Android开发之图片旋转功能实现方法【基于Matrix】

package cn.edu.pku;
import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
public class PictureRotateActivity extends Activity {
  /** Called when the activity is first created. */
  private GameRotateView1 gameview = null;
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    gameview = new GameRotateView1(this);
    setContentView(gameview);
  }
  @Override
  public boolean onKeyDown(int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub
    if ( gameview == null )
    {
      return false;
    }
    if ( keyCode == KeyEvent.KEYCODE_BACK)
    {
      this.finish();
      return true;
    }
    return gameview.onKeyDown(keyCode,event);
  }
  @Override
  public boolean onKeyUp(int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub
    super.onKeyUp(keyCode, event);
    return true;
  }
}

package cn.edu.pku;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.drawable.BitmapDrawable;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
public class GameRotateView1 extends View implements Runnable {
  Bitmap bitmap = null;
  int bitmapWidth = 0;
  int bitmapHeight = 0;
  float angle = 0.0f;
  Matrix matrix = new Matrix();
  public GameRotateView1(Context context) {
    super(context);
    // TODO Auto-generated constructor stub
    setFocusableInTouchMode(true); //设置可以捕捉键盘事件
    //获取图像资源
    bitmap = ((BitmapDrawable) getResources().getDrawable(R.drawable.cute)).getBitmap();
    bitmapWidth = bitmap.getWidth();
    bitmapHeight = bitmap.getHeight();
    new Thread(this).start();
  }
  public void run() {
    // TODO Auto-generated method stub
    while(!Thread.currentThread().isInterrupted()){
      try{
        Thread.sleep(100);
      }catch (InterruptedException e) {
        // TODO: handle exception
        Thread.currentThread().interrupt();
      }
      postInvalidate(); //可以直接在线程中更新界面
    }
  }
  @Override
  protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    super.onDraw(canvas);
    matrix.reset();
    matrix.setRotate(angle); //设置旋转
    //按照matrix的旋转构建新的Bitmap
    Bitmap bitmapcute = Bitmap.createBitmap(bitmap, 0, 0, bitmapWidth, bitmapHeight, matrix, true);
    //绘制旋转之后的图像
    GameRotateView1.DrawImage(canvas, bitmapcute, (320 - bitmapWidth)/2, 10);
    bitmapcute = null;
  }
  @Override
  public boolean onKeyDown(int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub
    if(keyCode == KeyEvent.KEYCODE_DPAD_LEFT){
      angle--;
    }else if(keyCode == KeyEvent.KEYCODE_DPAD_RIGHT){
      angle++;
    }
    return true;
  }
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    // TODO Auto-generated method stub
    return true;
  }
  @Override
  public boolean onKeyUp(int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub
    return false;
  }
  @Override
  public boolean onKeyMultiple(int keyCode, int repeatCount, KeyEvent event) {
    // TODO Auto-generated method stub
    return true;
  }
  /**
   * 绘制一个Bitmap
   * canvas  画布
   * bitmap  图片
   * x      屏幕上的x坐标
   * y      屏幕上的y坐标
   */
  public static void DrawImage(Canvas canvas, Bitmap _bitmap, int x, int y)
  {
    /* 绘制图像 */
    canvas.drawBitmap(_bitmap, x, y, null);
  }