Friday, July 28, 2017

Getting started with Quasar on Android with Linux

The problem

As usual the problem is setting up the development environment for a project. This time it's going to be project using the Quasar framework and building the app for Android. This guide assumes a clean environment that does not contain anything (no Java, no Node no nothing).

Solution

First we need to have NodeJS installed. I install mine using the Node Version Manager (or nvm for short). Follow the instructions on https://github.com/creationix/nvm or simply enter the following commands:

$ curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.2/install.sh | bash

At this stage you need to close the current terminal and open a new one for the installation to finish and then install the latest stable NodeJS like so:

$ nvm install stable

We'll need two more things: JDK and Gradle. I install mine using the SdkMan:

$ curl -s "https://get.sdkman.io" | bash

At this stage you need to close the current terminal and open a new one for the installation to finish and then install Java and Gradle like so:

$ sdk install java
$ sdk install gradle 2.14.1

The version of Gradle is important. Cordova works with specific versions so you might want to stick to 2.14.1 to avoid any issues

Next we need to have some basic tooling for NodeJS installed. This includes obviously the Quasar CLI but also Yarn and Cordova

$ npm install -g yarn quasar-cli cordova

Having all that installed we can now instantiate and build our first project

$ quasar init hello-world
$ cd hello-world
$ yarn
$ yarn build

At this stage we have have the hello-world type quasar application built. We can work on it as if it would be any other VueJS application by running

$ yarn dev

More on it in the official documentation for Quasar

What we need next is the Android SDK. This is the most troublesome part of all, but if scripted it doesn't seem to be all that hard. First you need to download and extract the Android SDK. To do that we'll use the unzip tool that understands the .zip archive format. Be patient. It takes forever to download and install all the components. On my connection it took almost 10 minutes!!!

$ sudo apt install -y unzip
$ mkdir -p ~/Android/Sdk
$ cd ~/Android/Sdk
$ wget -c https://dl.google.com/android/repository/sdk-tools-linux-3859397.zip
$ unzip -q sdk-tools-linux-3859397.zip
$ cd tools/bin
$ ./sdkmanager --update
$ ./sdkmanager emulator platform-tools
$ ./sdkmanager "build-tools;25.0.3"
$ ./sdkmanager "platforms;android-25"
$ ./sdkmanager "system-images;android-25;google_apis;x86"
$ ./avdmanager create avd --force \
               --name test \
               --package "system-images;android-25;google_apis;x86" \
               --tag google_apis \
               --device 'Nexus 4'

Starting the emulator takes some time - be patient!

$ ~/Android/Sdk/tools/emulator -avd test -skin 768x1280

After it is up we have a platform to run our Quasar application on. Let's use it to run our new and shiny app.

$ cd [your_project_folder]
$ quasar wrap cordova
$ cd cordova
$ ANDROID_HOME=~/Android/Sdk cordova platform add android
$ ANDROID_HOME=~/Android/Sdk cordova build
$ ANDROID_HOME=~/Android/Sdk cordova run

That's it! The application should be running on your virtual Android device. Of course you should make the ANDROID_HOME variable more permanent by adding it to your .profile or .bashrc startup files but I'll leave it up to you.

Have fun!

Sunday, May 28, 2017

Vue.js cheatsheet

If you ever wondered why Vue.js is so easy take a look at this cheatsheet!

Vue/Vuex - a natural way forward

For a few days I have been creating an application to help with retrospection meetings in our distributed team. Obviously, as one might have guessed, the backend is in Node.js and, obviously, the frontend is in Vue.js. After a trial and error of a few approaches I decided that the state management is basically killing me so I went for Vuex to do its job. I knew little to nothing about Vuex but obviously I have had a lot of experience with Redux and since both do the same thing I thought things won't be too difficult. And I was right!

I followed this great article by Matt Bradford on how to get started with Vue+Vuex and I need to say that he hit the nail in the head with that article. Easy to follow, clear in message - just perfect. Then I went on to the official docs and, as usual with all things related to Vue.js, the guide was just perfect. It took me about 2 hours while creating the app to get used to it, learn the API, understand the difference between actions and mutations - basically a walk in the park!

The key takeaway from this experience for me is that documentation matters, a lot! It has to be good, easy to understand and fun to follow. Like a well written book that you can't take your eyes off late in the evening. Of course it helps if the thing the documentation describes is easy and fun but that is just about 30% - the rest is the craftsmanship of the author of the documentation. To underline that I have been reading some very ugly specs at work, written like someone didn't want to read what he wrote. That was just crazy! After that getting my hands on the Vuex guide helped me keep up the hopes for humanity :P

The bottom line is: if you feel like you're struggling with managing the state, even just a little bit - you need Vuex!

The next thing I desperately wanted to try was to make a system that through websockets to distribute the changes to other connected clients. This means that when you add a card on one browser that information is then posted via the websocket and the server broadcasts that information back to other browsers. I must say I am extremely surprised how well that worked! One thing to note is that when working on the store full page reloads do happen a lot. Each full reload causes the socket to be closed and reopened - which isn't all that bad. However restarting the server is a whole other story because websockets don't reconnect automagically. In this case, after trying out what I thought would work I ended up using reconnecting-websocket module. And it works absolutely great!

