From 9ce3eba7eb8190b04f29830beba1253bd26fe1d7 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Mon, 22 Feb 2021 07:38:04 +1100
Subject: [PATCH] Only draw each pixel once

---
 .../imagedraw_rounded_rectangle_both.png      | Bin 0 -> 530 bytes
 .../images/imagedraw_rounded_rectangle_x.png  | Bin 0 -> 567 bytes
 .../images/imagedraw_rounded_rectangle_y.png  | Bin 0 -> 528 bytes
 Tests/test_imagedraw.py                       |  24 ++++
 src/PIL/ImageDraw.py                          | 103 +++++++++++++-----
 5 files changed, 98 insertions(+), 29 deletions(-)
 create mode 100644 Tests/images/imagedraw_rounded_rectangle_both.png
 create mode 100644 Tests/images/imagedraw_rounded_rectangle_x.png
 create mode 100644 Tests/images/imagedraw_rounded_rectangle_y.png

diff --git a/Tests/images/imagedraw_rounded_rectangle_both.png b/Tests/images/imagedraw_rounded_rectangle_both.png
new file mode 100644
index 0000000000000000000000000000000000000000..24f600e3913ebc74a9c301e815f06f4ac0cfdd94
GIT binary patch
literal 530
zcmeAS@N?(olHy`uVBq!ia0vp^DIm<j1SJ1AFflVQFy8cZaSW-L^LCD7UW<VMi}}xp
zPn$LDZ~xI@FLG#Tj4SV7yW-WJL(VIYyRA9<m=UNC1~~7ziGMi${Q6P;dG}RI=NJWD
zTe?7O@sZw%UpFl?{d&qPHB#oS=H_p4CVpo^zMPWQnpFBc&2HVLkHwFbUUnQ!ojZG1
z$(HALqOOF8g`K{_-S=(Fnx{3asj{;+WkeOP(0QV5dhq&;tXN}{r|v0JXIkwnIy8Mh
z@AuGWCb>7ZFWD}C_M}wCs{)<;eRDP)o0Zj@@g?*-%YXh2Cub>!tu2gw`02!~<0084
z-RnK1`%I^<ZnX41ppZTJgJjay4J()I7xtXyuzt-Z@q96>)u!s%^W<VaTyvJ@Qt)2j
zeQnF@2U3q`d2C{tpxU6rn8K;x%@E0SLdann14!tCYW8RGXLDm6zvirZ_4D>rko*Ci
z>}`Huu3gs7ZhQOk`^z=c%tQ=M%qsIWS=Y?1;;o>R-BzHQ_2I-V^_n&7FNirrZ+iA|
z>TR8qb5tKpF?HUtsJZ~?m)F{Rqb-XLEvk_Jv-s5<*OYTsYmCG<ZW7j9$+_=L_|u!R
zeyyAZ_W~LwuVE@>Kebp|D?4uWRojEl-z|T`s&c<n;6b+{Q%yG;EN&PW6b|bju5ZcO
SsaN(EB<Sht=d#Wzp$Pydq3>h>

literal 0
HcmV?d00001

diff --git a/Tests/images/imagedraw_rounded_rectangle_x.png b/Tests/images/imagedraw_rounded_rectangle_x.png
new file mode 100644
index 0000000000000000000000000000000000000000..4bf5211a3340d62724b64a5517693c1fa2403e7d
GIT binary patch
literal 567
zcmeAS@N?(olHy`uVBq!ia0vp^DIm<j1SJ1AFflVQF#hv&aSW-L^LCD7-eChCmdkZ(
z{zhJ$ztsNqL0gt>snv^Py)@I#H6G!aHYxGIp1VMO3=9uSE2Lu&$j^^gx8G4e{Yv2p
zkI3asQ9VNDZr3i)l3N)brgi#JhWE^^-xt*;EnB3$euc-isrH`>r}fR}?p~rSHoY|G
z)s>6WlCuNjBO`T#{Vi@?+BEI6=#;J5rxv}O7@MjXzmj?1v5@Su7beP23{88L@U%t0
zUOI2}narq-xt{s<vnHEfxbiOUUX5jHuj$oW7hkM?$N5h_VX~?7nyBBq4n3V{+Q0JJ
zJF)nQW-{4Y;mqmN8XT`_Jv2U&l^E(-uRckqF)lJy|DH}sShn9a8`~WZ*0!68I81Yx
zz9#eiLHC|=rISJq(-=0fOi*pmVNBsv@Mef)Izfg|$;qf%x00u)?^K0_ey#cC0x~gS
znrXCp)$5m2O%Hd>cwG|aEzKp7;#;jQ_5L91BvpZlrp`NrOe<1yh3&3|zc8+e-t_F_
zROyHVGgTi<0ZJ_@HaK%q>b175p^DMd6%}G<*JfP{d~)X2S|jm|n^pz@L+woX(?2?D
zn>h_W`!{4xVk&ixUF^)86}S4T?ZM~&{BLr5q-k>-Y>jTH`~Z%~^+)udCACbFI5_JE
Oi0|p@=d#Wzp$Pyx_3|kI

