gphoto2 3.2.2

//! Library context
use crate::{
  abilities::AbilitiesList,
  camera::Camera,
  helper::{as_ref, chars_to_string, to_c_string},
  list::CameraList,
  list::{CameraDescriptor, CameraListIter},
  port::PortInfoList,
  task::{BackgroundPtr, Task},
  try_gp_internal, Error, Result,
};
use std::ffi;
use std::ops::DerefMut;
use std::os::raw::{c_char, c_float, c_uint, c_void};
use std::sync::{Arc, Mutex};

/// Progress handler trait
pub trait ProgressHandler: 'static + Send {
  /// This method is called when a progress starts.
  ///
  /// It must return a unique ID which is passed to the following functions
  fn start(&mut self, target: f32, message: String) -> u32;

  /// Progress has updated
  fn update(&mut self, id: u32, progress: f32);

  /// Progress has stopped
  fn stop(&mut self, id: u32);
}

/// Cancel handler trait
pub(crate) trait CancelHandler: 'static + Send {
  fn cancel(&mut self) -> bool;
}

/// Context used internally by libgphoto2
///
/// ## Example
///
/// ```no_run
/// use gphoto2::{Context, Result};
///
/// # fn main() -> Result<()> {
/// let context = Context::new()?;
///
/// // Use first camera in the camera list
///
/// let camera_desc = context.list_cameras().wait()?.next().ok_or("No cameras found")?;
/// let camera = context.get_camera(&camera_desc).wait()?;
///
/// # Ok(())
/// # }
///
/// ```
pub struct Context {
  pub(crate) inner: BackgroundPtr<libgphoto2_sys::GPContext>,
  progress_handler: Option<Arc<Mutex<dyn ProgressHandler>>>,
  cancel_handler: Option<Arc<Mutex<dyn CancelHandler>>>,
}

impl Drop for Context {
  fn drop(&mut self) {
    let context = self.inner;

    unsafe {
      Task::new(move || libgphoto2_sys::gp_context_unref(*context));
    }
  }
}

impl Clone for Context {
  fn clone(&self) -> Self {
    unsafe {
      libgphoto2_sys::gp_context_ref(*self.inner);
    }

    Self {
      inner: self.inner,
      progress_handler: self.progress_handler.clone(),
      cancel_handler: self.cancel_handler.clone(),
    }
  }
}

as_ref!(Context -> libgphoto2_sys::GPContext, **self.inner);

// TODO: once CoerceUnsized is stable, make this a function.
macro_rules! alloc_handler {
  ($handler:expr) => {{
    let mut handler = Arc::new(Mutex::new($handler));

    // Now that handler is on the heap, the pointer should be stable.
    // Also, we know that there are and won't be other mutable references to it,
    // so we can safely retrieve a raw mutable pointer from the Mutex
    // and give it to the C code.
    let handler_ptr: *mut _ = Arc::get_mut(&mut handler).unwrap().get_mut().unwrap();

    (handler, handler_ptr.cast::<c_void>())
  }};
}

impl Context {
  /// Create a new context
  pub fn new() -> Result<Self> {
    #[cfg(feature = "extended_logs")]
    crate::helper::hook_gp_log();

    let context_ptr = unsafe { libgphoto2_sys::gp_context_new() };

    if context_ptr.is_null() {
      return Err(Error::new(libgphoto2_sys::GP_ERROR_NO_MEMORY, None));
    }

    #[cfg(not(feature = "extended_logs"))]
    crate::helper::hook_gp_context_log_func(context_ptr);

    Ok(Self { inner: BackgroundPtr(context_ptr), progress_handler: None, cancel_handler: None })
  }

  /// Lists all available cameras and their ports
  ///
  /// Returns a list of (camera_name, port_path)
  /// which can be used in [`Context::get_camera`].
  pub fn list_cameras(&self) -> Task<Result<CameraListIter>> {
    let context = self.clone().inner;

    unsafe {
      Task::new(move || {
        let camera_list = CameraList::new()?;
        try_gp_internal!(gp_camera_autodetect(*camera_list.inner, *context)?);

