Category Archives: Mobile development

Small presentation of my cross-platform engine for mobile and desktop applications

I made small presentation about my cross-platform engine for mobile and desktop applications. Codename Kobald. Click on image to play it in new window (use arrows and space to move through):

Screenshot 2015-01-21 21.53.14

This is not-so-technical presentation and main info about engine will come later as separate post.

Easing functions for your animations

Today’s design guidelines state that all animated movement inside your application should contain so called easing. You can read this section from google material design. If your UI-framework does not contain implementations for standard set of easings you can create your own.

Easing functions

Easing functions

Here is place where you can check out animated plottings for basic easing functions. And here you can find source code for them in several languages (JS,Java,Lua,C#,C++,C).

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Dockerfile example how to compile libcurl for Android inside Docker container

If you never heard of Docker be sure to check it out as fast as possible. There are lot of publications out there. At first it looks like another virtualisation software but it is actually more like new paradigm. Someone may call it very advanced chroot, someone may call virtual containers with version control and building scripts, and so on. I like it as the idea of application-centric containers – your application can keep whole operating system as a coating and its making perfect separation from outside influence. As well you can easily reproduce production process environment at another location. It makes virtualisation easy and fun.

Libcurl in docker

Almost everything can be done inside containers now. Recently i had to recompile curl for Android as static lib using latest NDK toolchain. Its not so complicated to do on your local machine (if it is not Windows) but now there is a more clean way to do this time-wasting operation. You can go to digital ocean, create droplet with Docker and using Dockerfile from the end of this post compile it while drinking coffee.

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Small guide: how to support immersive mode under Android 4.4+

In Android 4.4 version we have new Immersive mode which allows to make system bars translucent and extend application area to fit all screen. This looks great as it gives more space to application in terms of usability and it creates more stylish look if application design is done accordingly.

Immersive mode for TripBudget

I added support of immersive mode to TripBudget. And there were some unexpected troubles on the way so i decided to write some kind of guide here.

Note: I talk here about immersive mode where bottom navigation bar is hidden – using SYSTEM_UI_FLAG_IMMERSIVE_STICKY flag. This guide is aimed to gather and solve all problems which prevent sticky mode to work properly.

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Public localizator – web service for online localization of applications

Here i present small but powerful web instrument for public localization of applications and some more thoughts on software translations, which soon will be published as open-source after some tests in real projects.

Public localizator

Public localizator (beta) – is online web solution for fast translation of application strings to many languages by its users. Of course if you have money to invest in localization by paid services – it will be better solution, but if you have project which has wide range of users, which are interested in translation why not to create interface for them. As i had some positive experience of user translation i decided to create simple web tool. This approach is much better than sending some files/tools to your translators –  translation is easy, its continuous process and you can monitor progress at any time.

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How to create parallax effect using accelerometer

This is short guide how to create parallax effect using accelerometer on mobile platforms. Some code is related to Android, but all concept is applicable to iOS, etc.

What is parallax effect? There are some more complex definitions but i would define as simple as the following – you move your phone/device in space and some objects inside your application are shifting accordingly to compensate this movement. This allows to create some strong feeling of 3d interface as well as nice interaction effect.

As good example you can check out my live wallpaper (link on market), which is using this effect while rendering particle system of moving objects. More information about this application can be found here.

To create parallax effect we need to grab data from accelerometer sensor (as i found out gyroscope is not present at majority of phones while accelerometer gives enough of data to be happy with it), convert sensor data to relative rotation angles and shift some parts of application interface accordingly. 3 steps:

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Stackblur – C++ multi-threaded version of fast blur algorithm

I found nice algorithm for blurring images – Stackblur by Mario Klingemann. It could do the job relatively fast and gives decent quality. You can check it here – web demonstration. As you can see it can be usable even in web projects.

stackblursample

As i wanted to include it to my cross-platform engine i found two c++ implementations: 

First is SSE friendly, second contains some division optimization via static tables. However, both are not using all cpu cores. I took second one as foundation for my implementation, as i expected my code to work on mobile devices with no SSE support. Single-core processing of 1920×1200 rgba image with 100 px radius took only 219 ms (Intel Q9550, Windows 7).

I improved stackblur code to multi-threaded version – on my quad-core cpu speed results as expected showed 4x improvement – 63ms for the same task. You can download the part my lib below and use it as a foundation to your needs.

Download multi-threaded 32bit-color (RGBA) version of StackBlur:  stackblur.cpp

I believe algorithm can be optimized even further – any suggestions are welcome.

Compact lib for JSON parsing (cross-platform C++)

Recently i was in search of compact C++ source code for parsing  of JSON format. This is very simple minimalistic format and its very popular – but i was surprised when found a lot of complex parsers and no simple implementation inside one cpp-h pair. So i wrote one.

mvjsonlogo

Here it is – tiny C++ cross-platform solution for JSON decoding without any dependencies like boost or something: MVJSON.cpp MVJSON.h (version 1.0)

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