Android之多媒体编程

 public void click(View v) {
    	//位图工场解析图片的参数封装在Options对象中
    	 Options opts = new Options(); 
    	 //不为像素申请内存，不返回位图对象
    	 opts.inJustDecodeBounds = true;
    	 BitmapFactory.decodeResource(getResources(),R.drawable.person,opts);
    	 //拿到图片宽高
    	 int imageHeight = opts.outHeight;
    	 int imageWidth = opts.outWidth;
    	 //拿到手机屏幕
    	Display dis =  getWindowManager().getDefaultDisplay();
    	//获得手机屏幕的宽高
    	int screenHeight = dis.getHeight();
    	int screenWidth = dis.getWidth();
    	
    	//计算缩放比例
    	int scale = 1;
    	int scaleHeight = imageHeight / screenHeight;
    	int scaleWidth = imageWidth / screenWidth;
    	if(scaleHeight >= scaleWidth && scaleHeight >= 1) {
    		scale = scaleHeight;
    	}else if(scaleWidth>=scaleHeight && scaleWidth>=1) {
    		scale = scaleWidth;
    	}
    	//设置缩放属性
    	opts.inSampleSize = scale;
    	opts.inJustDecodeBounds = false;
    	Bitmap bm = BitmapFactory.decodeResource(getResources(),R.drawable.person,opts);
    	ImageView iv = (ImageView) findViewById(R.id.iv);
    	iv.setImageBitmap(bm); 
    }

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Bitmap bt = BitmapFactory.decodeResource(getResources(), R.drawable.person);
        //创建一个与原图一样大小的白纸
        Bitmap btCopy = Bitmap.createBitmap(bt.getWidth(), bt.getHeight(), bt.getConfig());
        Paint pt = new Paint();
        //创建画板对象，把白纸铺在画板上Canvas
        Canvas cv = new Canvas(btCopy);
        //4.开始作画，把原图的内容绘制在白纸上
        cv.drawBitmap(bt, new Matrix(), pt);
        ImageView iv_bitmap = (ImageView) findViewById(R.id.iv1);
        ImageView iv_copyMap = (ImageView) findViewById(R.id.iv2);
        iv_bitmap.setImageBitmap(bt);
        iv_copyMap.setImageBitmap(btCopy);
    }

}

public class MainActivity extends Activity {

    private Canvas cancas;
	private Paint paint;
	private ImageView iv_drawBoard;
	private Bitmap bt_copy;

	@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
　　　　//使用图片副本拿到可修改的副本图片
       Bitmap bt =  BitmapFactory.decodeResource(getResources(), R.drawable.bg);
       bt_copy = Bitmap.createBitmap(bt.getWidth(), bt.getHeight(), bt.getConfig());
       paint = new Paint();
       cancas = new Canvas(bt_copy);
       cancas.drawBitmap(bt, new Matrix(), paint);
       iv_drawBoard = (ImageView) findViewById(R.id.iv_drawBoard);
       iv_drawBoard.setImageBitmap(bt_copy);
　　//设置触摸监听
       iv_drawBoard.setOnTouchListener(new OnTouchListener() {
		
		private int startX;
		private int startY;
　　　　　　　　//完成滑动画笔功能
		@Override
		public boolean onTouch(View v, MotionEvent event) {
			int action = event.getAction();
			switch (action) {
			case MotionEvent.ACTION_DOWN :
				startX = (int) event.getX();
				startY = (int) event.getY();
				break;
			case MotionEvent.ACTION_MOVE :
				int X = (int) event.getX();
				int Y = (int) event.getY();
				cancas.drawLine(startX, startY, X, Y, paint);
				startX = X;
				startY = Y;
				 iv_drawBoard.setImageBitmap(bt_copy);
				break;
			case MotionEvent.ACTION_UP :
				
				break;
			}
			return true;
		}
	});
    }
    //改变画笔颜色
    public void click_red(View v) {
    	paint.setColor(Color.RED);
    }
    public void click_green(View v) {
    	paint.setColor(Color.GREEN);
    }
//改变画笔粗细
    public void click_rough(View v) {
    	paint.setStrokeWidth(7);
    }
//将图片保存
    public void click_save(View v) {
    	File file = new File(Environment.getExternalStorageDirectory(), "dazuo.PNG");
    	FileOutputStream stream = null;
		try {
			stream = new FileOutputStream(file);
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
//位图对象的compress方法可以保存图片
    	bt_copy.compress(CompressFormat.PNG, 100, stream);
//如果需要在图片应用看到图片，需要在保存图片之后发送广播，告知系统去遍历sd卡，把图片添加到MediaStore数据库
    	Intent intent = new Intent();
    	intent.setAction(Intent.ACTION_MEDIA_MOUNTED);
    	intent.setData(Uri.fromFile(Environment.getExternalStorageDirectory()));
    	sendBroadcast(intent);
    }
}