如何使用位图区域作为画笔绘制相同的位图？

Question

我正在尝试使用位图区域作为位图画笔从同一图像中选择，然后使用该画笔绘制其他区域。所以基本上它将有两种模式  1.选择模式：用作画笔  2.绘画模式：使用在选择模式中选择的画笔进行绘画。  到目前为止，我已经提出了以下算法，只是在没有任何选择的情况下绘制绿色。请接受我的帮助。

package com.example.android.apptouch;

import java.io.FileNotFoundException;

import android.app.Activity;
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.util.Log;
import android.view.Display;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ImageView;
import java.io.OutputStream;
import android.content.ContentValues;
import android.graphics.Bitmap.CompressFormat;
import android.provider.MediaStore.Images.Media;
import android.widget.Toast;

public class apptouch extends Activity implements OnClickListener,
        OnTouchListener {

    ImageView choosenImageView;
    Button choosePicture;
    Button savePicture;
    Button NewButton;
    Bitmap bmp;
    Bitmap alteredBitmap;
    Canvas canvas;
    Paint paint;
    Matrix matrix;
    float downx = 0;
    float downy = 0;
    float upx = 0;
    float upy = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_apptouch);

        choosenImageView = (ImageView) this.findViewById(R.id.ChoosenImageView);
        choosePicture = (Button) this.findViewById(R.id.ChoosePictureButton);
        savePicture = (Button) this.findViewById(R.id.SavePictureButton);

        savePicture.setOnClickListener(this);
        choosePicture.setOnClickListener(this);
        choosenImageView.setOnTouchListener(this);

    }

    public void NewButton(View view) {
        ImageInpaint image= new ImageInpaint(bmp);
        image.init(true);
    }

    public void onClick(View v) {

        if (v == choosePicture) {
            Intent choosePictureIntent = new Intent(
                    Intent.ACTION_PICK,
                    android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
            startActivityForResult(choosePictureIntent, 0);
        } else if (v == savePicture) {

            if (alteredBitmap != null) {
                ContentValues contentValues = new ContentValues(3);
                contentValues.put(Media.DISPLAY_NAME, "Draw On Me");

                Uri imageFileUri = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, contentValues);
                try {
                    OutputStream imageFileOS = getContentResolver().openOutputStream(imageFileUri);
                    alteredBitmap.compress(CompressFormat.JPEG, 90, imageFileOS);
                    Toast t = Toast.makeText(this, "Saved!", Toast.LENGTH_SHORT);
                    t.show();

                } catch (Exception e) {
                    Log.v("EXCEPTION", e.getMessage());
                }
            }
        }


    }

    protected void onActivityResult(int requestCode, int resultCode,
                                    Intent intent) {
        super.onActivityResult(requestCode, resultCode, intent);

        if (resultCode == RESULT_OK) {
            Uri imageFileUri = intent.getData();
            try {
                BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
                bmpFactoryOptions.inJustDecodeBounds = true;
                bmp = BitmapFactory.decodeStream(getContentResolver().openInputStream(
                        imageFileUri), null, bmpFactoryOptions);

                bmpFactoryOptions.inJustDecodeBounds = false;
                bmp = BitmapFactory.decodeStream(getContentResolver().openInputStream(
                        imageFileUri), null, bmpFactoryOptions);

                alteredBitmap = Bitmap.createBitmap(bmp.getWidth(), bmp
                        .getHeight(), bmp.getConfig());
                canvas = new Canvas(alteredBitmap);
                paint = new Paint();
                paint.setColor(Color.GREEN);
                paint.setStrokeWidth(5);
                matrix = new Matrix();
                canvas.drawBitmap(bmp, matrix, paint);

                choosenImageView.setImageBitmap(alteredBitmap);
                choosenImageView.setOnTouchListener(this);
            } catch (Exception e) {
                Log.v("ERROR", e.toString());
            }
        }
    }
    public boolean onTouch(View v, MotionEvent event) {
        int action = event.getAction();
        switch (action) {
            case MotionEvent.ACTION_DOWN:
                downx = event.getX();
                downy = event.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                upx = event.getX();
                upy = event.getY();
                canvas.drawLine(downx, downy, upx, upy, paint);
                choosenImageView.invalidate();
                downx = upx;
                downy = upy;
                break;
            case MotionEvent.ACTION_UP:
                upx = event.getX();
                upy = event.getY();
                canvas.drawLine(downx, downy, upx, upy, paint);
                choosenImageView.invalidate();
                break;
            case MotionEvent.ACTION_CANCEL:
                break;
            default:
                break;
        }
        return true;
    }
}