Sets a scale that is multiplied to the device coordinates determined
by the CTM when drawing to the surface. One common use for this is to
render to very high resolution display devices at a scale factor, so
that code that assumes 1 pixel will be a certain size will still work.
Setting a transformation via ccontext:Scale() isn't
sufficient to do this, since functions like
ccontext:DeviceToUser() will expose the hidden scale.
Note that the scale affects drawing to the surface as well as
using the surface in a source pattern.