// Try labels every 1, 2, 5, 10, 20, 50, 100, etc.
// Calculate the resulting tick spacing (i.e. this.height_ / nTicks).
// The first spacing greater than pixelsPerYLabel is what we use.
// Try labels every 1, 2, 5, 10, 20, 50, 100, etc.
// Calculate the resulting tick spacing (i.e. this.height_ / nTicks).
// The first spacing greater than pixelsPerYLabel is what we use.