2015-07-31 16:05 UTC-0800 Pritpal Bedi (bedipritpal at hotmail.com)(r417)
+ hbqtqmlparts

• hbqtqmlparts/resources
• hbqtqmlparts/resources/png
• hbqtqmlparts/resources/png/left-32.png
• hbqtqmlparts/resources/png/refresh-32.png
• hbqtqmlparts/resources/png/right-32.png
• hbqtqmlparts/resources/png/stop-32.png
• hbqtqmlparts/resources/qml
• hbqtqmlparts/resources/qml/BarcodeReader.qml
• hbqtqmlparts/resources/qml/WebView.qml
• hbqtqmlparts/resources/wav
• hbqtqmlparts/resources/wav/barcode-beep.wav

• hbqtqmlparts/resources/wav/camera-flash.wav

• hbqtqmlparts/misc.prg

• hbqtqmlparts/qmlbridge.prg
• hbqtqmlparts/barcodereader.prg

• hbqtqmlparts/webview.prg

• hbqtqmlparts/hbqtqmlparts.hbc

• hbqtqmlparts/hbqtqmlparts.hbp
• hbqtqmlparts/hbqtqmlparts.hbx

• hbqtqmlparts/hbqtqmlparts.qrc

• hbqtqmlparts/tests

• hbqtqmlparts/tests/demobarcodereader.prg
• hbqtqmlparts/tests/demowebview.prg

• hbqtqmlparts/tests/hbmk.hbm

• qtcontribs.hbp

  • Added: hbqtqmlparts/hbqtqmlparts.hbp

  Initial commit of Harbour engine for QML manipulation.

  QML is the next-generation offering by Qt which facilitates to develop
  modern-looking, javaScript based applications. QML is also the core
  language adopted by Ubuntu mobile plaforms and its concept of
  one-os-fit-all-devices shift. So seems QML is set to become the
  protocol of choice for so many applications.

  Harbour's implementation of Qt, i.e. HbQt, is essentially a widget
  based implementation. It took me a while to turn to QML because
  of the necessity to have barcode reading inside my mobile offerings.
  I remained reluctant to give QML a try for a long time because of the
  complexity how Signal/Slot mechanism is implemented in Harbour.
  But when I took initiative, I found that it is simpler than my fear.
  Bottom line is : we can start using QML to some extent alsong-with
  and within our existing widget based apps.

  CLASS HbQtQmlBridge() provides the building blocks to stream-line
  the complexity of signal/slots, set/get properties, execute methods, etc.

  CLASS HbQtQmlBridge()

  METHOD init( oParent )
  METHOD create( oParent )

  METHOD setQml( cQml ) -> lSuccess
  METHOD show() -> NIL
  METHOD setProperty( cProperty, xValue ) -> lSuccess
  METHOD setChildProperty( cChild, cProperty, xValue ) -> lSuccess
  METHOD getProperty( cProperty ) -> oQVariant | NIL
  METHOD getChildProperty( cChild, cProperty ) -> oQVariant | NIL
  METHOD invokeMethod( cMethod, ... ) -> oQVariant | NIL
  METHOD connect( cSignal, bBlock ) -> lSuccess
  METHOD connectChild( cChild, cSignal, bBlock ) -> lSuccess

  :create() only initiates a QQuickWidget(), set some of its
  properties, connects it to error handeling slots and
  lays it in a best-judged layout on its parent.

  :setQml( cQml ) is where all the action happens.
  This is the only place where we could know if a QML
  document has been loaded or not. All subsequest operations
  are executable only if we succeed here. Be noted that QML
  engine is a scripting engine and is based on JavaScript
  heavily.

  Lets disect CLASS HbQtBarcodeReader() and BarcodeReader.qml in
  relevant context only. HbQtBarcodeReader() is developed to provide
  one-line calling methodology in mind and has many other constructs
  you are already familiar with.

  METHOD HbQtBarcodeReader:create( oParent )
  ...
  ...
  // register C++ classes in order to access them inside QML
  // immediately before those are about to be Used
  //
  HBQAbstractVideoSurface():registerQmlTypes()
  QZXing():registerQmlTypes()

  ::oQmlBridge := HbQtQmlBridge():new():create( ::oQmlContainerWidget )

  // provide the QML document location needed
  //
  IF ::oQmlBridge:setQml( "qrc:/hbqtqml/resources/qml/BarcodeReader.qml" )
  ::stopCamera()

   #ifndef __ANDROID__
      // because QVideoProbe() is only available for Android
      // we need render the frame ourselves, so this connection
      //
      ::oQmlBridge:connectChild( "videosurface", "imageAvailable(QImage)", {| oImage | ::dispImage( oImage ) } )
   #endif
   // we could have connected the "qzxing" child also for the same effect
   // but we decided to receive signal via QML document as it implements 
   // more constructs.
   //
   ::oQmlBridge:connect( "tagFound(QString)", {| cTag | ::manageBarcodeFound( cTag ) } )
  
   __hbqtAppRefresh()
  

  ENDIF
  ...
  ...
  RETURN self

  BarcodeReader.qml [ only relevant parts ]:

  Rectangle {
  id : cameraUI
  objectName : "camerainterface" // name to access the object
  // as this is the root object
  // it can be accessed directly.

  property bool stopScanningFrames   // can be set/get via :setProperty
  
  signal imageCaptured( string image )
  signal tagFound( string tag )      // signal we will receive via :connect
  
  function startScanning() {
     stopScanningFrames = false;
  }
  function stopScanning() {
     stopScanningFrames = true;
  }
  function stopCamera() {            // method we will invoke via :invokeMethod
      cameraUI.stopScanning();
      camera.stop();
  }
  function startCamera() {
      camera.start();
      cameraUI.startScanning();
      myVideoSurface.decoder = decoder;
      myVideoSurface.source  = camera;
  }
  
  Camera {
      id: camera
      objectName: "camera"           // can be accessed as QObject
                                     // from PRG QObject can only be 
                                     // exploited via :connect()
  }
  
  VideoOutput {
      id               : viewfinder
      objectName       : "viewfinder"
      source           : Qt.platform.os == "android" ? camera : myVideoSurface
  }
  
  QZXing{
      id         : decoder
      objectName : "qzxing"
      onTagFound : {
          if( ! cameraUI.stopScanningFrames )
          {
              cameraUI.stopScanningFrames = true;
              playSoundCameraFlash.play();
              cameraUI.tagFound( tag ); // emit the signal which we :connect()ed
          }
      }
  }
  
  HBQAbstractVideoSurface{
      id         : myVideoSurface
      objectName : "videosurface"   // will connect via :connectChild()
  }
  
  SoundEffect {
      id      : playSoundCameraFlash
      source  : "qrc:/hbqtqml/resources/wav/barcode-beep.wav"
  }
  

  }

  A convinient function, one-liner, can be fired to scan a barcode as:
  __hbqtActivateBarcodeReader( {|cBarcode| LetMePushIntoField( cBarcode ) } )

  I hope this class will flourish with passage of time as we will gain
  more experience into QML and allied technology. I am impressed with
  results and plan to share with you whatever meaningful I could muster.

  Enjoy and stay tuned!

Pritpal Bedi
a student of software analysis & concepts

Pritpal,

Many thanks for telling us

Great job!