Remove reassigning variables with new types, pass Mypy

adafruit_imageload/__init__.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 #
 # SPDX-License-Identifier: MIT
 
@@ -77,10 +77,15 @@ def load(
 
             return pnm.load(file, header, bitmap=bitmap, palette=palette)
         if header.startswith(b"GIF"):
+            if not bitmap:
+                raise RuntimeError("bitmap argument required")
+
             from . import gif
 
             return gif.load(file, bitmap=bitmap, palette=palette)
         if header.startswith(b"\x89PN"):
+            if not bitmap:
+                raise RuntimeError("bitmap argument required")
             from . import png
 
             return png.load(file, bitmap=bitmap, palette=palette)

adafruit_imageload/bmp/__init__.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 #
 # SPDX-License-Identifier: MIT
 
@@ -29,9 +29,9 @@
 def load(
     file: BufferedReader,
     *,
-    bitmap: BitmapConstructor = None,
-    palette: PaletteConstructor = None
-) -> Tuple[Bitmap, Optional[Palette]]:
+    bitmap: Optional[BitmapConstructor] = None,
+    palette: Optional[PaletteConstructor] = None
+) -> Tuple[Optional[Bitmap], Optional[Palette]]:
     """Loads a bmp image from the open ``file``.
 
     Returns tuple of bitmap object and palette object.

adafruit_imageload/bmp/indexed.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 #
 # SPDX-License-Identifier: MIT
 
@@ -43,9 +43,9 @@ def load(
     color_depth: int,
     compression: int,
     *,
-    bitmap: BitmapConstructor = None,
-    palette: PaletteConstructor = None,
-) -> Tuple[Bitmap, Optional[Palette]]:
+    bitmap: Optional[BitmapConstructor] = None,
+    palette: Optional[PaletteConstructor] = None,
+) -> Tuple[Optional[Bitmap], Optional[Palette]]:
     """Loads indexed bitmap data into bitmap and palette objects.
 
     :param file file: The open bmp file
@@ -54,19 +54,24 @@ def load(
     :param int data_start: Byte location where the data starts (after headers)
     :param int colors: Number of distinct colors in the image
     :param int color_depth: Number of bits used to store a value
-    :param int compression: 0 - none, 1 - 8bit RLE, 2 - 4bit RLE"""
+    :param int compression: 0 - none, 1 - 8bit RLE, 2 - 4bit RLE
+    :param BitmapConstructor bitmap: a function that returns a displayio.Bitmap
+    :param PaletteConstructor palette: a function that returns a displayio.Palette
+    """
     # pylint: disable=too-many-arguments,too-many-locals,too-many-branches
+    palette_obj = None
     if palette:
-        palette = palette(colors)  # type: Palette
+        palette_obj = palette(colors)
 
         file.seek(data_start - colors * 4)
         for value in range(colors):
             c_bytes = file.read(4)
             # Need to swap red & blue bytes (bytes 0 and 2)
-            palette[value] = bytes(
+            palette_obj[value] = bytes(
                 b"".join([c_bytes[2:3], c_bytes[1:2], c_bytes[0:1], c_bytes[3:1]])
             )
 
+    bitmap_obj = None
     if bitmap:
         minimum_color_depth = 1
         while colors > 2**minimum_color_depth:
@@ -78,7 +83,7 @@ def load(
 
             # convert unsigned int to signed int when height is negative
             height = negative_height_check(height)
-        bitmap = bitmap(width, abs(height), colors)  # type: Bitmap
+        bitmap_obj = bitmap(width, abs(height), colors)
         file.seek(data_start)
         line_size = width // (8 // color_depth)
         if width % (8 // color_depth) != 0:
@@ -97,10 +102,9 @@ def load(
             range3 = 1
 
         if compression == 0:
-
             if _bitmap_readinto:
                 _bitmap_readinto(
-                    bitmap,
+                    bitmap_obj,
                     file,
                     bits_per_pixel=color_depth,
                     element_size=4,
@@ -120,17 +124,17 @@ def load(
                         pixel = (
                             chunk[i] >> (8 - color_depth * (x % pixels_per_byte + 1))
                         ) & mask
-                        bitmap[offset + x] = pixel
+                        bitmap_obj[offset + x] = pixel
         elif compression in (1, 2):
             decode_rle(
-                bitmap=bitmap,
+                bitmap=bitmap_obj,
                 file=file,
                 compression=compression,
                 y_range=(range1, range2, range3),
                 width=width,
             )
 
-    return bitmap, palette
+    return bitmap_obj, palette_obj
 
 
 def decode_rle(

adafruit_imageload/gif.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2019 Radomir Dopieralski for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 #
 # SPDX-License-Identifier: MIT
 
@@ -32,7 +32,7 @@ def load(
     file: BufferedReader,
     *,
     bitmap: BitmapConstructor,
-    palette: PaletteConstructor = None
+    palette: Optional[PaletteConstructor] = None
 ) -> Tuple[Bitmap, Optional[Palette]]:
     """Loads a GIF image from the open ``file``.
 
