Created
August 11, 2021 20:13
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public setPreviewImage(imgURL: string): void | |
{ | |
if (this._canvas !== undefined) | |
{ | |
const img: HTMLImageElement = new Image(); | |
this._url = imgURL; | |
img.crossOrigin = 'anonymous'; | |
// TODO This only works for a single image load. As an exercise, modify to handle deletion (including handlers) | |
// and re-initializing of a new Image if the setPreviewImage() method is called multiple times | |
img.onload = () => | |
{ | |
// which dimension is binding? | |
const w: number = img.width as number; | |
const h: number = img.height as number; | |
const s1: number = w / this._canvas.width; | |
const s2: number = h / this._canvas.height; | |
const ctx: CanvasRenderingContext2D = this._canvas.getContext('2d') as CanvasRenderingContext2D; | |
let d: number; | |
let left: number = 0; | |
let top: number = 0; | |
let right: number = 0; | |
let bottom: number = 0; | |
if (s1 >= s2) | |
{ | |
d = this._canvas.height - (h/s1); | |
left = 0; | |
top = Math.round(0.5*d); | |
right = this._canvas.width; | |
bottom = h / s1; | |
} | |
else | |
{ | |
d = this._canvas.width - (w/s2); | |
left = Math.round(0.5*d); | |
top = 0; | |
right = w / s2; | |
bottom = this._canvas.height; | |
} | |
ctx.drawImage(img, left, top, right, bottom); | |
const data: Uint8ClampedArray = this._canvas.getContext("2d")!.getImageData(left, top, right, bottom).data; | |
const n: number = data.length; | |
let i: number; | |
// process rgb and skip over alpha | |
for (i = 0; i < n; i+=4) { | |
this._rgbArr.push( {r: data[i], g: data[i+1], b: data[i+2]} ); | |
} | |
this._onLoaded.emit(this._url); | |
}; | |
img.onerror = () => this._onImgError.emit(this._url); | |
img.style.display = 'none'; | |
img.src = imgURL; | |
} | |
} |
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Hi!
You can set the extension of the file to give it code highlights and to make it more readable.
instead of "setPreviewImage" use "setPreviewImage.ts".
Helpful Article! Thank you.