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/*******************************************************************************
 * Copyright (c) 2000, 2009 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.eclipse.jface.preference;

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.layout.GridData;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Label;

/**
 * A field editor for a boolean type preference.
 */
public class BooleanFieldEditor extends FieldEditor {

    /**
	 * Style constant (value 0) indicating the default layout where
	 * the field editor's check box appears to the left of the label.
     */
    public static final int DEFAULT = 0;

    /**
	 * Style constant (value 1) indicating a layout where the field
	 * editor's label appears on the left with a check box on the right.
     */
    public static final int SEPARATE_LABEL = 1;

    /**
	 * Style bits. Either DEFAULT or SEPARATE_LABEL.
     */
    private int style;

    /**
     * The previously selected, or "before", value.
     */
    private boolean wasSelected;

    /**
     * The checkbox control, or null if none.
     */
    private Button checkBox = null;

    /**
     * Creates a new boolean field editor 
     */
    protected BooleanFieldEditor() {
    }

    /**
     * Creates a boolean field editor in the given style.
     * 
	 * @param name
	 *            the name of the preference this field editor works on
	 * @param labelText
	 *            the label text of the field editor
	 * @param style
	 *            the style, either DEFAULT or
     *   SEPARATE_LABEL
	 * @param parent
	 *            the parent of the field editor's control
     * @see #DEFAULT
     * @see #SEPARATE_LABEL
     */
	public BooleanFieldEditor(String name, String labelText, int style, Composite parent) {
        init(name, labelText);
        this.style = style;
        createControl(parent);
    }

    /**
     * Creates a boolean field editor in the default style.
     * 
	 * @param name
	 *            the name of the preference this field editor works on
	 * @param label
	 *            the label text of the field editor
	 * @param parent
	 *            the parent of the field editor's control
     */
    public BooleanFieldEditor(String name, String label, Composite parent) {
        this(name, label, DEFAULT, parent);
    }

	/*
	 * (non-Javadoc) Method declared on FieldEditor.
     */
    protected void adjustForNumColumns(int numColumns) {
        if (style == SEPARATE_LABEL) {
			numColumns--;
		}
        ((GridData) checkBox.getLayoutData()).horizontalSpan = numColumns;
    }

	/*
	 * (non-Javadoc) Method declared on FieldEditor.
     */
    protected void doFillIntoGrid(Composite parent, int numColumns) {
        String text = getLabelText();
        switch (style) {
        case SEPARATE_LABEL:
            getLabelControl(parent);
            numColumns--;
            text = null;
			//$FALL-THROUGH$
        default:
            checkBox = getChangeControl(parent);
            GridData gd = new GridData();
            gd.horizontalSpan = numColumns;
            checkBox.setLayoutData(gd);
            if (text != null) {
				checkBox.setText(text);
			}
        }
    }

	/**
	 * Returns the control responsible for displaying this field editor's label.
	 * This method can be used to set a tooltip for a
	 * BooleanFieldEditor. Note that the normal pattern of
	 * getLabelControl(parent).setToolTipText(tooltipText) does not
	 * work for boolean field editors, as it can lead to duplicate text (see bug
	 * 259952).
	 * 
	 * @param parent
	 *            the parent composite
	 * @return the control responsible for displaying the label
	 * 
	 * @since 1.3
     */
	public Control getDescriptionControl(Composite parent) {
		if (style == SEPARATE_LABEL) {
			return getLabelControl(parent);
		}
		return getChangeControl(parent);
	}

	/*
	 * (non-Javadoc) Method declared on FieldEditor. Loads the value from the
	 * preference store and sets it to the check box.
	 */
    protected void doLoad() {
        if (checkBox != null) {
			boolean value = getPreferenceStore().getBoolean(getPreferenceName());
            checkBox.setSelection(value);
            wasSelected = value;
        }
    }

	/*
	 * (non-Javadoc) Method declared on FieldEditor. Loads the default value
	 * from the preference store and sets it to the check box.
     */
    protected void doLoadDefault() {
        if (checkBox != null) {
			boolean value = getPreferenceStore().getDefaultBoolean(getPreferenceName());
            checkBox.setSelection(value);
            wasSelected = value;
        }
    }

	/*
	 * (non-Javadoc) Method declared on FieldEditor.
     */
    protected void doStore() {
		getPreferenceStore().setValue(getPreferenceName(), checkBox.getSelection());
    }

    /**
     * Returns this field editor's current value.
     *
     * @return the value
     */
    public boolean getBooleanValue() {
        return checkBox.getSelection();
    }

    /**
     * Returns the change button for this field editor.
     *
	 * @param parent
	 *            The Composite to create the receiver in.
	 * 
     * @return the change button
     */
    protected Button getChangeControl(Composite parent) {
        if (checkBox == null) {
            checkBox = new Button(parent, SWT.CHECK | SWT.LEFT);
            checkBox.setFont(parent.getFont());
            checkBox.addSelectionListener(new SelectionAdapter() {
                public void widgetSelected(SelectionEvent e) {
                    boolean isSelected = checkBox.getSelection();
                    valueChanged(wasSelected, isSelected);
                    wasSelected = isSelected;
                }
            });
            checkBox.addDisposeListener(new DisposeListener() {
                public void widgetDisposed(DisposeEvent event) {
                    checkBox = null;
                }
            });
        } else {
            checkParent(checkBox, parent);
        }
        return checkBox;
    }

	/*
	 * (non-Javadoc) Method declared on FieldEditor.
     */
    public int getNumberOfControls() {
        switch (style) {
        case SEPARATE_LABEL:
            return 2;
        default:
            return 1;
        }
    }

	/*
	 * (non-Javadoc) Method declared on FieldEditor.
     */
    public void setFocus() {
        if (checkBox != null) {
            checkBox.setFocus();
        }
    }

	/*
	 * (non-Javadoc) Method declared on FieldEditor.
     */
    public void setLabelText(String text) {
        super.setLabelText(text);
        Label label = getLabelControl();
        if (label == null && checkBox != null) {
            checkBox.setText(text);
        }
    }

    /**
	 * Informs this field editor's listener, if it has one, about a change to
	 * the value (VALUE property) provided that the old and new
	 * values are different.
     *
	 * @param oldValue
	 *            the old value
	 * @param newValue
	 *            the new value
     */
    protected void valueChanged(boolean oldValue, boolean newValue) {
        setPresentsDefaultValue(false);
        if (oldValue != newValue) {
			fireStateChanged(VALUE, oldValue, newValue);
		}
    }

    /*
     * @see FieldEditor.setEnabled
     */
    public void setEnabled(boolean enabled, Composite parent) {
        //Only call super if there is a label already
        if (style == SEPARATE_LABEL) {
			super.setEnabled(enabled, parent);
		}
        getChangeControl(parent).setEnabled(enabled);
    }

}




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