literal 0
HcmV?d00001

diff --git a/Tests/images/imagedraw_rounded_rectangle_y.png b/Tests/images/imagedraw_rounded_rectangle_y.png
new file mode 100644
index 0000000000000000000000000000000000000000..9b391b95e28ea723f75e90210945f1481d93d402
GIT binary patch
literal 528
zcmeAS@N?(olHy`uVBq!ia0vp^DIm<j1SJ1AFflVQFkbg`aSW-L^Y+f&+`|SuZh>37
zx6T&5yXNj1ekQKN^_ScyZq&GA?4T4MP&VO)CM!@M7`Rka-?Xl+W8L@TeEEa!|J}W!
zQZKw>cC3i#Pr23Q@l59RM>qGrtM~54Wu6K;S{iCM`Re8c{U?e)<R51`=6*);TJ6dU
zZtmZ&vQ_sU+okpOk(+z?RkteMqgJ|KE0(RjoboL0oA94MOHUoGI<vecd5y?Yt>bai
zaw}?<TN=NW*}i0#{L_<OQLE;x4W6s78+I?~YJ&cG{|~2ylTzhZXQk|@N?sed%ILdM
z-r+q<wQm2iOy}H{^mdua?}*Udi(lOA^qICmHv8QAFG?o;A@kOleoI&?$9+4%LB~<~
z+NA3Tbzjapk;2)bsxYk~f+-1^k#XeKU!I%A>Hd1Vm3RHWIrXHFfVaZ&s7&=$$1nAL
zofUm1{en%<wuK9{fyTJJw2Cl{WJ+H1=5T6seg2xqQ=Yv|-Nza*V~uH5?;V|!mfj1F
zp0bN+{{G<9<f+@Q|G0bVn7WS8UH14t^EMmI+w6Bg^PFIDjndJ&CjX14zu%Od$0ht>
z&%y@vNY;7$Q~ax)mtGGqnm7N!^FOmL6o&p;-`r5oBlscS1QtC<elS~>v}Ao?m#zm1
NdAj<!taD0e0st%j_Y?pC

literal 0
HcmV?d00001

diff --git a/Tests/test_imagedraw.py b/Tests/test_imagedraw.py
index 0a2c7937d..55a4b03e2 100644
--- a/Tests/test_imagedraw.py
+++ b/Tests/test_imagedraw.py
@@ -734,6 +734,30 @@ def test_rounded_rectangle_zero_radius():
     assert_image_equal_tofile(im, "Tests/images/imagedraw_rectangle_width_fill.png")
 
 
+@pytest.mark.parametrize(
+    "xy, suffix",
+    [
+        ((20, 10, 80, 90), "x"),
+        ((10, 20, 90, 80), "y"),
+        ((20, 20, 80, 80), "both"),
+    ],
+)
+def test_rounded_rectangle_translucent(xy, suffix):
+    # Arrange
+    im = Image.new("RGB", (W, H))
+    draw = ImageDraw.Draw(im, "RGBA")
+
+    # Act
+    draw.rounded_rectangle(
+        xy, 30, fill=(255, 0, 0, 127), outline=(0, 255, 0, 127), width=5
+    )
+
+    # Assert
+    assert_image_equal_tofile(
+        im, "Tests/images/imagedraw_rounded_rectangle_" + suffix + ".png"
+    )
+
+
 def test_floodfill():
     red = ImageColor.getrgb("red")
 
diff --git a/src/PIL/ImageDraw.py b/src/PIL/ImageDraw.py
index 41ef1194e..8988e4233 100644
--- a/src/PIL/ImageDraw.py
+++ b/src/PIL/ImageDraw.py
@@ -264,43 +264,88 @@ class ImageDraw:
         else:
             x0, y0, x1, y1 = xy
 
