android Bitmap旋转问题

//画笔，定义绘制属性

private Paint myPaint;

private Paint mBitmapPaint;



// 绘制路径

private Path myPath;



// 画布及其底层位图

private Bitmap myBitmap0;

private Bitmap myBitmap1;

private Canvas myCanvas;

public MyPaintView(Context context, AttributeSet attrs){

	super(context, attrs);

	myBitmap0 = BitmapFactory.decodeFile("/storage/sdcard/a.png").copy(Bitmap.Config.ARGB_8888, true);

	myBitmap1 = Bitmap.createBitmap(myBitmap0);

	if(i == 0){

		initialize();

	}else if(i == 1){

		initWhite();

	}

	//	开启线程

	new Thread(this).start();

}

public void initialize(){

	// 绘制自由曲线用的画笔

	myPaint = new Paint();

	myPaint.setAntiAlias(true);

	myPaint.setDither(true);

	myPaint.setColor(RGBColor.getColor());

	myPaint.setStyle(Paint.Style.STROKE);

	myPaint.setStrokeJoin(Paint.Join.ROUND);

	myPaint.setStrokeCap(Paint.Cap.ROUND);

	myPaint.setStrokeWidth(RGBColor.getFontSize());

	myPath = new Path();

	mBitmapPaint = new Paint(Paint.DITHER_FLAG);

}

@Override

protected void onDraw(Canvas canvas){

	super.onDraw(canvas);

	// 背景颜色

	canvas.drawColor(R.color.white);

 	canvas.drawBitmap(myBitmap1, 0, 0, mBitmapPaint);



	canvas.drawPath(myPath, myPaint);

	myCanvas = new Canvas(myBitmap1);

}



/**

* 图片旋转

 * */

public void picPost(int nPostExtent){

	matrix.reset();

	matrix.postScale(Scale, Scale);

	matrix.postRotate(nPostExtent);

        // 下面这句话如果把myBitmap1都改为myBitmap0的话顺时针和逆时针旋转都没有问题，现在需要用myBitmap1,是因为在这个位图上面先涂鸦了再旋转的话就会清空以前涂鸦内容，所以选用myBitmap1，但是用它的话只能朝着一个方向旋转，先顺时针完了，逆时针就回不来了

	myBitmap1 = Bitmap.createBitmap(myBitmap1, 0, 0, myBitmap1.getWidth(), myBitmap1.getHeight(), matrix, true);

}