Adding a radial gauge to the library

[davidgs]

A radial gauge (with or without hash-marks) for the display

[audreylim]

Thanks for the APIs. Can you provide some images on how it looks like, as well as code snippets on how it might be used?

[davidgs]

Screenshot:

I'm currently using it with the InfluxDB app I wrote:

  while (result.next()) {
      // Get the value of the "_value" column
      FluxValue value = result.getValueByName("_value");
      double a = value.getDouble();
      int color = TFT_WHITE;
      if (a <= STAT_LOWER) {
        color = TFT_BLUE;
      } else if (a > STAT_LOWER && a <= STAT_MID) {
        color = TFT_GREEN;
      } else if (a > STAT_MID && a <= STAT_UPPER) {
        color = TFT_YELLOW;
      } else {
        color = TFT_RED;
      }
      ui.drawGauge(STAT_LABEL.c_str(), SUFFIX.c_str(), a, 50, 0, TFT_WHITE, color, true);
    } 

[audreylim]

I think your editor's formatting may make the code more readable, so let's leave it.

The gauge looks great and the code LGTM. Just a minor fix and we can merge this.

We'll probably add an examples folder to this repo in future.

[davidgs]

Are we ok to merge this?

[audreylim]

One more thing, it works well but only for static data. Is this meant to be constantly refreshing? We would need to draw it on a large sprite if so.