Added code to optimize PNG images file size (indexed colors with all-or-nothing alpha)

.gitignore

@@ -3,3 +3,4 @@
 __pycache__/
 *.py[cod]
 *$py.class
+/pydev/

ahb_raster_view.py

@@ -252,6 +252,20 @@ class RasterView:
 				composite_img = prev_parts_img.copy()
 				composite_img.paste(new_parts_img, None, new_parts_img)
 			
+			# Optimize the image to reduce storage size
+			if not fast_render:
+				num_colors = 32
+				
+				# All-or-nothing alpha: we use a white background and only make pixels fully transparent where alpha is zero, to not loose antialiasing
+				bg_img = Image.new(composite_img.mode, composite_img.size, color = '#ffffff')
+				bg_img.paste(composite_img.convert('RGB'), composite_img)
+				final_alpha = composite_img.split()[3].point(lambda p: 0 if p <= int(255/num_colors+0.5) else 255)
+				composite_img = bg_img
+				composite_img.putalpha(final_alpha)
+				
+				# Convert to indexed colors
+				composite_img = composite_img.quantize(colors=num_colors, dither=Image.Dither.NONE)
+			
 		finally:
 			# restore properties on objects we have modified
 			for obj, props in objects_to_reset.items():
@@ -271,7 +285,7 @@ class RasterView:
 		# Crop the image, which is also used to deduce the center of the source view
 		original_size = composite_img.size
 		
-		diff_source_img = composite_img.split()[3]
+		diff_source_img = composite_img.split()[-1]
 		bg = Image.new(diff_source_img.mode, diff_source_img.size, '#000000') # fills an image with the background color
 		diff = ImageChops.difference(diff_source_img, bg) # diff between the actual image and the background color
 		bbox = diff.getbbox() # finds border size (non-black portion of the image)