/***************************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others. 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: IBM Corporation - initial API and implementation
 **************************************************************************************/
package org.erlide.ui.prefs.plugin.internal;

import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.ColorDialog;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;

/**
 * A "button" of a certain color determined by the color picker.
 *
 *
 */
public class ColorEditor {

    /** The extent. */
    Point fExtent;

    /** The image for the push button. */
    Image fImage;

    /** The current RGB color value. */
    RGB fColorValue;

    /** The current color. */
    Color fColor;

    /** The image push button which open the color dialog. */
    Button fButton;

    /**
     * Creates and returns a new color editor.
     *
     * @param parent
     *            the parent composite of this color editor
     */
    public ColorEditor(final Composite parent) {
        fButton = new Button(parent, SWT.PUSH);
        fExtent = computeImageSize(parent);
        fImage = new Image(parent.getDisplay(), fExtent.x, fExtent.y);

        final GC gc = new GC(fImage);
        gc.setBackground(fButton.getBackground());
        gc.fillRectangle(0, 0, fExtent.x, fExtent.y);
        gc.dispose();

        fButton.setImage(fImage);
        fButton.addSelectionListener(new SelectionAdapter() {

            @Override
            public void widgetSelected(final SelectionEvent event) {
                final ColorDialog colorDialog = new ColorDialog(fButton.getShell());
                colorDialog.setRGB(fColorValue);
                final RGB newColor = colorDialog.open();
                if (newColor != null) {
                    fColorValue = newColor;
                    updateColorImage();
                }
            }
        });

        fButton.addDisposeListener(new DisposeListener() {

            @Override
            public void widgetDisposed(final DisposeEvent event) {
                if (fImage != null) {
                    fImage.dispose();
                    fImage = null;
                }
                if (fColor != null) {
                    fColor.dispose();
                    fColor = null;
                }
            }
        });
    }

    /**
     * Returns the current RGB color value.
     *
     * @return an rgb with the current color value
     */
    public RGB getColorValue() {
        return fColorValue;
    }

    /**
     * Sets the current RGB color value.
     *
     * @param rgb
     *            the new value for the rgb color value
     */
    public void setColorValue(final RGB rgb) {
        fColorValue = rgb;
        updateColorImage();
    }

    /**
     * Returns the image push button.
     *
     * @return the button which shows the current color as image
     */
    public Button getButton() {
        return fButton;
    }

    /**
     * Updates the color of the button image.
     */
    protected void updateColorImage() {

        final Display display = fButton.getDisplay();

        final GC gc = new GC(fImage);
        gc.setForeground(display.getSystemColor(SWT.COLOR_BLACK));
        gc.drawRectangle(0, 2, fExtent.x - 1, fExtent.y - 4);

        if (fColor != null) {
            fColor.dispose();
        }

        fColor = new Color(display, fColorValue);
        gc.setBackground(fColor);
        gc.fillRectangle(1, 3, fExtent.x - 2, fExtent.y - 5);
        gc.dispose();

        fButton.setImage(fImage);
    }

    /**
     * Computes the size for the image.
     *
     * @param window
     *            the window on which to render the image
     * @return the point with the image size
     */
    protected Point computeImageSize(final Control window) {
        final GC gc = new GC(window);
        final Font f = JFaceResources.getFontRegistry().get(JFaceResources.DEFAULT_FONT);
        gc.setFont(f);
        final int height = gc.getFontMetrics().getHeight();
        gc.dispose();
        final Point p = new Point(height * 3 - 6, height);
        return p;
    }
}