        Ok(CameraListIter::new(camera_list))
      })
    }
    .context(self.inner)
  }

  /// Auto chooses a camera
  ///
  /// ```no_run
  /// use gphoto2::{Context, Result};
  ///
  /// # fn main() -> Result<()> {
  /// let context = Context::new()?;
  /// if let Ok(camera) = context.autodetect_camera().wait() {
  ///   println!("Successfully autodetected camera '{}'", camera.abilities().model());
  /// } else {
  ///   println!("Could not autodetect camera");
  /// }
  /// # Ok(())
  /// # }
  /// ```
  pub fn autodetect_camera(&self) -> Task<Result<Camera>> {
    let context = self.clone();

    unsafe {
      Task::new(move || {
        try_gp_internal!(gp_camera_new(&out camera_ptr)?);
        try_gp_internal!(gp_camera_init(camera_ptr, *context.inner)?);

        Ok(Camera::new(BackgroundPtr(camera_ptr), context))
      })
      .context(self.inner)
    }
  }

  /// Initialize a camera knowing its model name and port path
  ///
  /// ```no_run
  /// use gphoto2::{Context, Result};
  ///
  /// # fn main() -> Result<()> {
  /// let context = Context::new()?;
  ///
  /// let camera_desc = context.list_cameras().wait()?.next().ok_or("No cameras found")?;
  /// let camera = context.get_camera(&camera_desc).wait()?;
  ///
  /// # Ok(())
  /// # }
  pub fn get_camera(&self, camera_descriptor: &CameraDescriptor) -> Task<Result<Camera>> {
    let context = self.clone();
    let camera_descriptor = camera_descriptor.clone();

    unsafe {
      Task::new(move || {
        let abilities_list = AbilitiesList::new_inner(&context)?;
        let port_info_list = PortInfoList::new_inner()?;

        try_gp_internal!(gp_camera_new(&out camera)?);

        try_gp_internal!(let model_index = gp_abilities_list_lookup_model(
          *abilities_list.inner,
          to_c_string!(camera_descriptor.model.as_str())
        )?);

        try_gp_internal!(gp_abilities_list_get_abilities(
          *abilities_list.inner,
          model_index,
          &out model_abilities
        )?);
        try_gp_internal!(gp_camera_set_abilities(camera, model_abilities)?);

        try_gp_internal!(let p = gp_port_info_list_lookup_path(
          port_info_list.inner,
          to_c_string!(camera_descriptor.port.as_str())
        )?);
        let port_info = port_info_list.get_port_info(p)?;
        try_gp_internal!(gp_camera_set_port_info(camera, port_info.inner)?);

        Ok(Camera::new(BackgroundPtr(camera), context))
      })
    }
    .context(self.inner)
  }

  /// Set context progress functions
  ///
  /// `libgphoto2` allows you to set progress functions to a context, these
  /// allow you to show some progress bars whenever eg. an image is being downloaded.
  ///
  /// # Example
  ///
  /// An example can be found in the examples directory
  pub fn set_progress_handlers<H: ProgressHandler>(&mut self, handler: H) {
    unsafe extern "C" fn start_func<H: ProgressHandler>(
      _ctx: *mut libgphoto2_sys::GPContext,
      target: c_float,
      message: *const c_char,
      data: *mut c_void,
    ) -> c_uint {
      as_handler::<H>(data).start(target, chars_to_string(message))
    }

    unsafe extern "C" fn update_func<H: ProgressHandler>(
      _ctx: *mut libgphoto2_sys::GPContext,
      id: c_uint,
      current: c_float,
      data: *mut c_void,
    ) {
      as_handler::<H>(data).update(id, current)
    }

    unsafe extern "C" fn stop_func<H: ProgressHandler>(
      _ctx: *mut libgphoto2_sys::GPContext,
      id: c_uint,
      data: *mut c_void,
    ) {
      as_handler::<H>(data).stop(id)
    }

    let (progress_handler, progress_handler_ptr) = alloc_handler!(handler);

    unsafe {
      libgphoto2_sys::gp_context_set_progress_funcs(
        *self.inner,
        Some(start_func::<H>),
        Some(update_func::<H>),
        Some(stop_func::<H>),
        progress_handler_ptr,
      );
    }

