// background color is set with setBackground

sclass JMultiColorBar > JComponentWithChangeListeners {

  class Entry {

    // absolute value from the left!

    settable double value;

    settable Color color;

    settable S text;

    settable S toolTip;

    Entry previous() {

      ret elementBefore(entries, this);

    }

    double relativeValue() {

      Entry p = previous();

      ret p == null ? value : value-p.value;

    }

  }

  L<Entry> entries = notifyingList(l0 repaint);

  settableWithVar double max = 100;

  settable L<Color> defaultColors = ll(Color.red, Color.blue);

  InstantNeverHideToolTip toolTipMaker;

  swappable Color defaultColor(int index) {

    ret getCyclic(defaultColors, index);

  }

  Entry makeEntry(double relativeValue) {

    Entry prev = last(entries);

    double value = prev == null ? relativeValue : relativeValue+prev.value;

    ret new Entry().+value.color(defaultColor(l(entries)));

  }

  Entry addEntry aka add(S text, double relativeValue) {

    ret addAndReturn(entries, makeEntry(relativeValue).+text);

  }

  Entry addEntry aka add(double relativeValue, Color color) {

    ret addAndReturn(entries, makeEntry(relativeValue).+color);

  }

  S toolTipForEntry(Entry e) {

    ret e == null ?: spaceCombine(or2(e.toolTip, e.text), renderValue(e.relativeValue()));

  }

  swappable S renderValue(double value) { ret str(value); }

  scaffolded S toolTipForPosition(Pt p) {

    int w = getWidth();

    Entry e = firstThat(entries, _e -> p.x < xForEntry(_e, w));

    if (scaffolded()) printVars(+e, xs := map(entries, _e -> xForEntry(_e, w)));

    ret toolTipForEntry(e);

  }

  *() {

    varMax().onChange(l0 repaint);

    jMinSize(50, 10, this);

    toolTipMaker = new InstantNeverHideToolTip(l1 toolTipForPosition, this);

  }

  int xForEntry(Entry e, int w) {

    ret iround(w*clampZeroToOne(doubleRatio(e.value, max)));

  }

  public void paintComponent(Graphics g) {

    super.paintComponent(g); // paint background

    int w = getWidth(), h = getHeight();

    int x = 0;

    for (e : entries) {

      int x2 = main max(x, xForEntry(e, w));

      if (x2 > x)

        fillRect(g, x+1, 0, x2-x, h, e.color);

      x = x2;

    }

  }

}