Correctly position text with nonzero descent with afm fonts / ps output.

anntzer · anntzer · commit 0362a4e3078d · 2020-09-18T12:04:24.000+02:00
See e.g.
```
rcParams["ps.useafm"] = True
text(.5, .5, "qk")
axhline(.5)
savefig("/tmp/test.ps")
```
Previously the bottom of the tip of the "q" would be on the baseline;
now the baseline is correctly positioned.

(I picked a relatively generic name for the test because we could later
update the baseline image "in place" for more afm tests.)
diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
@@ -541,7 +541,6 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
             scale = 0.001 * fontsize
 
             thisx = 0
-            thisy = font.get_str_bbox_and_descent(s)[4] * scale
             last_name = None
             lines = []
             for c in s:
@@ -558,7 +557,7 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
                 last_name = name
                 thisx += kern * scale
 
-                lines.append('%f %f m /%s glyphshow' % (thisx, thisy, name))
+                lines.append('%f 0 m /%s glyphshow' % (thisx, name))
 
                 thisx += width * scale
 
diff --git a/lib/matplotlib/tests/baseline_images/test_backend_ps/useafm.eps b/lib/matplotlib/tests/baseline_images/test_backend_ps/useafm.eps
diff --git a/lib/matplotlib/tests/test_backend_ps.py b/lib/matplotlib/tests/test_backend_ps.py
@@ -148,3 +148,12 @@ def test_partial_usetex(caplog):
     plt.savefig(io.BytesIO(), format="ps")
     assert caplog.records and all("as if usetex=False" in record.getMessage()
                                   for record in caplog.records)
+
+
+@image_comparison(["useafm.eps"])
+def test_useafm():
+    mpl.rcParams["ps.useafm"] = True
+    fig, ax = plt.subplots()
+    ax.set_axis_off()
+    ax.axhline(.5)
+    ax.text(.5, .5, "qk")
