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/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.widgets;


import org.eclipse.swt.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.internal.gtk.*;
import org.eclipse.swt.internal.gtk3.*;

/**
 * Instances of the receiver represent a selectable user
 * interface object that present a range of continuous
 * numeric values.
 * 
 * Styles:
 * HORIZONTAL, VERTICAL
 * Events:
 * Selection
 * 
 * 
 * Note: Only one of the styles HORIZONTAL and VERTICAL may be specified.
 * 
 * 
 * IMPORTANT: This class is not intended to be subclassed.
 * 
 *
 * @see Scale snippets
 * @see SWT Example: ControlExample
 * @see Sample code and further information
 * @noextend This class is not intended to be subclassed by clients.
 */
public class Scale extends Control {

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * 
 * The style value is either one of the style constants defined in
 * class SWT which is applicable to instances of this
 * class, or must be built by bitwise OR'ing together
 * (that is, using the int "|" operator) two or more
 * of those SWT style constants. The class description
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * 
 *
 * @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 
 *    ERROR_NULL_ARGUMENT - if the parent is null
 * 
 * @exception SWTException 
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
 *    ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass
 * 
 *
 * @see SWT#HORIZONTAL
 * @see SWT#VERTICAL
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public Scale (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 SelectionListener
 * interface.
 * 
 * widgetSelected is called when the user changes the receiver's value.
 * widgetDefaultSelected is not called.
 * 
 *
 * @param listener the listener which should be notified
 *
 * @exception IllegalArgumentException 
 *    ERROR_NULL_ARGUMENT - if the listener is null
 * 
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 *
 * @see SelectionListener
 * @see #removeSelectionListener
 */
public void addSelectionListener (SelectionListener listener) {
	addTypedListener(listener, SWT.Selection, SWT.DefaultSelection);
}

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

@Override
Point computeSizeInPixels (int wHint, int hHint, boolean changed) {
	checkWidget();
	if (wHint != SWT.DEFAULT && wHint < 0) wHint = 0;
	if (hHint != SWT.DEFAULT && hHint < 0) hHint = 0;
	Point size = computeNativeSize(handle, wHint, hHint, changed);
	if ((style & SWT.HORIZONTAL) != 0) {
		if (wHint == SWT.DEFAULT) size.x = 2 * size.x;
	} else {
		if (hHint == SWT.DEFAULT) size.y = 2 * size.y;
	}
	return size;
}

@Override
void createHandle (int index) {
	state |= HANDLE | THEME_BACKGROUND;
	fixedHandle = OS.g_object_new (display.gtk_fixed_get_type (), 0);
	if (fixedHandle == 0) error (SWT.ERROR_NO_HANDLES);
	long hAdjustment = GTK.gtk_adjustment_new (0, 0, 100, 1, 10, 0);
	if (hAdjustment == 0) error (SWT.ERROR_NO_HANDLES);
	if ((style & SWT.HORIZONTAL) != 0) {
		handle = GTK.gtk_scale_new (GTK.GTK_ORIENTATION_HORIZONTAL, hAdjustment);
	} else {
		handle = GTK.gtk_scale_new (GTK.GTK_ORIENTATION_VERTICAL, hAdjustment);
	}
	if (handle == 0) error (SWT.ERROR_NO_HANDLES);

	if (GTK.GTK4) {
		OS.swt_fixed_add(fixedHandle, handle);
	} else {
		GTK3.gtk_widget_set_has_window(fixedHandle, true);
		GTK3.gtk_container_add (fixedHandle, handle);
	}

	GTK.gtk_scale_set_digits (handle, 0);
	GTK.gtk_scale_set_draw_value (handle, false);
}

@Override
void hookEvents () {
	super.hookEvents ();
	OS.g_signal_connect_closure (handle, OS.value_changed, display.getClosure (VALUE_CHANGED), false);
}

/**
 * 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 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public int getIncrement () {
	checkWidget ();
	long hAdjustment = GTK.gtk_range_get_adjustment (handle);
	return (int) GTK.gtk_adjustment_get_step_increment (hAdjustment);
}

/**
 * Returns the maximum value which the receiver will allow.
 *
 * @return the maximum
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public int getMaximum () {
	checkWidget ();
	long hAdjustment = GTK.gtk_range_get_adjustment (handle);
	return (int) GTK.gtk_adjustment_get_upper (hAdjustment);
}

