Add 16, 24, and 32-bit bmp support

adafruit_imageload/bmp/__init__.py

@@ -62,12 +62,20 @@ def load(
     file.seek(0x2E)  # Number of colors in the color palette
     colors = int.from_bytes(file.read(4), "little")
 
-    if colors == 0 and color_depth >= 16:
-        raise NotImplementedError("True color BMP unsupported")
-
     if compression > 2:
         raise NotImplementedError("bitmask compression unsupported")
 
+    if colors == 0 and color_depth >= 16:
+        from . import truecolor
+
+        return truecolor.load(
+            file,
+            _width,
+            _height,
+            data_start,
+            color_depth,
+            bitmap=bitmap,
+        )
     if colors == 0:
         colors = 2**color_depth
     from . import indexed

adafruit_imageload/bmp/truecolor.py

@@ -0,0 +1,93 @@
+# SPDX-FileCopyrightText: 2018 Scott Shawcroft for Adafruit Industries
+# SPDX-FileCopyrightText: 2022-2023 Melissa LeBlanc-Williams
+#
+# SPDX-License-Identifier: MIT
+
+"""
+`adafruit_imageload.bmp.truecolor`
+====================================================
+
+Load pixel colors into a bitmap from an truecolor BMP and return the correct colorconverter.
+
+* Author(s): Melissa LeBlanc-Williams
+
+"""
+
+import sys
+
+try:
+    from typing import Tuple, Optional
+    from io import BufferedReader
+    from displayio import Bitmap
+    from ..displayio_types import BitmapConstructor
+except ImportError:
+    pass
+
+from displayio import ColorConverter, Colorspace
+
+__version__ = "0.0.0+auto.0"
+__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_ImageLoad.git"
+
+
+def load(
+    file: BufferedReader,
+    width: int,
+    height: int,
+    data_start: int,
+    color_depth: int,
+    *,
+    bitmap: Optional[BitmapConstructor] = None,
+) -> Tuple[Optional[Bitmap], Optional[ColorConverter]]:
+    """Loads truecolor bitmap data into bitmap and palette objects. Due to the 16-bit limit
+    that the bitmap object can hold, colors will be converted to 16-bit RGB565 values.
+
+    :param file file: The open bmp file
+    :param int width: Image width in pixels
+    :param int height: Image height in pixels
+    :param int data_start: Byte location where the data starts (after headers)
+    :param int color_depth: Number of bits used to store a value
+    :param BitmapConstructor bitmap: a function that returns a displayio.Bitmap
+    """
+    # pylint: disable=too-many-arguments,too-many-locals,too-many-branches
+    converter_obj = None
+    bitmap_obj = None
+    if bitmap:
+        # Set up a ColorConverter object and set appropriate colorspace
+        # to convert from based on the color depth
+        input_colorspace = Colorspace.RGB888
+        if color_depth == 16:
+            input_colorspace = Colorspace.RGB555
+        converter_obj = ColorConverter(input_colorspace=input_colorspace)
+        if sys.maxsize > 1073741823:
+            # pylint: disable=import-outside-toplevel, relative-beyond-top-level
+            from .negative_height_check import negative_height_check
+
+            # convert unsigned int to signed int when height is negative
+            height = negative_height_check(height)
+        bitmap_obj = bitmap(width, abs(height), 65535)
+        file.seek(data_start)
+        line_size = width * (color_depth // 8)
+        # Set the seek direction based on whether the height value is negative or positive
+        if height > 0:
+            range1 = height - 1
+            range2 = -1
+            range3 = -1
+        else:
+            range1 = 0
+            range2 = abs(height)
+            range3 = 1
+        chunk = bytearray(line_size)
+        for y in range(range1, range2, range3):
+            file.readinto(chunk)
+            bytes_per_pixel = color_depth // 8
+            offset = y * width
+
+            for x in range(width):
+                i = x * bytes_per_pixel
+                if color_depth == 16:
+                    pixel = chunk[i] | chunk[i + 1] << 8
+                else:
+                    pixel = chunk[i + 2] << 16 | chunk[i + 1] << 8 | chunk[i]
+                bitmap_obj[offset + x] = converter_obj.convert(pixel)
+
+    return bitmap_obj, ColorConverter(input_colorspace=Colorspace.RGB565)