android 抽奖转盘

【核心代码】

package com.choujiang;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Path;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;

public class LuckyPanView extends SurfaceView implements Callback, Runnable
{

	private SurfaceHolder mHolder;
	/**
	 * 与SurfaceHolder绑定的Canvas
	 */
	private Canvas mCanvas;
	/**
	 * 用于绘制的线程
	 */
	private Thread t;
	/**
	 * 线程的控制开关
	 */
	private boolean isRunning;

	/**
	 * 抽奖的文字
	 */
	private String[] mStrs = new String[] { "单反相机", "IPAD", "恭喜发财", "IPHONE",
			"妹子一只", "恭喜发财" };
	/**
	 * 每个盘块的颜色
	 */
	private int[] mColors = new int[] { 0xFFFFC300, 0xFFF17E01, 0xFFFFC300,
			0xFFF17E01, 0xFFFFC300, 0xFFF17E01 };
	/**
	 * 与文字对应的图片
	 */
	private int[] mImgs = new int[] { R.mipmap.danfan, R.mipmap.ipad,
			R.mipmap.f040, R.mipmap.iphone, R.mipmap.meizi,
			R.mipmap.f040 };

	/**
	 * 与文字对应图片的bitmap数组
	 */
	private Bitmap[] mImgsBitmap;
	/**
	 * 盘块的个数
	 */
	private int mItemCount = 6;

	/**
	 * 绘制盘块的范围
	 */
	private RectF mRange = new RectF();
	/**
	 * 圆的直径
	 */
	private int mRadius;
	/**
	 * 绘制盘快的画笔
	 */
	private Paint mArcPaint;

	/**
	 * 绘制文字的画笔
	 */
	private Paint mTextPaint;

	/**
	 * 滚动的速度
	 */
	private double mSpeed;
	private volatile float mStartAngle = 0;
	/**
	 * 是否点击了停止
	 */
	private boolean isShouldEnd;

	/**
	 * 控件的中心位置
	 */
	private int mCenter;
	/**
	 * 控件的padding，这里我们认为4个padding的值一致，以paddingleft为标准
	 */
	private int mPadding;

	/**
	 * 背景图的bitmap
	 */
	private Bitmap mBgBitmap = BitmapFactory.decodeResource(getResources(),
			R.mipmap.bg2);
	/**
	 * 文字的大小
	 */
	private float mTextSize = TypedValue.applyDimension(
			TypedValue.COMPLEX_UNIT_SP, 20, getResources().getDisplayMetrics());

	public LuckyPanView(Context context)
	{
		this(context, null);
	}

	public LuckyPanView(Context context, AttributeSet attrs)
	{
		super(context, attrs);

		mHolder = getHolder();
		mHolder.addCallback(this);

		// setZOrderOnTop(true);// 设置画布 背景透明
		// mHolder.setFormat(PixelFormat.TRANSLUCENT);

		setFocusable(true);
		setFocusableInTouchMode(true);
		this.setKeepScreenOn(true);

	}

	/**
	 * 设置控件为正方形
	 */
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
	{
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);

		int width = Math.min(getMeasuredWidth(), getMeasuredHeight());
		// 获取圆形的直径
		mRadius = width - getPaddingLeft() - getPaddingRight();
		// padding值
		mPadding = getPaddingLeft();
		// 中心点
		mCenter = width / 2;
		setMeasuredDimension(width, width);
	}

	@Override
	public void surfaceCreated(SurfaceHolder holder)
	{
		// 初始化绘制圆弧的画笔
		mArcPaint = new Paint();
		mArcPaint.setAntiAlias(true);
		mArcPaint.setDither(true);
		// 初始化绘制文字的画笔
		mTextPaint = new Paint();
		mTextPaint.setColor(0xFFffffff);
		mTextPaint.setTextSize(mTextSize);
		// 圆弧的绘制范围
		mRange = new RectF(getPaddingLeft(), getPaddingLeft(), mRadius
				  getPaddingLeft(), mRadius   getPaddingLeft());

		// 初始化图片
		mImgsBitmap = new Bitmap[mItemCount];
		for (int i = 0; i < mItemCount; i  )
		{
			mImgsBitmap[i] = BitmapFactory.decodeResource(getResources(),
					mImgs[i]);
		}

		// 开启线程
		isRunning = true;
		t = new Thread(this);
		t.start();
	}

	@Override
	public void surfaceChanged(SurfaceHolder holder, int format, int width,
			int height)
	{
		// TODO Auto-generated method stub

	}

	@Override
	public void surfaceDestroyed(SurfaceHolder holder)
	{
		// 通知关闭线程
		isRunning = false;
	}

	@Override
	public void run()
	{
		// 不断的进行draw
		while (isRunning)
		{
			long start = System.currentTimeMillis();
			draw();
			long end = System.currentTimeMillis();
			try
			{
				if (end - start < 50)
				{
					Thread.sleep(50 - (end - start));
				}
			} catch (InterruptedException e)
			{
				e.printStackTrace();
			}

		}

	}

	private void draw()
	{
		try
		{
			// 获得canvas
			mCanvas = mHolder.lockCanvas();
			if (mCanvas != null)
			{
				// 绘制背景图
				drawBg();

