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SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by both ImageJ and SCIFIO.

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/*
 * #%L
 * SciJava Common shared library for SciJava software.
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 * Institute of Molecular Cell Biology and Genetics.
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 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
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package org.scijava.ui.dnd;

import java.util.List;

import org.scijava.display.Display;
import org.scijava.plugin.Parameter;
import org.scijava.plugin.Plugin;

/**
 * Drag-and-drop handler for lists of objects.
 * 
 * @author Curtis Rueden
 * @author Barry DeZonia
 */
@Plugin(type = DragAndDropHandler.class)
public class ListDragAndDropHandler extends AbstractDragAndDropHandler>
{

	@Parameter(required = false)
	private DragAndDropService dragAndDropService;

	// -- DragAndDropHandler methods --

	@Override
	public boolean supports(final List list, final Display display) {
		if (dragAndDropService == null) return false;
		if (!super.supports(list, display)) return false;

		// empty lists are trivially compatible
		if (list.size() == 0) return true;

		// the list is deemed compatible if at least one item is compatible
		for (final Object item : list) {
			if (dragAndDropService.supports(item, display)) return true;
		}
		return false;
	}

	@Override
	public boolean drop(final List list, final Display display) {
		if (dragAndDropService == null) return false;
		check(list, display);
		if (list == null) return true; // trivial case

		// dropping an empty list trivially succeeds
		if (list.size() == 0) return true;

		// use the drag-and-drop service to handle each item separately
		boolean success = false;
		for (final Object item : list) {
			if (dragAndDropService.supports(item, display)) {
				final boolean result = dragAndDropService.drop(item, display);
				if (result) success = true;
			}
		}
		return success;
	}

	// -- Typed methods --

	@Override
	@SuppressWarnings({ "rawtypes", "unchecked" })
	public Class> getType() {
		return (Class) List.class;
	}

}