TST: Cover content stream renaming, scaling and merging of PageObject

tests/test_page.py

@@ -1935,3 +1935,123 @@ def test_translate_value_inline_image_colorspace_not_found(resources):
     custom_name = NameObject("/CustomCS")
     with pytest.raises(PdfReadError, match=r"^Cannot find resource entry .+ for .+$"):
         page._translate_value_inline_image("/CS", custom_name)
+
+
+def test_content_stream_rename__device_color_space_abbreviation_in_inline_image_is_not_renamed() -> None:
+    """
+    Renaming a resource called /G does not change /CS /G in an inline image.
+
+    In an inline image, /G always means DeviceGray and never refers to a
+    resource in the ColorSpace subdictionary (ISO 32000-2:2020, 8.9.7, NOTE 3).
+    Renaming it to /G-0 would leave the image with an unknown color space.
+    """
+    content = ContentStream(None, None)
+    # The same name /G appears twice:
+    # * "/G cs" is the control. The operand of cs is a resource in the
+    #   ColorSpace subdictionary unless it is DeviceGray, DeviceRGB, DeviceCMYK
+    #   or Pattern (8.6.8, Table 73), and the abbreviation G is only valid in
+    #   inline images (8.9.7). So this /G is the resource and is renamed.
+    # * In the inline image (BI ... ID ... EI), /G means DeviceGray and is kept.
+    #   The image is 1x1 gray (8.9.7, Table 91 for the abbreviations): one byte
+    #   of data, \x80.
+    content.set_data(b"/G cs BI /W 1 /H 1 /CS /G /BPC 8 ID \x80 EI")
+    rename = {NameObject("/G"): NameObject("/G-0")}
+
+    renamed = PageObject._content_stream_rename(content, rename, None)
+
+    (cs_operands, cs_operator), (image_operands, image_operator) = renamed.operations
+    assert (cs_operands, cs_operator) == ([NameObject("/G-0")], b"cs")
+    assert image_operator == b"INLINE IMAGE"
+    assert image_operands["settings"]["/CS"] == "/G"
+    assert image_operands["data"] == b"\x80"
+
+
+@pytest.mark.parametrize("as_array", [True, False])
+def test_scale__viewport_bounding_box(as_array: bool) -> None:
+    """
+    scale() scales the bounding box of a viewport together with the page.
+
+    The /BBox of a viewport is given in default user space (ISO 32000-2:2020,
+    12.9.1, Table 265), so it has to follow the page content. /VP has to be an
+    array of viewport dictionaries (Table 31); a single dictionary is malformed,
+    but is scaled as well.
+    """
+    page = PageObject.create_blank_page(None, 100, 100)
+    viewport = DictionaryObject({NameObject("/BBox"): RectangleObject((0, 0, 10, 20))})
+    page[NameObject("/VP")] = ArrayObject([viewport]) if as_array else viewport
+
+    # Different factors for x and y, so swapped axes would be noticed.
+    page.scale(2, 3)
+
+    scaled_viewport = page["/VP"][0] if as_array else page["/VP"]
+    assert scaled_viewport["/BBox"] == RectangleObject((0, 0, 20, 60))
+
+
+def test_extract_text__visitor_receives_text_without_end_operator() -> None:
+    """
+    visitor_text receives the text of a text object that is not closed.
+
+    A text object ends with ET (ISO 32000-2:2020, 9.4.1). Without it, the text
+    is still pending when the content stream ends, and has to be passed to the
+    visitor then.
+    """
+    from .test_text_extraction import _page_with_helvetica  # noqa: PLC0415
+
+    # A text object with BT, but without ET.
+    page = PdfReader(_page_with_helvetica(b"BT /F1 12 Tf (Hello) Tj")).pages[0]
+    parts = []
+    assert page.extract_text(visitor_text=lambda text, *_: parts.append(text)) == "Hello"
+    assert "".join(parts) == "Hello"
+    assert parts[-1] == "Hello"
+
+
+@pytest.mark.xfail(
+    reason="#4335: Annotations are dropped if the target page has a null /Annots entry", strict=True
+)
+def test_merge_page__target_with_null_annotations() -> None:
+    """
+    merge_page() adds the annotations of the merged page to a target page with
+    /Annots null.
+
+    A null value is the same as a missing entry (ISO 32000-2:2020, 7.3.9), so
+    the target page has no annotations yet (/Annots, Table 31). After the merge,
+    it has an /Annots array with the merged annotation.
+    """
+    source = PdfWriter()
+    source.add_blank_page(100, 100)
+    # ISO 32000-2:2020, Table 182: the four vertices in counterclockwise order.
+    quad_points = ArrayObject(FloatObject(value) for value in (10, 10, 20, 10, 20, 20, 10, 20))
+    source.add_annotation(0, Highlight(rect=(10, 10, 20, 20), quad_points=quad_points))
+    # Write and read the source, so the annotation is a plain dictionary and #3467 does not interfere.
+    source_data = BytesIO()
+    source.write(source_data)
+    writer = PdfWriter()
+    target = writer.add_blank_page(100, 100)
+    target[NameObject("/Annots")] = NullObject()
+
+    target.merge_page(PdfReader(source_data).pages[0])
+
+    assert len(target["/Annots"]) == 1
+
+
+@pytest.mark.xfail(
+    reason="#3467: Cloning annotations created with pypdf.annotations fails", strict=True
+)
+def test_merge_page__annotation_added_by_writer() -> None:
+    """
+    merge_page() copies an annotation that was added with
+    PdfWriter.add_annotation() and not yet written.
+
+    The writer keeps the Highlight object itself, whose constructor requires
+    arguments, so cloning it with self.__class__() fails.
+    """
+    source = PdfWriter()
+    source.add_blank_page(100, 100)
+    # ISO 32000-2:2020, Table 182: the four vertices in counterclockwise order.
+    quad_points = ArrayObject(FloatObject(value) for value in (10, 10, 20, 10, 20, 20, 10, 20))
+    source.add_annotation(0, Highlight(rect=(10, 10, 20, 20), quad_points=quad_points))
+    target = PdfWriter().add_blank_page(100, 100)
+
+    target.merge_page(source.pages[0])
+
+    assert len(target["/Annots"]) == 1