Building RingQt Applications for Mobile

In this chapter we will learn about Building RingQt Applications for Mobile.

Download Requirements

Check the next link : http://doc.qt.io/qt-5/androidgs.html

Download

Update the Android SDK

Update the Android SDK to get the API and tools packages required for development

Tested using Android 4.4.2 (API 19)
  • In Windows - Define the next Environment Variables based on your system.
  1. JAVA_HOME
For Example : C:\Program Files (x86)\Java\jdk1.8.0_05
  1. ANDROID_HOME
For Example : C:\JavaAndroid\AndroidSDK

Install Qt for Android

Using Ring2EXE

We can use Ring2EXE to quickly prepare Qt project for our application

Example:

ring2exe myapp.ring -dist -mobileqt

Note

We can use the Distribute Menu in Ring Notepad

Tip

The option ( Prepare Qt project for Mobile devices ) in the Distribute Menu

The Qt project for your Ring application

After using Ring2EXE or the Distribute Menu in Ring Notepad

  • Using the Qt Creator Open the generated Qt project

    Folder : target/mobile/qtproject

    Project file : project.pro

  • Using Qt Creator, You will find the compiled Ring application in the resources (YourAppName.ringo)

    This file (Ring Object File) is generated by the Ring compiler using

ring YourAppName.ring -go -norun
  • You can build your application using Qt Creator

  1. You can add your application images to the resources

    Or You can use any text editor (Notepad) and modify : project.qrc

  2. To find images from your Ring application, You need to use the file name in resources

    Example

if isandroid()
        mypic = new QPixmap(":/cards.jpg")
else
        mypic = new QPixmap("cards.jpg")
ok

Comments about developing for Android using RingQt

  1. The main project file is main.cpp

    This file load Ring Compiler/Virtual Machine and RingQt

    Then get the Ring Object File during the runtime from the resources

    Then run the Ring Object File (ringapp.ringo) using the Ring VM

    Through main.cpp you can extract more files from the resources to temp. folder once you add them (create projects with many files).

  2. The next functions are missing from this Ring edition

    • Database (ODBC, SQLite & MySQL)
    • Security and Internet functions (LibCurl & OpenSSL)
    • RingAllegro (Allegro Library)
    • RingLibSDL (LibSDL Library)

    Just use Qt Classes through RingQt.

    For database access use the QSqlDatabase Class

Note

All of the missing libraries ((LibCurl, OpenSSL & Allegro) can be compiled for Android, but they are not included in this Qt project.

  1. use if isandroid() when you want to modify the code just for android

Example:

if isandroid()
        // Android code
else
        // other platforms
ok

(4) Sometimes you will find that the button text/image is repeated in drawing ! it’s Qt problem that you can avoid using the next code.

if isandroid()
        setStyleSheet("
                border-style: outset;
                border-width: 2px;
                border-radius: 4px;
                border-color: black;
                padding: 6px;")
 ok
  1. Always use Layouts instead of manual setting of controls position and size.

This is the best way to get the expected user interface to avoid problems like (controls with small/extra size)

  1. When you deal with Qt Classes you can determine the images from resources (you don’t need to copy them using main.cpp)

Example:

if isandroid()
    mypic = new QPixmap(":/cards.jpg")
else
    mypic = new QPixmap("cards.jpg")
ok

Now RingQt comes with the AppFile() function to determine the file name

Example:

mypic = new QPixmap(AppFile("cards.jpg"))  # Desktop or Android
  1. When you update your project code, You don’t have to use Ring2EXE to generate the Qt project again

Just use the Distribute Menu in Ring Notepad and select (Generate Ring Object File)

Then copy the YourAppName.ringo file to target/mobile/qtproject folder and accept replacing files.

  1. If your application folder contains a Qt resource file (project.qrc)

Then when you use Ring2EXE or Ring Notepad (Distribute - Prepare Qt project for Mobile devices) the resource file will be used

See ring/applications/cards game as an example.