ChartPanelView.java

/*
 *  Copyright 2012 Axel Winkler, Daniel Dunér
 * 
 *  This file is part of Daxplore Presenter.
 *
 *  Daxplore Presenter 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 2.1 of the License, or
 *  (at your option) any later version.
 *
 *  Daxplore Presenter 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 Daxplore Presenter.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.daxplore.presenter.chart;

import org.daxplore.presenter.chart.display.Chart;
import org.daxplore.presenter.chart.resources.ChartConfig;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.core.client.Scheduler.ScheduledCommand;
import com.google.gwt.uibinder.client.UiBinder;
import com.google.gwt.uibinder.client.UiField;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.ScrollPanel;
import com.google.gwt.user.client.ui.SimplePanel;
import com.google.gwt.user.client.ui.Widget;
import com.google.inject.Inject;

/**
 * A wrapper panel for charts.
 * 
 * <p>When a new chart should be displayed, call the setChart method. It will
 * display the new chart, once that chart is loaded.</p>
 */
public class ChartPanelView extends Composite {
	interface ChartUiBinder extends UiBinder<Widget, ChartPanelView> { /* Empty UiTemplate interface */	}

	private static ChartUiBinder uiBinder = GWT.create(ChartUiBinder.class);

	@UiField(provided = true)
	protected final SimplePanel headerPanel;
	@UiField(provided = true)
	protected final SimplePanel chartContainerPanel = new SimplePanel();

	/**
	 * The chart that belongs to this panel.
	 */
	private Chart chart;
	
	/**
	 * Fields used to figure out and adjust the size of the chart and
	 * chartPanel.
	 */
	private int resizeRecursions;
	protected int maxWidth, maxHeight, chartWidth, chartHeight;
	private ScrollPanel chartScrollPanel = new ScrollPanel();
	private boolean scrolling = false, forceScrolling = false;

	@Inject
	protected ChartPanelView(ChartConfig chartConfig) {
		chartContainerPanel.setStylePrimaryName("daxplore-ChartContainerPanel");

		headerPanel = new SimplePanel();

		initWidget(uiBinder.createAndBindUi(this));
		setStylePrimaryName("daxplore-ChartPanel");

		maxWidth = 800; // TODO this is temporary, the wanted value is set using setMaxWidth(int width)
		maxHeight = chartConfig.chartHeight();
	}

	public void setChart(Chart chart) {
		headerPanel.setWidget(chart.getExternalHeader());
		if (scrolling) {
			chartScrollPanel.setWidget(chart);
		} else {
			chartContainerPanel.setWidget(chart);
		}
		this.chart = chart;
		adjustSizeRecursively();
	}
	
	/**
	 * Set the maximal allowed size of the chart panel, and in turn the chart.
	 * 
	 * <p>This is not guaranteed to result in the given width due to limitations
	 * in HTML layout and how GChart works internally.</p>
	 * 
	 * @param width
	 *            The wanted with of this ChartPanel.
	 */
	public void setMaxWidth(int width) {
		maxWidth = width;
		adjustSizeRecursively();
	}

	/**
	 * Try to adjust the size of the chartPanel, based on maxWidth and
	 * maxHeight.
	 * 
	 * <p>The size will automatically be updated and adjusted in a number of
	 * iterations. This is needed because the browser must draw the panel before
	 * its size can be calculated.</p>
	 */
	private void adjustSizeRecursively() {
		resizeRecursions = 0;
		forceScrolling = false;
		adjustSizeRecursivelySub();
	}

	/**
	 * A recursive subprocess started by adjustSizeRecursively. <b>Do not call
	 * this method directly!</b>
	 * 
	 * <p>Adjusts the size of the chart based on the chart panel's actual size
	 * (reported by the browser). Puts the chart in a scrollPanel if the chart
	 * is too wide.</p>
	 * 
	 * <p>The method calls itself repeatedly until a correct size has been
	 * found.</p>
	 */
	private void adjustSizeRecursivelySub() {
		int actualWidth = getOffsetWidth();
		int actualHeight = chartContainerPanel.getOffsetHeight() + headerPanel.getOffsetHeight();
		int diffWidth = maxWidth - actualWidth;
		int diffHeight = maxHeight - actualHeight;

		if (chart == null 
				|| (resizeRecursions != 0 && actualWidth == maxWidth && actualHeight == maxHeight) 
				|| (resizeRecursions != 0 && diffWidth == 0 && diffHeight == 0)) {
			return;
		}

		chartWidth += diffWidth;
		chartWidth = Math.max(0, chartWidth);

		chartHeight += diffHeight;
		chartHeight = Math.max(0, chartHeight);

		if (chartWidth < chart.getMinWidth() || forceScrolling) {
			if (!scrolling) {
				chartContainerPanel.setWidget(chartScrollPanel);
				chartScrollPanel.setWidget(chart);
				scrolling = true;
				forceScrolling = true;
			}
			chartScrollPanel.setSize(chartWidth + "px", chartHeight + "px");
			chart.setChartSizeSmart(chart.getMinWidth(), chartHeight - 40);
		} else if (chartWidth >= chart.getMinWidth()) {
			if (scrolling) {
				chartContainerPanel.setWidget(chart);
				scrolling = false;
			}
			chart.setChartSizeSmart(chartWidth, chartHeight);
		}

		resizeRecursions++;
		if (resizeRecursions < 10) {
			Scheduler.get().scheduleFinally(new ScheduledCommand() {
				@Override
				public void execute() {
					adjustSizeRecursivelySub();
				}
			});
		}
	}


}