Some things I learned about drawing on Android

I have been playing with 2D graphics in Android and it was a little hard to understand how to do some things that I needed. The API documentation for some functions doesn’t really do much of explaining you exactly what each argument does and how you can use them. After a little research I was able to draw everything I needed so I am going to try to summarize what I learned.

Paint

Most of the drawing functions on Android will take a Paint object as an argument. To use it you just need to instantiate the Paint class:

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Paint p = new Paint();

You can specify one of three drawing styles: FILL, FILL_AND_STROKE, STROKE. In a very simple scenario you might want to fill a shape using a blue color, and you could do it like this:

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Paint p = new Paint();
p.setStyle(Paint.Style.FILL);
p.setColor(Color.BLUE);
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Drawing on an android view

I am building a simple app that will need to graph some data, so I found myself in the need of using Android’s drawing library. There are a few good tutorials out there of how to do this using a canvas, but I read somewhere that it was possible to draw directly into a view and I wanted to try that. Drawing directly into the view is useful when you have data that you don’t need to redraw very often. When you use a canvas you have to manually call the onDraw method every time you want to show something, which makes sense for animations. For more static data you can draw directly into the view and the onDraw method will be called automatically every time the view it is shown to the user.

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Debugging node apps using built in debugger

When it comes to debugging node applications you have a few options. Most people I know use their IDE’s debugger which does the work really well for them. The next option for people who don’t use IDE’s is usually node inspector, which does a pretty good job too. Not long ago I found out that Node comes with a command line built in debugger which I tried and I think is easy enough that may become my debugger of choice.

To start debugging an application just use the debug command before running it:

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node debug app.js

When you do this your script will be loaded but the execution will stop at the first line. You will also get a debug> prompt where you can issue debugger commands.

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Debugging Android applications

Recently I have been exploring Android development and it was just a matter of time to find myself in the need to debug some of the code I write. Android documentation talks a little about debugging using Eclipse, but I try to stay away from bloated IDEs, so I have to pay by not getting the sugar they offer. The alternatives are not as easy and pretty as using an IDE with a compatible debugger, but hopefully they will do the job.

Logging

I come from PHP and JavaScript, so logging or dumping stuff is something that I am used to doing. When I started using JavaScript and I wanted to know what my code was doing or the value of a variable in a specific point in time I used console.log to print it to the browser terminal. Using this approach is really easy and very helpful in a lot of scenarios.

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Twitter Bootstrap

Twitter bootstrap is a front end framework that helps rapidly develop responsive web apps. Everybody says it is awesome, so I thought it was time to explore what it does.

I started by downloading it from Twitter Bootstrap Website. Twitter Bootstrap depends on jQuery and requires an HTML5 doctype so make sure your page has both.

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Android Menus

There are three different types of menus that can be added to an Android app:

Action bar – For older devices this is the menu that you get when you click on the menu button on your device. Since most new devices don’t have this button anymore the recommended way to create this type of global menus is by using the action bar which is visible by default and located on the top of the screen.

Contextual action mode – This menu allows you to perform actions on selected elements. The contextual action bar can be found in the same place where the action bar was, but it only appears when elements are selected and actions can be performed against them.

Popup menu – This is a modal popup menu that should be used to perform actions related to the current view.

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Creating a chrome extension

A few days ago I found that I wanted to create a browser extension for fixing some things that annoyed me about Jira, so I started my Journey of learning how to do this for Chrome. I had in the past written an extension for Firefox and I am not sure if it is because I did it so long ago or because chrome system is more friendly, but I felt this time was a lot easier.

Setting up the environment

The step of setting up the environment is extremely easy. Chrome gives you a lot of flexibility to do things the way you like, so basically the first thing you need is a folder and a manifest.json file inside of it. Here is an example of one:

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Creating user interfaces with android (Part 2 of 2)

This is part 2 of an introduction to creating user interfaces for Android.

Styling

If you come from a web development background, you probably find it ugly to define styles inline. Luckily as with HTML and CSS, you can define your styles in an external file. The syntax is completely different so it may take some time to get used to, but I think of it as assigning classes to the elements I want to style and then defining their styles.

To create a stylesheet we need to create an XML file in the res/values/ directory, it should look something like this:

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<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="FillWidth">
        <item name="android:layout_width">fill_parent</item>
        <item name="android:layout_height">wrap_content</item>
    </style>
</resources>
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Creating user interfaces with android (Part 1 of 2)

I am resuming my journey to learning Android development and for this article I will focus on the UI. On this post I will explain how to add labels, buttons and related elements so the user can interact with our app.

The way I see building UIs for Android is very similar to they way they are built for the web. You can do it in two ways: programmatically or declaratively. Programmatically means creating elements using Java code and declaratively means using XML files. If you are familiar with web development, this is analogous to how JavaScript and HTML interact. As on Web, the recommended way is to do it declaratively whenever possible since it is usually faster.

While designing a user interface for android it is important to keep in mind Android design guidelines to give the user a consistent experience among different apps.

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Creating web applications with Node and Express

Express is a web framework which allows you to easily make web applications on node. I already wrote about writing a simple server with node, but this time I will focus more on the application structure.

Lets start by creating a folder for our app called app/ and put a file inside named package.json. This is a special file used to define node projects. You can find more information about it on node JSON documentation, in this example I’ll use just the basics:

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{
  "name": "app",
  "description": "A simple sample app",
  "version": "0.0.1",
  "dependencies": {
    "express": "3.x"
  }
}

An important thing to mention is that this has to be a JSON file, so all the json attributes and values must be wrapped by double quotes (“). Most of the fields are just information about the project, but the dependencies attribute defines which packages my projects depends on. These packages will by default be downloaded from npmjs.com. We specified that we want the latest revision of version 3 of Express for our project.

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