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

1. 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

2. 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

3. 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

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.

3. 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

5. 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)

6. 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

7. 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.

8. 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.