Android实现图片随手指旋转功能

在View中进行重绘，主要是通过计算角度及距离来实现。实现类代码如下：

[java]
package com.example.roatedemo;

import java.util.Calendar;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

public class RotateView extends View {
    private Paint mPaint = new Paint();
    private Bitmap bitmaplittele;//中间不动的图片
    private Bitmap bitmapBig;//随手指转动的图片
    private Bitmap bitmapOut;//外围不动的图片
    // 圆心坐标
    private float mPointX = 0, mPointY = 0;

    private int flag = 0;
    // 半径
    private int mRadius = 0;
    // 旋转角度
    private int mAngle = 0;
    private int beginAngle = 0, currentAngle = 0;
    private String TAG = "NewView";
    int bitMap[] = { R.drawable.circle0, R.drawable.circle1, R.drawable.circle2 };
    int imageIndex = 0;
    boolean isUp = false,isTouch=false;
    Context mContext;
    RotateViewListener listener;
    long beginTime,endTime;
    Calendar now;

    public RotateView(Context context, int px, int py, int radius,RotateViewListener listener) {
        super(context);
        mContext = context;
        this.listener = listener;
        mPointX = px;
        mPointY = py;
        mRadius = radius;
        bitmaplittele = BitmapFactory.decodeResource(getResources(),
                R.drawable.a1_pointer).copy(Bitmap.Config.ARGB_8888, true);
        bitmapBig = BitmapFactory.decodeResource(getResources(), bitMap[0])
                .copy(Bitmap.Config.ARGB_8888, true);
        bitmapOut = BitmapFactory.decodeResource(getResources(),
                R.drawable.bigcir).copy(Bitmap.Config.ARGB_8888, true);
        setBackgroundResource(R.drawable.back);
        Log.e(TAG, "RotateViewBegin");
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent e) {
        switch (e.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            now = Calendar.getInstance();
            beginTime = now.getTimeInMillis();
            beginAngle = computeCurrentAngle(e.getX(), e.getY());
            isUp = false;
            //如果点击触摸范围在圈外，则不处理
            if (getDistance(e.getX(), e.getY())>bitmapOut.getWidth()/2) {
                isTouch=false;
            }else {
                isTouch=true;
            }
            return true;
        case MotionEvent.ACTION_MOVE:
            if (!isTouch) {
                return true;
            }
            currentAngle = computeCurrentAngle(e.getX(), e.getY());
            invalidate();
            return true;
        case MotionEvent.ACTION_UP:
            isUp = true;
            if (!isTouch) {
                return true;
            }
            now = Calendar.getInstance();
            endTime = now.getTimeInMillis();
            if (SetClick(e.getX(), e.getY())) {
                return true;
            }
            if (mAngle > 0) {
                int count = mAngle / 120 + (mAngle % 120 > 60 ? 1 : 0);
                imageIndex = (imageIndex + count) % 3;
            } else if (mAngle < 0) {
                mAngle = -mAngle;
                int count = mAngle / 120 + (mAngle % 120 > 60 ? 1 : 0);
                imageIndex = (imageIndex + 3 - count) % 3;
            }
            bitmapBig = BitmapFactor

补充：移动开发 , Android ,