performance improvements to new blending

Author: FredHappyface

layeredimage/io/common.py

@@ -3,7 +3,8 @@
 
 from typing import Any
 
-from blendmodes.blend import BlendType, blendLayers
+import numpy as np
+from blendmodes.blend import BlendType
 from loguru import logger
 from PIL import Image
 
@@ -30,12 +31,89 @@ def expandLayersToCanvas(layeredImage: LayeredImage, imageFormat: str) -> list[I
 			extra={"imageFormat": imageFormat},
 		)
 	return [
-		blendLayers(
-			background=Image.new("RGBA", layeredImage.dimensions, (0, 0, 0, 0)),
+		expandLayer(
+			dimensions=layeredImage.dimensions,
 			foreground=layer.image,
-			blendType=layer.blendmode,
 			opacity=layer.opacity,
 			offsets=layer.offsets,
 		)
 		for layer in layeredImage.extractLayers()
 	]
+
+
+def expandLayer(
+	dimensions: tuple[int, int],
+	foreground: np.ndarray | Image.Image,
+	opacity: float = 1.0,
+	offsets: tuple[int, int] = (0, 0),
+) -> Image.Image:
+	"""
+	Args:
+	----
+		foreground (np.ndarray | Image.Image): The foreground layer (must be the same size as the background).
+		opacity (float, optional): The opacity of the foreground image. Defaults to 1.0.
+		offsets (Tuple[int, int], optional): Offsets for the foreground layer. Defaults to (0, 0).
+
+	Returns:
+	-------
+		Image.Image: The image.
+
+	"""
+	# Convert the Image.Image to a numpy array if required
+	if isinstance(foreground, Image.Image):
+		foreground = np.array(foreground.convert("RGBA"))
+
+	# do any offset shifting first
+	if offsets[0] > 0:
+		foreground = np.hstack(
+			(np.zeros((foreground.shape[0], offsets[0], 4), dtype=np.float64), foreground)
+		)
+	elif offsets[0] < 0:
+		if offsets[0] > -1 * foreground.shape[1]:
+			foreground = foreground[:, -1 * offsets[0] :, :]
+		else:
+			# offset offscreen completely, there is nothing left
+			return Image.fromarray(np.zeros(dimensions, dtype=np.uint8))
+	if offsets[1] > 0:
+		foreground = np.vstack(
+			(np.zeros((offsets[1], foreground.shape[1], 4), dtype=np.float64), foreground)
+		)
+	elif offsets[1] < 0:
+		if offsets[1] > -1 * foreground.shape[0]:
+			foreground = foreground[-1 * offsets[1] :, :, :]
+		else:
+			# offset offscreen completely, there is nothing left
+			return Image.fromarray(np.zeros(dimensions, dtype=np.uint8))
+
+	# resize array to fill small images with zeros
+	if foreground.shape[0] < dimensions[0]:
+		foreground = np.vstack(
+			(
+				foreground,
+				np.zeros(
+					(dimensions[0] - foreground.shape[0], foreground.shape[1], 4),
+					dtype=np.float64,
+				),
+			)
+		)
+	if foreground.shape[1] < dimensions[1]:
+		foreground = np.hstack(
+			(
+				foreground,
+				np.zeros(
+					(foreground.shape[0], dimensions[1] - foreground.shape[1], 4),
+					dtype=np.float64,
+				),
+			)
+		)
+
+	# crop the source if the backdrop is smaller
+	foreground = foreground[: dimensions[0], : dimensions[1], :]
+
+	upper_norm = foreground
+
+	upper_alpha = upper_norm[:, :, 3] * opacity
+	upper_rgb = upper_norm[:, :, :3]
+
+	arr = np.nan_to_num(np.dstack((upper_rgb, upper_alpha)), copy=False)
+	return Image.fromarray(np.uint8(np.around(arr, 0)))

layeredimage/io/lsr.py

@@ -3,9 +3,7 @@
 
 from pathlib import Path
 
-from blendmodes.blend import blendLayers
-from PIL import Image
-
+from layeredimage.io.common import expandLayer
 from layeredimage.layeredimage import LayeredImage
 from layeredimage.layergroup import Group, Layer
 
@@ -47,10 +45,9 @@ def saveLayer_LSR(fileName: str, layeredImage: LayeredImage) -> None:
 		else:
 			imageData = [
 				pylsr.LSRImageData(
-					blendLayers(
-						background=Image.new("RGBA", group.dimensions, (0, 0, 0, 0)),
+					expandLayer(
+						dimensions=group.dimensions,
 						foreground=layer.image,
-						blendType=layer.blendmode,
 						opacity=layer.opacity,
 						offsets=layer.offsets,
 					),