加载大图片
	Options options=new Options();
	options.inJustDecodeBounds=true;//不加载图片，只加载文件信息
	//加载图片，获取到配置信息
	BitmapFactory.decodeFile(Environment.getExternalStorageDirectory()+"/a.jpg",options);
	int width=options.outWidth;//获取到图片的真是宽度
	int height=options.outHeight;//获取到图片的真是的高度
	//获取到手机屏幕显示对象
	Display display = getWindowManager().getDefaultDisplay();
	int h = display.getHeight();//获取屏幕的高度
	int w = display.getWidth();//获取到平局的宽度
	//计算缩放的比率
	int scale=1;
	int scaley=width/w;
	int scalex=height/h;
	if(scalex<1 && scaley<1){
		
	}else{
		//如果缩放的宽，大于高，则安照宽的缩放比率，因为高的缩放比率小，那么按照高的缩放比率的话，宽则超出了屏幕的宽
		scale=scalex>scaley?scalex:scaley;
	}
	
	options.inJustDecodeBounds=true;
	options.inSampleSize=scale;//指定缩放比率
	//根据配置信息，重新生成有一个bitmap对象，这就得到的是缩放之后的图片
	Bitmap bitmap = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory()+"/a.jpg",options);
	img.setImageBitmap(bitmap);

涂鸦
        1、首先加载一个图片Bitmap bitmap = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory() + "/a.jpg");
	2.创建一个空的图片，bit = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(),bitmap.getConfig());
	3.创建一个画布，Canvas canvas=new Canvas(bit);
	4.创建一个画笔 panint paint=new Paint(); paint.setcolor(Color.red);
	5.把加载的图片画到画布上 canvas.drawBitmap(bitmap)
	6.在图片上设置触摸事件，根据按下和移动的位置开始画线

加水印
	和上面的一样，只是加了一句canvas.drawText("饿哦我到底发生", 100,100, paint);


保存图片通知相册扫描该图片

	bit.compress(CompressFormat.JPEG, 100, new FileOutputStream(Environment.getExternalStorageDirectory()+"/hdksh.jpg"));
	Intent intent=new Intent();
	intent.setAction("android.intent.action.MEDIA_MOUNTED");
	intent.setData(Uri.fromFile(new File(Environment.getExternalStorageDirectory()+"hdksh.jpg")));
	sendBroadcast(intent);//发送广播，通知相册扫描

图片的旋转
	Bitmap bitmap=BitmapFactory.decodeFile(Environment.getExternalStorageDirectory()+"/mm.jpg");
	Bitmap bit = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
	Canvas canvas=new Canvas(bit);
	Matrix matrix=new Matrix();
	matrix.setRotate(180, bitmap.getWidth()/2, bitmap.getHeight()/2);
	Paint paint=new Paint();
	paint.setColor(Color.RED);
	canvas.drawBitmap(bitmap, matrix, paint);
	img.setImageBitmap(bit)

镜面效果
	Bitmap bitmap = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory()+"/mm.jpg");
	Bitmap bit = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
	Canvas canvas=new Canvas(bit);
	Paint paint=new Paint();
	Matrix matrix=new Matrix();
	matrix.setScale(-1, 1);//反转
	matrix.postTranslate(bitmap.getWidth(), 0);//移动
	canvas.drawBitmap(bitmap, matrix, paint);
	img.setImageBitmap(bit);