HB Blog 149: Cross Platform Development.

In computing, cross-platform software (also multi-platform software or platform-independent software) is computer software that is implemented on multiple computing platforms. Cross-platform software may be divided into two types; one requires individual building or compilation for each platform that it supports, and the other one can be directly run on any platform without special preparation. Cross-platform programming is the practice of actively writing software that will work on more than one platform.

There are a number of tools which are available to help facilitate the process of cross-platform programming:

1.     8th: A cross-platform development language, which utilizes Juce as its GUI layer. The platforms it currently supports are: Android, iOS, Windows, macOS, Linux and Raspberry Pi.
2.     Anant Computing: A mobile application platform that works in all Indian languages, including their keyboards, which is also supports AppWallet and Native performance inside all operating systems.
3.     Appcelerator: It helps in building native apps by deploying just a single JavaScript code base. It provides your web content in a native application, ensuring your code is not wrapped around a web container unlike few other such solutions.
4.     AppearIQ: A framework that supports the workflow of app development and deployment in an enterprise environment. Natively developed containers present hardware features of the mobile devices or tablets through an API to HTML5 code thus facilitating the development of mobile apps that run on different platforms.
5.     Cairo: A free software library used to provide a vector graphics-based, device-independent API. It is designed to provide primitives for 2-dimensional drawing across a number of different backends. Cairo is written in C and has bindings for many programming languages.
6.     Cocos2d: An open source toolkit and game engine for developing 2D and simple 3D cross-platform games and applications.
7.     Delphi: A cross platform IDE, which uses Pascal language for Development. Currently it supports Android, iOS, Windows, macOS.
8.     Ecere SDK: A cross platform GUI & 2D/3D graphics toolkit and IDE, written in eC and with support for additional languages such as C and Python. Currently it supports Linux, FreeBSD, Windows, Android, macOS and the Web through Emscripten or Binaryen (WebAssembly)
9.     Eclipse: An open source cross-platform development environment. Implemented in Java with a configurable architecture which supports many tools for software development. Add-ons are available for several languages, including Java and C++.
10.     FLTK: Another open source cross platform toolkit, but more lightweight because it restricts itself to the GUI.
11.     fpGUI: An open source widget toolkit that is completely implemented in Object Pascal. It currently supports Linux, Windows and a bit of Windows CE.
12.     GeneXus: A Windows rapid software development solution for cross-platform application creation and deployment based on knowledge representation and supporting C#, COBOL, Java including Android and BlackBerry smart devices, Objective-C for Apple mobile devices, RPG, Ruby, Visual Basic, and Visual FoxPro.
13.     GLBasic: A BASIC dialoect and compiler that generates C++ code. It includes cross compilers for many platforms and supports numerous platform (Windows, Mac, Linux, Android,iOS and some exotic handhelds).
14.     GTK+: An open source widget toolkit for Unix-like systems with X11 and Microsoft Windows.
15.     Haxe: An open source cross-platform language.
16.     Juce: An application framework written in C++, used to write native software on numerous systems (Microsoft Windows, POSIX, macOS), with no change to the code.
17.     Lazarus: A programming environment for the FreePascal Compiler. It supports the creation of self-standing graphical and console applications and runs on Linux, MacOSX, iOS, Android, WinCE, Windows and WEB.
18.     Max/MSP: A visual programming language that encapsulates platform-independent code with a platform-specific runtime environment into applications for macOS and Windows.
19.     MechDome: A cross-platform Android runtime. It allows unmodified Android apps to run natively on iOS and macOS
20.     MonoCross: An open-source model-view-controller design pattern where the model and controller are shared cross-platform but the view is platform-specific.
21.     Mono: An open-source cross-platform version of Microsoft .NET (a framework for applications and programming languages)
22.     MoSync: An open-source SDK for mobile platform app development in the C++ family
23.     Mozilla application framework: An open source platform for building macOS, Windows and Linux applications
24.     OpenGL: A cross-platform 3D graphics library.
25.     PhoneGap: It enables software programmers to build applications for mobile devices using CSS3, HTML5, and JavaScript instead of relying on platform-specific APIs like those in Android, iOS, or Windows Phone.
26.     PureBasic: A proprietary cross-platform language and IDE for building macOS, Windows and Linux applications
27.     Qt: An application framework and widget toolkit for Unix-like systems with X11, Microsoft Windows, macOS, and other systems—available under both open source and proprietary licenses.
28.     Simple and Fast Multimedia Library: A multimedia C++ API that provides low and high level access to graphics, input, audio, etc.
29.     Simple DirectMedia Layer: An open-source cross-platform multimedia library written in C that creates an abstraction over various platforms’ graphics, sound, and input APIs. It runs on many operating systems including Linux, Windows and macOS and is aimed at games and multimedia applications.
30.     Smartface: A cross platform native app development tool to create mobile applications for Android and iOS, using WYSIWYG design editor with JavaScript code editor.
31.     Tcl/Tk
32.     Ultimate++: A C++ cross-platform rapid application development framework focused on programmers productivity. It includes a set of libraries (GUI, SQL, etc..), and an integrated development environment. It supports Windows and Unix-like OS-s. The U++ competes with popular scripting languages while preserving C/C++ runtime characteristics. It has its own integrated development environment, TheIDE, which features BLITZ-build technology to speedup C++ rebuilds up to 4 times.
33.     Unity: Another cross-platform SDK which uses Unity Engine.
34.     Unreal: A cross-platform SDK which uses Unreal Engine.
35.     V-Play Engine: V-Play is a cross-platform development SDK based on the popular Qt framework. V-Play apps and games are created within Qt Creator.
36.     WaveMaker: A Cross-platform low-code development tool to create responsive web and hybrid mobile (Android & iOS) applications.
37.     WinDev: Integrated Development Environment for Windows, Linux, .Net and Java (also with support for Internet and Intranet)
38.     wxWidgets: An open source widget toolkit that is also an application framework.[14] It runs on Unix-like systems with X11, Microsoft Windows and macOS. It permits applications written to use it to run on all of the systems that it supports, if the application does not use any operating system-specific programming in addition to it.
39.     Xamrin: With a C#-shared codebase, developers can use Xamarin tools to write native Android, iOS, and Windows apps with native user interfaces and share code across multiple platforms, including Windows and macOS. 
40.     Xojo: A RAD IDE developed by Xojo, Inc. that uses an object-oriented programming language to create desktop, web and iOS apps. Xojo makes native, compiled desktop apps for macOS, Windows, Linux and Raspberry Pi. It creates compiled web apps that can be run as standalone servers or through CGI. And it recently added the ability to create native iOS apps.

