✨ Rework of Pillow recipe adding WebP support

We add `optional` support for [WebP](https://developers.google.com/speed/webp) images, but to enable it, you must add `libwebp` to your build requirements.

We also:
  - 🎨 sort imports
  - 📝 add docstrings to Pillow recipe
  - 🎨 move to python3's f-strings...to increase readability
  - 💡 add inline comments

Author: opacam

pythonforandroid/recipes/Pillow/__init__.py

@@ -1,13 +1,33 @@
-from pythonforandroid.recipe import CompiledComponentsPythonRecipe
 from os.path import join
 
+from pythonforandroid.recipe import CompiledComponentsPythonRecipe
+
 
 class PillowRecipe(CompiledComponentsPythonRecipe):
+    """
+    A recipe for Pillow (previously known as Pil).
+
+    This recipe allow us to build the Pillow recipe with support for different
+    types of images and fonts. But you should be aware, that in order to  use
+    some of the features of  Pillow, we must build some libraries. By default
+    we automatically trigger the build of below libraries::
+
+        - freetype: rendering fonts support.
+        - harfbuzz: a text shaping library.
+        - jpeg: reading and writing JPEG image files.
+        - png: support for PNG images.
+
+    But you also could enable the build of some extra image types by requesting
+    the build of some libraries via argument `requirements`::
+
+        - libwebp: library to encode and decode images in WebP format.
+    """
 
     version = '7.0.0'
     url = 'https://github.com/python-pillow/Pillow/archive/{version}.tar.gz'
     site_packages_name = 'Pillow'
     depends = ['png', 'jpeg', 'freetype', 'setuptools']
+    opt_depends = ['libwebp']
     patches = [join('patches', 'fix-setup.patch')]
 
     call_hostpython_via_targetpython = False
@@ -36,20 +56,40 @@ def get_recipe_env(self, arch=None, with_flags_in_cc=True):
         harf_lib_dir = join(harfbuzz.get_build_dir(arch.arch), 'src', '.libs')
         harf_inc_dir = harfbuzz.get_build_dir(arch.arch)
 
-        env['JPEG_ROOT'] = '{}|{}'.format(jpeg_lib_dir, jpeg_inc_dir)
-        env['FREETYPE_ROOT'] = '{}|{}'.format(free_lib_dir, free_inc_dir)
-        env['ZLIB_ROOT'] = '{}|{}'.format(ndk_lib_dir, ndk_include_dir)
-
-        cflags = ' -I{}'.format(png_inc_dir)
-        cflags += ' -I{} -I{}'.format(harf_inc_dir, join(harf_inc_dir, 'src'))
-        cflags += ' -I{}'.format(free_inc_dir)
-        cflags += ' -I{}'.format(jpeg_inc_dir)
-        cflags += ' -I{}'.format(ndk_include_dir)
-
+        # these below env variables are defined at Pillow's `setup.py`
+        env['JPEG_ROOT'] = f'{jpeg_lib_dir}|{jpeg_inc_dir}'
+        env['FREETYPE_ROOT'] = f'{free_lib_dir}|{free_inc_dir}'
+        env['ZLIB_ROOT'] = f'{ndk_lib_dir}|{ndk_include_dir}'
+
+        # libwebp is an optional dependency, so we add the
+        # flags if we have it in our `ctx.recipe_build_order`
+        build_with_webp_support = 'libwebp' in self.ctx.recipe_build_order
+        if build_with_webp_support:
+            webp = self.get_recipe('libwebp', self.ctx)
+            webp_install = join(
+                webp.get_build_dir(arch.arch), 'installation'
+            )
+
+        # Add libraries includes to CFLAGS
+        cflags = f' -I{png_inc_dir}'
+        cflags += f' -I{harf_inc_dir} -I{join(harf_inc_dir, "src")}'
+        cflags += f' -I{free_inc_dir}'
+        cflags += f' -I{jpeg_inc_dir}'
+        if build_with_webp_support:
+            cflags += f' -I{join(webp_install, "include")}'
+        cflags += f' -I{ndk_include_dir}'
+
+        # Link the basic Pillow libraries...no need to add webp's libraries
+        # since it seems that the linkage is properly made without it :)
         env['LIBS'] = ' -lpng -lfreetype -lharfbuzz -ljpeg -lturbojpeg'
 