@@ -50,6 +50,8 @@ def load(
         "<HHBBB", file.read(7)
     )
     if (flags & 0x80) != 0:
+        if not palette:
+            raise RuntimeError("palette argument required")
         palette_size = 1 << ((flags & 0x07) + 1)
         palette_obj = palette(palette_size)
         for i in range(palette_size):

adafruit_imageload/png.py

@@ -1,4 +1,5 @@
 # SPDX-FileCopyrightText: 2022 Radomir Dopieralski
+# SPDX-FileCopyrightText: 2023 Matt Land
 #
 # SPDX-License-Identifier: MIT
 
@@ -9,13 +10,14 @@
 Load pixel values (indices or colors) into a bitmap and colors into a palette
 from a PNG file.
 
-* Author(s): Radomir Dopieralski
+* Author(s): Radomir Dopieralski, Matt Land
 
 """
 
 try:
-    # pylint: disable=unused-import
-    import typing
+    from io import BufferedReader
+    from typing import Optional, Tuple
+    from displayio import Palette, Bitmap
     from .displayio_types import PaletteConstructor, BitmapConstructor
 except ImportError:
     pass
@@ -28,25 +30,33 @@
 
 
 def load(
-    file: str, *, bitmap: BitmapConstructor, palette: PaletteConstructor = None
-):  # pylint: disable=too-many-locals,too-many-branches
-    """Loads a PNG image from the open ``file``.
+    file: BufferedReader,
+    *,
+    bitmap: BitmapConstructor,
+    palette: Optional[PaletteConstructor] = None
+) -> Tuple[Bitmap, Optional[Palette]]:
+    """
+    Loads a PNG image from the open ``file``.
 
     Returns tuple of bitmap object and palette object.
 
     :param file: The *.png file being loaded
     :param object bitmap: Type to store bitmap data. Must have API similar to
       `displayio.Bitmap`.
     :param object palette: Type to store the palette. Must have API similar to
-      `displayio.Palette`. Will be skipped if None"""
+      `displayio.Palette`. Will be skipped if None
+    """
+    # pylint: disable=too-many-locals,too-many-branches
     header = file.read(8)
     if header != b"\x89PNG\r\n\x1a\n":
         raise ValueError("Not a PNG file")
     del header
     data = bytearray()
     pal = None
     mode = None
-    depth = None
+    depth = 0
+    width = 0
+    height = 0
     while True:
         size, chunk = struct.unpack(">I4s", file.read(8))
         if chunk == b"IHDR":
@@ -81,16 +91,16 @@ def load(
         else:
             file.seek(size, 1)  # skip unknown chunks
         file.seek(4, 1)  # skip CRC
-    data = zlib.decompress(data)
+    data_bytes = zlib.decompress(data)
     bmp = bitmap(width, height, 1 << depth)
     scanline = (width * depth + 7) // 8
     mem = memoryview(bmp)
     for y in range(height):
         dst = y * scanline
         src = y * (scanline + 1) + 1
-        filter_ = data[src - 1]
+        filter_ = data_bytes[src - 1]
         if filter_ == 0:
-            mem[dst : dst + scanline] = data[src : src + scanline]
+            mem[dst : dst + scanline] = data_bytes[src : src + scanline]
         else:
             raise NotImplementedError("Filters not supported")
     return bmp, pal

adafruit_imageload/pnm/__init__.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 # SPDX-FileCopyrightText: Brooke Storm
 # SPDX-FileCopyrightText: Sam McGahan
 #
@@ -40,8 +40,8 @@ def load(
     file: BufferedReader,
     header: bytes,
     *,
-    bitmap: BitmapConstructor = None,
-    palette: PaletteConstructor = None
+    bitmap: Optional[BitmapConstructor] = None,
+    palette: Optional[PaletteConstructor] = None
 ) -> Tuple[Optional[Bitmap], Optional[Palette]]:
     """
     Scan for netpbm format info, skip over comments, and delegate to a submodule
@@ -92,19 +92,24 @@ def load(
                 )
 