HB Blog 68: Midlet Programming.

A MIDlet is an application that uses the Mobile Information Device Profile (MIDP) of the Connected Limited Device Configuration (CLDC) for the Java ME environment. Sun Microsystems uses the "let" suffix to name several different types of programs that fall within the Java technology umbrella. Applets, servlets,etc.

The development process for MIDlet is as follows,
1)Edit 
Sun Java Wireless Toolkit (SJWTK) is an environment used as editore for midlet programming. It is similar to java Applet.
The editor provides all features that are essential to develop midlet program.
2)Compile
Compilation is the process of compiling the Java source files into executable byte code. The compiler of the virtual machine compiles the Java source code.
3)Verification
Before execution process the pre-verification is process is performed. The byte code is verified as security aspect and then signed .jar file is created.
4)Run
Finally, the midelet program is ready to run on MIDP devices.

A MIDlet's main class extends javax.microedition.midlet.MIDlet. The main class defines three life-cycle notification methods: startApp(), pauseApp(), and destroyApp().

There are three possible states in a MIDlet's life-cycle:
Paused: The MIDlet instance has been constructed and is inactive. 
Active: The MIDlet is active. 
Destroyed: The MIDlet has been terminated and is ready for reclamation by the garbage collector.

The startApp() lifecycle method initiates active state whereas, pausedApp() method handles paused state. And destroyApp() method is used to manage destroyed state.

Here is a hello world program for MIDlet application,

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class HelloWorld extends MIDlet implements CommandListener {
    private Command exitCommand;
    private TextBox tbox;

    public HelloWorld() {
        exitCommand = new Command("Exit", Command.EXIT, 1);
        tbox = new TextBox("Hello world MIDlet", "Hello World!", 25, 0);
        tbox.addCommand(exitCommand);
        tbox.setCommandListener(this);
    }

    protected void startApp() {
        Display.getDisplay(this).setCurrent(tbox);
    }

    protected void pauseApp() {}
    protected void destroyApp(boolean bool) {}

    public void commandAction(Command cmd, Displayable disp) {
        if (cmd == exitCommand) {
            destroyApp(false);
            notifyDestroyed();
        }
    }
}