-        env['LDFLAGS'] += ' -L{} -L{} -L{} -L{}'.format(
-            png_lib_dir, harf_lib_dir, jpeg_lib_dir, ndk_lib_dir)
+        # Add libraries locations to LDFLAGS
+        env['LDFLAGS'] += f' -L{png_lib_dir}'
+        env['LDFLAGS'] += f' -L{harf_lib_dir}'
+        env['LDFLAGS'] += f' -L{jpeg_lib_dir}'
+        if build_with_webp_support:
+            env['LDFLAGS'] += f' -L{join(webp_install, "lib")}'
+        env['LDFLAGS'] += f' -L{ndk_lib_dir}'
         if cflags not in env['CFLAGS']:
             env['CFLAGS'] += cflags
         return env

pythonforandroid/recipes/Pillow/patches/fix-setup.patch

@@ -1,7 +1,7 @@
 --- Pillow-7.0.0/setup.py.orig	2020-01-02 06:19:26.000000000 +0100
-+++ Pillow-7.0.0/setup.py	2020-02-22 17:33:03.121976748 +0100
++++ Pillow-7.0.0/setup.py	2020-07-05 12:26:18.882948858 +0200
 @@ -29,13 +29,13 @@ def get_version():
- 
+
  NAME = "Pillow"
  PILLOW_VERSION = get_version()
 -FREETYPE_ROOT = None
@@ -14,12 +14,12 @@
  TIFF_ROOT = None
 -ZLIB_ROOT = None
 +ZLIB_ROOT = tuple(os.environ['ZLIB_ROOT'].split('|')) if 'ZLIB_ROOT' in os.environ else None
- 
- 
+
+
  if sys.platform == "win32" and sys.version_info >= (3, 9):
 @@ -317,7 +317,7 @@ class pil_build_ext(build_ext):
      )
- 
+
      def initialize_options(self):
 -        self.disable_platform_guessing = None
 +        self.disable_platform_guessing = True
@@ -28,7 +28,7 @@
          for x in self.feature:
 @@ -567,62 +567,6 @@ class pil_build_ext(build_ext):
                      feature.jpeg = "libjpeg"  # alternative name
- 
+
          feature.openjpeg_version = None
 -        if feature.want("jpeg2000"):
 -            _dbg("Looking for jpeg2000")
@@ -86,13 +86,13 @@
 -                    self, "libtiff"
 -                ):
 -                    feature.tiff = "libtiff"
- 
+
          if feature.want("freetype"):
              _dbg("Looking for freetype")
-@@ -647,40 +591,6 @@ class pil_build_ext(build_ext):
+@@ -647,15 +591,6 @@ class pil_build_ext(build_ext):
                      if subdir:
                          _add_directory(self.compiler.include_dirs, subdir, 0)
- 
+
 -        if feature.want("lcms"):
 -            _dbg("Looking for lcms")
 -            if _find_include_file(self, "lcms2.h"):
@@ -102,49 +102,24 @@
 -                    # alternate Windows name.
 -                    feature.lcms = "lcms2_static"
 -
--        if feature.want("webp"):
--            _dbg("Looking for webp")
--            if _find_include_file(self, "webp/encode.h") and _find_include_file(
--                self, "webp/decode.h"
--            ):
--                # In Google's precompiled zip it is call "libwebp":
--                if _find_library_file(self, "webp"):
--                    feature.webp = "webp"
--                elif _find_library_file(self, "libwebp"):
--                    feature.webp = "libwebp"
--
--        if feature.want("webpmux"):
--            _dbg("Looking for webpmux")
--            if _find_include_file(self, "webp/mux.h") and _find_include_file(
--                self, "webp/demux.h"
--            ):
--                if _find_library_file(self, "webpmux") and _find_library_file(
--                    self, "webpdemux"
--                ):
--                    feature.webpmux = "webpmux"
--                if _find_library_file(self, "libwebpmux") and _find_library_file(
--                    self, "libwebpdemux"
--                ):
--                    feature.webpmux = "libwebpmux"
--
-         for f in feature:
-             if not getattr(feature, f) and feature.require(f):
-                 if f in ("jpeg", "zlib"):
-@@ -717,8 +627,8 @@ class pil_build_ext(build_ext):
+         if feature.want("webp"):
+             _dbg("Looking for webp")
+             if _find_include_file(self, "webp/encode.h") and _find_include_file(
+@@ -717,8 +652,8 @@ class pil_build_ext(build_ext):
              defs.append(("HAVE_LIBTIFF", None))
          if sys.platform == "win32":
              libs.extend(["kernel32", "user32", "gdi32"])
 -        if struct.unpack("h", b"\0\1")[0] == 1:
 -            defs.append(("WORDS_BIGENDIAN", None))
 +        # if struct.unpack("h", b"\0\1")[0] == 1:
 +        #     defs.append(("WORDS_BIGENDIAN", None))
- 
+
          if sys.platform == "win32" and not (PLATFORM_PYPY or PLATFORM_MINGW):
              defs.append(("PILLOW_VERSION", '"\\"%s\\""' % PILLOW_VERSION))
-@@ -769,16 +679,6 @@ class pil_build_ext(build_ext):
+@@ -769,16 +704,6 @@ class pil_build_ext(build_ext):
                  )
              )
- 
+
 -        tk_libs = ["psapi"] if sys.platform == "win32" else []
 -        exts.append(
 -            Extension(
@@ -157,4 +132,4 @@
 -
          exts.append(Extension("PIL._imagingmath", ["src/_imagingmath.c"]))
          exts.append(Extension("PIL._imagingmorph", ["src/_imagingmorph.c"]))
- 
+