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/* eslint-disable @bitrix24/bitrix24-rules/no-typeof */
// Warning!
// This function uses in a resize workers.
// You cannot import anything from other files and extensions.
const createImagePreviewCanvas = (
imageSource: CanvasImageSource,
newWidth: number,
newHeight: number,
): HTMLCanvasElement | OffscreenCanvas => {
let width: number = Math.round(newWidth);
let height: number = Math.round(newHeight);
const isPageContext: boolean = (
typeof (window) !== 'undefined'
&& typeof (document) !== 'undefined'
&& typeof (parent) !== 'undefined'
);
const createCanvas = (canvasWidth: number, canvasHeight: number): HTMLCanvasElement | OffscreenCanvas => {
if (isPageContext)
{
const canvas: HTMLCanvasElement = document.createElement('canvas');
canvas.width = canvasWidth;
canvas.height = canvasHeight;
return canvas;
}
return new OffscreenCanvas(canvasWidth, canvasHeight);
};
if (imageSource.height <= height && imageSource.width <= width)
{
const canvas: HTMLCanvasElement = createCanvas(width, height);
const context: CanvasRenderingContext2D = canvas.getContext('2d');
context.imageSmoothingQuality = 'high';
context.drawImage(imageSource, 0, 0, width, height);
return canvas;
}
if (imageSource.height > imageSource.width)
{
width = Math.floor(height * (imageSource.width / imageSource.height));
}
else
{
height = Math.floor(width * (imageSource.height / imageSource.width));
}
let currentImageWidth: number = Math.floor(imageSource.width);
let currentImageHeight: number = Math.floor(imageSource.height);
let currentImageSource: CanvasImageSource = imageSource;
let resizingCanvas: HTMLCanvasElement = null;
while (currentImageWidth * 0.5 > width)
{
const halfImageWidth: number = Math.floor(currentImageWidth * 0.5);
const halfImageHeight: number = Math.floor(currentImageHeight * 0.5);
resizingCanvas = createCanvas(halfImageWidth, halfImageHeight);
const resizingCanvasContext: CanvasRenderingContext2D = resizingCanvas.getContext('2d');
resizingCanvasContext.imageSmoothingQuality = 'high';
resizingCanvasContext.drawImage(
currentImageSource,
0,
0,
currentImageWidth,
currentImageHeight,
0,
0,
halfImageWidth,
halfImageHeight,
);
currentImageWidth = halfImageWidth;
currentImageHeight = halfImageHeight;
currentImageSource = resizingCanvas;
}
const outputCanvas: HTMLCanvasElement = createCanvas(width, height);
const outputCanvasContext: CanvasRenderingContext2D = outputCanvas.getContext('2d');
outputCanvasContext.imageSmoothingQuality = 'high';
outputCanvasContext.drawImage(
resizingCanvas === null ? imageSource : resizingCanvas,
0,
0,
currentImageWidth,
currentImageHeight,
0,
0,
width,
height,
);
if (resizingCanvas)
{
resizingCanvas.width = 0;
resizingCanvas.height = 0;
resizingCanvas = null;
currentImageSource.width = 0;
currentImageSource.height = 0;
currentImageSource = null;
}
return outputCanvas;
};
export default createImagePreviewCanvas;