),
                new Rect(),
                new Rect(),
        };
        paint.setTextSize(32);
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.FILL);
        paint.setTextAlign(Paint.Align.RIGHT);
        return paint;
    }

    private void updateTextSizes() {
        mMaxTextWidth = 0;
        mMaxTextHeight = 0;
        for (int i = 0; i < mBounds.length; i++) {
            if (i != K_INDEX) {
                mPaint.getTextBounds(String.valueOf(i), 0, 1, mBounds[i]);
            } else {
                mPaint.getTextBounds(K_SEPARATOR, 0, 1, mBounds[i]);
            }
            if (mMaxTextWidth < mBounds[i].width()) {
                mMaxTextWidth = mBounds[i].width();
            }
            if (mMaxTextHeight < mBounds[i].height()) {
                mMaxTextHeight = mBounds[i].height();
            }
        }
    }

    public CounterView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPaint = init();
        updateTextSizes();
    }

    public CounterView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        mPaint = init();
        updateTextSizes();
    }

    public void setTypeFace(Typeface typeFace) {
        mPaint.setTypeface(typeFace);
        requestLayout();
    }

    public void setTextSize(float textSize) {
        mPaint.setTextSize(textSize);
        requestLayout();
    }

    public void reset() {
        mLastDigitCount = 0;
        mKnownCount = 0;
        mKnownCountRefreshTime = -1;
        mVelocityPerMS = 0;
        mDigitAnimations.clear();
    }

    public long setKnownCount(long knownCount, double velocityPerMS, long knownCountRefreshTime) {
        if (knownCountRefreshTime > 0) {
            long time = System.currentTimeMillis();
            mKnownCount = (long) (knownCount + velocityPerMS * (time - knownCountRefreshTime));
            mKnownCountRefreshTime = time;
        } else {
            mKnownCount = knownCount;
        }
        mVelocityPerMS = velocityPerMS;
        synchronized (mLOCK) {
            mLastDigitCount = 0;
            mDigitAnimations.clear();
            invalidateDigitSize(true);
        }
        return mKnownCount;
    }

    public void pause() {
        mIsPaused = true;
        removeCallbacks(this);
    }

    public void resume() {
        if (mIsPaused) {
            mIsPaused = false;
            postInvalidate();
        }
    }

    public long getCount() {
        return (long) (mKnownCount + (mKnownCountRefreshTime > 0 ? mVelocityPerMS * (System.currentTimeMillis() - mKnownCountRefreshTime) : 0));
    }

    @Override
    public void onDraw(Canvas canvas) {
        int x = getMeasuredWidth();
        final int measuredHeight = getMeasuredHeight();
        synchronized (mLOCK) {
            int length = mDigitAnimations.size();
            String num = "";
            for (int i = 0; i < length; i++) {
                if (i >= 3 && i % 3 == 0) {
                    mPaint.setAlpha(255);
                    if (K_SEPARATOR.equals(".")) {
						canvas.drawText(K_SEPARATOR, x, (measuredHeight >> 1) + mBounds[K_INDEX].height() * 2.5f, mPaint);
						x -= (mBounds[K_INDEX].width() + 2.5f);
					} else {
						canvas.drawText(K_SEPARATOR, x, (measuredHeight >> 1) + mBounds[K_INDEX].height(), mPaint);
						x -= (mBounds[K_INDEX].width());
					}
                }
                DigitAnimation digitAnimation = mDigitAnimations.get(i);
                int digit = digitAnimation.mDrawingDigit;
                String digitText = String.valueOf(digit);
                final int y = getIntrinsicHeightForDigit(measuredHeight, digit);
                if (digitAnimation.mIsAnimating) {
                    long diff = (System.nanoTime() - digitAnimation.mAnimationStartTime);
                    double progress = diff / (double) digitAnimation.mAnimationDuration;
                    if (diff >= digitAnimation.mAnimationDuration || (digitAnimation.mCurrentAnimatingToDigit == digit && !mAnimationMode.pedometerAnimation)) {
                        num += digitAnimation.mCurrentAnimatingToDigit;
                        mPaint.setAlpha(255);
                        canvas.drawText(String.valueOf(digitAnimation.mCurrentAnimatingToDigit), x, y, mPaint);
                    } else {
                        int topY = (int) (y - (progress * (mBounds[digit].height() + DIGIT_SPACING_Y)));
                        if (digit != 0 || i != length - 1 || length == 1) {
                            if (mAnimationMode.alphaAnimation) {
                                mPaint.setAlpha((int) ((1 - progress) * 255));
                            }
                            canvas.drawText(digitText, x, topY, mPaint);
                        }
                        num += digitText;
                        int botY = topY + mBounds[digit].height() + DIGIT_SPACING_Y;
                        if (mAnimationMode.alphaAnimation) {
                            mPaint.setAlpha((int) (progress * 255));
                        }
                        canvas.drawText(String.valueOf(digitAnimation.mCurrentAnimatingToDigit), x, botY, mPaint);
                    }
                } else {
                    num += digitText;
                    mPaint.setAlpha(255);
                    canvas.drawText(digitText, x, y, mPaint);
                }
                x -= mMaxTextWidth + DIGIT_SPACING_X;
            }
            if (!num.equals(mLastPrint)) {
                mLastPrint = num;
            }
        }
        removeCallbacks(this);
        if (!mIsPaused) {
            postDelayed(this, FRAME_DELAY);
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        int width, height;

