# xyz values printed when dragging the mouse across window (default 3d view) horizontally,
# along the middle y position:
from pylab import *
from matplotlib.backend_bases import LocationEvent
rcdefaults(); rcParams["axes.unicode_minus"] = False  # use ascii minus
fig = figure()
ax = fig.add_subplot(projection="3d")
fig.canvas.draw()
xyzs = []
screen_ry = .5
# drag mouse across window horizontally, along the middle y position
for screen_rx in np.linspace(0, 1, 1001):
    screen_xy = fig.transFigure.transform((screen_rx, screen_ry))
    pseudo_xy = ax.transData.inverted().transform(screen_xy)
    ev = LocationEvent("", fig.canvas, *screen_xy)
    ev.xdata, ev.ydata = pseudo_xy
    if any([axis.pane.contains(ev)[0] for axis in ax._axis_map.values()]):
        s = ax.format_coord(*pseudo_xy)  # formatted string
        xyzs.append([float(part.split("=")[1]) for part in s.split(",")])  # displayed xyz
    else:  # out of Axes
        xyzs.append((np.nan, np.nan, np.nan))
xyzs = array(xyzs)
close(fig)
plot(xyzs[:, 0], label="x")
plot(xyzs[:, 1], label="y")
plot(xyzs[:, 2], label="z")
legend()
show()