-        # Do not allow the diameter to be greater than the width or height
-        d = min(radius * 2, x1 - x0, y1 - y0)
+        d = radius * 2
+
+        full_x = d >= x1 - x0
+        if full_x:
+            # The two left and two right corners are joined
+            d = x1 - x0
+        full_y = d >= y1 - y0
+        if full_y:
+            # The two top and two bottom corners are joined
+            d = y1 - y0
+        if full_x and full_y:
+            # If all corners are joined, that is a circle
+            return self.ellipse(xy, fill, outline, width)
+
         if d == 0:
+            # If the corners have no curve, that is a rectangle
             return self.rectangle(xy, fill, outline, width)
 
         ink, fill = self._getink(outline, fill)
+
+        def draw_corners(pieslice):
+            if full_x:
+                # Draw top and bottom halves
+                parts = (
+                    ((x0, y0, x0 + d, y0 + d), 180, 360),
+                    ((x0, y1 - d, x0 + d, y1), 0, 180),
+                )
+            elif full_y:
+                # Draw left and right halves
+                parts = (
+                    ((x0, y0, x0 + d, y0 + d), 90, 270),
+                    ((x1 - d, y0, x1, y0 + d), 270, 90),
+                )
+            else:
+                # Draw four separate corners
+                parts = (
+                    ((x1 - d, y0, x1, y0 + d), 270, 360),
+                    ((x1 - d, y1 - d, x1, y1), 0, 90),
+                    ((x0, y1 - d, x0 + d, y1), 90, 180),
+                    ((x0, y0, x0 + d, y0 + d), 180, 270),
+                )
+            for part in parts:
+                if pieslice:
+                    self.draw.draw_pieslice(*(part + (fill, 1)))
+                else:
+                    self.draw.draw_arc(*(part + (ink, width)))
+
         if fill is not None:
-            self.draw.draw_pieslice((x1 - d, y0, x1, y0 + d), 270, 360, fill, 1)
-            self.draw.draw_pieslice((x1 - d, y1 - d, x1, y1), 0, 90, fill, 1)
-            self.draw.draw_pieslice((x0, y1 - d, x0 + d, y1), 90, 180, fill, 1)
-            self.draw.draw_pieslice((x0, y0, x0 + d, y0 + d), 180, 270, fill, 1)
+            draw_corners(True)
 
-            self.draw.draw_rectangle((x0 + d / 2 + 1, y0, x1 - d / 2 - 1, y1), fill, 1)
-            self.draw.draw_rectangle(
-                (x0, y0 + d / 2 + 1, x0 + d / 2, y1 - d / 2 - 1), fill, 1
-            )
-            self.draw.draw_rectangle(
-                (x1 - d / 2, y0 + d / 2 + 1, x1, y1 - d / 2 - 1), fill, 1
-            )
+            if full_x:
+                self.draw.draw_rectangle(
+                    (x0, y0 + d / 2 + 1, x1, y1 - d / 2 - 1), fill, 1
+                )
+            else:
+                self.draw.draw_rectangle(
+                    (x0 + d / 2 + 1, y0, x1 - d / 2 - 1, y1), fill, 1
+                )
+            if not full_x and not full_y:
+                self.draw.draw_rectangle(
+                    (x0, y0 + d / 2 + 1, x0 + d / 2, y1 - d / 2 - 1), fill, 1
+                )
+                self.draw.draw_rectangle(
+                    (x1 - d / 2, y0 + d / 2 + 1, x1, y1 - d / 2 - 1), fill, 1
+                )
         if ink is not None and ink != fill and width != 0:
-            self.draw.draw_arc((x1 - d, y0, x1, y0 + d), 270, 360, ink, width)
-            self.draw.draw_arc((x1 - d, y1 - d, x1, y1), 0, 90, ink, width)
-            self.draw.draw_arc((x0, y1 - d, x0 + d, y1), 90, 180, ink, width)
-            self.draw.draw_arc((x0, y0, x0 + d, y0 + d), 180, 270, ink, width)
+            draw_corners(False)
 
-            self.draw.draw_rectangle(
-                (x1 - width + 1, y0 + d / 2 + 1, x1, y1 - d / 2 - 1), ink, 1
-            )
-            self.draw.draw_rectangle(
-                (x0 + d / 2 + 1, y1 - width + 1, x1 - d / 2 - 1, y1), ink, 1
-            )
-            self.draw.draw_rectangle(
-                (x0, y0 + d / 2 + 1, x0 + width - 1, y1 - d / 2 - 1), ink, 1
-            )
-            self.draw.draw_rectangle(
-                (x0 + d / 2 + 1, y0, x1 - d / 2 - 1, y0 + width - 1), ink, 1
-            )
+            if not full_x:
+                self.draw.draw_rectangle(
+                    (x0 + d / 2 + 1, y0, x1 - d / 2 - 1, y0 + width - 1), ink, 1
+                )
+                self.draw.draw_rectangle(
+                    (x0 + d / 2 + 1, y1 - width + 1, x1 - d / 2 - 1, y1), ink, 1
+                )
+            if not full_y:
+                self.draw.draw_rectangle(
+                    (x0, y0 + d / 2 + 1, x0 + width - 1, y1 - d / 2 - 1), ink, 1
+                )
+                self.draw.draw_rectangle(
+                    (x1 - width + 1, y0 + d / 2 + 1, x1, y1 - d / 2 - 1), ink, 1
+                )
 
     def _multiline_check(self, text):
         """Draw text."""