view转换成bitmap

View view =null;//这一部分怎样获取
if(view.isDrawingCacheEnabled()==false){
view.setDrawingCacheEnabled(true);
android.graphics.Bitmap bitmap=view.getDrawingCache();
}

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View view = findViewById(R.id.test);
Bitmap bit = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(bit);
view.draw(c);

?

?

View v=Activity.getWindow().getDecorView();