         if len(pnm_header) == 2 and magic_number in [b"P1", b"P4"]:
-            bitmap = bitmap(pnm_header[0], pnm_header[1], 1)  # type: Bitmap
+            if not bitmap:
+                raise RuntimeError(
+                    "A bitmap constructor is required for this type of pnm format file"
+                )
+            bitmap_obj = bitmap(pnm_header[0], pnm_header[1], 1)
+            palette_obj = None
             if palette:
-                palette = palette(1)  # type: Palette
-                palette[0] = b"\xFF\xFF\xFF"
+                palette_obj = palette(1)
+                palette_obj[0] = b"\xFF\xFF\xFF"
             if magic_number.startswith(b"P1"):
                 from . import pbm_ascii
 
                 return pbm_ascii.load(
                     file,
                     pnm_header[0],
                     pnm_header[1],
-                    bitmap=bitmap,
-                    palette=palette,
+                    bitmap=bitmap_obj,
+                    palette=palette_obj,
                 )
 
             from . import pbm_binary
@@ -113,8 +118,8 @@ def load(
                 file,
                 pnm_header[0],
                 pnm_header[1],
-                bitmap=bitmap,
-                palette=palette,
+                bitmap=bitmap_obj,
+                palette=palette_obj,
             )
 
         next_byte = file.read(1)

adafruit_imageload/pnm/pbm_ascii.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 # SPDX-FileCopyrightText: Brooke Storm
 # SPDX-FileCopyrightText: Sam McGahan
 #
@@ -32,7 +32,7 @@ def load(
     width: int,
     height: int,
     bitmap: Bitmap,
-    palette: Palette = None,
+    palette: Optional[Palette] = None,
 ) -> Tuple[Bitmap, Optional[Palette]]:
     """
     Load a P1 'PBM' ascii image into the displayio.Bitmap

adafruit_imageload/pnm/pbm_binary.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 # SPDX-FileCopyrightText: Brooke Storm
 # SPDX-FileCopyrightText: Sam McGahan
 #
@@ -31,7 +31,7 @@ def load(
     width: int,
     height: int,
     bitmap: Bitmap,
-    palette: Palette = None,
+    palette: Optional[Palette] = None,
 ) -> Tuple[Bitmap, Optional[Palette]]:
     """
     Load a P4 'PBM' binary image into the Bitmap

adafruit_imageload/pnm/pgm/__init__.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 # SPDX-FileCopyrightText: Brooke Storm
 # SPDX-FileCopyrightText: Sam McGahan
 #
@@ -29,8 +29,8 @@ def load(
     magic_number: bytes,
     header: List[int],
     *,
-    bitmap: BitmapConstructor = None,
-    palette: PaletteConstructor = None
+    bitmap: Optional[BitmapConstructor] = None,
+    palette: Optional[PaletteConstructor] = None
 ) -> Tuple[Optional[Bitmap], Optional[Palette]]:
     """
     Perform the load of Netpbm greyscale images (P2, P5)

adafruit_imageload/pnm/pgm/ascii.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
-# SPDX-FileCopyrightText: 2022 Matt Land
+# SPDX-FileCopyrightText: 2022-2023 Matt Land
 # SPDX-FileCopyrightText: Brooke Storm
 # SPDX-FileCopyrightText: Sam McGahan
 #
@@ -27,8 +27,8 @@ def load(
     file: BufferedReader,
     width: int,
     height: int,
-    bitmap: BitmapConstructor = None,
-    palette: PaletteConstructor = None,
+    bitmap: Optional[BitmapConstructor] = None,
+    palette: Optional[PaletteConstructor] = None,
 ) -> Tuple[Optional[Bitmap], Optional[Palette]]:
     """
     Load a PGM ascii file (P2)
@@ -46,11 +46,12 @@ def load(
             _palette_colors.add(int_pixel)
             pixel = bytearray()
         pixel += byte
+    palette_obj = None
     if palette:
-        palette = build_palette(palette, _palette_colors)  # type: Palette
+        palette_obj = build_palette(palette, _palette_colors)
+    bitmap_obj = None
     if bitmap:
-        bitmap = bitmap(width, height, len(_palette_colors))  # type: Bitmap
-        _palette_colors = list(_palette_colors)
+        bitmap_obj = bitmap(width, height, len(_palette_colors))
         file.seek(data_start)
         for y in range(height):
             for x in range(width):
@@ -61,8 +62,8 @@ def load(
                         break
                     pixel += byte
                 int_pixel = int("".join(["%c" % char for char in pixel]))
-                bitmap[x, y] = _palette_colors.index(int_pixel)
-    return bitmap, palette
+                bitmap_obj[x, y] = list(_palette_colors).index(int_pixel)
+    return bitmap_obj, palette_obj
 
 
 def build_palette(