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Backend

retroglyph::backend

Trait Backend 

Source 
pub trait Backend {
    // Required methods
    fn draw<'a, I>(&mut self, content: I)
       where I: Iterator<Item = (Pos, &'a Tile)>;
    fn flush(&mut self);
    fn size(&self) -> Size;
    fn clear(&mut self);
    fn poll_event(&mut self, timeout: Duration) -> Option<Event>;
    fn set_cursor_visible(&mut self, visible: bool);
    fn set_cursor_position(&mut self, position: Pos);

    // Provided methods
    fn draw_layers<'a, I>(&mut self, content: I)
       where I: Iterator<Item = (u8, Pos, &'a Tile)> { ... }
    fn needs_full_frame(&self) -> bool { ... }
    fn resize(&mut self, size: Size) { ... }
    fn is_connected(&self) -> bool { ... }
    fn push_event(&mut self, _event: Event) { ... }
}
Expand description

A rendering backend that presents grid content to a display and provides input events.

Required Methods§

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fn draw<'a, I>(&mut self, content: I)
where I: Iterator<Item = (Pos, &'a Tile)>,

Draw changed cells to the output surface.

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fn flush(&mut self)

Flush buffered output to the display.

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fn size(&self) -> Size

Return current display dimensions.

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fn clear(&mut self)

Clear the entire display.

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fn poll_event(&mut self, timeout: Duration) -> Option<Event>

Poll for an input event, waiting up to timeout.

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fn set_cursor_visible(&mut self, visible: bool)

Show or hide the cursor.

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fn set_cursor_position(&mut self, position: Pos)

Move the cursor to a position.

Provided Methods§

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fn draw_layers<'a, I>(&mut self, content: I)
where I: Iterator<Item = (u8, Pos, &'a Tile)>,

Draw changed cells across all layers.

The default implementation forwards layer-0 tiles to draw and ignores higher layers. Override this to support multi-layer compositing, sub-cell offsets, or transparency.

When needs_full_frame returns true, this receives all cells from every allocated layer, and the backend should clear its output surface before drawing.

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fn needs_full_frame(&self) -> bool

Returns true if the backend needs the entire frame (all cells on all layers) on every call to draw_layers, rather than just the changed cells.

Pixel-based backends (e.g. SoftwareRenderer) need this because sub-cell offsets can spill glyph pixels into adjacent cells — without a full redraw, orphaned pixels from the previous frame linger.

The default implementation returns false.

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fn resize(&mut self, size: Size)

Notify the backend of a terminal resize.

Called automatically by crate::Terminal::resize after both grids are resized. Backends that maintain internal state tied to terminal dimensions (such as Headless) should override this to update that state. The default implementation is a no-op.

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fn is_connected(&self) -> bool

Returns false if the backend has been disconnected from its output (e.g. the window was closed). The game loop should terminate when this returns false.

The default implementation always returns true. Override for backends that can detect disconnect.

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fn push_event(&mut self, _event: Event)

Push an event into the backend’s event buffer.

Backends that receive events externally (e.g., from a window event loop or a test harness) override this to queue events for poll_event. The default is a no-op.

  • Windowed backends: called by ApplicationHandler on each event.
  • Headless: called by tests to inject synthetic events.
  • Crossterm: reads from its own event stream; no-op here.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§