How do I color LabelField text within a ListField when the parent manager has the focus?

Answer 1

Hi. To switch color of LabelField we can check if it's selected in it's paint() method. But even then we'll have to repaint every row in ListField. And that's the problem: every time row selection of ListField is changed, there are only two calls of ListFieldCallback.drawRow() method - first for previous selected row (still in selected state) and second for new selected row (already in selected state)...

I've tried to save previous selected row index and redraw it on each call of drawRow(), but by some reason LabelField.paint() method was not triggered then.

So I come with simple, somehow ugly solution: schedule ListField.invalidate() TimerTask. Period in 100 ms is enough and doesn't hit performance as well.

Jason Emerick's code I've been used as a guide to extended ListField.

class LabelListField extends ListField implements ListFieldCallback {
    private Vector mValues;
    private Vector mRows;

    public LabelListField(Vector values) {
     super(0);
     setRowHeight(70);
     setCallback(this);

     mValues = values;
     fillListWithValues(values);

     scheduleInvalidate();
    }

    private void scheduleInvalidate() {
     Timer timer = new Timer();
     timer.scheduleAtFixedRate(new TimerTask() {
      public void run() {
       invalidate();
      }
     }, 0, 100);
    }

    private void fillListWithValues(Vector values) {
     mRows = new Vector();
     for (int i = 0; i < values.size(); i++) {
      TableRowManager row = new TableRowManager();
      String title = "Item# " + String.valueOf(i + 1);
      LabelField titleLabel = new LabelField(title);
      titleLabel.setFont(Font.getDefault().derive(Font.BOLD));
      row.add(titleLabel);
      String value = (String) values.elementAt(i);
      ListLabel valueLabel = new ListLabel(this, i, value);
      valueLabel.setFont(Font.getDefault().derive(Font.ITALIC));
      row.add(valueLabel);
      mRows.addElement(row);
     }
     setSize(mRows.size());
    }

    private class TableRowManager extends Manager {
     public TableRowManager() {
      super(0);
     }

     public void drawRow(Graphics g, int x, int y, 
      int width, int height) {
      layout(width, height);
      setPosition(x, y);
      g.pushRegion(getExtent());
      paintChild(g, getField(0));
      paintChild(g, getField(1));
      g.popContext();
     }

     protected void sublayout(int width, int height) {
      int fontHeight = Font.getDefault().getHeight();
      int preferredWidth = getPreferredWidth();
      Field field = getField(0);
      layoutChild(field, preferredWidth - 5, fontHeight + 1);
      setPositionChild(field, 5, 3);
      field = getField(1);
      layoutChild(field, preferredWidth - 5, fontHeight + 1);
      setPositionChild(field, 5, fontHeight + 6);
      setExtent(preferredWidth, getPreferredHeight());
     }

     public int getPreferredWidth() {
      return Display.getWidth();
     }

     public int getPreferredHeight() {
      return getRowHeight();
     }
    }

    public void drawListRow(ListField listField, Graphics g, 
      int index, int y, int width) {
     LabelListField list = (LabelListField) listField;
     TableRowManager rowManager = (TableRowManager) list.mRows
       .elementAt(index);
     rowManager.drawRow(g, 0, y, width, list.getRowHeight());

    }

    public Object get(ListField list, int index) {
     return mValues.elementAt(index);
    }

    public int indexOfList(ListField list, String prefix, int start) {
     for (int x = start; x < mValues.size(); ++x) {
      String value = (String) mValues.elementAt(x);
      if (value.startsWith(prefix)) {
       return x;
      }
     }
     return -1;
    }

    public int getPreferredWidth(ListField list) {
     return Display.getWidth();
    }

    class ListLabel extends LabelField {
     int mIndex = -1;

     public ListLabel(LabelListField list, int index, String text) {
      super(text);
      mIndex = index;
     }

     protected void paint(Graphics graphics) {
      if (getSelectedIndex() == mIndex)
       graphics.setColor(Color.RED);
      else
       graphics.setColor(Color.BLUE);
      super.paint(graphics);
     }
    }
}