ChartPreview.java

/***********************************************************************
 * Copyright (c) 2004, 2005 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 * Actuate Corporation - initial API and implementation
 ***********************************************************************/

package uk.ac.ed.inf.common.ui.plotting.dialogs;

import org.eclipse.birt.chart.device.IDeviceRenderer;
import org.eclipse.birt.chart.factory.GeneratedChartState;
import org.eclipse.birt.chart.factory.Generator;
import org.eclipse.birt.chart.factory.RunTimeContext;
import org.eclipse.birt.chart.model.Chart;
import org.eclipse.birt.chart.model.attribute.Bounds;
import org.eclipse.birt.chart.model.attribute.impl.BoundsImpl;
import org.eclipse.birt.chart.util.PluginSettings;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.events.ControlListener;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Display;

import uk.ac.ed.inf.common.ui.plotting.IChart;
import uk.ac.ed.inf.common.ui.plotting.internal.CommonChart;

/**
 * Typical usage: <br>
 * <code>
 * IChart chart = ... <br>
 * paintCanvas = new Canvas( composite, SWT.BORDER ); <br>
 * paintCanvas.setLayoutData( new GridData( GridData.FILL_BOTH ) ); <br>
 * paintCanvas.setBackground( Display.getDefault().getSystemColor( SWT.COLOR_WHITE ) ); <br>
 * preview = new ChartPreview( chart ); <br>
 * paintCanvas.addPaintListener( preview ); <br>
 * paintCanvas.addControlListener( preview );<br>
 * preview.setPreview( paintCanvas );<br>
 * preview.renderModel();<br> 
 * </code>
 */
public class ChartPreview implements PaintListener, ControlListener {

	private transient Canvas preview = null;

	private Chart cm = null;

	private transient boolean bIsPainting = false;

	private transient Image buffer;

	private static int X_OFFSET = 3;

	private static int Y_OFFSET = 3;

	public ChartPreview(IChart chart) {
		// Do nothing in the constructor
		this.cm = ((CommonChart) chart).getBirtChart();

	}

	/**
	 * @param cm
	 *            Chart Model
	 */
	public void renderModel() {
		// if ( cm == null )
		// {
		// return;
		// }

		if (preview != null && !preview.isDisposed()) {
			updateBuffer();
			preview.redraw();
		}
	}

	/**
	 * Generate and render the chart model,the chart image is stored in a
	 * buffer. The buffer will be updated only when the chart model is changed.
	 */
	private void updateBuffer() {
		if (bIsPainting) {
			return;
		}
		Throwable paintError = null;

		Rectangle re = preview.getClientArea();
		final Rectangle adjustedRe = new Rectangle(0, 0, re.width, re.height);

		if (adjustedRe.width - 2 * X_OFFSET <= 0
				|| adjustedRe.height - 2 * Y_OFFSET <= 0) {
			if (buffer != null && !buffer.isDisposed()) {
				buffer.dispose();
				buffer = null;
			}
			return;
		}

		if (cm == null) {
			buffer = null;
		} else {
			bIsPainting = true;
			Image oldBuffer = null;
			if (buffer == null) {
				buffer = new Image(Display.getDefault(), adjustedRe);
			} else {
				Rectangle ore = buffer.getBounds();

				oldBuffer = buffer;

				if (!adjustedRe.equals(ore)) {
					buffer = new Image(Display.getDefault(), adjustedRe);
				}
			}

			GC gc = new GC(buffer);

			// fill default backgournd as white.
			gc.setForeground(Display.getDefault().getSystemColor(
					SWT.COLOR_WHITE));
			gc.fillRectangle(buffer.getBounds());

			final Bounds bo = BoundsImpl.create(X_OFFSET, Y_OFFSET,
					adjustedRe.width - 2 * X_OFFSET, adjustedRe.height - 2
							* Y_OFFSET);

			IDeviceRenderer deviceRenderer = null;
			try {
				deviceRenderer = PluginSettings.instance().getDevice("dv.SWT"); //$NON-NLS-1$
				deviceRenderer
						.setProperty(IDeviceRenderer.GRAPHICS_CONTEXT, gc);
				bo.scale(72d / deviceRenderer.getDisplayServer()
						.getDpiResolution()); // CONVERT
				// TO
				// POINTS

				// GENERATE AND RENDER THE CHART
				final Generator gr = Generator.instance();
				RunTimeContext rtc = new RunTimeContext();

				GeneratedChartState state = gr.build(deviceRenderer
						.getDisplayServer(), cm, bo, null, rtc, null);

				gr.render(deviceRenderer, state);
			} catch (Exception ex) {
				paintError = ex;
			} finally {
				gc.dispose();
				if (deviceRenderer != null) {
					deviceRenderer.dispose();
				}
			}

			if (paintError != null) {
				buffer = oldBuffer;
			}
			if (oldBuffer != null && oldBuffer != buffer) {
				oldBuffer.dispose();
			}
			bIsPainting = false;
		}

	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.swt.events.PaintListener#paintControl(org.eclipse.swt.events
	 * .PaintEvent)
	 */
	public void paintControl(PaintEvent pe) {
		GC gc = pe.gc;
		if (buffer != null) {
			gc.drawImage(buffer, 0, 0);
		}
	}

	/**
	 * Set the preview canvas.
	 * 
	 * @param paintCanvas
	 */
	public void setPreview(Canvas paintCanvas) {
		this.preview = paintCanvas;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.swt.events.ControlListener#controlMoved(org.eclipse.swt.events
	 * .ControlEvent)
	 */
	public void controlMoved(ControlEvent e) {
		// TODO Auto-generated method stub

	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.swt.events.ControlListener#controlResized(org.eclipse.swt
	 * .events.ControlEvent)
	 */
	public void controlResized(ControlEvent e) {
		if (preview != null && !preview.isDisposed()) {
			updateBuffer();
			preview.redraw();
		}
	}
}