android给图片加水印的极简实现方式

工作日志：其实这是两年前就碰到的需求，之前没有整理，也没有继续优化和实现，这次又用到这样的需求，所以记录下来，既是一种代码记录，也是一种复习bitmap和canvas的好手段，这里提供一种思路，就是将原图的bitmap生成的canvas上绘制图片或者文字。

 

按照惯例上实现图：

上代码：

package com.example.testretrifit;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.os.Environment;
import android.text.Layout;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.google.gson.Gson;
import com.trello.rxlifecycle4.RxLifecycle;
import com.trello.rxlifecycle4.components.support.RxFragmentActivity;

import org.json.JSONObject;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.TimeUnit;

import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.disposables.Disposable;
import io.reactivex.schedulers.Schedulers;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.RequestBody;
import retrofit2.Retrofit;
import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private TextView tv_text;
    private Service service;
    private ImageView iv_bitmap;
    private ImageView iv_bitmap2;
    private Bitmap bitmap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        tv_text = findViewById(R.id.tv_text);


        iv_bitmap = findViewById(R.id.iv_bitmap);

        iv_bitmap2 = findViewById(R.id.iv_bitmap2);


        bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.a);
//        iv_bitmap.setImageBitmap(addTextWatermark(bitmap, 100, Color.WHITE, 0, bitmap.getHeight() / 2, true, "wdnmd,什么情况"));

        Bitmap bitmap2 = BitmapFactory.decodeResource(getResources(), R.mipmap.timg);
        iv_bitmap2.setImageBitmap(addTextWatermark(bitmap2, 20, Color.WHITE, 0, bitmap.getHeight() / 2, true, "wdnmd,什么情况"));


        tv_text.setOnClickListener(this);
        OkHttpClient client = new OkHttpClient()
                .newBuilder()
                .readTimeout(10000, TimeUnit.SECONDS)
                .connectTimeout(10000, TimeUnit.SECONDS)
                .addNetworkInterceptor(new HeaderInpterceptor())
                .build();
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://192.168.2.156/")
                .addConverterFactory(CommonGsonFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        service = retrofit.create(Service.class);

        Map map = new HashMap<>();
        map.put("username", "13666666666");
        map.put("password", "zaq1@WSX");

        Disposable disposable = service.login(RequestBody.create(MediaType.get("application/json"), new Gson().toJson(map)))
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(responseBody -> {


                            Configs.token = new JSONObject(responseBody.string()).getString("access_token");
                            getUserInfo();
                        }, throwable -> Toast.makeText(this, "出错", Toast.LENGTH_SHORT).show()
                );



/*
        Observable.create(new ObservableOnSubscribe() {
            @Override
            public void subscribe(ObservableEmitter emitter) throws Exception {
            }
        }).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(new Consumer() {
            @Override
            public void accept(ResponseBody responseBody) throws Exception {

            }
        }).dispose();
        */

      /*  Observable.just("hehe").subscribeOn(AndroidSchedulers.mainThread()).observeOn(AndroidSchedulers.mainThread()).subscribe(new Consumer() {
            @Override
            public void accept(String s) throws Exception {

                tv_text.setText(s);
            }
        }).dispose();*/


    }

    private void getUserInfo() {

        Disposable disposable = service.getInfo(new HashMap<>())
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(responseBody -> {

                    tv_text.setText(responseBody.string());

                });


    }

    public void downLoadFile() {
        Map map = new HashMap<>();
        map.put("fileUrl", "http://192.168.2.126:80/group1/M00/45/91/wKgCfl8RA9CAS4tZAAAtjJqlrzg697.png");
        Disposable disposable = service.downLoadFile(map)
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(responseBody -> {
                    InputStream is = null;
                    byte[] buf = new byte[512];
                    int len = 0;
                    FileOutputStream fos = null;

                    //储存下载文件的目录
                    File dir = new File(Environment.getExternalStorageDirectory().getAbsolutePath());
                    if (!dir.exists()) {
                        dir.mkdirs();
                    }
                    File file = new File(dir, "hehe");

                    try {

                        is = responseBody.byteStream();
                        Toast.makeText(MainActivity.this, is.available() + "", Toast.LENGTH_SHORT).show();
                        long total = is.available();
                        fos = new FileOutputStream(file);
                        long sum = 0;
                        while ((len = is.read(buf)) != -1) {
                            fos.write(buf, 0, len);
                            sum += len;
                            int progress = (int) (sum * 1.0f / total * 100);
                            //下载中更新进度条
//                            listener.onDownloading(progress);
                            tv_text.setText(progress + "");
                        }
                        fos.flush();
                        //下载完成
//                        listener.onDownloadSuccess(file);
                    } catch (Exception e) {
//                        listener.onDownloadFailed(e);
                    } finally {

                        try {
                            if (is != null) {
                                is.close();
                            }
                            if (fos != null) {
                                fos.close();
                            }
                        } catch (IOException e) {

                        }

                    }

                });
    }

    @Override
    public void onClick(View view) {
        downLoadFile();
    }


    /**
     * 给图片添加水印 当需要换行的时候，推荐使用StaticLayout 这种实现方式
     * @param src 原bitmap
     * @param textSize 文字大小
     * @param x  距离图片位图的左边距
     * @param y   距离图片位图的上边距
     * @param recycle  是否回收bitmap，建议true
     * @param text  绘制内容
     * */
    public Bitmap addTextWatermark(Bitmap src, int textSize, int color, float x, float y, boolean recycle, String text) {
        Objects.requireNonNull(src, "src is null");
        Bitmap ret = src.copy(src.getConfig(), true);
        TextPaint paint = new TextPaint(Paint.ANTI_ALIAS_FLAG);
        Canvas canvas = new Canvas(ret);
        paint.setColor(color);
        paint.setTextSize(src.getWidth() / 20);
        Rect bounds = new Rect();
        String content = "时    间：" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()) + "\n" + "内    容：" + text;
        /*
        单行文字的实现代码
        paint.getTextBounds(content, 0, content.length(), bounds);
        canvas.drawText(content, x, y, paint);*/

        canvas.translate(x, y);
        StaticLayout myStaticLayout = new StaticLayout(content, paint, canvas.getWidth(), Layout.Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);
        myStaticLayout.draw(canvas);

//        canvas.drawBitmap(bitmap, 0, 0, null);//绘制小图片使用的代码
        if (recycle && !src.isRecycled()) src.recycle();
        return ret;
    }
}

布局文件：