Trait Backend 

pub trait Backend {
    type Handle: Clone;

    // Required methods
    fn list_apps(&self) -> Result<Vec<AppInfo>>;
    fn capture(
        &self,
        app: &AppInfo,
        request: &CaptureRequest,
    ) -> Result<Capture<Self::Handle>>;
    fn perform_action(&self, element: &Self::Handle, action: &str) -> Result<()>;
    fn set_value(&self, element: &Self::Handle, value: &str) -> Result<()>;
    fn click(
        &self,
        target: InputTarget<'_>,
        point: Point,
        button: MouseButton,
        count: u32,
    ) -> Result<()>;
    fn scroll(
        &self,
        target: InputTarget<'_>,
        point: Point,
        dx: f64,
        dy: f64,
    ) -> Result<()>;
    fn drag(
        &self,
        target: InputTarget<'_>,
        from: Point,
        to: Point,
    ) -> Result<()>;
    fn type_text(&self, target: InputTarget<'_>, text: &str) -> Result<()>;
    fn press_key(&self, target: InputTarget<'_>, chord: &KeyChord) -> Result<()>;

    // Provided methods
    fn launch_app(&self, app: &AppInfo) -> Result<AppInfo> { ... }
    fn permissions(&self) -> Permissions { ... }
    fn request_permissions(&self) -> Permissions { ... }
    fn value(&self, element: &Self::Handle) -> Result<Option<String>> { ... }
    fn select_text(
        &self,
        element: &Self::Handle,
        value: &str,
        range: Range<usize>,
    ) -> Result<()> { ... }
    fn insert_text(&self, app: &AppInfo, text: &str) -> Result<bool> { ... }
}

OS primitives for observing and driving apps.

All coordinates are screen points with a top-left origin. Methods with default implementations return Error::Unsupported.

Required Associated Types

type Handle: Clone

Handle to a live accessibility element (e.g. AXUIElement, IUIAutomationElement).

Required Methods

fn list_apps(&self) -> Result<Vec<AppInfo>>

Running apps plus installed apps the user can launch.

Errors

Fails if the platform’s process or app registry cannot be read.

fn capture( &self, app: &AppInfo, request: &CaptureRequest, ) -> Result<Capture<Self::Handle>>

Captures the app’s current window.

Errors

Fails if the app has no usable window or permissions are missing.

fn perform_action(&self, element: &Self::Handle, action: &str) -> Result<()>

Invokes a named accessibility action (as listed in Action::name).

Errors

Fails if the element is gone or rejects the action.

fn set_value(&self, element: &Self::Handle, value: &str) -> Result<()>

Writes an element’s value.

Errors

Fails if the value is not settable.

fn click( &self, target: InputTarget<'_>, point: Point, button: MouseButton, count: u32, ) -> Result<()>

Clicks count times at a screen point.

Errors

Fails if the events cannot be posted.

fn scroll( &self, target: InputTarget<'_>, point: Point, dx: f64, dy: f64, ) -> Result<()>

Scrolls at a screen point by (dx, dy) points; positive dy reveals content below.

Errors

Fails if the events cannot be posted.

fn drag(&self, target: InputTarget<'_>, from: Point, to: Point) -> Result<()>

Presses the primary button at from, moves to to, and releases.

Errors

Fails if the events cannot be posted.

fn type_text(&self, target: InputTarget<'_>, text: &str) -> Result<()>

Types literal text.

Errors

Fails if the events cannot be posted.

fn press_key(&self, target: InputTarget<'_>, chord: &KeyChord) -> Result<()>

Presses and releases a key chord.

Errors

Fails if the key has no mapping on this platform or events cannot be posted.

Provided Methods

fn launch_app(&self, app: &AppInfo) -> Result<AppInfo>

Starts app without bringing it to the foreground and returns its running record.

Errors

Fails if the app cannot be started or does not appear in time.

fn permissions(&self) -> Permissions

Permissions currently held by this process.

fn request_permissions(&self) -> Permissions

Asks the OS to prompt the user for missing permissions, then reports the current state.

fn value(&self, element: &Self::Handle) -> Result<Option<String>>

Reads an element’s full, untruncated value.

Errors

Fails if the element is gone.

fn select_text( &self, element: &Self::Handle, value: &str, range: Range<usize>, ) -> Result<()>

Selects range (byte offsets into value, the element’s current value). An empty range places the caret.

Errors

Fails if the element does not support text selection.

fn insert_text(&self, app: &AppInfo, text: &str) -> Result<bool>

Inserts text at the caret of the focused element without synthesizing keystrokes. Returns Ok(false) when the focused element does not support it, so the caller can fall back to Backend::type_text.

Errors

Fails if insertion was attempted and rejected.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Backend for MacBackend

Available on macOS only.

type Handle = CFRetained<AXUIElement>