/*
 * Java-Gnome Bindings Library
 *
 * Copyright 1998-2004 the Java-Gnome Team, all rights reserved.
 *
 * The Java-Gnome bindings library is free software distributed under
 * the terms of the GNU Library General Public License version 2.
 */

package org.gnu.gtk;

import org.gnu.glib.EventMap;
import org.gnu.glib.EventType;
import org.gnu.glib.GObject;
import org.gnu.glib.Handle;
import org.gnu.glib.Type;
import org.gnu.gtk.event.ScaleEvent;
import org.gnu.gtk.event.ScaleListener;

/**
 * A Scale is a slider control used to select a numeric value. To use it, 
 * you'll probably want to investigate the methods on its base class, 
 * {@link Range}, in addition to the methods for Scale itself. To set the 
 * value of a scale, you would normally use {@link Range#setValue(double)}. 
 * To detect changes to the value, add RangeListener object to the widget.
 *
 * <p>The GtkScale widget is an abstract class, used only for deriving the 
 * subclasses {@link HScale} and {@link VScale}.
 * @see HScale
 * @see VScale
 */
public abstract class Scale extends Range {

	protected Scale(Handle handle) {
		super(handle);
	}

	/**
	 * Sets the number of decimal places that are displayed in the value. 
	 * Also causes the value of the adjustment to be rounded off to this number
	 * of digits, so the retrieved value matches the value the user saw.
	 * @param digits The number of decimal places to display, e.g. use 1 to 
	 * display 1.0, 2 to display 1.00 etc.
	 */
	public void setDigits(int digits) {
		gtk_scale_set_digits(getHandle(), digits);
	}

	/**
	 * Sets the position in which the current value is displayed.
	 * @param pos The position in which the current value is displayed.
	 */
	public void setValuePosition(PositionType pos) {
		gtk_scale_set_value_pos(getHandle(), pos.getValue());
	}

	/**
	 * Specifies whether the current value is displayed as a string next to the slider.
	 * @param setting If true, the value is displayed.
	 */
	public void setDrawValue(boolean setting) {
		gtk_scale_set_draw_value(getHandle(), setting);
	}

    /**
     * Returns whether the current value is displayed as a string next
     * to the slider.
     */
    public boolean getDrawValue() {
        return gtk_scale_get_draw_value(getHandle());
    }

	/* 
	 * EVENT HANDLING
	 */

	ScaleListener formatListener = null;

	/**
	 * Sets a listener to be used when a format-value request is called. 
	 */
	public void setFormatListener(ScaleListener listener) {
		if (null != formatListener)
			removeFormatListener();
		evtMap.initialize(this, ScaleEvent.Type.FORMAT_VALUE);
		formatListener = listener;
	}
	/**
	 * Removes the format listener
	 */
	public void removeFormatListener() {
		evtMap.uninitialize(this, ScaleEvent.Type.FORMAT_VALUE);
		formatListener = null;
	}

	public Class getEventListenerClass(String signal) {
		Class cls = evtMap.getEventListenerClass(signal);
		if (cls == null) cls = super.getEventListenerClass(signal);
		return cls;
	}

	public EventType getEventType(String signal) {
		EventType et = evtMap.getEventType(signal);
		if (et == null) et = super.getEventType(signal);
		return et;
	}

	private static EventMap evtMap = new EventMap();
	static {
		addEvents(evtMap);
	}

	private static void addEvents(EventMap anEvtMap) {
		anEvtMap.addEvent("format_value", "handleFormatValue", ScaleEvent.Type.FORMAT_VALUE, ScaleListener.class);
	}

	private String handleFormatValue(double value) {
		if (null == formatListener) {
			return (java.lang.Double.toString(value));
		} else {
			return (formatListener.formatScaleValue(new ScaleEvent(this), value));
		}
	}

    /**
     * Gets the {@link org.gnu.pango.Layout} used to display the scale.
     *
     * @return The {@link org.gnu.pango.Layout} for this scale, or
     * NULL if the {@link #getDrawValue} is FALSE.
     */
    public Layout getLayout() {
        Handle layout = gtk_scale_get_layout( getHandle() );
        GObject obj = getGObjectFromHandle( layout );
        if ( obj != null ) {
            return (Layout)obj;
        } else {
            return new Layout( layout );
        }
    }
    /**
     * Obtains the X coordinate where the scale will draw the
     * {@link org.gnu.pango.Layout} representing the text in the scale.
     * <p>
     * If {@link #getDrawValue} is FALSE, the return value is undefined.
     */
    public int getLayoutOffsetX() {
        int x[] = new int[1];
        int y[] = new int[1];
        gtk_scale_get_layout_offsets( getHandle(), x, y );
        return x[0];
    }
    /**
     * Obtains the Y coordinate where the scale will draw the
     * {@link org.gnu.pango.Layout} representing the text in the scale.
     * <p>
     * If {@link #getDrawValue} is FALSE, the return value is undefined.
     */
    public int getLayoutOffsetY() {
        int x[] = new int[1];
        int y[] = new int[1];
        gtk_scale_get_layout_offsets( getHandle(), x, y );
        return y[0];
    }

	/**
	 * Retrieve the runtime type used by the GLib library.
	 */
	public static Type getType() {
		return new Type(gtk_scale_get_type());
	}

	native static final protected int gtk_scale_get_type();
	native static final protected void gtk_scale_set_digits(Handle scale, int digits);
	native static final protected int gtk_scale_get_digits(Handle scale);
	native static final protected void gtk_scale_set_draw_value(Handle scale, boolean drawValue);
	native static final protected boolean gtk_scale_get_draw_value(Handle scale);
	native static final protected void gtk_scale_set_value_pos(Handle scale, int pos);
	native static final protected int gtk_scale_get_value_pos(Handle scale);
    native static final private Handle gtk_scale_get_layout(Handle scale);
    native static final private void gtk_scale_get_layout_offsets(Handle scale, int[] x, int[] y);

}