Struct show_image::ContextProxy

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pub struct ContextProxy { /* private fields */ }

Expand description

Proxy object to interact with the global context from a user thread.

You should not use proxy objects from withing the global context thread. The proxy objects often wait for the global context to perform some action. Doing so from within the global context thread would cause a deadlock.

Implementations§

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impl ContextProxy

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pub fn add_event_handler<F>(&self, handler: F)
where F: FnMut(&mut ContextHandle<'_>, &mut Event, &mut EventHandlerControlFlow) + Send + 'static,

Add a global event handler to the context.

Events that are already queued with the event loop will not be passed to the handler.

This function uses Self::run_function_wait internally, so it blocks until the event handler is added. To avoid blocking, you can use Self::run_function to post a lambda that adds an error handler instead.

§Panics

This function will panic if called from within the context thread.

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pub fn add_window_event_handler<F>( &self, window_id: WindowId, handler: F ) -> Result<(), InvalidWindowId>
where F: FnMut(WindowHandle<'_>, &mut WindowEvent, &mut EventHandlerControlFlow) + Send + 'static,

Add an event handler for a specific window.

Events that are already queued with the event loop will not be passed to the handler.

This function uses Self::run_function_wait internally, so it blocks until the event handler is added. To avoid blocking, you can use Self::run_function to post a lambda that adds an error handler instead.

§Panics

This function will panic if called from within the context thread.

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pub fn run_function<F>(&self, function: F)
where F: 'static + FnOnce(&mut ContextHandle<'_>) + Send,

Post a function for execution in the context thread without waiting for it to execute.

This function returns immediately, without waiting for the posted function to start or complete. If you want to get a return value back from the function, use Self::run_function_wait instead.

Note: You should not post functions to the context thread that block for a long time. Doing so will block the event loop and will make the windows unresponsive until the event loop can continue. Consider using Self::run_background_task for long blocking tasks instead.

§Panics

This function will panic if called from within the context thread.

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pub fn run_function_wait<F, T>(&self, function: F) -> T
where F: FnOnce(&mut ContextHandle<'_>) -> T + Send + 'static, T: Send + 'static,

Post a function for execution in the context thread and wait for the return value.

If you do not need a return value from the posted function, you can use Self::run_function to avoid blocking the calling thread until it completes.

Note: You should not post functions to the context thread that block for a long time. Doing so will block the event loop and will make the windows unresponsive until the event loop can continue. Consider using Self::run_background_task for long blocking tasks instead.

§Panics

This function will panic if called from within the context thread.

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pub fn run_background_task<F>(&self, task: F)
where F: FnOnce() + Send + 'static,

Run a task in a background thread and register it with the context.

The task will be executed in a different thread than the context. Currently, each task is spawned in a separate thread. In the future, tasks may be run in a dedicated thread pool.

The background task will be joined before the process is terminated when you use Self::exit() or one of the other exit functions of this crate.

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pub fn event_channel(&self) -> Receiver<Event>

Create a channel that receives events from the context.

To close the channel, simply drop de receiver.

Warning: The created channel blocks when you request an event until one is available. You should never use the receiver from within an event handler or a function posted to the global context thread. Doing so would cause a deadlock.

§Panics

This function will panic if called from within the context thread.

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pub fn window_event_channel( &self, window_id: WindowId ) -> Result<Receiver<WindowEvent>, InvalidWindowId>

Create a channel that receives events from a window.

To close the channel, simply drop de receiver. The channel is closed automatically when the window is destroyed.

Warning: The created channel blocks when you request an event until one is available. You should never use the receiver from within an event handler or a function posted to the global context thread. Doing so would cause a deadlock.