Node

In this tutorial we will run Digger game in Node.js and save game screenshot to the image.

Let's start with creating empty project:

npm init

To run DOS in browser we need to install emulators package. For creating screenshot we will use jimp library. So let's install them.

npm install --save emulators jimp

Next we need to download Digger js-dos bundle:

curl https://cdn.dos.zone/original/2X/2/24b00b14f118580763440ecaddcc948f8cb94f14.jsdos -o digger.jsdos

Let's create source file digger.js. We can run it with this command node digger.js

Use require to import all libraries

const fs = require("fs");
const jimp = require("jimp");

require("emulators");

const emulators = global.emulators;
emulators.pathPrefix = "./";

Now we need to read contents of jsdos bundle and start emulation

const bundle = fs.readFileSync("digger.jsdos");

emulators
    .dosDirect(bundle)
    .then((ci) => {
      // ...
    });

When dos emulation starts, we will receive Command Interface, we can use it to subscribe on frame updates and to send key/mouse events.

    ci.events().onFrame((rgb, rgba) => {
        // use rgb or rgba image data
    });

In the v7 we have frame in RGBA format with transparent alpha, let's fix this and save screenshot:

    const width = ci.width();
    const height = ci.height();
    
    for (let next = 3; next < width * height * 4; next = next + 4) {
        rgba[next] = 255;
    }

    new jimp({ data: rgba, width, height }, (err, image) => {
        image.write("./screenshot.png", () => {
            ci.exit();
        });
    });

If you execute node digger.js it will save the screenshot to ./screenshot.png.

Full code of digger.js:

const fs = require("fs");
const jimp = require("jimp");

require("emulators");

const emulators = global.emulators;
emulators.pathPrefix = "./";

const bundle = fs.readFileSync("digger.jsdos");

emulators
    .dosDirect(bundle)
    .then((ci) => {
        let rgba = new Uint8Array(0);
        ci.events().onFrame((_, _rgba) => {
            rgba = _rgba;
        });

        // capture the screen after 3 sec
        console.log("Will capture screen after 3 sec...");
        setTimeout(() => {
            const width = ci.width();
            const height = ci.height();

            for (let next = 3; next < width * height * 4; next = next + 4) {
                rgba[next] = 255;
            }           

            new jimp({ data: rgba, width, height }, (err, image) => {
                image.write("./screenshot.png", () => {
                    ci.exit();
                });
            });
        }, 3000);
    })
    .catch(console.error);

Last modified: 11 июля 2024