// 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;
    }
  }
}