Struct Renderer 

pub struct Renderer { /* private fields */ }

High-level WebGL2 renderer for terminal-style applications.

The Renderer manages the WebGL2 rendering context, canvas, and provides a simplified interface for rendering drawable objects. It handles frame management, viewport setup, and coordinate system transformations.

Implementations

impl Renderer

pub fn create(canvas_id: &str) -> Result<Self, Error>

Creates a new renderer by querying for a canvas element with the given ID.

This method searches the DOM for a canvas element with the specified ID, initializes a WebGL2 context, and sets up the renderer with orthographic projection matching the canvas dimensions.

Parameters

• canvas_id - CSS selector for the canvas element (e.g., “canvas” or “#my-canvas”)

Returns

• Ok(Renderer) - Successfully created renderer
• Err(Error) - Failed to find canvas, create WebGL context, or initialize renderer

Errors

• Error::UnableToRetrieveCanvas - Canvas element not found
• Error::FailedToRetrieveWebGl2RenderingContext - WebGL2 not supported or failed to initialize

pub fn canvas_padding_color(self, color: u32) -> Self

Sets the background color for the canvas area outside the terminal grid.

When the canvas dimensions don’t align perfectly with the terminal cell grid, there may be unused pixels around the edges. This color fills those padding areas to maintain a consistent appearance.

pub fn create_with_canvas(canvas: HtmlCanvasElement) -> Result<Self, Error>

Creates a new renderer from an existing HTML canvas element.

This method takes ownership of an existing canvas element and initializes the WebGL2 context and renderer state. Useful when you already have a reference to the canvas element.

Parameters

• canvas - HTML canvas element to use for rendering

Returns

• Ok(Renderer) - Successfully created renderer
• Err(Error) - Failed to create WebGL context or initialize renderer

pub fn resize(&mut self, width: i32, height: i32)

Resizes the canvas and updates the viewport.

This method changes the canvas resolution and adjusts the WebGL viewport to match. The projection matrix is automatically updated to maintain proper coordinate mapping.

Parameters

• width - New canvas width in pixels
• height - New canvas height in pixels

pub fn clear(&mut self, r: f32, g: f32, b: f32)

Clears the framebuffer with the specified color.

Sets the clear color and clears both the color and depth buffers. Color components should be in the range [0.0, 1.0].

Parameters

• r - Red component (0.0 to 1.0)
• g - Green component (0.0 to 1.0)
• b - Blue component (0.0 to 1.0)

pub fn begin_frame(&mut self)

Begins a new rendering frame.

pub fn render(&mut self, drawable: &impl Drawable)

Renders a drawable object.

This method calls the drawable’s prepare, draw, and cleanup methods in sequence, providing it with a render context containing.

Parameters

• drawable - Object implementing the Drawable trait

pub fn end_frame(&mut self)

Ends the current rendering frame.

This method finalizes the frame rendering. In future versions, this may handle buffer swapping or other post-rendering operations.

pub fn gl(&self) -> &WebGl2RenderingContext

Returns a reference to the WebGL2 rendering context.

pub fn canvas(&self) -> &HtmlCanvasElement

Returns a mutable reference to the WebGL2 rendering context.

pub fn canvas_size(&self) -> (i32, i32)

Returns the current canvas dimensions as a tuple.

Returns

Tuple containing (width, height) in pixels

pub fn is_context_lost(&self) -> bool

Checks if the WebGL context has been lost.

Returns true if the context is lost and needs to be restored. Use [restore_context] to recover from context loss.

pub fn restore_context(&mut self) -> Result<(), Error>

Restores the WebGL context after a context loss event.

This method obtains a fresh WebGL2 context from the canvas and reinitializes the renderer state. After calling this, you must also recreate GPU resources in other components (textures, buffers, etc.).

Returns

• Ok(()) - Context successfully restored
• Err(Error) - Failed to obtain new WebGL context

Note

This only restores the renderer’s context. You must separately call recreation methods on TerminalGrid and FontAtlas to fully recover.

Trait Implementations

impl Debug for Renderer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.