/*******************************************************************************

 * Copyright (c) 2000, 2007 IBM Corporation and others.

 * Portion Copyright (c) 2008 Nokia Corporation and/or its subsidiary(-ies).

 * 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

 *     Nokia Corporation - Qt implementation

 *******************************************************************************/

package org.eclipse.swt.widgets;

import org.eclipse.swt.SWT;

import org.eclipse.swt.internal.qt.OS;

import org.eclipse.swt.internal.qt.WidgetState;

import org.eclipse.swt.events.SelectionListener;

/**

 * 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. SWT

 * 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

 */

public class Slider extends Control {

    /**

     * This is used for storing the latest value that user has set the Slider

     * using setSelection(). If user changes the value of the Slider with

     * keys/mouse we get valueChanged() signal in which we send a

     * SelectionEvent. However, we get the same signal also after user sets the

     * selection using setSelection(). In that case we must not send a selection

     * event.

     */

    int     value          = -1;

    /**

     * QSlider does not have thumb support, so we emulate the API behavior in

     * Java side.

     */

    int     thumb          = 1;

    /**

     * This is used to store the information about key/mouse action that may

     * cause Slider value to change.

     */

    int     selectionCause = 0;

    /**

     * This is set to true when a DRAG event occurs, so that we can send a drag

     * end event when user releases the mouse.

     */

    boolean dragOccurred   = false;

    /**

     * 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>SWT</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>SWT</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 SWTException <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 SWT#HORIZONTAL

     * @see SWT#VERTICAL

     * @see Widget#checkSubclass

     * @see Widget#getStyle

     */

    public Slider(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>SWT.NONE</code> - for the end

     * of a drag. <code>SWT.DRAG</code>. <code>SWT.HOME</code>.

     * <code>SWT.END</code>. <code>SWT.ARROW_DOWN</code>.

     * <code>SWT.ARROW_UP</code>. <code>SWT.PAGE_DOWN</code>.

     * <code>SWT.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 SWTException  <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 == null) error(SWT.ERROR_NULL_ARGUMENT);

        TypedListener typedListener = new TypedListener(listener);

        addListener(SWT.Selection, typedListener);

        addListener(SWT.DefaultSelection, typedListener);

    }

    static int checkStyle(int style) {

        return checkBits(style, SWT.HORIZONTAL, SWT.VERTICAL, 0, 0, 0, 0);

    }

    void createHandle_pp(int index) {

        state |= WidgetState.HANDLE;

        topHandle = handle = OS.QSlider_new();

        if ((style & SWT.VERTICAL) != 0) {

            OS.QSlider_setOrientation(handle, OS.QT_VERTICAL);

        } else {

            OS.QSlider_setOrientation(handle, OS.QT_HORIZONTAL);

        }

    }

    void hookEvents_pp() {

        int signalProxy = OS.SignalHandler_new(handle, 

                OS.QSIGNAL_SLIDER_CHANGED);

        OS.QObject_connectOrThrow(handle, "valueChanged(int)", signalProxy,

                "widgetSignal(int)", OS.QT_AUTOCONNECTION);

    }

    /**

     * 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 SWTException <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 OS.QSlider_singleStep(handle);

    }

    /**

     * Returns the maximum value which the receiver will allow.

     * 

     * @return the maximum

     * 

     * @exception SWTException <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 OS.QSlider_maximum(handle);

    }

    /**

     * Returns the minimum value which the receiver will allow.

     * 

     * @return the minimum

     * 

     * @exception SWTException <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 OS.QSlider_minimum(handle);

    }

    /**

     * 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 SWTException <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 OS.QSlider_pageStep(handle);

    }

    /**

     * Returns the 'selection', which is the receiver's value.

     * 

     * @return the selection

     * 

     * @exception SWTException <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();

        return OS.QSlider_value(handle);

    }

    /**

     * Returns the size of the receiver's thumb relative to the difference

     * between its maximum and minimum values.

     * 

     * @return the thumb value

     * 

     * @exception SWTException <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 SWTException <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 == null) error(SWT.ERROR_NULL_ARGUMENT);

        if (eventTable == null) return;

        eventTable.unhook(SWT.Selection, listener);

        eventTable.unhook(SWT.DefaultSelection, listener);

    }

    /**

     * 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 SWTException <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;

        }

        OS.QSlider_setSingleStep(handle, 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 SWTException <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();

        int minimum = OS.QSlider_minimum(handle);

        if (value >= 0 && value > minimum) {

            thumb = Math.min(thumb, value - minimum);

            setValue(Math.min(OS.QSlider_value(handle), value - thumb));

            OS.QSlider_setMaximum(handle, value);

        }

    }

    /**

     * 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 SWTException <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;

        }

        int maximum = OS.QSlider_maximum(handle);

        if (value >= maximum) {

            return;

        }

        this.thumb = Math.min(thumb, maximum - value);

        setValue(Math.max(OS.QSlider_value(handle), value));

        OS.QSlider_setMinimum(handle, value);

    }

    /**

     * 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 SWTException <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;

        }

        OS.QSlider_setPageStep(handle, 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 SWTException <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();

        // Adjust the selection to range [minimum, maximum-thumb]

        setValue(Math.max(Math.min(value, OS.QSlider_maximum(handle) - thumb),

                OS.QSlider_minimum(handle)));

    }

    /**

     * 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 SWTException <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;

        }

        int selection = OS.QSlider_value(handle);

        int maximum = OS.QSlider_maximum(handle);

        value = Math.min(value, maximum - OS.QSlider_minimum(handle));

        this.thumb = value;

        setValue(Math.min(selection, 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 SWTException <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.thumb = thumb;

        OS.QSlider_setMaximum(handle, maximum);

        OS.QSlider_setMinimum(handle, minimum);

        OS.QSlider_setSingleStep(handle, increment);

        OS.QSlider_setPageStep(handle, pageIncrement);

        setValue(Math.min(Math.max(selection, minimum), maximum - thumb));

    }

    void setValue(int value) {

        this.value = value;

        OS.QSlider_setValue(handle, value);

    }

    boolean qt_event_mouseButtonRelease_pp(int widgetHandle, int button, 

            int x, int y, int state, int buttons) {

        this.selectionCause = SWT.NONE;

        /**

         * If user was dragging (i.e. we have sent drag events), send a drag end

         * when mouse button is released

         */

        if (this.dragOccurred) {

            this.dragOccurred = false;

            sendSliderSelectionEvent(this.selectionCause);

        }

        return super.qt_event_mouseButtonRelease_pp(widgetHandle, button, x,

                y, state, buttons);

    }

    boolean qt_event_mouseMove(int widgetHandle, int button, int x,

            int y, int state, int buttons) {

        this.selectionCause = SWT.DRAG;

        return super

                .qt_event_mouseMove(widgetHandle, button, x, y, state, buttons);

    }

    boolean qt_event_keypress_pp(int widgetHandle, int key, int modifier, int character, int nativeScanCode) {

        /**

         * The following keys can cause Slider selection to change, save the key

         * code here so that we can use it later when creating the selection

         * event.

         */

        switch (key) {

            case OS.QT_KEY_LEFT:

            case OS.QT_KEY_RIGHT:

            case OS.QT_KEY_UP:

            case OS.QT_KEY_DOWN:

            case OS.QT_KEY_HOME:

            case OS.QT_KEY_END:

            case OS.QT_KEY_PAGEUP:

            case OS.QT_KEY_PAGEDOWN:

                this.selectionCause = Display.translateKey(key, false);