/*******************************************************************************
 * Copyright (c) 2000, 2008 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
 *     
 * Port to the D programming language:
 *     Jacob Carlborg <doob@me.com>
 *******************************************************************************/
module dwt.widgets.Slider;

import dwt.dwthelper.utils;


import dwt.DWT;
import dwt.DWTException;
import dwt.events.SelectionEvent;
import dwt.events.SelectionListener;
import dwt.graphics.Point;
import dwt.internal.cocoa.NSRect;
import dwt.internal.cocoa.NSScroller;
import dwt.internal.cocoa.OS;
import dwt.internal.cocoa.SWTScroller;

import Carbon = dwt.internal.c.Carbon;
import dwt.widgets.Composite;
import dwt.widgets.Control;
import dwt.widgets.Event;
import dwt.widgets.TypedListener;

/**
 * Instances of this class are selectable user interface
 * objects that represent a range of positive, numeric values. 
 * <p>
 * At any given moment, a given slider will have a 
 * single 'selection' that is considered to be its
 * value, which is constrained to be within the range of
 * values the slider represents (that is, between its
 * <em>minimum</em> and <em>maximum</em> values).
 * </p><p>
 * Typically, sliders will be made up of five areas:
 * <ol>
 * <li>an arrow button for decrementing the value</li>
 * <li>a page decrement area for decrementing the value by a larger amount</li>
 * <li>a <em>thumb</em> for modifying the value by mouse dragging</li>
 * <li>a page increment area for incrementing the value by a larger amount</li>
 * <li>an arrow button for incrementing the value</li>
 * </ol>
 * Based on their style, sliders are either <code>HORIZONTAL</code>
 * (which have a left facing button for decrementing the value and a
 * right facing button for incrementing it) or <code>VERTICAL</code>
 * (which have an upward facing button for decrementing the value
 * and a downward facing buttons for incrementing it).
 * </p><p>
 * On some platforms, the size of the slider's thumb can be
 * varied relative to the magnitude of the range of values it
 * represents (that is, relative to the difference between its
 * maximum and minimum values). Typically, this is used to
 * indicate some proportional value such as the ratio of the
 * visible area of a document to the total amount of space that
 * it would take to display it. DWT supports setting the thumb
 * size even if the underlying platform does not, but in this
 * case the appearance of the slider will not change.
 * </p>
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>HORIZONTAL, VERTICAL</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Selection</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @see ScrollBar
 * @see <a href="http://www.eclipse.org/swt/snippets/#slider">Slider snippets</a>
 * @see <a href="http://www.eclipse.org/swt/examples.php">DWT Example: ControlExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */
public class Slider : Control {
    bool dragging;
    int minimum, maximum, thumb;
    int increment = 1;
    int pageIncrement = 10;
    
/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * <p>
 * The style value is either one of the style constants defined in
 * class <code>DWT</code> which is applicable to instances of this
 * class, or must be built by <em>bitwise OR</em>'ing together 
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>DWT</code> style constants. The class description
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * </p>
 *
 * @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
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 * </ul>
 * @exception DWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see DWT#HORIZONTAL
 * @see DWT#VERTICAL
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public this (Composite parent, int style) {
    super (parent, checkStyle (style));
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the user changes the receiver's value, by sending
 * it one of the messages defined in the <code>SelectionListener</code>
 * interface.
 * <p>
 * When <code>widgetSelected</code> is called, the event object detail field contains one of the following values:
 * <code>DWT.NONE</code> - for the end of a drag.
 * <code>DWT.DRAG</code>.
 * <code>DWT.HOME</code>.
 * <code>DWT.END</code>.
 * <code>DWT.ARROW_DOWN</code>.
 * <code>DWT.ARROW_UP</code>.
 * <code>DWT.PAGE_DOWN</code>.
 * <code>DWT.PAGE_UP</code>.
 * <code>widgetDefaultSelected</code> is not called.
 * </p>
 *
 * @param listener the listener which should be notified when the user changes the receiver's value
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see SelectionListener
 * @see #removeSelectionListener
 * @see SelectionEvent
 */
public void addSelectionListener(SelectionListener listener) {
    checkWidget();
    if (listener is null) error (DWT.ERROR_NULL_ARGUMENT);
    TypedListener typedListener = new TypedListener(listener);
    addListener(DWT.Selection,typedListener);
    addListener(DWT.DefaultSelection,typedListener);
}

