Java tutorial
/******************************************************************************* * Copyright (c) 2003, 2015 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 * Wedia - Joel DRIGO (joel.drigo@wedia-group.com): Bug 470866 *******************************************************************************/ package org.eclipse.jface.preference; import static org.eclipse.swt.events.SelectionListener.widgetSelectedAdapter; import org.eclipse.swt.SWT; import org.eclipse.swt.layout.GridData; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Control; import org.eclipse.swt.widgets.Scale; /** * A field editor for an integer type preference. This class may be used as is, * or subclassed as required. * * @since 3.0 */ public class ScaleFieldEditor extends FieldEditor { /** * Value that will feed Scale.setIncrement(int). */ private int incrementValue; /** * Value that will feed Scale.setMaximum(int). */ private int maxValue; /** * Value that will feed Scale.setMinimum(int). */ private int minValue; /** * Old integer value. */ private int oldValue; /** * Value that will feed Scale.setPageIncrement(int). */ private int pageIncrementValue; /** * The scale, or <code>null</code> if none. */ protected Scale scale; /** * Creates a scale field editor. * * @param name * the name of the preference this field editor works on * @param labelText * the label text of the field editor * @param parent * the parent of the field editor's control */ public ScaleFieldEditor(String name, String labelText, Composite parent) { super(name, labelText, parent); setDefaultValues(); } /** * Creates a scale field editor with particular scale values. * * @param name * the name of the preference this field editor works on * @param labelText * the label text of the field editor * @param parent * the parent of the field editor's control * @param min * the value used for Scale.setMinimum(int). * @param max * the value used for Scale.setMaximum(int). * @param increment * the value used for Scale.setIncrement(int). * @param pageIncrement * the value used for Scale.setPageIncrement(int). */ public ScaleFieldEditor(String name, String labelText, Composite parent, int min, int max, int increment, int pageIncrement) { super(name, labelText, parent); setValues(min, max, increment, pageIncrement); } @Override protected void adjustForNumColumns(int numColumns) { ((GridData) scale.getLayoutData()).horizontalSpan = numColumns - 1; } @Override protected void doFillIntoGrid(Composite parent, int numColumns) { Control control = getLabelControl(parent); GridData gd = new GridData(); control.setLayoutData(gd); scale = getScaleControl(parent); gd = new GridData(GridData.FILL_HORIZONTAL); gd.verticalAlignment = GridData.FILL; gd.horizontalSpan = numColumns - 1; gd.grabExcessHorizontalSpace = true; scale.setLayoutData(gd); updateScale(); } @Override protected void doLoad() { if (scale != null) { int value = getPreferenceStore().getInt(getPreferenceName()); scale.setSelection(value); oldValue = value; } } @Override protected void doLoadDefault() { if (scale != null) { int value = getPreferenceStore().getDefaultInt(getPreferenceName()); scale.setSelection(value); } valueChanged(); } @Override protected void doStore() { getPreferenceStore().setValue(getPreferenceName(), scale.getSelection()); } /** * Returns the value that will be used for Scale.setIncrement(int). * * @return the value. * @see org.eclipse.swt.widgets.Scale#setIncrement(int) */ public int getIncrement() { return incrementValue; } /** * Returns the value that will be used for Scale.setMaximum(int). * * @return the value. * @see org.eclipse.swt.widgets.Scale#setMaximum(int) */ public int getMaximum() { return maxValue; } /** * Returns the value that will be used for Scale.setMinimum(int). * * @return the value. * @see org.eclipse.swt.widgets.Scale#setMinimum(int) */ public int getMinimum() { return minValue; } @Override public int getNumberOfControls() { return 2; } /** * Returns the value that will be used for Scale.setPageIncrement(int). * * @return the value. * @see org.eclipse.swt.widgets.Scale#setPageIncrement(int) */ public int getPageIncrement() { return pageIncrementValue; } /** * Returns this field editor's scale control. * * @return the scale control, or <code>null</code> if no scale field is * created yet */ public Scale getScaleControl() { return scale; } /** * Returns this field editor's scale control. The control is created if it * does not yet exist. * * @param parent * the parent * @return the scale control */ private Scale getScaleControl(Composite parent) { if (scale == null) { scale = new Scale(parent, SWT.HORIZONTAL); scale.setFont(parent.getFont()); scale.addSelectionListener(widgetSelectedAdapter(event -> valueChanged())); scale.addDisposeListener(event -> scale = null); } else { checkParent(scale, parent); } return scale; } /** * Set default values for the various scale fields. These defaults are:<br> * <ul> * <li>Minimum = 0 * <li>Maximim = 10 * <li>Increment = 1 * <li>Page Increment = 1 * </ul> */ private void setDefaultValues() { setValues(0, 10, 1, 1); } @Override public void setFocus() { if (scale != null && !scale.isDisposed()) { scale.setFocus(); } } /** * Set the value to be used for Scale.setIncrement(int) and update the * scale. * * @param increment * a value greater than 0. * @see org.eclipse.swt.widgets.Scale#setIncrement(int) */ public void setIncrement(int increment) { this.incrementValue = increment; updateScale(); } /** * Set the value to be used for Scale.setMaximum(int) and update the * scale. * * @param max * a value greater than 0. * @see org.eclipse.swt.widgets.Scale#setMaximum(int) */ public void setMaximum(int max) { this.maxValue = max; updateScale(); } /** * Set the value to be used for Scale.setMinumum(int) and update the * scale. * * @param min * a value greater than 0. * @see org.eclipse.swt.widgets.Scale#setMinimum(int) */ public void setMinimum(int min) { this.minValue = min; updateScale(); } /** * Set the value to be used for Scale.setPageIncrement(int) and update the * scale. * * @param pageIncrement * a value greater than 0. * @see org.eclipse.swt.widgets.Scale#setPageIncrement(int) */ public void setPageIncrement(int pageIncrement) { this.pageIncrementValue = pageIncrement; updateScale(); } /** * Set all Scale values. * * @param min * the value used for Scale.setMinimum(int). * @param max * the value used for Scale.setMaximum(int). * @param increment * the value used for Scale.setIncrement(int). * @param pageIncrement * the value used for Scale.setPageIncrement(int). */ private void setValues(int min, int max, int increment, int pageIncrement) { this.incrementValue = increment; this.maxValue = max; this.minValue = min; this.pageIncrementValue = pageIncrement; updateScale(); } /** * Update the scale particulars with set values. */ private void updateScale() { if (scale != null && !scale.isDisposed()) { scale.setMinimum(getMinimum()); scale.setMaximum(getMaximum()); scale.setIncrement(getIncrement()); scale.setPageIncrement(getPageIncrement()); } } /** * Informs this field editor's listener, if it has one, about a change to * the value (<code>VALUE</code> property) provided that the old and new * values are different. * <p> * This hook is <em>not</em> called when the scale is initialized (or * reset to the default value) from the preference store. * </p> */ protected void valueChanged() { setPresentsDefaultValue(false); int newValue = scale.getSelection(); if (newValue != oldValue) { fireStateChanged(IS_VALID, false, true); fireValueChanged(VALUE, Integer.valueOf(oldValue), Integer.valueOf(newValue)); oldValue = newValue; } } /** * Bug 470866 fix */ @Override public void setEnabled(boolean enabled, Composite parent) { super.setEnabled(enabled, parent); getScaleControl().setEnabled(enabled); } }