Android中使用图片水印，并且能够在线下载字体并应用于水印

要在Android中使用图片水印，并且能够在线下载字体并应用于水印，可以按照以下步骤进行：

1.使用Picasso、Glide或其他图片加载库加载图片：

ImageView imageView = findViewById(R.id.image_view);
String imageUrl = "https://example.com/image.jpg";
Picasso.get().load(imageUrl).into(imageView);

2.创建一个带有水印的Drawable：

BitmapDrawable watermarkDrawable = createWatermarkDrawable("Watermark Text", "font.ttf", 16);

3.创建水印的方法：

private BitmapDrawable createWatermarkDrawable(String text, String fontPath, int textSize) {
    Typeface typeface = Typeface.createFromFile(fontPath);

    // 创建一个空白的Bitmap作为画布
    Bitmap bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);

    // 设置画布属性
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.WHITE);
    paint.setTextSize(textSize);
    paint.setTypeface(typeface);
    paint.setTextAlign(Paint.Align.LEFT);

    // 测量文本的宽度和高度
    Rect textBounds = new Rect();
    paint.getTextBounds(text, 0, text.length(), textBounds);

    // 计算水印的位置
    int x = (bitmap.getWidth() - textBounds.width()) / 2;
    int y = (bitmap.getHeight() + textBounds.height()) / 2;

    // 在画布上绘制文本
    canvas.drawText(text, x, y, paint);

    return new BitmapDrawable(getResources(), bitmap);
}

4.将水印应用到图片上：

Drawable imageDrawable = imageView.getDrawable();
Drawable[] layers = new Drawable[2];
layers[0] = imageDrawable;
layers[1] = watermarkDrawable;
LayerDrawable layerDrawable = new LayerDrawable(layers);
imageView.setImageDrawable(layerDrawable);

5.在线下载字体文件： 你可以使用DownloadManager来下载字体文件，并在下载完成后将其应用于水印：

private void downloadFont(String fontUrl, String fontName) {
    DownloadManager downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
    DownloadManager.Request request = new DownloadManager.Request(Uri.parse(fontUrl));
    request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, fontName);
    long downloadId = downloadManager.enqueue(request);
    
    // 注册一个广播接收器监听下载完成事件
    BroadcastReceiver onCompleteReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            long receivedDownloadId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
            if (receivedDownloadId == downloadId) {
                // 下载完成，应用字体
                String fontPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath() + "/" + fontName;
                BitmapDrawable updatedWatermarkDrawable = createWatermarkDrawable("Watermark Text", fontPath, 16);
                Drawable[] updatedLayers = new Drawable[2];
                updatedLayers[0] = imageDrawable;
                updatedLayers[1] = updatedWatermarkDrawable;
                LayerDrawable updatedLayerDrawable = new LayerDrawable(updatedLayers);
                imageView.setImageDrawable(updatedLayerDrawable);
                
                // 注销广播接收器
                unregisterReceiver(this);
            }
        }
    };
    registerReceiver(onCompleteReceiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
}

例子中使用了DownloadManager来下载字体文件，并在下载完成后应用于水印。请注意，在AndroidManifest.xml中，你需要添加相关权限声明：

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

另外，记得在合适的时机调用

downloadFont

方法，并提供正确的字体文件URL和文件名。