Uncategorized – Page 4 – Kev's Development Toolbox

March 5, 2017

BASIC 10liner 2017 contest entry – Boulder Jumper

I’ve seen posts about the BASIC 10Liner contest before, but this time I spotted posts for the 2017 contest with time to put an entry together. This weekend I spent a few hours putting together an entry using Sinclair BASIC on an emulated Spectrum, using Fuse for MacOS.

My entry is a take on the infinite runner style games, like Temple Run, but re-imagined in glorious 8 bit Sinclair BASIC style, I’ve called it ‘Boulder Jumper’.

If that’s not enough I went completely retro and implemented the graphics using only characters. This is my first entry to the BASIC 10Liner contest, and the first time I’ve written any Sinclair BASIC for maybe 33 or maybe more years.

My first thoughts were how can you possibly write a fully functioning game in 10 lines of code, but you can have multiple statements per line, and enter in either the 80 chars, 120, or 256 characters per line category. I think I’m just about squeezing into 120 per line.

Here’s a screenshot of the awesome gameplay:

Your character is a ‘b’ character, and rocks come from the right moving to the left, as ‘o’ characters. You press ‘m’ to jump and jump over the rocks or get squashed. You get points per rock you jump over, and have 3 lives.

Here’s the code in all it’s Sinclar BASIC glory:

And here’s the 10 lines in the Fuse emulator:

It’s not great and you could do a lot better (this is probably better suited to a ZX-81 than the ZX Spectrum), but it’s my first attempt for the 10Lines contest, and I had run writing and playing it!

February 26, 2017

Installed probably the last custom ROM update on my Galaxy S3 this year

I’ve been running custom CyanogenMod builds on my now aging Galaxy S3 for a while now (12.1, 13). Given that support for CyanogenMod ended at the end of last year, I thought it would be worth one last new ROM before I upgrade my phone this year, and installed the new LineageOS.

Using the already installed TWRP recovery that I already have installed, I downloaded the latest nightly LineageOS build from here, the latest Google Apps for Android 7.1 from here, booted into Recovery, deleted cache files etc, installed both new ROMs and now I’m up and running.

Even on my aging Galaxy S3, I have to say, this Android 7.1 build is surprisingly snappy, even faster than the last CyanogenMod build that I had that was pretty good.

November 18, 2016

Android development: drawing text on a Canvas

I have an Android project bubbling away. More details soon 🙂

I’m using a SurfaceView and needed to draw some text on it. The rest of the app is mostly drawing on the SurfaceView Canvas directly, but I need some text too.

I’ve dabbled with some Android development before, and I have to admit getting the layouts to do what you want them too almost seems to suck up the majority of my development time 🙁 This time round I got sidetracked trying to create a layout that was using a mix of TextView elements and adding my SurfaceView programmatically. This didn’t go too well, didn’t work at all, so I found a few posts like this, and worked out you need to draw directly on the canvas. Something like this does the job:

Paint textPaint = new Paint();
textPaint.setColor(Color.WHITE);
this.canvas.drawText("Hello world!", 20,50, textPaint);

This code is in the middle of a game display loop, but for completeness, to be able to draw to the Canvas first you need:

SurfaceHolder surfaceHolder = this.getHolder();

if (surfaceHolder.getSurface().isValid()) {
    this.canvas = surfaceHolder.lockCanvas();
   ...
}

And then to release the Canvas after you’ve finished drawing:

this.surfaceHolder.unlockCanvasAndPost(this.canvas);

Ok, next up, what about custom TTF fonts? Drop the TTF font you want to use in your assets/fonts folder, and then load it up with:

Typeface typeFace = Typeface.createFromAsset(this.context.getAssets(), 
    "fonts/yourfont.ttf");

To use this font with the text snippet above, just call setTypeface() and pass it in:

textPaint.setTypeface(this.typeFace);

Ok, how about specifying a font size that’s proportional to the resolution of the user’s screen? This is an interesting question. To avoid using fixed pixel size fonts and then having them not scale appropriately for different devices with different screen resolutions, Android uses a concept called ‘scale independent pixels’, or SP. This is described in this post here. In short, defines an SP value in /res/values/dimens.xml/dimens.xml like:

<dimen name="scoreFontSize">20sp</dimen>

And then reference and set it like this:

int fontSize = getResources().getDimensionPixelSize(R.dimen.scoreFontSize);
textPaint.setTextSize(fontSize);

Done! (I’ll share more on what I’m working on in a few days 🙂

October 6, 2016

Building a multi-container Spring Boot and MongoDB webapp with Docker 1.12.x – part 2

In the first part of this article, I showed how I split the frontend, backend and database all into their own containers, and how each could be individually scaled using docker-compose.

If you’re already familiar with docker-compose and using haproxy for load balancing against container, you might have noticed there’s a limitation in my approach, as both the backend REST service was exposing it’s port 8080 externally, and so I don’t think HTTP requests from the frontend browser in the app were ever passing through the haproxy to be load balanced, only the requests to load the front end on port 80 were being load balanced.

I looked into how I could configure haproxy with multiple backends, listening on different ports, but eventually came to the conclusion that adding two different haproxy containers, one load balancing for port 80 and one for port 8080 was easy to do.

I’m not sure if this is the best way to approach this, but it certainly. works. Leave me a comment if you have any suggestions.

Here’s my final docker-compose.yml:

version: '2'
  
services:
    mongodata:
        image: mongo:3.2
        volumes:
        - /data/db
        entrypoint: /bin/bash
    mongo:
        image: mongo:3.2
        depends_on: 
            - mongodata
        volumes_from:
            - mongodata
        ports:
            - "27017"
    addressbook:
        image: addressbook
        depends_on: 
            - mongo
        environment:
            - MONGODB_DB_NAME=addressbook
        ports:
            - "8080"
        links:
            - mongo
    web:
        image: docker-web-angularjs
        ports:
            - "80"
    lb-web:
        image: dockercloud/haproxy
        depends_on: 
            - web
        environment:
            - STATS_PORT=1936
            - STATS_AUTH="admin:your-password"
        links:
            - web
        volumes:
            - /var/run/docker.sock:/var/run/docker.sock
        ports:
            - 80:80
            - 1936:1936
    lb-addressbook:
        image: dockercloud/haproxy
        depends_on: 
            - addressbook
        environment:
            - STATS_PORT=1937
            - STATS_AUTH="admin:your-password"
        links:
            - addressbook
        volumes:
            - /var/run/docker.sock:/var/run/docker.sock
        ports:
            - 8080:80
            - 1937:1937