Struct tetra::graphics::Canvas

pub struct Canvas { /* fields omitted */ }

A texture that can be used for off-screen rendering.

This is sometimes referred to as a 'render texture' or 'render target' in other frameworks.

Canvases can be useful if you want to do some rendering upfront and then cache the result (e.g. a static background), or if you want to apply transformations/shaders to multiple things simultaneously.

Note that creating a canvas is a relatively expensive operation! You rarely (if ever) should create them in your draw or update methods. Instead, add it as a member of your State struct.

Examples

struct GameState {
    canvas: Canvas,
}

impl GameState {
    fn new(ctx: &mut Context) -> tetra::Result<GameState> {
        Ok(GameState {
            canvas: Canvas::new(ctx, 640, 480)?
        })
    }
}

impl State for GameState {
    fn draw(&mut self, ctx: &mut Context) -> tetra::Result {
        graphics::set_canvas(ctx, &self.canvas);

        // Draw some stuff to the canvas here, using the normal graphics API.

        // When you're done, reset the canvas:
        graphics::reset_canvas(ctx);

        // Now you can draw the canvas to the screen:
        graphics::clear(ctx, Color::BLACK);
        graphics::draw(ctx, &self.canvas, Vec2::new(0.0, 0.0));

        Ok(())
    }
}

Methods

impl Canvas

pub fn new(ctx: &mut Context, width: i32, height: i32) -> Result<Canvas>

Creates a new canvas.

Errors

• TetraError::PlatformError will be returned if the underlying graphics API encounters an error.

pub fn width(&self) -> i32

Returns the width of the canvas.

pub fn height(&self) -> i32

Returns the height of the canvas.

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

Returns the size of the canvas.

pub fn filter_mode(&self) -> FilterMode

Returns the filter mode being used by the canvas.

pub fn set_filter_mode(&mut self, ctx: &mut Context, filter_mode: FilterMode)

Sets the filter mode that should be used by the canvas.

pub fn texture(&self) -> &Texture

Returns a reference to the canvas' underlying texture.

Trait Implementations

impl Clone for Canvas

fn clone(&self) -> Canvas

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Canvas

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

Formats the value using the given formatter.

impl Drawable for Canvas

fn draw<P>(&self, ctx: &mut Context, params: P) where
    P: Into<DrawParams>, 

Draws self to the screen (or a canvas, if one is enabled), using the specified parameters.

impl PartialEq<Canvas> for Canvas

fn eq(&self, other: &Canvas) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Canvas) -> bool

This method tests for !=.

impl StructuralPartialEq for Canvas