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Flashlight / src / com.example.android.wearable.flashlight /

PartyLightView.java

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/*
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 * Copyright (C) 2014 The Android Open Source Project
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *      http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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package com.example.android.wearable.flashlight;
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import android.animation.ArgbEvaluator;
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import android.content.Context;
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import android.graphics.Canvas;
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import android.graphics.Color;
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import android.os.Handler;
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import android.os.Message;
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import android.util.AttributeSet;
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import android.view.View;
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/**
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 * Flashing party lights!
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 */
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public class PartyLightView extends View {
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    private int[] mColors = new int[] {
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            Color.RED,
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            Color.GREEN,
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            Color.BLUE,
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            Color.CYAN,
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            Color.MAGENTA
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    };
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    private int mFromColorIndex;
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    private int mToColorIndex;
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    /**
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     * Value b/t 0 and 1.
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     */
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    private float mProgress;
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    private ArgbEvaluator mEvaluator;
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    private int mCurrentColor;
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    private Handler mHandler;
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    public PartyLightView(Context context) {
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        super(context);
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        init();
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    }
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    public PartyLightView(Context context, AttributeSet attrs) {
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        super(context, attrs);
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        init();
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    }
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    @Override
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    protected void onDraw(Canvas canvas) {
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        canvas.drawColor(mCurrentColor);
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        super.onDraw(canvas);
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    }
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    public void startCycling() {
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        mHandler.sendEmptyMessage(0);
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    }
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    public void stopCycling() {
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        mHandler.removeMessages(0);
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    }
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    private void init() {
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        mEvaluator = new ArgbEvaluator();
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        mHandler = new Handler() {
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            @Override
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            public void handleMessage(Message msg) {
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                mCurrentColor = getColor(mProgress, mColors[mFromColorIndex],
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                        mColors[mToColorIndex]);
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                postInvalidate();
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                mProgress += 0.1;
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                if (mProgress > 1.0) {
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                    mFromColorIndex = mToColorIndex;
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                    // Find a new color.
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                    mToColorIndex++;
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                    if (mToColorIndex >= mColors.length) {
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                        mToColorIndex = 0;
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                    }
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                }
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                mHandler.sendEmptyMessageDelayed(0, 100);
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            }
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        };
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    }
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    private int getColor(float fraction, int colorStart, int colorEnd) {
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        int startInt = colorStart;
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        int startA = (startInt >> 24) & 0xff;
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        int startR = (startInt >> 16) & 0xff;
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        int startG = (startInt >> 8) & 0xff;
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        int startB = startInt & 0xff;
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        int endInt = colorEnd;
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        int endA = (endInt >> 24) & 0xff;
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        int endR = (endInt >> 16) & 0xff;
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        int endG = (endInt >> 8) & 0xff;
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        int endB = endInt & 0xff;
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        return (startA + (int)(fraction * (endA - startA))) << 24 |
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                (startR + (int)(fraction * (endR - startR))) << 16 |
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                (startG + (int)(fraction * (endG - startG))) << 8 |
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                ((startB + (int)(fraction * (endB - startB))));
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    }
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}
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