Java tutorial
/** * Copyright (c) 2015 Genuitec LLC. * 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: * Piotr Tomiak <piotr@genuitec.com> - initial API and implementation */ package tern.eclipse.ide.server.nodejs.internal.ui.preferences; import org.eclipse.core.runtime.Assert; import org.eclipse.jface.preference.FieldEditor; 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.Button; import org.eclipse.swt.widgets.Combo; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Control; /** * A field editor for a checkboxed combo box that allows the drop-down selection * of one of a list of items. */ public class CheckComboFieldEditor extends FieldEditor { /** * The checkbox widget */ private Button fButton; /** * Checkbox text */ private String checkboxText; /** * The <code>Combo</code> widget. */ private Combo fCombo; /** * The value (not the name) of the currently selected item in the Combo * widget. */ private String fValue; /** * The names (labels) and underlying values to populate the combo widget. * These should be arranged as: { {name1, value1}, {name2, value2}, ...} */ private String[][] fEntryNamesAndValues; /** * The value when checkbox is unselected */ private String unselectedValue; /** * 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 CheckComboFieldEditor(String name, String labelText, String[][] entryNamesAndValues, String unselectedValue, Composite parent) { init(name, ""); //$NON-NLS-1$ Assert.isTrue(checkArray(entryNamesAndValues)); fEntryNamesAndValues = entryNamesAndValues; checkboxText = labelText; this.unselectedValue = unselectedValue; createControl(parent); } /** * Checks whether given <code>String[][]</code> is of "type" * <code>String[][2]</code>. * * @return <code>true</code> if it is ok, and <code>false</code> otherwise */ private boolean checkArray(String[][] table) { if (table == null) { return false; } for (int i = 0; i < table.length; i++) { String[] array = table[i]; if (array == null || array.length != 2) { return false; } } return true; } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#adjustForNumColumns(int) */ @Override protected void adjustForNumColumns(int numColumns) { if (numColumns > 1) { int left = numColumns - 1; ((GridData) fButton.getLayoutData()).horizontalSpan = 1; Control control = getLabelControl(); if (control != null) { ((GridData) control.getLayoutData()).exclude = true; } ((GridData) fCombo.getLayoutData()).horizontalSpan = left; } else { ((GridData) fButton.getLayoutData()).horizontalSpan = 1; Control control = getLabelControl(); if (control != null) { ((GridData) control.getLayoutData()).exclude = true; } ((GridData) fCombo.getLayoutData()).horizontalSpan = 1; } } /* * (non-Javadoc) * * @see * org.eclipse.jface.preference.FieldEditor#doFillIntoGrid(org.eclipse.swt * .widgets.Composite, int) */ @Override protected void doFillIntoGrid(Composite parent, int numColumns) { int comboC = 1; if (numColumns > 1) { comboC = numColumns - 1; } Control control = getCheckControl(parent); GridData gd = new GridData(); gd.horizontalSpan = 1; control.setLayoutData(gd); control.setFont(parent.getFont()); control = getLabelControl(parent); gd = new GridData(); gd.exclude = true; control.setLayoutData(gd); control = getComboBoxControl(parent); gd = new GridData(); gd.horizontalSpan = comboC; gd.horizontalAlignment = GridData.FILL; control.setLayoutData(gd); control.setFont(parent.getFont()); } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#doLoad() */ @Override protected void doLoad() { updateComboForValue(getPreferenceStore().getString(getPreferenceName())); } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#doLoadDefault() */ @Override protected void doLoadDefault() { updateComboForValue(getPreferenceStore().getDefaultString(getPreferenceName())); } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#doStore() */ @Override protected void doStore() { if (fValue == null) { getPreferenceStore().setToDefault(getPreferenceName()); return; } getPreferenceStore().setValue(getPreferenceName(), fValue); } public String getValue() { return fValue; } public int getSelection() { return fCombo.getSelectionIndex(); } @Override public int getNumberOfControls() { return 3; } /* * Lazily create and return the Combo control. */ private Combo getComboBoxControl(Composite parent) { if (fCombo == null) { fCombo = new Combo(parent, SWT.READ_ONLY); fCombo.setFont(parent.getFont()); for (int i = 0; i < fEntryNamesAndValues.length; i++) { fCombo.add(fEntryNamesAndValues[i][0], i); } fCombo.addSelectionListener(new SelectionAdapter() { @Override public void widgetSelected(SelectionEvent evt) { updateValue(fButton.getSelection(), fCombo.getText()); } }); } return fCombo; } /* * Given the name (label) of an entry, return the corresponding value. */ private String getValueForName(String name) { for (int i = 0; i < fEntryNamesAndValues.length; i++) { String[] entry = fEntryNamesAndValues[i]; if (name.equals(entry[0])) { return entry[1]; } } return fEntryNamesAndValues[0][0]; } /* * Set the name in the combo widget to match the specified value. */ private void updateComboForValue(String value) { boolean select = !value.equals(unselectedValue); fButton.setSelection(select); updateComboBoxEnablement(fCombo.getParent(), select); fValue = value; for (int i = 0; i < fEntryNamesAndValues.length; i++) { if (value.equals(fEntryNamesAndValues[i][1])) { fCombo.setText(fEntryNamesAndValues[i][0]); return; } } if (fEntryNamesAndValues.length > 0) { if (select) { fValue = fEntryNamesAndValues[0][1]; } fCombo.setText(fEntryNamesAndValues[0][0]); } refreshValidState(); if (!isValid()) { fireStateChanged(IS_VALID, true, false); } } public boolean isCheckboxSelected() { return fButton == null || fButton.getSelection(); } /* * (non-Javadoc) * * @see org.eclipse.jface.preference.FieldEditor#setEnabled(boolean, * org.eclipse.swt.widgets.Composite) */ @Override public void setEnabled(boolean enabled, Composite parent) { Button check = getCheckControl(parent); check.setEnabled(enabled); enabled = check.getSelection(); super.setEnabled(enabled, parent); updateComboBoxEnablement(parent, enabled); } private void updateValue(boolean selected, String name) { String oldValue = fValue; if (selected) { fValue = getValueForName(name); } else { fValue = unselectedValue; } setPresentsDefaultValue(false); boolean oldState = isValid(); refreshValidState(); if (isValid() != oldState) { fireStateChanged(IS_VALID, oldState, isValid()); } if (!fValue.equals(oldValue)) { fireValueChanged(VALUE, oldValue, fValue); } } protected void updateComboBoxEnablement(Composite parent, boolean enabled) { getComboBoxControl(parent).setEnabled(enabled); boolean oldState = isValid(); refreshValidState(); if (isValid() != oldState) { fireStateChanged(IS_VALID, oldState, isValid()); } } private Button getCheckControl(final Composite parent) { if (fButton == null) { fButton = new Button(parent, SWT.CHECK); fButton.setFont(parent.getFont()); fButton.setText(checkboxText); fButton.addSelectionListener(new SelectionAdapter() { @Override public void widgetSelected(SelectionEvent evt) { updateComboBoxEnablement(parent, fButton.getSelection()); updateValue(fButton.getSelection(), fCombo.getText()); } }); } return fButton; } }