javafx.scene.input.ScrollEvent#SCROLL_STARTED源码实例Demo

private void sendScrollEventToFX(EventType<ScrollEvent> eventType,
		double scrollX, double scrollY, int x, int y, int stateMask,
		boolean inertia) {
	// up to and including SWT 4.5, direction was inverted for pan
	// gestures on the Mac
	// (see https://bugs.eclipse.org/bugs/show_bug.cgi?id=481331)
	final double multiplier = ("cocoa".equals(SWT.getPlatform())
			&& SWT.getVersion() < 4600) ? -5.0 : 5.0;

	if (eventType == ScrollEvent.SCROLL_STARTED) {
		totalScrollX = 0;
		totalScrollY = 0;
	} else if (inertia) {
		// inertia events do not belong to the gesture,
		// thus total scroll is not accumulated
		totalScrollX = scrollX;
		totalScrollY = scrollY;
	} else {
		// accumulate total scroll as long as the gesture occurs
		totalScrollX += scrollX;
		totalScrollY += scrollY;
	}

	final Point los = toDisplay(x, y);
	scheduleSceneRunnable(new ISceneRunnable() {
		@Override
		public void run(TKSceneListenerWrapper sceneListener) {
			sceneListener.scrollEvent(eventType, scrollX, scrollY,
					totalScrollX, totalScrollY, multiplier, multiplier,
					0, 0, 0, 0, 0, x, y, los.x, los.y,
					(stateMask & SWT.SHIFT) != 0,
					(stateMask & SWT.CONTROL) != 0,
					(stateMask & SWT.ALT) != 0,
					(stateMask & SWT.COMMAND) != 0, false, inertia);
		}
	});
}
 

@Override
public void handle( ScrollEvent event ) {
	EventType<? extends Event> eventType = event.getEventType();
	if ( eventType == ScrollEvent.SCROLL_STARTED ) {
		//mouse wheel events never send SCROLL_STARTED
		ignoring = true;
	} else if ( eventType == ScrollEvent.SCROLL_FINISHED ) {
		//end non-mouse wheel event
		ignoring = false;

	} else if ( eventType == ScrollEvent.SCROLL &&
	            //If we are allowing mouse wheel zooming
	            mouseWheelZoomAllowed.get() &&
	            //If we aren't between SCROLL_STARTED and SCROLL_FINISHED
	            !ignoring &&
	            //inertia from non-wheel gestures might have touch count of 0
	            !event.isInertia() &&
	            //Only care about vertical wheel events
	            event.getDeltaY() != 0 &&
	            //mouse wheel always has touch count of 0
	            event.getTouchCount() == 0 ) {

		//Find out which axes to zoom based on the strategy
		double eventX = event.getX();
		double eventY = event.getY();
		DefaultChartInputContext context = new DefaultChartInputContext( chartInfo, eventX, eventY );
		AxisConstraint zoomMode = mouseWheelAxisConstraintStrategy.getConstraint( context );

		if ( zoomMode == AxisConstraint.None )
			return;

		//If we are are doing a zoom animation, stop it. Also of note is that we don't zoom the
		//mouse wheel zooming. Because the mouse wheel can "fly" and generate a lot of events,
		//animation doesn't work well. Plus, as the mouse wheel changes the view a small amount in
		//a predictable way, it "looks like" an animation when you roll it.
		//We might experiment with mouse wheel zoom animation in the future, though.
		zoomAnimation.stop();

		//At this point we are a mouse wheel event, based on everything I've read
		Point2D dataCoords = chartInfo.getDataCoordinates( eventX, eventY );

		//Determine the proportion of change to the lower and upper bounds based on how far the
		//cursor is along the axis.
		double xZoomBalance = getBalance( dataCoords.getX(),
		                                  getXAxisLowerBound(), getXAxisUpperBound() );
		double yZoomBalance = getBalance( dataCoords.getY(),
		                                  getYAxisLowerBound(), getYAxisUpperBound() );

		//Are we zooming in or out, based on the direction of the roll
		double direction = -Math.signum( event.getDeltaY() );

		//TODO: Do we need to handle "continuous" scroll wheels that don't work based on ticks?
		//If so, the 0.2 needs to be modified
		double zoomAmount = 0.2 * direction;

		if ( zoomMode == AxisConstraint.Both || zoomMode == AxisConstraint.Horizontal ) {
			double xZoomDelta = ( getXAxisUpperBound() - getXAxisLowerBound() ) * zoomAmount;
			xAxis.setAutoRanging( false );
			setXAxisLowerBound( getXAxisLowerBound() - xZoomDelta * xZoomBalance );
			setXAxisUpperBound( getXAxisUpperBound() + xZoomDelta * ( 1 - xZoomBalance ) );
		}

		if ( zoomMode == AxisConstraint.Both || zoomMode == AxisConstraint.Vertical ) {
			double yZoomDelta = ( getYAxisUpperBound() - getYAxisLowerBound() ) * zoomAmount;
			yAxis.setAutoRanging( false );
			setYAxisLowerBound( getYAxisLowerBound() - yZoomDelta * yZoomBalance );
			setYAxisUpperBound( getYAxisUpperBound() + yZoomDelta * ( 1 - yZoomBalance ) );
		}
	}
}