static int checkStyle (int style) {
    return checkBits (style, DWT.HORIZONTAL, DWT.VERTICAL, 0, 0, 0, 0);
}

public Point computeSize (int wHint, int hHint, bool changed) {
    checkWidget();
    int width = 0, height = 0;
    if ((style & DWT.HORIZONTAL) !is 0) {
        height = cast(int)NSScroller.scrollerWidth();
        width = height * 10;
    } else {
        width = cast(int)NSScroller.scrollerWidth();
        height = width * 10;
    }
    if (wHint !is DWT.DEFAULT) width = wHint;
    if (hHint !is DWT.DEFAULT) height = hHint;
    return new Point (width, height);
}

void createHandle () {
    NSScroller widget = cast(NSScroller)(new SWTScroller()).alloc();
    NSRect rect = NSRect();
    if ((style & DWT.HORIZONTAL) !is 0) {
        rect.width = 1;
    } else {
        rect.height = 1;
    }
    widget.initWithFrame(rect);
    widget.setEnabled(true);
    widget.setTarget(widget);
    widget.setAction(OS.sel_sendSelection);
    view = widget;
    updateBar(0, minimum, maximum, thumb);
}

void createWidget () {
    maximum = 100;
    thumb = 10;
    super.createWidget();
}

/**
 * Returns the amount that the receiver's value will be
 * modified by when the up/down (or right/left) arrows
 * are pressed.
 *
 * @return the increment
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getIncrement () {
    checkWidget();
    return increment;
}

/**
 * Returns the maximum value which the receiver will allow.
 *
 * @return the maximum
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getMaximum () {
    checkWidget();
    return maximum; 
}

/**
 * Returns the minimum value which the receiver will allow.
 *
 * @return the minimum
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getMinimum () {
    checkWidget();
    return minimum;
}

/**
 * Returns the amount that the receiver's value will be
 * modified by when the page increment/decrement areas
 * are selected.
 *
 * @return the page increment
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getPageIncrement () {
    checkWidget();
    return pageIncrement;
}

/**
 * Returns the 'selection', which is the receiver's value.
 *
 * @return the selection
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getSelection () {
    checkWidget();
    NSScroller widget = cast(NSScroller)view;
    double value = widget.doubleValue();
    return cast(int)((maximum - thumb - minimum) * value + minimum);
}

/**
 * Returns the size of the receiver's thumb relative to the
 * difference between its maximum and minimum values.
 *
 * @return the thumb value
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public int getThumb () {
    checkWidget();
    return thumb;
}

/**
 * Removes the listener from the collection of listeners who will
 * be notified when the user changes the receiver's value.
 *
 * @param listener the listener which should no longer be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see SelectionListener
 * @see #addSelectionListener
 */
public void removeSelectionListener(SelectionListener listener) {
    checkWidget();
    if (listener is null) error (DWT.ERROR_NULL_ARGUMENT);
    if (eventTable is null) return;
    eventTable.unhook(DWT.Selection, listener);
    eventTable.unhook(DWT.DefaultSelection,listener);
}

void sendSelection () {
    Event event = new Event();
    NSScrollerPart hitPart = (cast(NSScroller)view).hitPart();
    int value = getSelection ();
    switch (hitPart) {
        case OS.NSScrollerDecrementLine:
            event.detail = DWT.ARROW_UP;
            value -= increment;
            break;
        case OS.NSScrollerDecrementPage:
            value -= pageIncrement;
            event.detail = DWT.PAGE_UP;
            break;
        case OS.NSScrollerIncrementLine:
            value += increment;
            event.detail = DWT.PAGE_DOWN;
            break;
        case OS.NSScrollerIncrementPage:
            value += pageIncrement;
            event.detail = DWT.ARROW_DOWN;
            break;
        case OS.NSScrollerKnob:
            event.detail = DWT.DRAG;
            break;
        default:
    }
    if (event.detail !is DWT.DRAG) {
        setSelection(value);
    }
    sendEvent(DWT.Selection, event);
}

