Android實現圖片隨手指旋轉功能

在View中進行重繪，主要是通過計算角度及距離來實現。實現類代碼如下：

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;//中間不動的圖片
 private Bitmap bitmapBig;//隨手指轉動的圖片
 private Bitmap bitmapOut;//外圍不動的圖片
 // 圓心坐標
 private float mPointX = 0, mPointY = 0;

 private int flag = 0;
 // 半徑
 private int mRadius = 0;
 // 旋轉角度
 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;
   //如果點擊觸摸范圍在圈外，則不處理
   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");
  // 大圓
  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);
  // 小圓(中間的圓心)
  drawInCenter(canvas, bitmaplittele, mPointX, mPointY - 10, TAG);
 }

 Bitmap adjustPhotoRotation(Bitmap bm, final int orientationDegree) {
  if (orientationDegree == 0) {
   return bm;
  }
  Matrix m = new Matrix();
  m.setRotate(orientationDegree, (float) bm.getWidth() / 2,
    (float) bm.getHeight() / 2);

  try {
   Bitmap bm1 = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(),
     bm.getHeight(), m, true);

   return bm1;

  } catch (OutOfMemoryError ex) {
  }

  return null;

 }

 private void drawInCenter(Canvas canvas, Bitmap bitmap, float left,
   float top, String text) {
  canvas.drawBitmap(bitmap, left - bitmap.getWidth() / 2,
    top - bitmap.getHeight() / 2, null);
 }

 // 子控件位置改變重新計算角度
 private int computeCurrentAngle(float x, float y) {
  // 根據圓心坐標計算角度
  float distance = (float) Math
    .sqrt(((x - mPointX) * (x - mPointX) + (y - mPointY)
      * (y - mPointY)));
  int degree = (int) (Math.acos((x - mPointX) / distance) * 180 / Math.PI);
  if (y < mPointY) {
   degree = -degree;
  }
  if (degree < 0) {
   degree += 360;
  }

  // Log.i("RoundSpinView", "x:" + x + ",y:" + y + ",degree:" + degree);
  return degree;
 }

 // 獲取距離圓心的距離
 private float getDistance(float x, float y) {
  // 根據圓心坐標計算角度
  float distance = (float) Math
    .sqrt(((x - mPointX) * (x - mPointX) + (y - mPointY)
      * (y - mPointY)));
  return distance;
 }

 //點擊
 private boolean SetClick(float x, float y) {
  float distance = getDistance(x, y);
  if (mAngle>10||mAngle<-10) {
   return false;
  }else if(endTime-beginTime>1000){
   return false;
  }
  if (distance < bitmapBig.getWidth() / 2) {
   int mod = 0;
   
   if (beginAngle < 90 || 330 < beginAngle) {
    mod = (imageIndex+3-1)%3;       
   }
   else if (90 < beginAngle && 210 > beginAngle) {
    mod = (imageIndex+3-2)%3;   
   }
   else{
    mod = imageIndex;   
   }
   //回調到主界面進行處理。
   listener.onModClick(mod);
  }
  return true;
 }
 
 public interface RotateViewListener { 
  void onModClick(int mode);
  void onModChange(int mode);
 }
}