    self.progress_handler = Some(progress_handler);
  }

  pub(crate) fn set_cancel_handler<H>(&mut self, handler: H)
  where
    H: CancelHandler,
  {
    use libgphoto2_sys::GPContextFeedback;

    unsafe extern "C" fn handle_cancel<H: CancelHandler>(
      _ctx: *mut libgphoto2_sys::GPContext,
      data: *mut c_void,
    ) -> GPContextFeedback {
      if as_handler::<H>(data).cancel() {
        GPContextFeedback::GP_CONTEXT_FEEDBACK_CANCEL
      } else {
        GPContextFeedback::GP_CONTEXT_FEEDBACK_OK
      }
    }

    let (cancel_handler, cancel_handler_ptr) = alloc_handler!(handler);

    unsafe {
      libgphoto2_sys::gp_context_set_cancel_func(
        *self.inner,
        Some(handle_cancel::<H>),
        cancel_handler_ptr,
      );
    }

    self.cancel_handler = Some(cancel_handler);
  }

  pub(crate) fn unset_progress_handlers(&mut self) {
    unsafe {
      libgphoto2_sys::gp_context_set_progress_funcs(
        *self.inner,
        None,
        None,
        None,
        std::ptr::null_mut(),
      );
    }

    self.progress_handler = None;
  }

  pub(crate) fn unset_cancel_handlers(&mut self) {
    unsafe {
      libgphoto2_sys::gp_context_set_cancel_func(*self.inner, None, std::ptr::null_mut());
    }

    self.cancel_handler = None;
  }
}

impl Context {
  pub(crate) fn from_ptr(ptr: BackgroundPtr<libgphoto2_sys::GPContext>) -> Self {
    Self { cancel_handler: None, inner: ptr, progress_handler: None }
  }
}

unsafe fn as_handler<H>(data: *mut c_void) -> &'static mut H {
  &mut *data.cast()
}

impl ProgressHandler for Box<dyn ProgressHandler> {
  fn start(&mut self, target: f32, message: String) -> u32 {
    self.deref_mut().start(target, message)
  }

  fn update(&mut self, id: u32, progress: f32) {
    self.deref_mut().update(id, progress)
  }

  fn stop(&mut self, id: u32) {
    self.deref_mut().stop(id)
  }
}

#[cfg(all(test, feature = "test"))]
mod tests {
  // Compile-only test to ensure that Context is Send + Sync.
  const _: () = {
    const fn assert_send_sync<T: Send + Sync>() {}
    assert_send_sync::<super::Context>()
  };

  #[test]
  fn test_list_cameras() {
    let cameras = crate::sample_context().list_cameras().wait().unwrap().collect::<Vec<_>>();
    insta::assert_debug_snapshot!(cameras);
  }

  #[test]
  fn test_progress() {
    use std::fmt::Write;

    let context = crate::sample_context();

    #[derive(Default)]
    struct TestProgress {
      log_lines: String,
      next_progress_id: u32,
    }

    impl Drop for TestProgress {
      fn drop(&mut self) {
        insta::assert_snapshot!("progress", self.log_lines);
      }
    }

    impl crate::context::ProgressHandler for TestProgress {
      fn start(&mut self, target: f32, message: String) -> u32 {
        let id = self.next_progress_id;

        // For some reason, gphoto2 discovers each dynamic library twice on Windows.
        #[cfg(windows)]
        let target = target / 2.0;

        self.next_progress_id += 1;
        writeln!(
          self.log_lines,
          "start #{id}: target: {target}, message: {message}",
          message = message.replace(
            &libgphoto2_sys::test_utils::libgphoto2_dir().to_str().unwrap().replace('\\', "/"),
            "$LIBGPHOTO2_DIR"
          ),
        )
        .unwrap();
        id
      }

      fn update(&mut self, id: u32, progress: f32) {
        writeln!(self.log_lines, "update #{id}: progress: {progress}").unwrap();
      }

      fn stop(&mut self, id: u32) {
        writeln!(self.log_lines, "stop #{id}").unwrap();
      }
    }

    let mut task = context.list_cameras();

    task.set_progress_handler(TestProgress::default());

    let _ = task.wait();
  }
}