Qt for Android development example tutorial

Qt for Android development example tutorial

This article describes how to use Qt5.3.0 to develop Android applications. Due to a small amount of official information, we will record the problems encountered during the development process and solutions. The procedure is as follows:

1. Only qml MediaPlayer can be used for video playback on the Android platform.

2. file: // For example:

 
 

  
  
Image{ 
  
  
  source: "file:///mnt/usbhost1/Config/logo.png" 
  
  
} 
 
 

3. Interaction between C ++ and qml js Methods

 
 

  
  
QQuickView view;
  
  
View. setSource (QUrl (QStringLiteral ("qrc: // qml/MainView. qml ")));
  
  
QObject * qmlObj = (QObject *) view. rootObject ();
  
  
MainWnd * w = new MainWnd (object );
  
  
// Expose the C ++ class to qml for calling. The alias is mainWndClass.
  
  
View. engine ()-> rootContext ()-> setContextProperty (QLatin1String ("mainWndClass"), w );
  
  
 
  
  
// C ++ calls the js method in qml
  
  
// The parameter must be converted to QVariant
  
  
QMetaObject: invokeMethod (qmlObj, "showRight", Q_ARG (QVariant, 1 ));
  
  
// Call the subitem's js method
  
  
QmlPlayer = qmlObj-> findChild <QObject *> ("playerArea ");
  
  
QMetaObject: invokeMethod (qmlPlayer, "setVideoFile", Q_ARG (QVariant, currentVideoFile ));
 
 

 
 

  
  
// MainView. qml
  
  
Rectangle {
  
  
Anchors. fill: parent
  
  
Property int leftAreaWidth: this. width/5*4
  
  
Property int rightAreaWidth: this. width/5
  
  
Property int queueFontSize
  
  
Function showRight (isShow ){
  
  
....
  
  
}
  
  
Player {
  
  
Id: playerArea
  
  
// Set objectName, which can be found in c ++
  
  
ObjectName: "playerArea"
  
  
Width: parent. width
  
  
Height: parent. height
  
  
}
  
  
}
 
 

4. c ++ calls java Android api

Create the \ android \ src \ org \ rophie \ ProjectName \ JavaClass. java directory under the project directory

 
 

  
  
Org \ rophie \ ProjectName is the package name of the java class org. rophie. ProjectName;
 
 

For example, I call the Android API to adjust the system volume.

 
 

  
  
Package org. rophie. ProjectName;
  
  
Import org. qtproject. qt5.android. bindings. QtActivity;
  
  
Import android. widget. Toast;
  
  
Import android. media. AudioManager;
  
  
Import android. content. Context;
  
  
Public class JavaClass extends QtActivity {
  
  
Private static JavaClass m_instance;
  
  
Private static AudioManager mAudioManager;
  
  
Public JavaClass ()
  
  
{
  
  
// The constructor is required
  
  
M_instance = this;
  
  
}
  
  
Public static void setVolume (int vol ){
  
  
If (mAudioManager = null ){
  
  
MAudioManager = (AudioManager) m_instance.getSystemService (Context. AUDIO_SERVICE );
  
  
}
  
  
MAudioManager. setStreamVolume (AudioManager. STREAM_MUSIC, vol, 0 );
  
  
}
  
  
}
 
 

C ++ call:

 
 

  
  
QAndroidJniObject: callStaticMethod <void> ("org/rophie/ProjectName/JavaClass", "setVolume", "(I) V", 3 );
  
  
 
  
  

  
  
// For details, refer to the QAndroidJniObject class.
 
 

5. BroadcastReceiver enables Automatic startup, which is exactly the same as Android

 
 

  
  
Public void onReceive (Context context, Intent intent ){
  
  
......
  
  
// JavaClass is the java main class that inherits QtActivity
  
  
Intent intent2 = new Intent (context, JavaClass. class );
  
  
......
  
  
}
 
 

6. Call a third-party jar package, create a directory libs under the src directory at the same level, and import. jar packages to use

I hope this method will be helpful for Android development.