The server side uses the no database approach with a simple on-line events store and commands that mirror the mutations in Vuex. Easy and very, very fast! It looks like event sourcing is actually a good thing :)

You can find the sources for the project on Github.

Happy coding!

Thursday, May 18, 2017

Vue, Vue CLI, Webpack template, Nightwatch and page obect pattern

Today I tried to use the page object pattern with Nightwatch.js that is created when using the webpack template in vue-cli. It turns out they are not configured by default. This means you need to add

page_objects_path: ['test/e2e/pages'],
to your tests/e2e/nightwatch.conf.js file to start using it.

The usage scenario is quite simple

  1. Create a file describing the page
  2. Use it in a test

Everything you need to know about page object pattern and Nightwatch is here so don't hesitate to check it out. Here's a basic example, the initial e2e test created when the app was scaffolded, but this time rewritten using page object patter.

// For authoring Nightwatch tests, see
// http://nightwatchjs.org/guide#usage

module.exports = {
  'default e2e tests': function (browser) {
    // automatically uses dev Server port from /config.index.js
    // default: http://localhost:8080
    // see nightwatch.conf.js
    const devServer = browser.globals.devServerURL

    browser.page.home()
      .open(devServer)
      .assertMainContentPresent()
      .assertHeaderText('Welcome to Your Vue.js App')
      .assertMainLogoPresent()

    browser.end()
  }
}

And now the page definition in tests/pages/home.js:

module.exports = {
  elements: {
    container: {
      selector: "#app"
    },
    hello: {
      selector: ".hello"
    },
    title: {
      selector: "h1"
    },
    logo: {
      selector: "#app > img"
    },
  },
  commands: [ {
    open(url) {
      return this
        .navigate(url)
        .waitForElementVisible('@container', 5000)
    },
    assertHeaderText(content) {
      return this.assert.containsText('@title', content)
    },
    assertMainContentPresent() {
      return this.assert.elementPresent('@hello')
    },
    assertMainLogoPresent() {
      return this.assert.elementCount('@logo', 1)
    },
  } ]
}

Basically a page object is what a module exports. It is divided into 3 sections

  • elements - definition how to find certain elements
  • commands - pieces of work the page does
  • sections - (absent in this example)grouping mechanism for definitions

That's it

Wednesday, May 17, 2017

Performance of frontend frameworks

This is going to be just a quick note to myself

Don't base your choice on performance only. Currently pretty much all frameworks yield similar results (yes, even Ember is catching up with Glimmer, even though it is still slower than the other ones from the big 4). Use common sense, which is not so common, and let the simplicity and flexibility of use be your guiding star. If however the performance is not acceptable from the start and the framework doesn't have you on your knees begging to use it then just don't go for it.

Even though Ember is getting faster (I just threw up in my mouth a little bit) it doesn't mean it is sane to use it in any project of any size with Vue, Angular and React being out there

Happy coding

Monday, May 1, 2017

Vue directive NAME/V

Have you ever tried to remember the elements of a Vue's directive? But there are so many of them! Don't worry - they are very easy to remember!

Name - the part that comes right after "v-"

Argument - the part that comes right after the colon

Modifiers - the part that comes after dot

Expression / Value - the expression put inside the parameter value and the evaluated value

NAME / V - for short

Happy coding!

Tuesday, April 4, 2017

Recording screencast with Atom and Firefox

The need

I have recently started work on a video course about VueJS. The major part of it are screen recordings. I went through the original documentation my editor provided and it was just for Win/Mac (no surprise there) so I needed to go and figure it out for myself.

The how

As it turns out recording screen on Linux is quite easy. There are lots of good applications for it. I went with the good old ffmpeg

$ Xephyr :1 -ac -screen 1280x720 -br -reset &
$ sleep 2
$ setxkbmap -display :0 -print | xkbcomp - :1 &> /dev/null
$ DISPLAY=:1 evilwm -snap 50 &
$ DISPLAY=:1 atom &
$ DISPLAY=:1 firefox &

Now that we have all the apps running in a nice enclosure let's record the action:

$ ffmpeg \
    -f pulse -ac 2 -i default \
    -f x11grab -r 25 -s 1270x720 -i :1 -c:v libx264 \
    "./$(date).mp4"
This will create a new file with human readable timestamp each time you run this command encoding the 720p video in h.264 format and audio in AAC putting it all into an MPEG4 container.

Making Atom captures easy to edit

When editing the video in post production, for example using Blender's NLE, it is hard to fit the blinking intervals when cutting parts of the video. For that reason I recommend disabling the blink cursor in Atom. Select "Open your stylesheet" menu item and enter the following snippet

atom-text-editor.editor .is-focused .cursors .cursor {
  opacity: 1
}

That's it. Now the cursor is solid and editing is easy again

Happy recording!