ChartControl.java

package de.slothsoft.charts.swt;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Composite;

import de.slothsoft.charts.Chart;
import de.slothsoft.charts.PaintInstructions;
import de.slothsoft.charts.RefreshListener;

/**
 * A SWT control displaying a {@link Chart} and hooking it to the SWT framework.
 *
 * @author Stef Schulz
 * @since 0.1.0
 */

public class ChartControl extends Canvas {

    private Chart model;
    private SwtGraphicContext graphicContext;

    private final RefreshListener refreshListener = e -> redraw();

    /**
     * Constructs a new instance of this class given its parentand a style value
     * describing its behavior and appearance.
     *
     * @param parent a composite control which will be the parent of the new instance
     *            (cannot be null)
     * @param style the style of control to construct
     */

    public ChartControl(Composite parent, int style) {
        super(parent, style | SWT.DOUBLE_BUFFERED);
        addPaintListener(this::paintControl);
        addDisposeListener(e -> dispose());
    }

    private void paintControl(PaintEvent e) {
        final Rectangle rect = getClientArea();
        e.gc.setAntialias(SWT.ON);

        if (this.model != null) {
            if (this.graphicContext == null) {
                this.graphicContext = new SwtGraphicContext(e.gc);
            } else {
                this.graphicContext.delegate(e.gc);
            }

            final PaintInstructions instructions = new PaintInstructions(
                    new de.slothsoft.charts.Area(rect.x, rect.y, rect.width, rect.height));
            this.model.paintOn(this.graphicContext, instructions);
        }
    }

    /**
     * Returns the {@link Chart} that gets displayed by this control.
     *
     * @return the chart
     */

    public Chart getModel() {
        return this.model;
    }

    /**
     * Sets the {@link Chart} that gets displayed by this control.
     *
     * @param newModel the chart
     * @return this instance
     */

    public ChartControl model(Chart newModel) {
        setModel(newModel);
        return this;
    }

    /**
     * Sets the {@link Chart} that gets displayed by this control.
     *
     * @param model the chart
     */

    public void setModel(Chart model) {
        if (this.model != null) {
            this.model.removeRefreshListener(this.refreshListener);
        }
        this.model = model;
        if (this.model != null) {
            this.model.addRefreshListener(this.refreshListener);
        }
        redraw();
    }

    @Override
    public void dispose() {
        if (this.graphicContext != null) {
            this.graphicContext.dispose();
        }
        if (this.model != null) {
            this.model.removeRefreshListener(this.refreshListener);
        }
        super.dispose();
    }

}