创建一个图片的拷贝

package visizen.com.getimagegallery;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.net.Uri;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;

import java.io.FileNotFoundException;
import java.io.InputStream;

public class MainActivity extends AppCompatActivity {

    private ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        imageView = (ImageView) this.findViewById(R.id.imageView);
    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public void getImageFromGallery(View view) {
        Intent intent = new Intent();
        intent.setAction("android.intent.action.PICK");
        intent.addCategory("android.intent.category.DEFAULT");
        intent.setType("image/*");
        startActivityForResult(intent, 0);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (data != null) {

            Uri uri = data.getData();

            System.out.println(uri.toString());

            //imageView.setImageURI(uri);

            try {

                InputStream is = getContentResolver().openInputStream(uri);

                int width = getWindowManager().getDefaultDisplay().getWidth();

                int height = getWindowManager().getDefaultDisplay().getHeight();

                BitmapFactory.Options options = new BitmapFactory.Options();

                options.inJustDecodeBounds = true;

                BitmapFactory.decodeStream(is, null, options);

                int imageWidth = options.outWidth;

                int imageHeight = options.outHeight;

                if (imageHeight > width || imageWidth > width) {

                    int scaleX = imageWidth / width;

                    int scaleY = imageHeight / height;

                    if (scaleX > scaleY) {

                        options.inSampleSize = scaleX;

                    } else {

                        options.inSampleSize = scaleY;

                    }
                } else {
                    options.inSampleSize = 1;
                }

                options.inJustDecodeBounds = false;
                //注意上面的流已经用完，需要从新获取
                is = getContentResolver().openInputStream(uri);

                Bitmap bitmap = BitmapFactory.decodeStream(is, null, options);

                //创建一个空白的bitmap
                Bitmap blankBitmap = bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());

                //创建一个画布，画布参数必需是一个可变的Bitmap
                Canvas canvas = new Canvas(blankBitmap);

                canvas.drawBitmap(bitmap, new Matrix(), new Paint());

                Paint paint = new Paint();

                paint.setColor(Color.RED);

                paint.setTextSize(50);

                canvas.drawText("我是复制的一张图片", 10, 100, paint);

                imageView.setImageBitmap(blankBitmap);

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
}