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ImageAdapter interface ​

  • Provides image per-pixel access to underlying image resource.
  • Stores image virtual viewport.
  • Creates blank images for distorted output images.
  • Stores image settings: background color, quantum range.

There is built-in ImageAdapter for use in browser environment Canvas, which underlying image Resource is HTMLCanvasElement or OffscreenCanvas.

For use in Node.js with Jimp there is Lens-Jimp ImageAdapter implementation.

ts
interface ImageAdapter<ResourceType> {
  readonly width: number;
  readonly height: number;
  getViewport(): Viewport;
  setViewport(viewport: Viewport): void;
  getBackgroundColor(): Color;
  setBackgroundColor(color: Color): void;
  getQuantumRange(): number;
  getPixelColor(x: number, y: number): Color;
  setPixelColor(x: number, y: number, color: Color): void;
  getAverageColor(): Color;
  getBlank(viewport: Viewport): ImageAdapter<ResourceType>;
  scale(scale: number): ImageAdapter<ResourceType>;
  getResource(): ResourceType;
  commit(): void;
}

Properties ​

width ​

  • Type: number

Read-only image width.

height ​

  • Type: number

Read-only image height.

Methods ​

getViewport() ​

  • Returns: Viewport

Returns image virtual viewport.

WARNING

Returned viewport is mutable! Do not modify it, unless you know what you do.

setViewport() ​

  • Param: viewport: Viewport - Viewport instance

Sets image virtual viewport to given Viewport instance.

getBackgroundColor() ​

  • Returns: Color

Returns image background color.

setBackgroundColor() ​

  • Param: color: Color - color

Sets image background color. It doesn't change anything on image - this color is used in virtual pixel methods and in color interpolation.

getQuantumRange() ​

  • Returns: number

Returns image quantum range.

getPixelColor() ​

  • Params: x: number, y: number - pixel coordinates.
  • Returns: Color

Returns image pixel color at given image coordinates.

setPixelColor() ​

  • Params:
    • x: number, y: number - pixel coordinates
    • color: Color - color

Sets image pixel color at given coordinates to given color.

getAverageColor() ​

  • Returns: Color

Returns average color of whole image.

getBlank() ​

  • Param: viewport: Viewport - Viewport class instance.
  • Returns: ImageInterface<ResourceType>

Returns new instance of ImageInterface with empty underlying image resource, which will be used as 'canvas' for drawing distorted image pixel by pixel.

scale() ​

  • Param: scale: number - scale factor.
  • Returns: ImageInteface<ResourceType>

Returns new image adapter instance with underlying image resource and virtual viewport scaled by given scale factor.

getResource() ​

  • Returns: ResourceType

Returns underlying image resource, which depends on concrete implementation.

TIP

Built-in browser image adapter Canvas will return either OffscreenCanvas if offscreen canvas was passed to constructor, or HTMLCanvasElement if canvas element was passed to constructor.

Lens-Jimp adapter will return Jimp.

commit() ​

  • Returns: void

This method is called after image distortion is processed, and used to sync changes to image pixel data and underlying image resource.

Type Guard ​

isImageAdapter() function checks if given argument is ImageAdapter and can be used as type guard:

ts
import { isImageAdapter, type ImageAdapter } from "@alxcube/lens";

function getResource<T>(mayBeAdapter: ImageAdapter<T> | T): T {
  if (isImageAdapter(mayBeAdapter)) {
    return mayBeAdapter.getResource();
  }
  return mayBeAdapter;
}