How to use Drag event and Recognizer

DragGestureRecognizer creates and registers a SoWinTouchScreen in order to release Windows touch events. It creates an SoDragGestureRecognizer and adds it into the recognizer list. A SoEventCallback is created to manipulate SoDragGestureEvent events.

Example : DragGestureRecognizer

#include <Inventor/Qt/SoQt.h>
#include <Inventor/nodes/SoCone.h>
#include <Inventor/nodes/SoDirectionalLight.h>
#include <Inventor/nodes/SoEventCallback.h>
#include <Inventor/nodes/SoMaterial.h>
#include <Inventor/nodes/SoOrthographicCamera.h>
#include <Inventor/nodes/SoSeparator.h>
#include <Inventor/touch/devices/SoQtTouchScreen.h>
#include "SoDragGestureRecognizer.h"
 
SoOrthographicCamera* myCamera;
SoQtRenderArea* myRenderArea;
SoMaterial* color;
 
void
myDragCB( void* userData, SoEventCallback* eventCB )
{
  SoDragGestureEvent* dragEvent = ( SoDragGestureEvent* )eventCB->getEvent();
  SbColor init = color->diffuseColor[0];
  SbVec2f dist = dragEvent->getDraggedDistance();
 
  color->diffuseColor.setValue( init[0] + dist[0] / 10000, init[1] + dist[1] / 10000, init[2] );
}
 
int
main( int, char** argv )
{
  SoDragGestureRecognizer dragGestureRecognizer;
 
  Widget appWindow = SoQt::init( argv[0] );
  if ( appWindow == NULL )
    exit( 1 );
 
  // Create and set up the root node
  SoSeparator* root = new SoSeparator;
  root->ref();
 
  // Add a camera
  myCamera = new SoOrthographicCamera;
  root->addChild( myCamera );
  root->addChild( new SoDirectionalLight );
 
  color = new SoMaterial;
  root->addChild( color );
  SoCone* cone = new SoCone;
  root->addChild( cone );
 
  myRenderArea = new SoQtRenderArea( appWindow );
 
  SoEventCallback* myEventCB = new SoEventCallback;
 
  SoDragGestureEvent::initClass();
 
  myEventCB->addEventCallback( SoDragGestureEvent::getClassTypeId(), myDragCB, myRenderArea->getSceneManager()->getSceneGraph() );
  root->addChild( myEventCB );
 
  // Register the touch screen device.
  SoQtTouchScreen touchScreenDevice( appWindow );
  myRenderArea->registerDevice( &touchScreenDevice );
 
  touchScreenDevice.getTouchManager()->addRecognizer( &dragGestureRecognizer );
 
  myRenderArea->setSceneGraph( root );
  myRenderArea->setTitle( "DragGestureRecognizer" );
 
  // Make the camera see the whole scene
  SbViewportRegion viewportRegion = myRenderArea->getViewportRegion();
  myCamera->viewAll( root, viewportRegion, 2.0f );
 
  // Show our application window, and loop forever...
  myRenderArea->show();
  SoQt::show( appWindow );
  SoQt::mainLoop();
 
  root->unref();
 
  SoDragGestureEvent::exitClass();
 
  delete myRenderArea;
  SoQt::finish();
 
  return 0;
}