chinapandaman · chinapandaman · Apr 12, 2024 · Apr 12, 2024 · Apr 12, 2024 · Apr 12, 2024
diff --git a/PyPDFForm/filler.py b/PyPDFForm/filler.py
@@ -148,20 +148,20 @@ def simple_fill(
             key = get_widget_key(annot.get_object())
 
             widget = widgets.get(key)
-            if widget is None:
+            if widget is None or widget.value is None:
                 continue
 
-            if type(widget) is Checkbox and widget.value is True:
-                simple_update_checkbox_value(annot)
+            if type(widget) is Checkbox:
+                simple_update_checkbox_value(annot, widget.value)
             elif isinstance(widget, Radio):
                 if key not in radio_button_tracker:
                     radio_button_tracker[key] = 0
                 radio_button_tracker[key] += 1
                 if widget.value == radio_button_tracker[key] - 1:
                     simple_update_radio_value(annot)
-            elif isinstance(widget, Dropdown) and widget.value is not None:
+            elif isinstance(widget, Dropdown):
                 simple_update_dropdown_value(annot, widget)
-            elif isinstance(widget, Text) and widget.value:
+            elif isinstance(widget, Text):
                 simple_update_text_value(annot, widget)
 
             if flatten:

diff --git a/PyPDFForm/patterns.py b/PyPDFForm/patterns.py
@@ -80,12 +80,13 @@
 ]
 
 
-def simple_update_checkbox_value(annot: DictionaryObject) -> None:
+def simple_update_checkbox_value(annot: DictionaryObject, check: bool = False) -> None:
     """Patterns to update values for checkbox annotations."""
 
     for each in annot[AP][D]:  # noqa
-        if str(each) != Off:
+        if (check and str(each) != Off) or (not check and str(each) == Off):
             annot[NameObject(AS)] = NameObject(each)
+            annot[NameObject(V)] = NameObject(each)
             break
 
 

diff --git a/pdf_samples/simple/dropdown/dropdown_four.pdf b/pdf_samples/simple/dropdown/dropdown_four.pdf
diff --git a/pdf_samples/simple/dropdown/dropdown_one.pdf b/pdf_samples/simple/dropdown/dropdown_one.pdf
diff --git a/pdf_samples/simple/dropdown/dropdown_three.pdf b/pdf_samples/simple/dropdown/dropdown_three.pdf
diff --git a/pdf_samples/simple/dropdown/dropdown_two.pdf b/pdf_samples/simple/dropdown/dropdown_two.pdf
diff --git a/pdf_samples/simple/dropdown/dropdown_two_simple.pdf b/pdf_samples/simple/dropdown/dropdown_two_simple.pdf
diff --git a/pdf_samples/simple/max_length_text_field_related/comb_text_field_all_chars.pdf b/pdf_samples/simple/max_length_text_field_related/comb_text_field_all_chars.pdf
diff --git a/pdf_samples/simple/max_length_text_field_related/comb_text_field_even_chars.pdf b/pdf_samples/simple/max_length_text_field_related/comb_text_field_even_chars.pdf
diff --git a/...samples/simple/max_length_text_field_related/comb_text_field_even_chars_right_aligned.pdf b/...samples/simple/max_length_text_field_related/comb_text_field_even_chars_right_aligned.pdf
diff --git a/pdf_samples/simple/max_length_text_field_related/comb_text_field_odd_chars.pdf b/pdf_samples/simple/max_length_text_field_related/comb_text_field_odd_chars.pdf
diff --git a/pdf_samples/simple/max_length_text_field_related/max_length_text_field_all_chars.pdf b/pdf_samples/simple/max_length_text_field_related/max_length_text_field_all_chars.pdf
diff --git a/pdf_samples/simple/max_length_text_field_related/max_length_text_field_even_chars.pdf b/pdf_samples/simple/max_length_text_field_related/max_length_text_field_even_chars.pdf
diff --git a/pdf_samples/simple/max_length_text_field_related/max_length_text_field_odd_chars.pdf b/pdf_samples/simple/max_length_text_field_related/max_length_text_field_odd_chars.pdf
diff --git a/pdf_samples/simple/paragraph/sample_filled_sejda_complex.pdf b/pdf_samples/simple/paragraph/sample_filled_sejda_complex.pdf
diff --git a/pdf_samples/simple/paragraph/sample_filled_sejda_complex_flatten.pdf b/pdf_samples/simple/paragraph/sample_filled_sejda_complex_flatten.pdf
diff --git a/pdf_samples/simple/sample_filled.pdf b/pdf_samples/simple/sample_filled.pdf
diff --git a/pdf_samples/simple/sample_filled_sejda.pdf b/pdf_samples/simple/sample_filled_sejda.pdf
diff --git a/pdf_samples/simple/scenario/existed/illinois-gun-bill-of-sale_expected.pdf b/pdf_samples/simple/scenario/existed/illinois-gun-bill-of-sale_expected.pdf
diff --git a/pdf_samples/simple/scenario/issues/437_expected.pdf b/pdf_samples/simple/scenario/issues/437_expected.pdf
diff --git a/pdf_samples/simple/scenario/tools/docfly_expected.pdf b/pdf_samples/simple/scenario/tools/docfly_expected.pdf
diff --git a/pdf_samples/simple/scenario/tools/pdf_escape_expected.pdf b/pdf_samples/simple/scenario/tools/pdf_escape_expected.pdf
diff --git a/pdf_samples/simple/undo/sample_template_filled.pdf b/pdf_samples/simple/undo/sample_template_filled.pdf
diff --git a/pdf_samples/simple/undo/test_undo_checkbox.pdf b/pdf_samples/simple/undo/test_undo_checkbox.pdf
diff --git a/tests/test_functional_simple.py b/tests/test_functional_simple.py
@@ -127,3 +127,25 @@ def test_fill_complex_fonts(sample_template_with_complex_fonts, pdf_samples, req
         if os.name != "nt":
             assert len(obj.read()) == len(expected)
             assert obj.stream == expected
+
+
+def test_undo_checkbox(pdf_samples, request):
+    expected_path = os.path.join(pdf_samples, "simple", "undo", "test_undo_checkbox.pdf")
+    with open(expected_path, "rb+") as f:
+        obj = FormWrapper(
+            os.path.join(pdf_samples, "simple", "undo", "sample_template_filled.pdf")
+        ).fill(
+            {
+                "check": False,
+                "check_2": False,
+                "check_3": False,
+            },
+        )
+
+        request.config.results["expected_path"] = expected_path
+        request.config.results["stream"] = obj.read()
+
+        expected = f.read()
+
+        assert len(obj.stream) == len(expected)
+        assert obj.stream == expected