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：

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 = BitmapFactory.decodeResource(getResources(),
     bitMap[imageIndex]).copy(Bitmap.Config.ARGB_8888, true);
   bitmapBig = adjustPhotoRotation(bitmapBig, imageIndex * 120);
   invalidate();
   if (mAngle >= 60) {
    listener.onModChange(imageIndex);
   }   
   return true;
  }

return false;
 }

@Override
 public void onDraw(Canvas canvas) {
  // Log.i(TAG, "onDraw");
  // 大圆
  drawInCenter(canvas, bitmapOut, mPointX, mPointY, TAG);
  // 外圈
  if (isUp) {
   mAngle = 0;
  } else {
   mAngle = currentAngle - beginAngle;
  }

Bitmap tempBig = adjustPhotoRotation(bitmapBig, mAngle);
  // Log.i(TAG, "mAngle:"+mAngle);
  drawInCenter(canvas, tempBig, mPointX, mPointY + 10, TAG);
  // 小圆(中间的圆心)
  drawInCenter(canvas, bitmaplittele, mPointX, mPointY - 10, TAG);
 }