Class HtmlCanvasAdapter

Browser based canvas adapter

Hierarchy

HtmlCanvasAdapter

Implements

CanvasAdapter

Index

Constructors

constructor

Methods

create createImage createImageData disposeCanvas disposeImage drawText getImageData initialize isInitialized measureText mergeCanvas scaleImage scaleImageToDimensions toBytes toDataURL writeImageToBytes

Constructors

constructor

new HtmlCanvasAdapter(): HtmlCanvasAdapter
Returns HtmlCanvasAdapter

Methods

create

create(width: number, height: number): any
Creates a canvas object
Parameters
- width: number
- height: number
Returns any
Implementation of CanvasAdapter.create
- Defined in lib/canvas/htmlCanvasAdapter.ts:32

createImage

createImage(data: string | Buffer | Uint8Array | Blob, contentType: string): Promise<GeoPackageImage>
Creates an Image object to be used in the context.drawImage function
Parameters
- data: string | Buffer | Uint8Array | Blob
- contentType: string
Returns Promise<GeoPackageImage>
Implementation of CanvasAdapter.createImage
- Defined in lib/canvas/htmlCanvasAdapter.ts:42

createImageData

createImageData(width: any, height: any): ImageData
Creates an ImageData object
Parameters
- width: any
- height: any
Returns ImageData
Implementation of CanvasAdapter.createImageData
- Defined in lib/canvas/htmlCanvasAdapter.ts:69

disposeCanvas

disposeCanvas(canvas: any): void
Performs any cleanup needed for the specified canvas. The canvas should not be used after calling this function.
Parameters
- canvas: any
Returns void
Implementation of CanvasAdapter.disposeCanvas
- Defined in lib/canvas/htmlCanvasAdapter.ts:76

disposeImage

disposeImage(image: GeoPackageImage): void
Performs any cleanup needed for the specified image
Parameters
- image: GeoPackageImage
Returns void
Implementation of CanvasAdapter.disposeImage
- Defined in lib/canvas/htmlCanvasAdapter.ts:154

drawText

drawText(context: any, text: string, location: number[], fontFace: string, fontSize: number, fontColor: string): void
Draws text centered at the location specified in the canvas rendering context
Parameters
- context: any
- text: string
- location: number[]
- fontFace: string
- fontSize: number
- fontColor: string
Returns void
Implementation of CanvasAdapter.drawText
- Defined in lib/canvas/htmlCanvasAdapter.ts:97

getImageData

getImageData(image: GeoPackageImage): ImageData
Gets the image as ImageData
Parameters
- image: GeoPackageImage
Returns ImageData
Implementation of CanvasAdapter.getImageData
- Defined in lib/canvas/htmlCanvasAdapter.ts:173

initialize

initialize(): Promise<void>
Initializes the adapter for use.

Returns Promise<void>
Implementation of CanvasAdapter.initialize
- Defined in lib/canvas/htmlCanvasAdapter.ts:15

isInitialized

isInitialized(): boolean
Returns if the Adapter has been initialized.

Returns boolean
Implementation of CanvasAdapter.isInitialized
- Defined in lib/canvas/htmlCanvasAdapter.ts:25

measureText

measureText(context: any, fontFace: string, fontSize: number, text: string): number
Returns the width of the text in the given font face and font size
Parameters
- context: any
- fontFace: string
- fontSize: number
- text: string
Returns number
Implementation of CanvasAdapter.measureText
- Defined in lib/canvas/htmlCanvasAdapter.ts:84

mergeCanvas

mergeCanvas(fromCanvas: any, toContext: any): void
Draw content of fromCanvas into the toContext
Parameters
- fromCanvas: any
- toContext: any
Returns void
Implementation of CanvasAdapter.mergeCanvas
- Defined in lib/canvas/htmlCanvasAdapter.ts:185

scaleImage

scaleImage(image: GeoPackageImage, scale: number): Promise<GeoPackageImage>
Scales an image created using this adapter.
Parameters
- image: GeoPackageImage
- scale: number
Returns Promise<GeoPackageImage>
Implementation of CanvasAdapter.scaleImage
- Defined in lib/canvas/htmlCanvasAdapter.ts:117

scaleImageToDimensions

scaleImageToDimensions(image: GeoPackageImage, scaledWidth: number, scaledHeight: number): Promise<GeoPackageImage>
Scales an image created using this adapter.
Parameters
- image: GeoPackageImage
- scaledWidth: number
- scaledHeight: number
Returns Promise<GeoPackageImage>
Implementation of CanvasAdapter.scaleImageToDimensions
- Defined in lib/canvas/htmlCanvasAdapter.ts:129

toBytes

toBytes(canvas: any, imageFormat: ImageType, compressionQuality?: number): Promise<Uint8Array>
Converts the contents drawn in a canvas to a byte array

Returns
Promise
Parameters
- canvas: any
- imageFormat: ImageType
- Optional compressionQuality: number
Returns Promise<Uint8Array>
Implementation of CanvasAdapter.toBytes
- Defined in lib/canvas/htmlCanvasAdapter.ts:196

toDataURL

toDataURL(canvas: any, format?: string, compressionQuality?: number): Promise<string>
Converts the canvas to a base64 data url in the format specified
Parameters
- canvas: any
- format: string = 'image/png'
- Optional compressionQuality: number
  
  0 to 1
Returns Promise<string>
Implementation of CanvasAdapter.toDataURL
- Defined in lib/canvas/htmlCanvasAdapter.ts:146

writeImageToBytes

writeImageToBytes(image: GeoPackageImage, imageFormat: ImageType, compressionQuality: number): Promise<Uint8Array>
Writes the image to a buffer
Parameters
- image: GeoPackageImage
- imageFormat: ImageType
- compressionQuality: number
  
  a Number between 0 and 1 indicating the image quality to be used when creating images using file formats that support lossy compression (such as jpg)
Returns Promise<Uint8Array>
Implementation of CanvasAdapter.writeImageToBytes
- Defined in lib/canvas/htmlCanvasAdapter.ts:159

Class HtmlCanvasAdapter

Hierarchy

Implements

Index

Constructors

Methods

Constructors

constructor

Returns HtmlCanvasAdapter

Methods

create

Parameters

width: number

height: number

Returns any

createImage

Parameters

data: string | Buffer | Uint8Array | Blob

contentType: string

Returns Promise<GeoPackageImage>

createImageData

Parameters

width: any

height: any

Returns ImageData

disposeCanvas

Parameters

canvas: any

Returns void

disposeImage

Parameters

image: GeoPackageImage

Returns void

drawText

Parameters

context: any

text: string

location: number[]

fontFace: string

fontSize: number

fontColor: string

Returns void

getImageData

Parameters

image: GeoPackageImage

Returns ImageData

initialize

Returns Promise<void>

isInitialized

Returns boolean

measureText

Parameters

context: any

fontFace: string

fontSize: number

text: string

Returns number

mergeCanvas

Parameters

fromCanvas: any

toContext: any

Returns void

scaleImage

Parameters

image: GeoPackageImage

scale: number

Returns Promise<GeoPackageImage>

scaleImageToDimensions

Parameters

image: GeoPackageImage

scaledWidth: number

scaledHeight: number

Returns Promise<GeoPackageImage>

toBytes

Returns

Parameters

canvas: any

imageFormat: ImageType

Optional compressionQuality: number

Returns Promise<Uint8Array>

`Optional` compressionQuality: number

`Optional` compressionQuality: number