GroupDisplay.java

/*
 * Copyright 2010 kk-electronic a/s. 
 * 
 * This file is part of KKPortal.
 *
 * KKPortal is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * KKPortal is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with KKPortal.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
package com.kk_electronic.kkportal.core.ui;

import java.util.HashSet;
import java.util.List;

import com.google.gwt.core.client.Scheduler;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.event.dom.client.MouseDownEvent;
import com.google.gwt.event.dom.client.MouseDownHandler;
import com.google.gwt.event.dom.client.MouseUpEvent;
import com.google.gwt.layout.client.Layout;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.ui.IsWidget;
import com.google.gwt.user.client.ui.LayoutPanel;
import com.google.gwt.user.client.ui.Widget;
import com.google.inject.Inject;
import com.kk_electronic.kkportal.core.dnd.DND;
import com.kk_electronic.kkportal.core.dnd.DragSource;
import com.kk_electronic.kkportal.core.dnd.DND.DropSink;

public class GroupDisplay<T extends IsWidget & KnownHeight & DragSource> implements DropSink<T>,IsWidget {
	LayoutPanel canvas = new LayoutPanel();
	private final DND<T> dnd;
	private double margin = 1;
	private Unit marginunit = Unit.EM;
	
	public static interface Handler<T>{
		public void onElementDrop(double x, int y, T element);
	}
	
	private Handler<T> handler;
	
	public void setHandler(Handler<T> handler) {
		this.handler = handler;
	}

	@Inject
	public GroupDisplay(DND<T> dnd) {
		this.dnd = dnd;
		dnd.registerDropSink(this);
	}
	
	private native Layout iHateJavaProtection(LayoutPanel layoutPanel) /*-{
		return layoutPanel.@com.google.gwt.user.client.ui.LayoutPanel::layout;
	}-*/;
	
	HashSet<Widget> displayed = new HashSet<Widget>();
	
	public void setWidgets(List<List<T>> widgets){
		if(canvas.isAttached() == false){
			return;
		}
		if(widgets == null){
			canvas.clear();
			displayed.clear();
			return;
		}
		HashSet<Widget> needRemoval = new HashSet<Widget>(displayed);
	
		Layout l = iHateJavaProtection(canvas);
		
		double x = margin * l.getUnitSize(marginunit, false)/l.getUnitSize(Unit.PCT, false);
		double y = margin * l.getUnitSize(marginunit, true);
		
		double left = x;
		for(List<T> column:widgets){
			double top = y;
			//TODO: Support weighted column sizes
			double width = (100.0-x) / widgets.size()-x;
			for(final T face:column){
				final Widget widget = face.asWidget();
				int height = face.getDesiredHeight();
				if(!displayed.contains(widget)){
					canvas.add(widget);
					canvas.getWidgetContainerElement(widget).getStyle().clearOverflow();
					displayed.add(widget);
					face.getDragHandle().addMouseDownHandler(new MouseDownHandler() {
						
						@Override
						public void onMouseDown(MouseDownEvent event) {
							dnd.startDrag(event, face);
						}
					});
				}
				canvas.setWidgetLeftWidth(widget, left, Unit.PCT, width, Unit.PCT);
				canvas.setWidgetTopHeight(widget, top, Unit.PX, height, Unit.PX);
				top += height+y;
				needRemoval.remove(face);
			}
			left += width + x;
		}
		for(Widget toRemove : needRemoval){
			canvas.remove(toRemove);
			displayed.remove(toRemove);
			//TODO:remove handler
		}
		canvas.animate(150);
	}
	
	@Override
	public boolean Drop(MouseUpEvent event, final T element) {
		Widget widget = element.asWidget();
		int height = widget.getOffsetHeight();
		event.setRelativeElement(canvas.getElement());
		final int x = event.getX();
		final int y = event.getY();
		/*
		 * Note must be 100.0 and not 100 since the later would result in
		 * integer division which most likely would be 0
		 */
		double width = (100.0 * widget.getOffsetWidth()) / canvas.getOffsetWidth();
		final int top = widget.getAbsoluteTop() - canvas.getAbsoluteTop();
		final double left = (100.0 * (widget.getAbsoluteLeft() - canvas.getAbsoluteLeft()))
				/ canvas.getOffsetWidth();
		final double xpct = 100.0 * x / canvas.getOffsetWidth();
		canvas.add(widget);
		canvas.getWidgetContainerElement(widget).getStyle().clearOverflow();
		canvas.setWidgetTopHeight(widget, top, Unit.PX, height, Unit.PX);
		canvas.setWidgetLeftWidth(widget, left, Unit.PCT, width, Unit.PCT);
		if (handler != null) {
			Scheduler.get().scheduleDeferred(new Command() {

				@Override
				public void execute() {
					handler.onElementDrop(xpct, y, element);
				}
			});
			return true;
		}
		return false;
	}

	@Override
	public Widget asWidget() {
		return canvas;
	}
	
	public boolean checkForResizes() {
		if (canvas.getWidgetCount() == 0)
			return false;
		//ArrayList<Pair<Integer, Integer>> worklist = new ArrayList<Pair<Integer,Integer>>();
		
		boolean newSizes = false;
		for (int i = 0, l = canvas.getWidgetCount(); i < l; i++) {
			Widget widget = canvas.getWidget(i);

			int desiredHeight = 0;
			if (widget instanceof KnownHeight) {
				KnownHeight heightWidget = (KnownHeight) widget;
				desiredHeight = heightWidget.getDesiredHeight();
				if (desiredHeight != heightWidget.getLastHeight()) {
					//worklist.add(new Pair(heightWidget.getId(), desiredHeight));
					heightWidget.saveHeight(desiredHeight);
					newSizes = true;
				}
			}
		}
		return newSizes;
	}
}