/**
 * Returns the minimum value which the receiver will allow.
 *
 * @return the minimum
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public int getMinimum () {
	checkWidget ();
	long hAdjustment = GTK.gtk_range_get_adjustment (handle);
	return (int) GTK.gtk_adjustment_get_lower (hAdjustment);
}

/**
 * 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 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public int getPageIncrement () {
	checkWidget ();
	long hAdjustment = GTK.gtk_range_get_adjustment (handle);
	return (int) GTK.gtk_adjustment_get_page_increment (hAdjustment);
}

/**
 * Returns the 'selection', which is the receiver's position.
 *
 * @return the selection
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public int getSelection () {
	checkWidget ();
	long hAdjustment = GTK.gtk_range_get_adjustment (handle);
	return (int) GTK.gtk_adjustment_get_value (hAdjustment);
}

@Override
long gtk_value_changed(long range) {
	sendSelectionEvent(SWT.Selection);
	return 0;
}

/**
 * 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 
 *    ERROR_NULL_ARGUMENT - if the listener is null
 * 
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 *
 * @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 increment the new increment (must be greater than zero)
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public void setIncrement (int increment) {
	checkWidget ();
	if (increment < 1) return;
	OS.g_signal_handlers_block_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
	GTK.gtk_range_set_increments (handle, increment, getPageIncrement ());
	OS.g_signal_handlers_unblock_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
}

/**
 * Sets the maximum value that the receiver will allow.  This new
 * value will be ignored if it is not greater than the receiver's current
 * minimum value.  If the new maximum is applied then the receiver's
 * selection value will be adjusted if necessary to fall within its new range.
 *
 * @param value the new maximum, which must be greater than the current minimum
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public void setMaximum (int value) {
	checkWidget ();
	int minimum = getMinimum();
	if (value <= minimum) return;
	OS.g_signal_handlers_block_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
	GTK.gtk_range_set_range (handle, minimum, value);
	OS.g_signal_handlers_unblock_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
}

/**
 * Sets the minimum value that the receiver will allow.  This new
 * value will be ignored if it is negative or is not less than the receiver's
 * current maximum value.  If the new minimum is applied then the receiver's
 * selection value will be adjusted if necessary to fall within its new range.
 *
 * @param value the new minimum, which must be nonnegative and less than the current maximum
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public void setMinimum (int value) {
	checkWidget ();
	if (value < 0) return;
	int maximum = getMaximum ();
	if (value >= maximum) return;
	OS.g_signal_handlers_block_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
	GTK.gtk_range_set_range (handle, value, maximum);
	OS.g_signal_handlers_unblock_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
}

/**
 * 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 pageIncrement the page increment (must be greater than zero)
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public void setPageIncrement (int pageIncrement) {
	checkWidget ();
	if (pageIncrement < 1) return;
	OS.g_signal_handlers_block_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
	GTK.gtk_range_set_increments (handle, getIncrement (), pageIncrement);
	OS.g_signal_handlers_unblock_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
}

/**
 * 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 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public void setSelection (int value) {
	checkWidget ();
	OS.g_signal_handlers_block_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
	GTK.gtk_range_set_value (handle, value);
	OS.g_signal_handlers_unblock_matched (handle, OS.G_SIGNAL_MATCH_DATA, 0, 0, 0, 0, VALUE_CHANGED);
}

@Override
Point resizeCalculationsGTK3(long widget, int width, int height) {
	Point size = super.resizeCalculationsGTK3(widget, width, height);
	/*
	 * Bug 534204: (GTK 3.22) Scale with GridLayout height hint has no line
	 *
	 * Specifying a too low height hint for a scale, or shrinking the scale too much
	 * can result in a missing line for the scale. We specify a minimum height to avoid this.
	 * Due to the parent SwtFixed, the scale widget can still be resized below this minimum size.
	 * Instead of shrinking to comply with the too-small size, parts of it are hidden.
	 */
	if (widget == handle) {
		GtkRequisition naturalSize = new GtkRequisition();
		GtkRequisition minimumSize = new GtkRequisition();
		GTK.gtk_widget_get_preferred_size(handle, minimumSize, naturalSize);
		if ((style & SWT.VERTICAL) != 0) {
			size.x = Math.max(size.x, minimumSize.width);
		}
		if ((style & SWT.HORIZONTAL) != 0) {
			size.y = Math.max(size.y, minimumSize.height);
		}
	}
	return size;
}
}