The Ring programming language version 1.5.4 book - Part 71 of 185

1. CHAPTER
FIFTYSEVEN
BUILDING RINGQT APPLICATIONS FOR MOBILE
In this chapter we will learn about Building RingQt Applications for Mobile.
57.1 Download Requirements
Check the next link : http://doc.qt.io/qt-5/androidgs.html
Download
• The Android SDK Tools
https://developer.android.com/studio/index.html
• The Android NDK
https://developer.android.com/ndk/index.html
• Apache Ant v1.8 or later
http://ant.apache.org/bindownload.cgi
• Java SE Development Kit (JDK) v6 or later
http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
57.2 Update the Android SDK
Update the Android SDK to get the API and tools packages required for development
57.3 Install Qt for Android
• You can install Qt for Android from the next link
https://download.qt.io/archive/qt/5.5/5.5.1/
• Run Qt Creator, Select Tools > Options > Android to add the Android NDK and SDK paths.
http://doc.qt.io/qtcreator/creator-developing-android.html
• Using Qt Creator Open the project
Folder : ring/android/ringqt/project
Project file : project.pro
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• You will find the code in resourcestest.ring
You can modify the code then build and run for Desktop or Mobile.
57.4 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 copy files during the runtime from the resources to temp. folder
Then run the test.ring
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
57.4. Comments about developing for Android using RingQt 676

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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(":/resources/cardsimage")
else
mypic = new QPixmap("cards.jpg")
ok
In the previous example, cards.jpg is added to the resources then we write the “cardsimage” as alias for “cards.jpg”
57.4. Comments about developing for Android using RingQt 677

4. CHAPTER
FIFTYEIGHT
OBJECTS LIBRARY FOR RINGQT APPLICATION
In this chapter we will learn about the objects library for RingQt applications.
Ring comes with the Objects library for RingQt applications. Instead of using global variables for windows objects
and connecting events to objects using the object name, the Objects Library will manage the GUI objects and will
provide a more natural API to quickly create one or many windows from the same class and the library provide a way
to quickly set methods to be executed when an event is fired. Also the library provide a natural interface to quickly
use the parent or the caller windows from the child or sub windows.
The Objects Library is designed to be used with the MVC Design Pattern.
The Objects Library is merged in RingQt so you can use it directly when you use RingQt
58.1 Library Usage
• Use the Open_Window(cWindowControllerClassName) function to open new Windows
• Create at least Two Classes for each window, The Controller Class and the View Class
• Create each controller class from the WindowsControllerParent Class
• Create each view class from the WindowsViewParent Class
• Use the Last_Window() function to get the object of the last window created (The Controller object).
• When you call a sub window, use the SetParentObject() method and pass the self object.
• In the View Class, To determine the event method use the Method(cMethodName) function.
• The Method(cMethodName) function determine the method in the controller class that will be executed.
• Each controller class contains by default the CloseAction() method that you can call to close the window.
• You don’t need to call the Show() Method for each window, When you use Open_Window() It will be called.
• In the view class, Define the GUI window object as an attribute called win.
• You can use Open_WindowNoShow() to avoid displaying the window.
• You can use Open_WindowAndLink() to quickly get methods to access the windows.
58.2 Example
In the next example we will create two types of windows.
• Main Window contains a button. When the user click on the button a sub window will be opened.
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• The User Can click on the button many times to open many sub windows.
• Each Sub Window contains Two buttons.
• The first button in the sub window change the Main and the Sub Windows Titles.
• The second button in the sub window close the Sub Window.
load "guilib.ring"
new qApp {
open_window( :MainWindowController )
exec()
}
class MainWindowController from WindowsControllerParent
oView = new MainWindowView
func SubWindowAction
Open_window( :SubWindowController )
Last_Window().SetParentObject(self)
class MainWindowView from WindowsViewParent
win = new qWidget() {
SetWindowTitle("Main Window")
btnSub = new qPushButton(win) {
setText("Sub Window")
setClickEvent( Method( :SubWindowAction ) )
}
resize(400,400)
}
class SubWindowController from WindowsControllerParent
oView = new SubWindowView
func SetMainWindowTitleAction
Parent().oView.win.SetWindowTitle("Message from the Sub Window")
oView.win.SetWindowTitle("Click Event Done!")
class SubWindowView from WindowsViewParent
win = new qWidget() {
SetWindowTitle("Sub Window")
btnMsg = new qPushButton(win) {
setText("Set Main Window Title")
setClickEvent( Method( :SetMainWindowTitleAction ) )
}
btnClose = new qPushButton(win) {
Move(200,0)
setText("Close")
setClickEvent( Method( :CloseAction ) )
}
resize(400,400)
}
The next screen shot after creating three sub windows.
58.2. Example 679

