From a86c83d24da26b7ae9c380bfb10a7b2a0e8a7281 Mon Sep 17 00:00:00 2001
From: Antony Lee <anntzer.lee@gmail.com>
Date: Thu, 5 Nov 2020 19:00:40 +0100
Subject: [PATCH] Better positioning of mathtext glyphs.

---
 lib/matplotlib/mathtext.py | 107 ++++++++++++++++++-------------------
 1 file changed, 53 insertions(+), 54 deletions(-)

diff --git a/lib/matplotlib/mathtext.py b/lib/matplotlib/mathtext.py
index 37589e267726..7497c4178426 100644
--- a/lib/matplotlib/mathtext.py
+++ b/lib/matplotlib/mathtext.py
@@ -101,70 +101,69 @@ class MathtextBackendAgg(MathtextBackend):
     Render glyphs and rectangles to an FTImage buffer, which is later
     transferred to the Agg image by the Agg backend.
     """
-    def __init__(self):
-        self.ox = 0
-        self.oy = 0
-        self.image = None
-        self.mode = 'bbox'
-        self.bbox = [0, 0, 0, 0]
-        super().__init__()
-
-    def _update_bbox(self, x1, y1, x2, y2):
-        self.bbox = [min(self.bbox[0], x1),
-                     min(self.bbox[1], y1),
-                     max(self.bbox[2], x2),
-                     max(self.bbox[3], y2)]
 
-    def set_canvas_size(self, w, h, d):
-        super().set_canvas_size(w, h, d)
-        if self.mode != 'bbox':
-            self.image = FT2Image(np.ceil(w), np.ceil(h + max(d, 0)))
+    def __init__(self):
+        MathtextBackend.__init__(self)
+        self._xmin = self._ymin = np.inf
+        self._xmax = self._ymax = -np.inf
+        self._glyphs = []
+        self._rects = []
+
+    ox = cbook.deprecated("3.4")(property(lambda self: 0))
+    oy = cbook.deprecated("3.4")(property(lambda self: 0))
+    mode = cbook.deprecated("3.4")(property(lambda self: "bbox"))
+    image = cbook.deprecated("3.4")(property(lambda self: None))
+    bbox = cbook.deprecated("3.4")(property(
+        lambda self: [self._xmin, self._ymin, self._xmax, self._ymax]))
 
     def render_glyph(self, ox, oy, info):
-        if self.mode == 'bbox':
-            self._update_bbox(ox + info.metrics.xmin,
-                              oy - info.metrics.ymax,
-                              ox + info.metrics.xmax,
-                              oy - info.metrics.ymin)
-        else:
-            info.font.draw_glyph_to_bitmap(
-                self.image, ox, oy - info.metrics.iceberg, info.glyph,
-                antialiased=rcParams['text.antialiased'])
+        self._glyphs.append((ox, oy, info))
+        metrics = info.metrics
+        self._xmin = min(self._xmin, ox + metrics.xmin)
+        self._ymin = min(self._ymin, self.height - oy + metrics.ymin)
+        self._xmax = max(self._xmax, ox + metrics.xmax)
+        self._ymax = max(self._ymax, self.height - oy + metrics.ymax)
 
     def render_rect_filled(self, x1, y1, x2, y2):
-        if self.mode == 'bbox':
-            self._update_bbox(x1, y1, x2, y2)
-        else:
+        self._rects.append((x1, y1, x2, y2))
+        self._xmin = min(self._xmin, x1)
+        self._xmax = max(self._xmax, x2)
+        self._ymin = min(self._ymin, y1)
+        self._ymax = max(self._ymax, y2)
+
+    def get_results(self, box, used_characters):
+        orig_height = box.height
+        orig_depth = box.depth
+        _mathtext.ship(0, 0, box)
+        xmin = np.floor(self._xmin)
+        xmax = np.ceil(self._xmax)
+        ymin = np.floor(self._ymin)
+        ymax = np.ceil(self._ymax)
+        dxmin = self._xmin - xmin
+        dymin = self._ymin - ymin
+        image = FT2Image(np.ceil(xmax - xmin) + 1, np.ceil(ymax - ymin) + 1)
+
+        for ox, oy, info in self._glyphs:
+            info.font.draw_glyph_to_bitmap(
+                image, ox + dxmin, oy - info.metrics.iceberg + dymin,
+                info.glyph, antialiased=rcParams['text.antialiased'])
+        for x1, y1, x2, y2 in self._rects:
+            x1 += dxmin
+            x2 += dymin
+            y1 += dxmin
+            y2 += dymin
             height = max(int(y2 - y1) - 1, 0)
             if height == 0:
-                center = (y2 + y1) / 2.0
-                y = int(center - (height + 1) / 2.0)
+                center = (y2 + y1) / 2
+                y = int(center - (height + 1) / 2)
             else:
                 y = int(y1)
-            self.image.draw_rect_filled(int(x1), y, np.ceil(x2), y + height)
+            image.draw_rect_filled(int(x1), y, np.ceil(x2), y + height)
 
-    def get_results(self, box, used_characters):
-        self.mode = 'bbox'
-        orig_height = box.height
-        orig_depth  = box.depth
-        _mathtext.ship(0, 0, box)
-        bbox = self.bbox
-        bbox = [bbox[0] - 1, bbox[1] - 1, bbox[2] + 1, bbox[3] + 1]
-        self.mode = 'render'
-        self.set_canvas_size(
-            bbox[2] - bbox[0],
-            (bbox[3] - bbox[1]) - orig_depth,
-            (bbox[3] - bbox[1]) - orig_height)
-        _mathtext.ship(-bbox[0], -bbox[1], box)
-        result = (self.ox,
-                  self.oy,
-                  self.width,
-                  self.height + self.depth,
-                  self.depth,
-                  self.image,
-                  used_characters)
-        self.image = None
-        return result
+        return (0, 0,
+                np.ceil(xmax - xmin), np.ceil(ymax - ymin), -ymin,
+                image,
+                used_characters)
 
     def get_hinting_type(self):
         from matplotlib.backends import backend_agg