				/**
				 * 绘制每个块块，每个块块上的文本，每个块块上的图片
				 */
				float tmpAngle = mStartAngle;
				float sweepAngle = (float) (360 / mItemCount);
				for (int i = 0; i < mItemCount; i  )
				{
					// 绘制快快
					mArcPaint.setColor(mColors[i]);
//					mArcPaint.setStyle(Style.STROKE);
					mCanvas.drawArc(mRange, tmpAngle, sweepAngle, true,
							mArcPaint);
					// 绘制文本
					drawText(tmpAngle, sweepAngle, mStrs[i]);
					// 绘制Icon
					drawIcon(tmpAngle, i);

					tmpAngle  = sweepAngle;
				}

				// 如果mSpeed不等于0，则相当于在滚动
				mStartAngle  = mSpeed;

				// 点击停止时，设置mSpeed为递减，为0值转盘停止
				if (isShouldEnd)
				{
					mSpeed -= 1;
				}
				if (mSpeed <= 0)
				{
					mSpeed = 0;
					isShouldEnd = false;
				}
				// 根据当前旋转的mStartAngle计算当前滚动到的区域
				calInExactArea(mStartAngle);
			}
		} catch (Exception e)
		{
			e.printStackTrace();
		} finally
		{
			if (mCanvas != null)
				mHolder.unlockCanvasAndPost(mCanvas);
		}

	}

	/**
	 * 根据当前旋转的mStartAngle计算当前滚动到的区域 绘制背景，不重要，完全为了美观
	 */
	private void drawBg()
	{
		mCanvas.drawColor(0xFFFFFFFF);
		mCanvas.drawBitmap(mBgBitmap, null, new Rect(mPadding / 2,
				mPadding / 2, getMeasuredWidth() - mPadding / 2,
				getMeasuredWidth() - mPadding / 2), null);
	}

	/**
	 * 根据当前旋转的mStartAngle计算当前滚动到的区域
	 * 
	 * @param startAngle
	 */
	public void calInExactArea(float startAngle)
	{
		// 让指针从水平向右开始计算
		float rotate = startAngle   90;
		rotate %= 360.0;
		for (int i = 0; i < mItemCount; i  )
		{
			// 每个的中奖范围
			float from = 360 - (i   1) * (360 / mItemCount);
			float to = from   360 - (i) * (360 / mItemCount);

			if ((rotate > from) && (rotate < to))
			{
				Log.d("TAG", mStrs[i]);
				return;
			}
		}
	}

	/**
	 * 绘制图片
	 * 
	 * @param startAngle
	 * @param i
	 */
	private void drawIcon(float startAngle, int i)
	{
		// 设置图片的宽度为直径的1/8
		int imgWidth = mRadius / 8;

		float angle = (float) ((30   startAngle) * (Math.PI / 180));

		int x = (int) (mCenter   mRadius / 2 / 2 * Math.cos(angle));
		int y = (int) (mCenter   mRadius / 2 / 2 * Math.sin(angle));

		// 确定绘制图片的位置
		Rect rect = new Rect(x - imgWidth / 2, y - imgWidth / 2, x   imgWidth
				/ 2, y   imgWidth / 2);

		mCanvas.drawBitmap(mImgsBitmap[i], null, rect, null);

	}

	/**
	 * 绘制文本
	 * 
	 * @param startAngle
	 * @param sweepAngle
	 * @param string
	 */
	private void drawText(float startAngle, float sweepAngle, String string)
	{
		Path path = new Path();
		path.addArc(mRange, startAngle, sweepAngle);
		float textWidth = mTextPaint.measureText(string);
		// 利用水平偏移让文字居中
		float hOffset = (float) (mRadius * Math.PI / mItemCount / 2 - textWidth / 2);// 水平偏移
		float vOffset = mRadius / 2 / 6;// 垂直偏移
		mCanvas.drawTextOnPath(string, path, hOffset, vOffset, mTextPaint);
	}

	/**
	 * 点击开始旋转
	 * 
	 * @param luckyIndex
	 */
	public void luckyStart(int luckyIndex)
	{
		// 每项角度大小
		float angle = (float) (360 / mItemCount);
		// 中奖角度范围（因为指针向上，所以水平第一项旋转到指针指向，需要旋转210-270；）
		float from = 270 - (luckyIndex   1) * angle;
		float to = from   angle;
		// 停下来时旋转的距离
		float targetFrom = 4 * 360   from;
		/**
		 * <pre>
		 *  (v1   0) * (v1 1) / 2 = target ;
		 *  v1*v1   v1 - 2target = 0 ;
		 *  v1=-1 (1*1   8 *1 * target)/2;
		 * </pre>
		 */
		float v1 = (float) (Math.sqrt(1 * 1   8 * 1 * targetFrom) - 1) / 2;
		float targetTo = 4 * 360   to;
		float v2 = (float) (Math.sqrt(1 * 1   8 * 1 * targetTo) - 1) / 2;

		mSpeed = (float) (v1   Math.random() * (v2 - v1));
		isShouldEnd = false;
	}

	public void luckyEnd()
	{
		mStartAngle = 0;
		isShouldEnd = true;
	}

	public boolean isStart()
	{
		return mSpeed != 0;
	}

	public boolean isShouldEnd()
	{
		return isShouldEnd;
	}

}