javafx.scene.control.skin.VirtualContainerBase Maven / Gradle / Ivy
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package javafx.scene.control.skin;
import javafx.event.EventHandler;
import javafx.scene.control.Control;
import javafx.scene.control.IndexedCell;
import javafx.scene.control.ScrollToEvent;
import javafx.scene.control.SkinBase;
/**
* Parent class to control skins whose contents are virtualized and scrollable.
* This class handles the interaction with the VirtualFlow class, which is the
* main class handling the virtualization of the contents of this container.
*
* @since 9
*/
public abstract class VirtualContainerBase extends SkinBase {
/* *************************************************************************
* *
* Private fields *
* *
**************************************************************************/
private boolean itemCountDirty;
/**
* The virtualized container which handles the layout and scrolling of
* all the cells.
*/
private final VirtualFlow flow;
private EventHandler> scrollToEventHandler;
/* *************************************************************************
* *
* Constructors *
* *
**************************************************************************/
/**
*
* @param control the control
*/
public VirtualContainerBase(final C control) {
super(control);
flow = createVirtualFlow();
scrollToEventHandler = event -> {
// Fix for RT-24630: The row count in VirtualFlow was incorrect
// (normally zero), so the scrollTo call was misbehaving.
if (itemCountDirty) {
// update row count before we do a scroll
updateItemCount();
itemCountDirty = false;
}
flow.scrollToTop(event.getScrollTarget());
};
control.addEventHandler(ScrollToEvent.scrollToTopIndex(), scrollToEventHandler);
}
/* *************************************************************************
* *
* Abstract API *
* *
**************************************************************************/
/**
* Returns the total number of items in this container, including those
* that are currently hidden because they are out of view.
* @return the total number of items in this container
*/
protected abstract int getItemCount();
/**
* This method is called when it is possible that the item count has changed (i.e. scrolling has occurred,
* the control has resized, etc). This method should recalculate the item count and store that for future
* use by the {@link #getItemCount} method.
*/
protected abstract void updateItemCount();
/* *************************************************************************
* *
* Public API *
* *
**************************************************************************/
/**
* Create the virtualized container that handles the layout and scrolling of
* all the cells. This enables skin subclasses to provide
* a custom {@link VirtualFlow} implementation.
* If not overridden, this method intantiates a default VirtualFlow instance.
* @return newly created VirtualFlow instance
* @since 10
*/
protected VirtualFlow createVirtualFlow() {
return new VirtualFlow<>();
}
/**
* {@inheritDoc}
* Overridden to remove EventHandler.
*/
@Override
public void dispose() {
if (getSkinnable() == null) return;
getSkinnable().removeEventHandler(ScrollToEvent.scrollToTopIndex(), scrollToEventHandler);
super.dispose();
}
/**
* Get the virtualized container.
* Subclasses can invoke this method to get the VirtualFlow instance.
* @return the virtualized container
* @since 10
*/
protected final VirtualFlow getVirtualFlow() {
return flow;
}
/**
* Call this method to indicate that the item count should be updated on the next pulse.
*/
protected final void markItemCountDirty() {
itemCountDirty = true;
}
/** {@inheritDoc} */
@Override protected void layoutChildren(double x, double y, double w, double h) {
checkState();
}
/* *************************************************************************
* *
* Private methods *
* *
**************************************************************************/
double getMaxCellWidth(int rowsToCount) {
return snappedLeftInset() + flow.getMaxCellWidth(rowsToCount) + snappedRightInset();
}
double getVirtualFlowPreferredHeight(int rows) {
double height = 1.0;
for (int i = 0; i < rows && i < getItemCount(); i++) {
height += flow.getCellLength(i);
}
return height + snappedTopInset() + snappedBottomInset();
}
void checkState() {
if (itemCountDirty) {
updateItemCount();
itemCountDirty = false;
}
}
void requestRebuildCells() {
flow.rebuildCells();
}
}