/**
 * Sets the amount that the receiver's value will be
 * modified by when the up/down (or right/left) arrows
 * are pressed to the argument, which must be at least 
 * one.
 *
 * @param value the new increment (must be greater than zero)
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setIncrement (int value) {
    checkWidget();
    if (value < 1) return;
    increment = value;
}

/**
 * Sets the maximum. If this value is negative or less than or
 * equal to the minimum, the value is ignored. If necessary, first
 * the thumb and then the selection are adjusted to fit within the
 * new range.
 *
 * @param value the new maximum, which must be greater than the current minimum
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMaximum (int value) {
    checkWidget();
    if (value < 0) return;
    if (value <= minimum) return;
    if (value - minimum < thumb) {
        thumb = value - minimum;
    }
    int selection = Math.max(minimum, Math.min (getSelection (), value - thumb));
    this.maximum = value;
    updateBar(selection, minimum, value, thumb);
}

/**
 * Sets the minimum value. If this value is negative or greater
 * than or equal to the maximum, the value is ignored. If necessary,
 * first the thumb and then the selection are adjusted to fit within
 * the new range.
 *
 * @param value the new minimum
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setMinimum (int value) {
    checkWidget();
    if (value < 0) return;
    if (value >= maximum) return;
    if (maximum - value < thumb) {
        thumb = maximum - value;
    }
    int selection = Math.min(maximum - thumb, Math.max (getSelection (), value));
    this.minimum = value;
    updateBar(selection, value, maximum, thumb);
}

/**
 * Sets the amount that the receiver's value will be
 * modified by when the page increment/decrement areas
 * are selected to the argument, which must be at least
 * one.
 *
 * @param value the page increment (must be greater than zero)
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setPageIncrement (int value) {
    checkWidget();
    if (value < 1) return;
    pageIncrement = value;
}

/**
 * Sets the 'selection', which is the receiver's
 * value, to the argument which must be greater than or equal
 * to zero.
 *
 * @param value the new selection (must be zero or greater)
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setSelection (int value) {
    checkWidget();
    updateBar(value, minimum, maximum, thumb);
}

void updateBar (int selection, int minimum, int maximum, int thumb) {
    NSScroller widget = cast(NSScroller)view;
    selection = Math.max (minimum, Math.min (maximum - thumb, selection));
    int range = maximum - thumb - minimum;
    float fraction = range <= 0 ? 1 : cast(float)(selection - minimum) / range;
    Carbon.CGFloat knob = range <= 0 ? 1 : cast(Carbon.CGFloat)thumb / (maximum - minimum);
    widget.setFloatValue (fraction, knob);
}

/**
 * Sets the size of the receiver's thumb relative to the
 * difference between its maximum and minimum values.  This new
 * value will be ignored if it is less than one, and will be
 * clamped if it exceeds the receiver's current range.
 *
 * @param value the new thumb value, which must be at least one and not
 * larger than the size of the current range
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setThumb (int value) {
    checkWidget();
    if (value < 1) return;
    value = Math.min (value, maximum - minimum);
    this.thumb = value;
    updateBar(getSelection(), minimum, maximum, value);
}

/**
 * Sets the receiver's selection, minimum value, maximum
 * value, thumb, increment and page increment all at once.
 * <p>
 * Note: This is similar to setting the values individually
 * using the appropriate methods, but may be implemented in a 
 * more efficient fashion on some platforms.
 * </p>
 *
 * @param selection the new selection value
 * @param minimum the new minimum value
 * @param maximum the new maximum value
 * @param thumb the new thumb value
 * @param increment the new increment value
 * @param pageIncrement the new pageIncrement value
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public void setValues (int selection, int minimum, int maximum, int thumb, int increment, int pageIncrement) {
    checkWidget();
    if (minimum < 0) return;
    if (maximum < 0) return;
    if (thumb < 1) return;
    if (increment < 1) return;
    if (pageIncrement < 1) return;
    thumb = Math.min (thumb, maximum - minimum);
    this.increment = increment;
    this.pageIncrement = pageIncrement;
    updateBar(selection, minimum, maximum, thumb);
}

}