From a526e3b23b674a5cbeef5f4040d9683c460c176c Mon Sep 17 00:00:00 2001
From: "Jorj X. McKie" <jorj.x.mckie@outlook.de>
Date: Thu, 5 Sep 2024 15:32:23 -0400
Subject: [PATCH] Address 3848

---
 src/__init__.py      |  9 ++++++---
 src/utils.py         |  3 +++
 tests/test_pixmap.py | 10 ++++++++++
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/__init__.py b/src/__init__.py
index 2ee9bd6ff..6fb8356a5 100644
--- a/src/__init__.py
+++ b/src/__init__.py
@@ -10021,11 +10021,14 @@ def color_count(self, colors=0, clip=None):
 
     def color_topusage(self, clip=None):
         """Return most frequent color and its usage ratio."""
+        if clip is not None:
+            clip = IRect(self.irect) & clip
+            if clip.is_empty:
+                raise ValueError("clip must not be empty")
         allpixels = 0
         cnt = 0
-        if clip is not None and self.irect in Rect(clip):
-            clip = self.irect
-        for pixel, count in self.color_count(colors=True,clip=clip).items():
+ 
+        for pixel, count in self.color_count(colors=True, clip=clip).items():
             allpixels += count
             if count > cnt:
                 cnt = count
diff --git a/src/utils.py b/src/utils.py
index 670403d92..aa8d44853 100644
--- a/src/utils.py
+++ b/src/utils.py
@@ -881,6 +881,9 @@ def get_pixmap(
     if colorspace.n not in (1, 3, 4):
         raise ValueError("unsupported colorspace")
 
+    if clip is not None and pymupdf.IRect(clip).is_empty:
+        raise ValueError("clip must not be empty")
+
     dl = page.get_displaylist(annots=annots)
     pix = dl.get_pixmap(matrix=matrix, colorspace=colorspace, alpha=alpha, clip=clip)
     dl = None
diff --git a/tests/test_pixmap.py b/tests/test_pixmap.py
index c456f05fc..7231d81b6 100644
--- a/tests/test_pixmap.py
+++ b/tests/test_pixmap.py
@@ -264,6 +264,16 @@ def test_3177():
     pixmap = pymupdf.Pixmap(path)
     pixmap2 = pymupdf.Pixmap(None, pixmap)
 
+def test_3848():
+    path = os.path.abspath(f"{__file__}/../../tests/resources/img-transparent.png")
+    pix = pymupdf.Pixmap(path)
+    error = False
+    try:
+        top = pix.color_topusage(clip=(0, 0, 0, 0))
+    except ValueError:
+        error = True
+    assert error
+
 
 def test_3493():
     '''