android Bitmap圍繞一個點進行旋轉

在項目中需要使用定位功能，也就是一個點圍繞一個圓心進行旋轉，查看了canvas的函數也就只有一個 canvas.drawBitmap(bitmap, matrix, paint)通過使用Matrix來實現旋轉，這裡實現一個demo，功能就是小原點順時針繪製一個原然後逆時針撤銷這個圓，通過Timer來實現。代碼如下:

Surface.java這個是實現繪製圖形的類

package com.example.test;import java.util.Timer;import java.util.TimerTask;import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.PixelFormat;import android.graphics.PorterDuff.Mode;import android.os.Handler;import android.os.Message;import android.util.Log;import android.view.SurfaceHolder;import android.view.SurfaceView;import android.view.SurfaceHolder.Callback;@SuppressLint("HandlerLeak")class Surface extends SurfaceView implements Callback{Bitmap bmp;private Paint mPaint;private SurfaceHolder mHolder;public Surface(Context context) {super(context);mHolder = getHolder();mHolder.addCallback(this);        mPaint = new Paint();        mPaint.setColor(Color.GREEN);        mPaint.setAntiAlias(true);//消除鋸齒        setFocusable(true);        setFocusableInTouchMode(true);//        setZOrderOnTop(true);//        mHolder.setFormat(PixelFormat.TRANSPARENT);//設定背景透明bmp = BitmapFactory.decodeResource(getResources(), R.drawable.camera_r_local); bmp = Bitmap.createScaledBitmap(bmp, 15, 15, false);}public Handler handler = new Handler(){@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case 0:canvas_ok();break;}super.handleMessage(msg);}};public void canvas_ok(){ Canvas canvas = null;try {canvas = mHolder.lockCanvas();canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);//清除螢幕//        canvas.save();        Matrix matrix = new Matrix();        matrix.postTranslate(130, 0);        matrix.postRotate(degree, 130 ,130);        canvas.drawBitmap(bmp, matrix, mPaint);//        canvas.restore();} catch (Exception e) {}finally {            if(canvas != null) {                mHolder.unlockCanvasAndPost(canvas);            }        }}int degree = 0;Timer timer = new Timer();boolean flag = true;@Overridepublic void surfaceCreated(SurfaceHolder holder) {canvas_ok();timer.schedule(new TimerTask() {@Overridepublic void run() {if (flag) {degree++;if (degree == 360) {flag = false;}}else {degree--;if(degree == -360 || degree == 0){flag = true;}}Log.e("flag", degree+"  : "+flag);handler.sendEmptyMessage(0);}}, 50, 50);}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {if (timer != null) {timer.cancel();timer = null;}}}

Main7.java是主類

package com.example.test;import android.app.Activity;import android.os.Bundle;import android.widget.RelativeLayout;public class Main7 extends Activity{Surface surface;RelativeLayout.LayoutParams laParams;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);surface = new Surface(this);laParams = new RelativeLayout.LayoutParams(260,  260);setContentView(surface, laParams);}}

如下：