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The next screen shot after clicking on the button in each sub window.
58.2. Example 680

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58.3 Open_WindowAndLink() Function
We can use the Open_WindowAndLink() function to connect between the application windows, pass messages (call
methods) between the objects.
This function uses Meta-programming to define dynamic methods in the Caller Class to use the dynamic objects of
other windows that we create.
Example : (Uses the Form Designer)
First Window
1. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/twowindowspart5/firstwindowView.ring
2. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/twowindowspart5/firstwindowController.ring
Second Window
1. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/twowindowspart5/secondwindowView.ring
2. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/twowindowspart5/secondwindowController.ring
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In the next code for example (from FirstWindowController.ring)
The Open_WindowAndLink() will create an object from the SecondWindowController Class
Then will add the Method : SecondWindow(), IsSecondWindow() Methods to the FirstWindowController Class
Also will add the Method : FirstWindow(), IsFirstWindow() Methods to the SecondWindowController Class
So the SendMessage() method in FirstWindowController class can use the SecondWindow() method to access the
object.
This is more simple than using Last_Window(), Parent() and SetParentObject() methods.
class firstwindowController from windowsControllerParent
oView = new firstwindowView
func OpenSecondWindow
Open_WindowAndLink(:SecondWindowController,self)
func SendMessage
if IsSecondWindow()
SecondWindow().setMessage("Message from the first window")
ok
func setMessage cMessage
oView.Label1.setText(cMessage)
58.4 Open_WindowInPackages() Function
The Open_WindowInPackages() function is the same as Open_Window() but takes an extra list that determine the
packages to import before opening the window.
Syntax:
Open_WindowInPackages(cClassName,aPackagesList)
Example:
The next example from the Form Designer source code, Open the Window Flags window using the
open_windowInPackages() function.
We determine the class name “WindowFlagsController” and the packages name.
The Window Flags window uses the FormDesigner and System.GUI packages.
open_windowInPackages(:WindowFlagsController,[
"formdesigner",
"System.GUI"
])
58.5 Objects Library Source Code
The library source code is very simple, You can check the source code files
• https://github.com/ring-lang/ring/blob/master/extensions/ringqt/objectslib/objects.ring
• https://github.com/ring-lang/ring/blob/master/extensions/ringqt/objectslib/subwindows.ring
58.4. Open_WindowInPackages() Function 682

9. CHAPTER
FIFTYNINE
USING THE FORM DESIGNER
In this chapter we will learn about using the Form Designer.
We can run the From Designer from Ring Notepad
From the Menubar in Ring Notepad - View Menu - We can Show/Hide the Form Designer window.
Also we can run the Form Designer in another window.
From the Ring Notepad - Tools Menu - Select the Form Designer.
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59.1 The Designer Windows
• Toolbox : To select controls to be added to the window.
• Properties : To set the properties of the active window or controls.
• Design Region : To select, move and resize the window and the controls.
59.2 The Toolbox
We have many buttons.
• Lock : We can use it to draw many controls of the same type quickly.
• Select : We can use it to select a control in the Design Region
• Controls Buttons : Select a control to be added to the window.
59.3 The Properties
• When we select the window or one control, We will have the selected object properties.
• Also In the properties window we have a combobox to select the active control.
• Some properties provide a button next to the property value. We can click on the button to get more options.
• When we select more than one control, We will have options for multi-selection
59.1. The Designer Windows 684