PyQtGraph: Retrieve size of GLTextItem

Question

I'm using pyqtgraph to plot radar data (in 2D and 3D) using a GLViewWidget. Adding and visualizing the data in 2D and 3D works well.

I also added text labels using GLTextItem, but they are a bit mispositioned because I cannot retrieve the width of a GLTextItem to take the text width into account when placing the label text (see the following screenshot -> apparently the anchor of a GLTextItem is the bottom left corner):

My question is how to retrieve the size of a GLTextItem?

The following code is used to generate the "angle labels" next to the individual segments:

def create_axes(self) -> None:
    """Create X, Y, Z axes for the 3D plot."""
    # Angle labels
    # Same idea as above: Use a vector and rotate it by the correct angle.
    # Apparently, PyQtGraph does not allow to retrieve the bounding rectangle of a "GLTextItem".
    # Therefore, hard-coded values for the offset correction must be used.
    segment_angle_size_deg = 2 * self.azimuth_angle / self.azimuth_segments
    for i in range(0, self.azimuth_segments + 1):
        base_angle = 90 - self.azimuth_angle
        angle_deg = base_angle + i * segment_angle_size_deg

        # Extend the vector a bit to avoid that labels fall on the segment lines.
        x_vector = (self.max_range + range_label_offset, 0)
        x_pos, z_pos = self.rotate_vector_2d(x_vector, -np.deg2rad(angle_deg))
        # -1 = correct to the left (in the right quadrants), 1 = correct to the right (in the left quadrants).
        correction_direction = -1 if x_pos > 0 else 1
        # Make the correction dependent on the current angle (i.e. at 90° no correction is necessary).
        x_pos += range_label_offset * np.cos(np.deg2rad(angle_deg)) * correction_direction

        angle_label = f"{abs(90 - angle_deg):.0f}"
        angle_tick = gl.GLTextItem(
            pos=(x_pos, 0, z_pos),
            text=f"{angle_label}",
            font=QFont("Helvetica", 10, QFont.Weight.ExtraLight),
            color=self.grid_color,
        )
        # TODO: Retrieve the width of the text to correct its position.
        self.gl_widget_items.append(angle_tick)
        

Answer 1

You can get the size in pixels using QFontMetrics with its method horizontalAdvance. I suggest putting the font type before calling GLTextItem.

    font = QFont("Helvetica", 10, QFont.Weight.ExtraLight)
    metrics = QtGui.QFontMetrics(font)
    text_width = metrics.horizontalAdvance(f"{angle_label}")