From a880db55a8395145c3de30067b2423655b324cf5 Mon Sep 17 00:00:00 2001
From: Pavel Malai <flagmansupport@gmail.com>
Date: Mon, 2 Jun 2025 18:05:40 +0200
Subject: [PATCH] Fix VP8X WebP dimension parsing bug

VP8X format stores canvas dimensions as (width-1, height-1) in the header,
but the parser was returning the raw values without adding 1, causing
incorrect dimensions to be reported.

Changes:
- Add +1 to both width and height when parsing VP8X headers
- Add test case for VP8X format with test_vp8x.webp (200x1)
- Follows WebP specification for VP8X chunk format

Fixes issue where VP8X images returned dimensions that were 1 pixel
smaller than actual size in both width and height.
---
 imagesize/imagesize.py     |   4 ++--
 test/images/test_vp8x.webp | Bin 0 -> 106 bytes
 test/test_get.py           |  10 ++++++++++
 3 files changed, 12 insertions(+), 2 deletions(-)
 create mode 100644 test/images/test_vp8x.webp

diff --git a/imagesize/imagesize.py b/imagesize/imagesize.py
index e6ed07e..e9213b6 100644
--- a/imagesize/imagesize.py
+++ b/imagesize/imagesize.py
@@ -253,8 +253,8 @@ def get(filepath):
             if head[12:16] == b"VP8 ":
                 width, height = struct.unpack("<HH", head[26:30])
             elif head[12:16] == b"VP8X":
-                width = struct.unpack("<I", head[24:27] + b"\0")[0]
-                height = struct.unpack("<I", head[27:30] + b"\0")[0]
+                width = struct.unpack("<I", head[24:27] + b"\0")[0] + 1
+                height = struct.unpack("<I", head[27:30] + b"\0")[0] + 1
             elif head[12:16] == b"VP8L":
                 b = head[21:25]
                 width = (((b[1] & 63) << 8) | b[0]) + 1
diff --git a/test/images/test_vp8x.webp b/test/images/test_vp8x.webp
new file mode 100644
index 0000000000000000000000000000000000000000..be7beae2c2c17097320e500dcde47d440938f982
GIT binary patch
literal 106
zcmWIYbaP8$U|<M$bqWXzu!!ISvIT(nI1n>1IQj&5fJ7MC13q_fxVZdh2C7jo0*Vwc
zGt6bwI>ErmU^mfYfsg7EWhJE!h7CfTnG6iV@8&z@e0spZ@bBwi*;oIsrr2!&>Hq-A
C!5qT?

literal 0
HcmV?d00001

diff --git a/test/test_get.py b/test/test_get.py
index d786296..45ccd2f 100644
--- a/test/test_get.py
+++ b/test/test_get.py
@@ -104,6 +104,16 @@ def test_littleendian_tiff_bytes(self):
         self.assertEqual(width, 800)
         self.assertEqual(height, 600)
 
+    def test_load_webp_vp8x(self):
+        """Test VP8X format WebP file parsing.
+        
+        VP8X format stores dimensions as (width-1, height-1) in the header,
+        so the parser must add 1 to get the actual dimensions.
+        """
+        width, height = imagesize.get(os.path.join(imagedir, "test_vp8x.webp"))
+        self.assertEqual(width, 200)
+        self.assertEqual(height, 1)
+
     @unittest.skipIf(Path is None, "requires pathlib support")
     def test_load_png_path(self):
         width, height = imagesize.get(Path(imagedir, "test.png"))