Trait RenderBackend 

pub trait RenderBackend {
    // Required methods
    fn clear(&self);
    fn clear_with_color(&self, color: &str);
    fn save(&self);
    fn restore(&self);
    fn set_fill_color(&self, color: &str);
    fn set_stroke_color(&self, color: &str);
    fn set_line_width(&self, width: f64);
    fn set_global_alpha(&self, alpha: f64);
    fn set_blend_mode(&self, mode: BlendMode);
    fn set_shadow(&self, config: &ShadowConfig);
    fn clear_shadow(&self);
    fn fill_rect(&self, position: Vector2D, width: f64, height: f64);
    fn stroke_rect(&self, position: Vector2D, width: f64, height: f64);
    fn fill_circle(&self, center: Vector2D, radius: f64);
    fn stroke_circle(&self, center: Vector2D, radius: f64);
    fn draw_line(&self, start: Vector2D, end: Vector2D);
    fn fill_text(&self, text: &str, position: Vector2D);
    fn set_font(&self, font: &str);
    fn draw_image(
        &self,
        image: &HtmlImageElement,
        position: Vector2D,
        width: f64,
        height: f64,
    );
    fn set_linear_gradient_fill(&self, gradient: &LinearGradient);
    fn set_radial_gradient_fill(&self, gradient: &RadialGradient);
}

An abstract rendering backend that decouples draw calls from the concrete canvas API, enabling future backends such as WebGL or WebGPU.

All methods mirror the CanvasRenderingContext2d interface so that CanvasRenderer can implement this trait with zero overhead.

Required Methods

fn clear(&self)

Clears the entire viewport.

fn clear_with_color(&self, color: &str)

Clears the viewport and fills it with the given CSS color string.

Arguments

• &str - The CSS color string (e.g., "#000000").

fn save(&self)

Saves the current rendering state onto the state stack.

fn restore(&self)

Restores the most recently saved rendering state.

fn set_fill_color(&self, color: &str)

Sets the fill color for subsequent fill operations.

Arguments

• &str - The CSS color string.

fn set_stroke_color(&self, color: &str)

Sets the stroke color for subsequent stroke operations.

Arguments

• &str - The CSS color string.

fn set_line_width(&self, width: f64)

Sets the line width for subsequent stroke operations.

Arguments

• f64 - The line width in pixels.

fn set_global_alpha(&self, alpha: f64)

Sets the global alpha (opacity) for all subsequent drawing operations.

Arguments

• f64 - The alpha value in the range 0.0 to 1.0.

fn set_blend_mode(&self, mode: BlendMode)

Sets the blend mode for compositing subsequent draw operations.

Arguments

• BlendMode - The blend mode to apply.

fn set_shadow(&self, config: &ShadowConfig)

Applies a shadow configuration for subsequent draw operations.

Arguments

• &ShadowConfig - The shadow configuration to apply.

fn clear_shadow(&self)

Clears any previously applied shadow, disabling shadow rendering.

fn fill_rect(&self, position: Vector2D, width: f64, height: f64)

Fills a rectangle at the given world-space position and dimensions.

Arguments

• Vector2D - The top-left position in world space.
• f64 - The width.
• f64 - The height.

fn stroke_rect(&self, position: Vector2D, width: f64, height: f64)

Strokes the outline of a rectangle at the given world-space position and dimensions.

Arguments

• Vector2D - The top-left position in world space.
• f64 - The width.
• f64 - The height.

fn fill_circle(&self, center: Vector2D, radius: f64)

Fills a circle at the given world-space center with the specified radius.

Arguments

• Vector2D - The center in world space.
• f64 - The radius.

fn stroke_circle(&self, center: Vector2D, radius: f64)

Strokes the outline of a circle at the given world-space center.

Arguments

• Vector2D - The center in world space.
• f64 - The radius.

fn draw_line(&self, start: Vector2D, end: Vector2D)

Draws a line segment between two world-space points.

Arguments

• Vector2D - The start point.
• Vector2D - The end point.

fn fill_text(&self, text: &str, position: Vector2D)

Fills text at the given world-space position.

Arguments

• &str - The text to draw.
• Vector2D - The position in world space.

fn set_font(&self, font: &str)

Sets the font for subsequent text rendering.

Arguments

• &str - The CSS font string (e.g., "16px sans-serif").

fn draw_image( &self, image: &HtmlImageElement, position: Vector2D, width: f64, height: f64, )

Draws an image element at the given world-space position and dimensions.

Arguments

• &HtmlImageElement - The image element to draw.
• Vector2D - The top-left position in world space.
• f64 - The destination width.
• f64 - The destination height.

fn set_linear_gradient_fill(&self, gradient: &LinearGradient)

Applies a linear gradient as the fill style for subsequent operations.

Arguments

• &LinearGradient - The linear gradient to use as fill style.

fn set_radial_gradient_fill(&self, gradient: &RadialGradient)

Applies a radial gradient as the fill style for subsequent operations.

Arguments

• &RadialGradient - The radial gradient to use as fill style.

Dyn Compatibility

This trait is dyn compatible.

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

Implementors

impl RenderBackend for CanvasRenderer

Implements the RenderBackend trait for CanvasRenderer, providing a backend-agnostic rendering interface.