保存图片到相册及图片变黑问题

今天写一下保存图片到手机相册的功能！

整个保存图片的代码如下：

public void saveImageToGallery(Context context, Bitmap bmp) {
        if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            return;
        }
        // 首先保存图片
        File appDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getAbsoluteFile();
        if (!appDir.exists()) {
            appDir.mkdir();
        }
        String fileName = System.currentTimeMillis() + ".png";
        File file = new File(appDir, fileName);
        try {
            FileOutputStream fos = new FileOutputStream(file);
            bmp.compress(Bitmap.CompressFormat.PNG, 100, fos);
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            return;
        } catch (IOException e) {
            e.printStackTrace();
            return;
        }
        try {
            MediaStore.Images.Media.insertImage(context.getContentResolver(),
                    file.getAbsolutePath(), fileName, null);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        // 最后通知图库更新
        context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + file.getAbsolutePath())));
    }

长按图片的事件

 imgView.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                saveImageToGallery(MainActivity.this, bitmap);
                return true;//true代表消费了该事件，不在往下传递，如果返回false，会触发onclicklistener时间
            }
        });

特别注意这点：调用getDrawingCache()前先要测量，否则的话得到的bitmap为null,也就是保存到相册里图片会变黑的问题

  imgView = findViewById(R.id.icon);
  imgView.setDrawingCacheEnabled(true);
        imgView.measure(View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
        imgView.layout(0, 0, imgView.getMeasuredWidth(), imgView.getMeasuredHeight());
        bitmap = Bitmap.createBitmap(imgView.getDrawingCache());
        imgView.setDrawingCacheEnabled(false);