Android中Bitmap与Drawable的区别有哪些

Though usually not visible to the application, Drawables may take a variety of forms: 尽管通常情况下对于应用是不可见的,Drawables 可以采取很多形式:Bitmap: the simplest Drawable, a PNG or JPEG image. Bitmap: 简单化的Drawable, PNG 或JPEG图像. Nine Patch: an extension to the PNG format allows it to specify information about how to stretch it and place things inside of it.Shape: contains simple drawing commands instead of a raw bitmap, allowing it to resize better in some cases.Layers: a compound drawable, which draws multiple underlying drawables on top of each other.States: a compound drawable that selects one of a set of drawables based on its state.Levels: a compound drawable that selects one of a set of drawables based on its level.Scale: a compound drawable with a single child drawable, whose overall size is modified based on the current level.