From a46bfd791630f5b681191a97d67136723cefac8f Mon Sep 17 00:00:00 2001
From: Quantum <quantum2048@gmail.com>
Date: Sat, 26 Sep 2020 19:37:48 -0400
Subject: [PATCH] Add support for shadows

---
 win2xcur/main.py   | 18 ++++++++++++++++++
 win2xcur/shadow.py | 28 ++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 win2xcur/shadow.py

diff --git a/win2xcur/main.py b/win2xcur/main.py
index 23174e1..7c3cd69 100644
--- a/win2xcur/main.py
+++ b/win2xcur/main.py
@@ -3,6 +3,7 @@ import os
 import sys
 import traceback
 
+from win2xcur import shadow
 from win2xcur.parser import open_blob
 from win2xcur.writer.x11 import check_xcursorgen, to_x11
 
@@ -13,6 +14,20 @@ def main() -> None:
                         help='Windows cursor files to convert (*.cur, *.ani)')
     parser.add_argument('-o', '--output', '--output-dir', default=os.curdir,
                         help='Directory to store converted cursor files.')
+    parser.add_argument('-s', '--shadow', action='store_true',
+                        help="Whether to emulate Windows's shadow effect")
+    parser.add_argument('-O', '--shadow-opacity', type=int, default=50,
+                        help='Opacity of the shadow (0 to 255)')
+    parser.add_argument('-r', '--shadow-radius', type=float, default=0.1,
+                        help='Radius of shadow blur effect (as fraction of width)')
+    parser.add_argument('-S', '--shadow-sigma', type=float, default=0.1,
+                        help='Sigma of shadow blur effect (as fraction of width)')
+    parser.add_argument('-x', '--shadow-x', type=float, default=0.05,
+                        help='x-offset of shadow (as fraction of width)')
+    parser.add_argument('-y', '--shadow-y', type=float, default=0.05,
+                        help='x-offset of shadow (as fraction of height)')
+    parser.add_argument('-c', '--shadow-color', default='#000000',
+                        help='color of the shadow')
 
     args = parser.parse_args()
 
@@ -27,6 +42,9 @@ def main() -> None:
             print('Error occurred while processing %s:' % (name,), file=sys.stderr)
             traceback.print_exc()
         else:
+            if args.shadow:
+                shadow.apply_to_frames(cursor.frames, color=args.shadow_color, radius=args.shadow_radius,
+                                       sigma=args.shadow_sigma, xoffset=args.shadow_x, yoffset=args.shadow_y)
             result = to_x11(cursor.frames)
             output = os.path.join(args.output, os.path.splitext(os.path.basename(name))[0])
             with open(output, 'wb') as f:
diff --git a/win2xcur/shadow.py b/win2xcur/shadow.py
new file mode 100644
index 0000000..6d32340
--- /dev/null
+++ b/win2xcur/shadow.py
@@ -0,0 +1,28 @@
+from typing import List
+
+from wand.image import BaseImage, Image
+
+from win2xcur.cursor import CursorFrame
+
+
+def apply_to_image(image: BaseImage, *, color: str, radius: float, sigma: float, xoffset: float,
+                   yoffset: float) -> Image:
+    opacity = Image(width=image.width, height=image.height, pseudo='xc:white')
+    opacity.composite(image.channel_images['opacity'], left=round(xoffset * image.width),
+                      top=round(yoffset * image.height))
+    opacity.gaussian_blur(radius * image.width, sigma * image.width)
+    opacity.negate()
+    opacity.modulate(50)
+
+    shadow = Image(width=image.width, height=image.height, pseudo='xc:' + color)
+    shadow.composite(opacity, operator='copy_opacity')
+
+    result = image.clone()
+    result.composite(shadow, operator='difference')
+    return result
+
+
+def apply_to_frames(frames: List[CursorFrame], **kwargs):
+    for frame in frames:
+        for cursor in frame:
+            cursor.image = apply_to_image(cursor.image, **kwargs)