split off packages to be installed

INSTALL

@@ -4,7 +4,7 @@ python-escpos
 This library is available over pypi. So for most of the use-cases it should be sufficient to run
 
 ```
-pip install python-escpos --user  # add --pre if you want to install pre-releases
+pip install python-escpos[all] --user  # add --pre if you want to install pre-releases
 ```
 
 For more information please read the documentation at https://python-escpos.readthedocs.io/en/latest/user/installation.html

doc/user/installation.rst

@@ -12,7 +12,7 @@ so you can simply enter:
 
     ::
 
-        pip install python-escpos
+        pip install python-escpos[all]
 
 This should install all necessary dependencies. Apart from that
 python-escpos is for some versions also available as a Debian package.

setup.cfg

@@ -35,10 +35,8 @@ python_requires = >=3.8
 zip_safe = false
 include_package_data = true
 install_requires =
-    pyusb>=1.0.0
     Pillow>=2.0
     qrcode>=4.0
-    pyserial
     python-barcode>=0.9.1,<1
     setuptools
     six
@@ -60,6 +58,21 @@ tests_require =
     flake8
     sphinxcontrib-spelling>=7.2.0
 
+[options.extras_require]
+usb =
+    pyusb>=1.0.0
+serial =
+    pyserial
+cups =
+    pycups
+win32 =
+    pywin32; platform_system=='Windows'
+all =
+    pyusb>=1.0.0
+    pyserial
+    pycups
+    pywin32; platform_system=='Windows'
+
 [flake8]
 exclude = .git,.tox,.github,.eggs,__pycache__,doc/conf.py,build,dist,capabilities-data,test,src/escpos/constants.py
 max-line-length = 120