Method screenshot

data/src/emulator.js:5931–6021

(callback, source, format, upscale)

    }

    screenshot(callback, source, format, upscale) {
        const imageFormat = format || this.getSettingValue("screenshotFormat") || this.capture.photo.format;
        const imageUpscale = upscale || parseInt(this.getSettingValue("screenshotUpscale") || this.capture.photo.upscale);
        const screenshotSource = source || this.getSettingValue("screenshotSource") || this.capture.photo.source;
        const videoRotation = parseInt(this.getSettingValue("videoRotation") || 0);
        const aspectRatio = this.gameManager.getVideoDimensions("aspect") || 1.333333;
        const gameWidth = this.gameManager.getVideoDimensions("width") || 256;
        const gameHeight = this.gameManager.getVideoDimensions("height") || 224;
        const videoTurned = (videoRotation === 1 || videoRotation === 3);
        let width = this.canvas.width;
        let height = this.canvas.height;
        let scaleHeight = imageUpscale;
        let scaleWidth = imageUpscale;
        let scale = 1;
        
        if (screenshotSource === "retroarch") {
            if (width >= height) {
                width = height * aspectRatio;
            } else if (width < height) {
                height = width / aspectRatio;
            }
            this.gameManager.screenshot().then(screenshot => {
                const blob = new Blob([screenshot], { type: "image/png" });
                if (imageUpscale === 0) {
                    callback(blob, "png");
                } else if (imageUpscale > 1) {
                    scale = imageUpscale;
                    const img = new Image();
                    const screenshotUrl = URL.createObjectURL(blob);
                    img.src = screenshotUrl;
                    img.onload = () => {
                        const canvas = document.createElement("canvas");
                        canvas.width = width * scale;
                        canvas.height = height * scale;
                        const ctx = canvas.getContext("2d", { alpha: false });
                        ctx.imageSmoothingEnabled = false;
                        ctx.scale(scaleWidth, scaleHeight);
                        ctx.drawImage(img, 0, 0, width, height);
                        canvas.toBlob((blob) => {
                            callback(blob, imageFormat);
                            img.remove();
                            URL.revokeObjectURL(screenshotUrl);
                            canvas.remove();
                        }, "image/" + imageFormat, 1);
                    }
                }
            });
        } else if (screenshotSource === "canvas") {
            if (width >= height && !videoTurned) {
                width = height * aspectRatio;
            } else if (width < height && !videoTurned) {
                height = width / aspectRatio;
            } else if (width >= height && videoTurned) {
                width = height * (1/aspectRatio);
            } else if (width < height && videoTurned) {
                width = height / (1/aspectRatio);
            }
            if (imageUpscale === 0) {