Android开发之大位图压缩水印处理

      我们在发微博或者csdn博文的时候都能够给图片加上一个水印。一个独立的标识，那是怎么实现的呢？先封装一个BitmapTools封装类。该类要解决的问题是一将突破存储至sdcard中，二给图片加上水印。

BitmapTools

package com.example.g11_bitmap04;

import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.os.Environment;

public class BitmapTools {
	
	public BitmapTools() {
		// TODO Auto-generated constructor stub
	}
	public static Bitmap createBitmap(Resources resources, int resid,
			String name) {
		Bitmap bitmap=BitmapFactory.decodeResource(resources, resid);
		//复制一份新的Bitmap,由于不能直接在原有的bitmap上进行水印操作
		//Bitmap.config存储的格式
		Bitmap newBitmap=bitmap.copy(Bitmap.Config.ARGB_8888, true);
		//使用自己定义画布
		Canvas canvas=new Canvas(newBitmap);
		Paint paint=new Paint();
		paint.setTextSize(200);
		canvas.drawText("hello", 100, 100, paint);
		//推断SDcard是否在可用状态
		if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
			//直接将图片保存在根文件夹下
			File root=Environment.getExternalStorageDirectory();
			OutputStream outputStream=null;
			try {
				
				outputStream=new FileOutputStream(new File(root, name));
				//对图片进行压缩并以png格式，保存在sdcard中
				newBitmap.compress(Bitmap.CompressFormat.PNG, 50, outputStream);
			} catch (Exception e) {
				// TODO: handle exception
			}
		}
		return newBitmap;

	}
}

MainActivtiy中调用该方法

package com.example.g11_bitmap04;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {
     private ImageView imageView;
     private Button button;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		imageView=(ImageView)this.findViewById(R.id.imageView1);
		button=(Button)this.findViewById(R.id.button1);
		button.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				
				Bitmap bitmap=BitmapTools.createBitmap(getResources(), R.drawable.a, "a.png");
				imageView.setImageBitmap(bitmap);
			}
		});
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}