perf: switch from pngjs to sharp

Author: DudaGod

lib/commands/screenshot.js

@@ -1,8 +1,6 @@
 'use strict';
 
-const {PNG} = require('pngjs');
-const concat = require('concat-stream');
-const streamifier = require('streamifier');
+const sharp = require('sharp');
 const {runInNativeContext} = require('../command-helpers/context-switcher');
 
 module.exports = (browser, {elementUtils}) => {
@@ -12,31 +10,13 @@ module.exports = (browser, {elementUtils}) => {
         const cropCoords = await runInNativeContext(browser, {fn: elementUtils.calcWebViewCoords.bind(elementUtils), args: [browser, {bodyWidth, pixelRatio}]});
         const screenshotResult = await baseScreenshotFn();
 
-        return new Promise((resolve, reject) => {
-            const handleError = (msg) => (err) => reject(`Error occured while ${msg}: ${err.message}`);
-
-            streamifier.createReadStream(Buffer.from(screenshotResult, 'base64'))
-                .on('error', handleError('converting buffer to readable stream'))
-                .pipe(new PNG())
-                .on('error', handleError('writing buffer to png data'))
-                .on('parsed', function() {
-                    const destination = new PNG({width: cropCoords.width, height: cropCoords.height});
-
-                    try {
-                        this.bitblt(destination, cropCoords.left, cropCoords.top, cropCoords.width, cropCoords.height);
-                    } catch (err) {
-                        reject(`Error occured while copying pixels from source to destination png: ${err.message}`);
-                    }
-
-                    destination.pack()
-                        .on('error', handleError('packing png data to buffer'))
-                        .pipe(concat((buffer) => {
-                            const strBase64 = buffer.toString('base64');
-
-                            resolve(strBase64);
-                        }))
-                        .on('error', handleError('concatenating png data to a single buffer'));
-                });
-        });
+        try {
+            return await sharp(Buffer.from(screenshotResult, 'base64'))
+                .extract(cropCoords)
+                .toBuffer()
+                .then(buf => buf.toString('base64'));
+        } catch (e) {
+            throw new Error(`Failed to take screenshot: ${e}`);
+        }
     });
 };