Change pattern of optional imports

Avoid additional `have_*` variables and just use the module name
instead.

src/pypdfium2/_cli/main.py

@@ -22,9 +22,7 @@
 try:
     import argcomplete
 except ImportError:
-    have_argcomplete = False
-else:
-    have_argcomplete = True
+    argcomplete = None
 
 
 Subcommands = {
@@ -56,7 +54,7 @@ def parse_args(argv=sys.argv[1:]):
     for cmd in Subcommands.values():
         cmd.attach_parser(subparsers)
 
-    if have_argcomplete:
+    if argcomplete is not None:
         argcomplete.autocomplete(parser)
 
     return parser.parse_args(argv)

src/pypdfium2/_helpers/document.py

@@ -28,9 +28,7 @@
 try:
     import uharfbuzz as harfbuzz
 except ImportError:
-    have_harfbuzz = False
-else:
-    have_harfbuzz = True
+    harfbuzz = None
 
 logger = logging.getLogger(__name__)
 
@@ -535,7 +533,7 @@ class HarfbuzzFont:
     """ Harfbuzz font data helper class. """
 
     def __init__(self, font_path):
-        if not have_harfbuzz:
+        if harfbuzz is None:
             raise RuntimeError("Font helpers require uharfbuzz to be installed.")
         self.blob = harfbuzz.Blob.from_file_path(font_path)
         self.face = harfbuzz.Face(self.blob)

src/pypdfium2/_helpers/page.py

@@ -23,23 +23,17 @@
 try:
     import uharfbuzz as harfbuzz
 except ImportError:
-    have_harfbuzz = False
-else:
-    have_harfbuzz = True
+    harfbuzz = None
 
 try:
     import PIL.Image
 except ImportError:
-    have_pil = False
-else:
-    have_pil = True
+    PIL = None
 
 try:
     import numpy.ctypeslib
 except ImportError:
-    have_numpy = False
-else:
-    have_numpy = True
+    numpy = None
 
 
 class PdfPage:
@@ -451,7 +445,7 @@ def render_tonumpy(self, **kwargs):
             (numpy.ndarray, str): NumPy array, and color format.
         """
 
-        if not have_numpy:
+        if numpy is None:
             raise RuntimeError("NumPy library needs to be installed for render_tonumpy().")
 
         c_array, cl_format, (width, height) = self.render_base(**kwargs)
@@ -471,7 +465,7 @@ def render_topil(self, **kwargs):
             PIL.Image.Image: An image of the page.
         """
 
-        if not have_pil:
+        if PIL is None:
             raise RuntimeError("Pillow library needs to be installed for render_topil().")
 
         c_array, cl_src, size = self.render_base(**kwargs)