Added gs_binary to control Ghostscript use on all platforms

Tests/test_file_eps.py

@@ -8,6 +8,7 @@
     assert_image_similar,
     assert_image_similar_tofile,
     hopper,
+    is_win32,
     mark_if_feature_version,
     skip_unless_feature,
 )
@@ -98,6 +99,20 @@
         assert im.load()[0, 0] == (255, 255, 255)
 
 
+def test_binary():
+    if HAS_GHOSTSCRIPT:
+        assert EpsImagePlugin.gs_binary is not None
+    else:
+        assert EpsImagePlugin.gs_binary is False
+
+    if not is_win32():
+        assert EpsImagePlugin.gs_windows_binary is None
+    elif not HAS_GHOSTSCRIPT:
+        assert EpsImagePlugin.gs_windows_binary is False
+    else:
+        assert EpsImagePlugin.gs_windows_binary is not None
+
+
 def test_invalid_file():
     invalid_file = "Tests/images/flower.jpg"
     with pytest.raises(SyntaxError):

docs/handbook/image-file-formats.rst

@@ -88,8 +88,13 @@ in ``L``, ``RGB`` and ``CMYK`` modes.
 Loading
 ~~~~~~~
 
+To use Ghostscript, Pillow searches for the "gs" executable. On Windows, it
+also searches for "gswin32c" and "gswin64c". To customise this behaviour,
+``EpsImagePlugin.gs_binary = "gswin64"`` will set the name of the executable to
+use. ``EpsImagePlugin.gs_binary = False`` will prevent Ghostscript use.
+
 If Ghostscript is available, you can call the :py:meth:`~PIL.Image.Image.load`
-method with the following parameters to affect how Ghostscript renders the EPS
+method with the following parameters to affect how Ghostscript renders the EPS.
 
 **scale**
     Affects the scale of the resultant rasterized image. If the EPS suggests

src/PIL/EpsImagePlugin.py

@@ -37,33 +37,39 @@
 split = re.compile(r"^%%([^:]*):[ \t]*(.*)[ \t]*$")
 field = re.compile(r"^%[%!\w]([^:]*)[ \t]*$")
 
+gs_binary = None
 gs_windows_binary = None
-if sys.platform.startswith("win"):
-    import shutil
-
-    for binary in ("gswin32c", "gswin64c", "gs"):
-        if shutil.which(binary) is not None:
-            gs_windows_binary = binary
-            break
-    else:
-        gs_windows_binary = False
 
 
 def has_ghostscript():
-    if gs_windows_binary:
-        return True
-    if not sys.platform.startswith("win"):
-        try:
-            subprocess.check_call(["gs", "--version"], stdout=subprocess.DEVNULL)
-            return True
-        except OSError:
-            # No Ghostscript
-            pass
-    return False
+    global gs_binary, gs_windows_binary
+    if gs_binary is None:
+        if sys.platform.startswith("win"):
+            if gs_windows_binary is None:
+                import shutil
+
+                for binary in ("gswin32c", "gswin64c", "gs"):
+                    if shutil.which(binary) is not None:
+                        gs_windows_binary = binary
+                        break
+                else:
+                    gs_windows_binary = False
+            gs_binary = gs_windows_binary
+        else:
+            try:
+                subprocess.check_call(["gs", "--version"], stdout=subprocess.DEVNULL)
+                gs_binary = "gs"
+            except OSError:
+                gs_binary = False
+    return gs_binary is not False
 
 
 def Ghostscript(tile, size, fp, scale=1, transparency=False):
     """Render an image using Ghostscript"""
+    global gs_binary
+    if not has_ghostscript():
+        msg = "Unable to locate Ghostscript on paths"
+        raise OSError(msg)
 
     # Unpack decoder tile
     decoder, tile, offset, data = tile[0]
@@ -113,7 +119,7 @@
 
     # Build Ghostscript command
     command = [
-        "gs",
+        gs_binary,
         "-q",  # quiet mode
         "-g%dx%d" % size,  # set output geometry (pixels)
         "-r%fx%f" % res,  # set input DPI (dots per inch)
@@ -132,19 +138,6 @@
         "showpage",
     ]
 
-    if gs_windows_binary is not None:
-        if not gs_windows_binary:
-            try:
-                os.unlink(outfile)
-                if infile_temp:
-                    os.unlink(infile_temp)
-            except OSError:
-                pass
-
-            msg = "Unable to locate Ghostscript on paths"
-            raise OSError(msg)
-        command[0] = gs_windows_binary
-
     # push data through Ghostscript
     try:
         startupinfo = None