Class Canvas2dBackend

constructor

• new Canvas2dBackend(): Canvas2dBackend

• Returns Canvas2dBackend

Readonlykind

beginFrame

• beginFrame(clear: boolean): void

• The same clear CanvasLayer.clearBitmap does, so the op stream is unchanged.

  Parameters

  • clear: boolean

  Returns void

destroy

• destroy(): void

• Release the context and any GPU resources. The pane removes the canvas.

  Returns void

drawSeries

• drawSeries(
      entry: RendererEntry,
      items: readonly DrawItem[],
      priceToY: (price: number) => number,
      barSpacing: number,
      dpr: number,
      style: SeriesStyle,
      rc: SeriesRenderContext,
  ): void

• Paint one series. Same contract as RendererEntry.draw minus the context: priceToY and items[].x are media px, and the renderer snaps to device pixels with dpr itself.

  Parameters

  • entry: RendererEntry
  • items: readonly DrawItem[]
  • priceToY: (price: number) => number
  • barSpacing: number
  • dpr: number
  • style: SeriesStyle
  • rc: SeriesRenderContext

  Returns void

endFrame

• endFrame(): void

• Every call above drew straight to the canvas; there is nothing to flush.

  Returns void

mount

• mount(canvas: HTMLCanvasElement, ctx2d: null | CanvasRenderingContext2D): void

• Take the pane's base data canvas. ctx2d is the 2D context the pane already holds on it, when it holds one: the canvas-2D backend draws on exactly that object, so a frame is one context's op stream and not two contexts' interleaved. A backend that owns the canvas outright ignores it.

  Parameters

  • canvas: HTMLCanvasElement
  • ctx2d: null | CanvasRenderingContext2D

  Returns void

overlay2d

• overlay2d(): null | CanvasRenderingContext2D

• A 2D context for what the backend does not draw natively (grid, axes, primitives), or null when the backend paints those itself.

  Returns null | CanvasRenderingContext2D

resize

• resize(_widthPx: number, _heightPx: number, _dpr: number): void

• Nothing to do: the pane's CanvasLayer owns the backing store and sized it already. Re-sizing it here would clear a bitmap that was just painted.

  Parameters

  • _widthPx: number
  • _heightPx: number
  • _dpr: number

  Returns void