tern.eclipse.ide.ui.preferences.ComboViewerFieldEditor.java Source code

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Here is the source code for tern.eclipse.ide.ui.preferences.ComboViewerFieldEditor.java

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/**
 *  Copyright (c) 2013-2016 Angelo ZERR.
 *  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:
 *  Angelo Zerr <angelo.zerr@gmail.com> - initial API and implementation
 */
package tern.eclipse.ide.ui.preferences;

import org.eclipse.jface.preference.FieldEditor;
import org.eclipse.jface.viewers.ArrayContentProvider;
import org.eclipse.jface.viewers.ComboViewer;
import org.eclipse.jface.viewers.IBaseLabelProvider;
import org.eclipse.jface.viewers.IContentProvider;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.jface.viewers.StructuredViewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;

/**
 * A field editor for a combo box that allows the drop-down selection of one of
 * a list of items with label/content provider.
 *
 */
public abstract class ComboViewerFieldEditor extends FieldEditor {

    /**
     * The custom combo box control.
     */
    private ComboViewer viewer;
    private Object selectedValue;
    private boolean isValid = true;

    /**
     * Create the combo box field editor.
     *
     * @param name
     *            the name of the preference this field editor works on
     * @param labelText
     *            the label text of the field editor
     * @param entryNamesAndValues
     *            the names (labels) and underlying values to populate the combo
     *            widget. These should be arranged as: { {name1, value1},
     *            {name2, value2}, ...}
     * @param parent
     *            the parent composite
     */
    public ComboViewerFieldEditor(String name, String labelText, Composite parent) {
        init(name, labelText);
        createControl(parent);
        setContentProvider(ArrayContentProvider.getInstance());
    }

    @Override
    protected void adjustForNumColumns(int numColumns) {
        Combo combo = viewer.getCombo();
        if (numColumns > 1) {
            Control control = getLabelControl();
            int left = numColumns;
            if (control != null) {
                ((GridData) control.getLayoutData()).horizontalSpan = 1;
                left = left - 1;
            }
            ((GridData) combo.getLayoutData()).horizontalSpan = left;
        } else {
            Control control = getLabelControl();
            if (control != null) {
                ((GridData) control.getLayoutData()).horizontalSpan = 1;
            }
            ((GridData) combo.getLayoutData()).horizontalSpan = 1;
        }
    }

    @Override
    protected void doFillIntoGrid(Composite parent, int numColumns) {
        int comboC = 1;
        if (numColumns > 1) {
            comboC = numColumns - 1;
        }
        Control control = getLabelControl(parent);
        GridData gd = new GridData();
        gd.horizontalSpan = 1;
        control.setLayoutData(gd);
        control = getComboBoxControl(parent);
        gd = new GridData();
        gd.horizontalSpan = comboC;
        gd.horizontalAlignment = GridData.FILL;
        control.setLayoutData(gd);
        control.setFont(parent.getFont());
    }

    @Override
    protected void doLoad() {
        updateComboForValue(getPreferenceStore().getString(getPreferenceName()));
    }

    @Override
    protected void doLoadDefault() {
        updateComboForValue(getPreferenceStore().getDefaultString(getPreferenceName()));
    }

    protected void updateComboForValue(String value) {
        selectedValue = getValueFromPreference(value);
        if (selectedValue != null) {
            viewer.setSelection(new StructuredSelection(selectedValue));
        }
    }

    @Override
    protected void doStore() {
        if (selectedValue == null) {
            getPreferenceStore().setToDefault(getPreferenceName());
            return;
        }
        getPreferenceStore().setValue(getPreferenceName(), getPreferenceValue(selectedValue));
    }

    @Override
    public int getNumberOfControls() {
        return 2;
    }

    /*
     * Lazily create and return the Combo control.
     */
    private Combo getComboBoxControl(Composite parent) {
        if (viewer == null) {
            Combo comboBox = new Combo(parent, SWT.READ_ONLY);
            comboBox.setFont(parent.getFont());
            viewer = new ComboViewer(comboBox);
            comboBox.addSelectionListener(new SelectionAdapter() {
                @Override
                public void widgetSelected(SelectionEvent evt) {
                    boolean oldValid = isValid;
                    Object oldValue = selectedValue;
                    selectedValue = viewer.getSelection().isEmpty() ? null
                            : ((IStructuredSelection) viewer.getSelection()).getFirstElement();
                    setPresentsDefaultValue(false);
                    fireValueChanged(VALUE, oldValue, selectedValue);

                    refreshValidState();
                    boolean newValid = isValid;
                    if (oldValid != newValid) {
                        fireValueChanged(IS_VALID, oldValid, newValid);
                    }
                }
            });
        }
        return viewer.getCombo();
    }

    @Override
    public void setEnabled(boolean enabled, Composite parent) {
        super.setEnabled(enabled, parent);
        getComboBoxControl(parent).setEnabled(enabled);
    }

    /**
     * @param labelProvider
     *            the label provider used
     * @see StructuredViewer#setLabelProvider(IBaseLabelProvider)
     */
    public void setLabelProvider(IBaseLabelProvider labelProvider) {
        viewer.setLabelProvider(labelProvider);
    }

    /**
     * @param provider
     *            the content provider used
     * @see StructuredViewer#setContentProvider(IContentProvider)
     * @since 3.7
     */
    public void setContentProvider(IStructuredContentProvider provider) {
        viewer.setContentProvider(provider);
    }

    /**
     * @param input
     *            the input used
     * @see StructuredViewer#setInput(Object)
     */
    public void setInput(Object input) {
        viewer.setInput(input);
        viewer.getCombo().select(0);
    }

    protected abstract String getPreferenceValue(Object selectedObject);

    protected abstract Object getValueFromPreference(String preferenceValue);

    public Object getSelectedValue() {
        return selectedValue;
    }

    @Override
    protected void refreshValidState() {
        isValid = checkState();
    }

    protected boolean checkState() {
        return true;
    }

    @Override
    public boolean isValid() {
        return isValid;
    }

    public ComboViewer getViewer() {
        return viewer;
    }
}