sclass G22SnPSelector > MetaWithChangeListeners is Swingable {

  settable new SnPSettings settings;

  // show powers of two in colors selector or all numbers?

  settableWithVar bool powerOfTwoColors = false;

  // show powers of two in pixelRows selector or all numbers?

  settableWithVar bool powerOfTwoPixelRows = true;

  settable int maxPixelRows = 512;

  settableWithVar bool allowDecolorizerSelection;

  settableWithVar bool showDecolorizerSelection;

  JLabel lblColors;

  SingleComponentPanel scpDecolorizer = scp();

  *() {}

  *(SnPSettings *settings) {}

  SnPSettings get() { ret settings; }

  cachedVisualize {

    var colors = jListSpinner(colorsList(), settings.colors);

    main onChange(colors, -> {

      settings.colors = intFromSpinner(colors);

      change();

    });

    varPowerOfTwoColors().onChange(->

      spinnerSetNumberList(colors, colorsList());

    swing {

      var menuItem = jLiveValueCheckBoxMenuItem("Only show powers of two", varPowerOfTwoColors());

      new JPopupMenu menu;

      menu.add(menuItem);

      colors.setComponentPopupMenu(menu);

    }

    var pixelRows = jListSpinner(pixelRowsList(), settings.pixelRows);

    main onChange(pixelRows, -> {

      settings.pixelRows = intFromSpinner(pixelRows);

      change();

    });

    varPowerOfTwoPixelRows().onChange(->

      spinnerSetNumberList(pixelRows, pixelRowsList());

    swing {

      var menuItem = jLiveValueCheckBoxMenuItem("Only show powers of two", varPowerOfTwoPixelRows());

      new JPopupMenu menu;

      menu.add(menuItem);

      pixelRows.setComponentPopupMenu(menu);

    }

    lblColors = jSimpleLabel(" colors ");

    bindChangeListenerToComponent(this, lblColors,

      -> toolTip(lblColors, makeToolTip()));

    L controls = ll(

      colors,

      lblColors,

      scpDecolorizer,

      jSimpleLabel("@ "),

      pixelRows,

      jlabel(" p"));

    if (allowDecolorizerSelection) {

      varShowDecolorizerSelection().onChangeAndNow(l0 updateDecolorizerView);

      controls.add(horizontalStrut(3));

      controls.add(jPopDownButton_noText(

        jLiveValueCheckBoxMenuItem("Select channel", varShowDecolorizerSelection())

      ));

    }

    var vis = hstack(controls);

    bindChangeListenerToComponent(settings, vis, l0 change);

    ret vis;

  }

  L<Int> colorsList() {

    ret powerOfTwoColors

      ? powersOfTwoUpTo(2, 256)

      : virtualCountList_incl(2, 256);

  }

  L<Int> pixelRowsList() {

    ret powerOfTwoPixelRows

      ? powersOfTwoUpTo(maxPixelRows)

      : virtualCountList_incl(1, maxPixelRows);

  }

  S makeToolTip() {

    long pixels = area(sixteenToNine_p(settings.pixelRows));

    int colorBits = numberOfBitsNeededToRepresentNOptions(settings.colors);

    int bytes = iceil_div(pixels*colorBits, 8);

    ret "Information per frame: " + nBytes(bytes) +" (assuming a 16:9 aspect ratio)";

  }

  L<Decolorizer> decolorizerList() {

    ret ll(

      new Decolorizer.Simple,

      new Decolorizer.Red,

      new Decolorizer.Green,

      new Decolorizer.Blue

    );

  }

  void updateDecolorizerView {

    if (!showDecolorizerSelection) {

      scpDecolorizer.clear();

      settings.decolorizer(null);

    } else {

      if (settings.decolorizer == null)

        settings.decolorizer(new Decolorizer.Simple);

      scpDecolorizer.set(hstack(

        jlabel("from channel "),

        bindComboBoxToVar(settings.varDecolorizer(),

          jTypedComboBox(decolorizerList())),

        horizontalStrut(3)

      ));

    }

  }

}