examples/org.eclipse.rap.e4.demo/src/org/eclipse/rap/e4/demo/parts/PreferenceSamplePart.java

package org.eclipse.rap.e4.demo.parts;

import javax.inject.Inject;

import org.eclipse.e4.core.di.annotations.Optional;
import org.eclipse.e4.core.di.extensions.Preference;
import org.eclipse.rap.e4.preferences.EPreference;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Text;

@SuppressWarnings({ "restriction", "serial" })
public class PreferenceSamplePart {

  private Label colorLabel;
  private Color currentColor;

  @Optional
  @Inject
  @Preference
  EPreference prefs;

  @Inject
  public PreferenceSamplePart(Composite parent) {
    parent.setLayout(new GridLayout(2, false));

    Label l1 = new Label(parent, SWT.NONE);
    l1.setText("Current Value:");

    colorLabel = new Label(parent, SWT.NONE);
    colorLabel.setText("-");

    Label l2 = new Label(parent, SWT.NONE);
    l2.setText("Color:");

    final Text t = new Text(parent, SWT.BORDER);
    Listener listener = new Listener() {
      public void handleEvent(Event event) {
        prefs.setString("colorPref", t.getText());
      }
    };
    t.addListener(SWT.DefaultSelection, listener);
    t.addListener(SWT.FocusOut, listener);
    t.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
  }

  @Inject
  public void updatePreference(@Optional @Preference("colorPref") String v) {
    if (v == null) {
      return;
    }
    colorLabel.setText(v);
    RGB rgb = toRGB(v);
    Color c = rgb != null ? new Color(colorLabel.getDisplay(), rgb) : null;
    colorLabel.setBackground(c);
    if (currentColor != null) {
      currentColor.dispose();
    }
    currentColor = c;

    colorLabel.getParent().layout(true);
  }

  private static RGB toRGB(String hexcolor) {
    try {
      if (hexcolor.length() == 3) {
        int r = Integer.parseInt(hexcolor.substring(0, 1), 16) * 17;
        int g = Integer.parseInt(hexcolor.substring(1, 2), 16) * 17;
        int b = Integer.parseInt(hexcolor.substring(2, 3), 16) * 17;
        return new RGB(r, g, b);
      }
      if (hexcolor.length() == 6) {
        int r = Integer.parseInt(hexcolor.substring(0, 2), 16);
        int g = Integer.parseInt(hexcolor.substring(2, 4), 16);
        int b = Integer.parseInt(hexcolor.substring(4, 6), 16);
        return new RGB(r, g, b);
      }
    } catch (NumberFormatException e) {
      // return fall back
    }
    return null;
  }
}