        updateTextSizes();

        if (widthMode == MeasureSpec.EXACTLY) {
            width = widthSize;
        } else {
            int digits = Math.max(mLastDigitCount, String.valueOf(mDrawingCount).length());
            width = (digits * (mMaxTextWidth + DIGIT_SPACING_X)) +
                    (digits / 3 * mBounds[K_INDEX].width()) +
                    getPaddingLeft() + getPaddingRight();
            if (heightMode == MeasureSpec.AT_MOST) {
                width = Math.min(width, widthSize);
            }
        }
        if (heightMode == MeasureSpec.EXACTLY) {
            height = heightSize;
        } else {
            height = mMaxTextHeight + getPaddingTop() + getPaddingBottom() + DIGIT_SPACING_Y;
            if (heightMode == MeasureSpec.AT_MOST) {
                height = Math.min(height, heightSize);
            }
        }
        Log.d(TAG, "onMeasure " + width + " * " + height);
        setMeasuredDimension(width, height);
    }

    private int getIntrinsicHeightForDigit(int measuredHeight, int digit) {
        return (measuredHeight + mBounds[digit].height()) >> 1;
    }

    public void invalidateCounterUI() {
        mCanAnimate = true;
    }

    /**
     * Adjust extraCount, this will trigger the animation.
     * @param extraCount
     */
    public void adjustExtraCount(long extraCount) {
        mExtraCount = extraCount;
    }

    private void invalidateDigitSize(boolean forceDigitSizeRecal) {
        synchronized (mLOCK) {
            if (mDigitAnimations.size() == 0) {
                mDigitAnimations.add(new DigitAnimation(0, mVelocityPerMS, mDrawingCount));
            }
            long currentCount = getCount() + mExtraCount;
            long currentTime = System.nanoTime();
            int digitCount = String.valueOf(mDrawingCount).length();
            long diffTimeMs = System.currentTimeMillis() - mLastAnimationTime;
            boolean shouldAnimateNext = currentCount > mDigitAnimations.get(0).mAnimatingCount;
            if (forceDigitSizeRecal || ( //If we got a new digit
                    diffTimeMs >= mMinAnimationSeparation && // Or (if min separation time has passed
                    (mCanAnimate || diffTimeMs >= mMaxAnimationSeparation))) { // AND we should)
                mLastAnimationTime = System.currentTimeMillis();
                int i = 0;
                long newDrawingCount = 0;
                while (i < digitCount || shouldAnimateNext) {
                    if (mDigitAnimations.size() <= i) {
                        mDigitAnimations.add(new DigitAnimation(i, mVelocityPerMS, mDrawingCount));
                    }
                    DigitAnimation digitAnim = mDigitAnimations.get(i);
                    shouldAnimateNext = digitAnim.invalidate(currentTime, currentCount, shouldAnimateNext);
                    if (NO_ANIMATE_TO_NEXT_NUMBER && forceDigitSizeRecal) {
                        digitAnim.mAnimationStartTime = 1;
                    }
                    newDrawingCount += i == 0 ? digitAnim.mDrawingDigit : digitAnim.mDrawingDigit * Math.pow(10, i);
                    i++;
                }
                setDrawingCount(newDrawingCount, forceDigitSizeRecal);
                if (mLastDigitCount != mDigitAnimations.size()) {
                    mLastDigitCount = mDigitAnimations.size();
                    requestLayout();
                }
                if (!mAnimationMode.continuousAnimation) {
                    mCanAnimate = false;
                }
            }
        }
    }
    
    private void setDrawingCount(long newDrawingCount, boolean invalidation) {
        mDrawingCount = newDrawingCount;
    }

    @Override
    public void run() {
       invalidateDigitSize(false);
        if ((!mIsPaused) && isShown()) {
            postInvalidate();
        }
    }
}