ImageView添加Drawable的一些问题

最近遇到添加svg不能解析为bitmap的情况，所以打算看一下imageView是怎么做的

ImageView的 setImageResource(int resId)
获取方式为AppCompatResources.getDrawable(mView.getContext(), resId);

1、AppCompatResources.getDrawable
调用了ResourceManagerInternal.get().getDrawable(context, resId);
函数中deawable有三种获取方式：
Drawable drawable = loadDrawableFromDelegates(context, resId);
drawable = createDrawableIfNeeded(context, resId);
drawable = ContextCompat.getDrawable(context, resId);
获取到drawable对象后需要做tintDrawable和fixDrawable检查

2、fixDrawable中通过取得的drawable的getName来判断类型
版本21 & VectorDrawable
执行DrawableUtils.forceDrawableStateChange(drawable);
版本29 - 31 &ColorStateListDrawable
执行forceDrawableStateChange(drawable);

不能强制转换
StateListDrawable cannot be cast to android.graphics.drawable.BitmapDrawable

对于svg转换的问题

if(drawable instance of VectorDrawable||drawable instance of VectorDrawableCompat){
	Bitmap bitmap=Bitmap.createBitmap(drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight(),Bitmap.Config.ARGB_8888);
	Canvas canvas=new Canvas(bitmap);
	drawable.setBounds(0,0,canvas.getWidth(),canvas.getHeight());
	drawable.draw(canvas);
//bitmap就是结果
}