Babylon.js/src/Misc/copyTools.ts

import { Nullable } from "../types";

declare type BaseTexture = import("../Materials/Textures/baseTexture").BaseTexture;

/**
 * Class used to host copy specific utilities
 */
export class CopyTools {
    /**
     * Reads the pixels stored in the webgl texture and returns them as a base64 string
     * @param texture defines the texture to read pixels from
     * @param faceIndex defines the face of the texture to read (in case of cube texture)
     * @param level defines the LOD level of the texture to read (in case of Mip Maps)
     * @returns The base64 encoded string or null
     */
    public static GenerateBase64StringFromTexture(texture: BaseTexture, faceIndex = 0, level = 0): Nullable<string> {

        var internalTexture = texture.getInternalTexture();
        if (!internalTexture) {
            return null;
        }

        var pixels = texture.readPixels(faceIndex, level);
        if (!pixels) {
            return null;
        }

        var size = texture.getSize();
        var width = size.width;
        var height = size.height;

        if (pixels instanceof Float32Array) {
            var len = pixels.byteLength / pixels.BYTES_PER_ELEMENT;
            var npixels = new Uint8Array(len);

            while (--len >= 0) {
                var val = pixels[len];
                if (val < 0) {
                    val = 0;
                } else if (val > 1) {
                    val = 1;
                }
                npixels[len] = val * 255;
            }

            pixels = npixels;
        }

        var canvas = document.createElement('canvas');
        canvas.width = width;
        canvas.height = height;

        var ctx = canvas.getContext('2d');
        if (!ctx) {
            return null;
        }

        var imageData = ctx.createImageData(width, height);
        var castData = <any>imageData.data;
        castData.set(pixels);
        ctx.putImageData(imageData, 0, 0);

        if (internalTexture.invertY) {
            var canvas2 = document.createElement('canvas');
            canvas2.width = width;
            canvas2.height = height;

            var ctx2 = canvas2.getContext('2d');
            if (!ctx2) {
                return null;
            }

            ctx2.translate(0, height);
            ctx2.scale(1, -1);
            ctx2.drawImage(canvas, 0, 0);

            return canvas2.toDataURL('image/png');
        }

        return canvas.toDataURL('image/png');
    }
}