diff --git a/src/main.rs b/src/main.rs index 9838ebc..2b08663 100644 --- a/src/main.rs +++ b/src/main.rs @@ -150,7 +150,7 @@ impl Handle { }) .unwrap() }; - (0..num_desc).map(move |i| self.get_descriptor(i as _).unwrap()) + (1..num_desc).map(move |i| self.get_descriptor(i as _).unwrap()) } fn get_descriptor(&self, index: usize) -> Option { let desc = unsafe { sane_get_option_descriptor(self.0, index as _) }; @@ -165,11 +165,9 @@ impl Handle { unsafe { checked(|| sane_get_parameters(self.0, parameters.as_mut_ptr()))? } Ok(Parameters(unsafe { parameters.assume_init() })) } - fn start(&self) -> Result<(), Error> { - unsafe { checked(|| sane_start(self.0)) } - } - fn cancel(&self) { - unsafe { sane_cancel(self.0) } + fn start(&self) -> Result { + unsafe { checked(|| sane_start(self.0)) }; + Ok(Acquisition { handle: &self }) } } @@ -212,6 +210,20 @@ impl Parameters { } } +struct Acquisition<'a> { + handle: &'a Handle, +} + +impl<'a> Acquisition<'a> { + fn cancel(self) {} +} + +impl Drop for Acquisition<'_> { + fn drop(&mut self) { + unsafe { sane_cancel(self.handle.0) } + } +} + fn main() { let (context, version) = Context::init().unwrap(); println!( @@ -242,6 +254,5 @@ fn main() { let parameters = handle.parameters().unwrap(); println!("{:?}", parameters); - handle.start().unwrap(); - handle.cancel(); + let acq = handle.start().unwrap(); }