❔ "Zooming" a WPF ScrollViewer to the center of the view

if (this.PART_ScrollViewer is ScrollViewer scroller) {
    double multiplier;
    if ((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift) {
        multiplier = e.Delta > 0 ? 1.05 : 0.95;
    }
    else {
        multiplier = e.Delta > 0 ? 1.1 : 0.9;
    }
    double oldzoom = this.UnitZoom;
    double newzoom = TimelineUtils.ClampUnit(oldzoom * multiplier);
    this.UnitZoom = newzoom;
    newzoom = this.UnitZoom;
    {
        double full_horizontal_offset = scroller.HorizontalOffset / this.UnitZoom;
        double visible_pixels = newzoom * this.ActualWidth;
        double width_ratio = (scroller.ExtentWidth / newzoom) / this.ActualWidth;
        double width_ratio_1 = scroller.ExtentWidth / this.ActualWidth;
        double ratio_diff = width_ratio_1 / width_ratio;
        double pixels_difference = (this.ActualWidth / oldzoom) - (this.ActualWidth / newzoom);
        double actual_pixel_change = pixels_difference * newzoom;
        double side_ratio_x = (scroller.HorizontalOffset / 2) / full_horizontal_offset;
        double new_offset = full_horizontal_offset - actual_pixel_change;
        scroller.ScrollToHorizontalOffset(scroller.HorizontalOffset + new_offset);
        return;
    }
}