Revert "Let TeX handle newlines itself."

This reverts commit 157b0be.

Author: QuLogic

lib/matplotlib/tests/test_text.py

@@ -806,11 +806,26 @@ def test_metrics_cache():
 
     fig = plt.figure()
     fig.text(.3, .5, "foo\nbar")
-    fig.text(.5, .5, "foo\nbar")
     fig.text(.3, .5, "foo\nbar", usetex=True)
     fig.text(.5, .5, "foo\nbar", usetex=True)
     fig.canvas.draw()
+    renderer = fig._get_renderer()
+    ys = {}  # mapping of strings to where they were drawn in y with draw_tex.
+
+    def call(*args, **kwargs):
+        renderer, x, y, s, *_ = args
+        ys.setdefault(s, set()).add(y)
+
+    renderer.draw_tex = call
+    fig.canvas.draw()
+    assert [*ys] == ["foo", "bar"]
+    # Check that both TeX strings were drawn with the same y-position for both
+    # single-line substrings.  Previously, there used to be an incorrect cache
+    # collision with the non-TeX string (drawn first here) whose metrics would
+    # get incorrectly reused by the first TeX string.
+    assert len(ys["foo"]) == len(ys["bar"]) == 1
 
     info = mpl.text._get_text_metrics_with_cache_impl.cache_info()
-    # Each string gets drawn twice, so the second draw results in a hit.
-    assert info.hits == info.misses
+    # Every string gets a miss for the first layouting (extents), then a hit
+    # when drawing, but "foo\nbar" gets two hits as it's drawn twice.
+    assert info.hits > info.misses

lib/matplotlib/texmanager.py

@@ -230,7 +230,7 @@ def _get_tex_source(cls, tex, fontsize):
             r"% last line's baseline.",
             rf"\fontsize{{{fontsize}}}{{{baselineskip}}}%",
             r"\ifdefined\psfrag\else\hbox{}\fi%",
-            rf"{{\obeylines{fontcmd} {tex}}}%",
+            rf"{{{fontcmd} {tex}}}%",
             r"\special{matplotlibbaselinemarker}%",
             r"\end{document}",
         ])

lib/matplotlib/text.py

@@ -334,8 +334,7 @@ def _get_layout(self, renderer):
         of a rotated text when necessary.
         """
         thisx, thisy = 0.0, 0.0
-        text = self.get_text()
-        lines = [text] if self.get_usetex() else text.split("\n")  # Not empty.
+        lines = self.get_text().split("\n")  # Ensures lines is not empty.
 
         ws = []
         hs = []