Makes a copy of the current state of cr and saves it on an internal stack of saved states for cr. When Context.restore() is called, cr will be restored to the saved state. Multiple calls to Context.save() and Context.restore() can be nested; each call to Context.restore() restores the state from the matching paired Context.save().

It isn't necessary to clear all saved states before a Context is freed. If the reference count of a Context drops to zero , any saved states will be freed along with the Context.