Building RingQt Applications for Mobile

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

Download Requirements

Install Qt 5.15.2
Install Qt Creator (Tested using Qt Creator 6.0.1)

Install Qt for Android

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

Run Qt Creator
Select Tools > Options > Devices > Android
Set the path for JDK, Android NDK and Android SDK Tools

Using Qt Creator, We can download these requirements

The Android SDK Tools (Tested using version 2.1)
The Android NDK (Tested using version 21.3)
Java SE Development Kit (JDK) v6 or later

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

Tested using Android 7.1 (API 25)

Screen Shot:

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

When we open the project file, We can select the Kit

After selecting the Kit, Click Configure Project

Now We can build & Run the application

The next screen shot for the application during the runtime

You can add your application images to the resources

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

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).
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.

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

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)

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

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.

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.