MAINT: Rename PdfWriter.create_viewer_preferences to PdfWriter.create_viewer_preferences (#2190)

Add documentation and fix a method name as discussed in #2105

Author: marcstober

CONTRIBUTORS.md

@@ -54,6 +54,7 @@ history and [GitHubs 'Contributors' feature](https://github.com/py-pdf/pypdf/gra
 * [WevertonGomes](https://github.com/WevertonGomesCosta)
 * [Wilson, Huon](https://github.com/huonw)
 * ztravis
+* [Stober, Marc](https://github.com/marcstober)
 
 ## Adding a new contributor
 

docs/index.rst

@@ -35,6 +35,7 @@ You can contribute to `pypdf on GitHub <https://github.com/py-pdf/pypdf>`_.
    user/add-watermark
    user/reading-pdf-annotations
    user/adding-pdf-annotations
+   user/viewer-preferences
    user/forms
    user/streaming-data
    user/file-size

docs/user/viewer-preferences.md

@@ -0,0 +1,79 @@
+# Adding Viewer Preferences
+
+It is possible to set viewer preferences of the PDF file.
+These properties are described in Section 12.2 of the [PDF 1.7 specification](https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008.pdf).
+
+Note that the `\ViewerPreferences` dictionary does not exist by default.
+If it's not already present, it must be created by calling the `create_viewer_preferences` method
+of the `PdfWriter` object.
+
+If viewer preferences exist in a PDF file being read with `PdfReader`,
+you can access them as properties of the `viewer_preferences` properties.
+Otherwise, the `viewer_preferences` property will be set to `None`.
+
+## Example
+
+```python
+from pypdf import PdfWriter
+from pypdf.generic import ArrayObject, NumberObject
+
+writer = PdfWriter()
+
+writer.create_viewer_preferences()
+
+# /HideToolbar
+writer.viewer_preferences.hide_toolbar = True
+# /HideMenubar
+writer.viewer_preferences.hide_menubar = True
+# /HideWindowUI
+writer.viewer_preferences.hide_windowui = True
+# /FitWindow
+writer.viewer_preferences.fit_window = True
+# /CenterWindow
+writer.viewer_preferences.center_window = True
+# /DisplayDocTitle
+writer.viewer_preferences.display_doctitle = True
+
+# /NonFullScreenPageMode
+writer.viewer_preferences.non_fullscreen_pagemode = "/UseNone"  # default
+writer.viewer_preferences.non_fullscreen_pagemode = "/UseOutlines"
+writer.viewer_preferences.non_fullscreen_pagemode = "/UseThumbs"
+writer.viewer_preferences.non_fullscreen_pagemode = "/UseOC"
+
+# /Direction
+writer.viewer_preferences.direction = "/L2R"  # default,
+writer.viewer_preferences.direction = "/R2L"
+
+# /ViewArea
+writer.viewer_preferences.view_area = "/CropBox"
+# /ViewClip
+writer.viewer_preferences.view_clip = "/CropBox"
+# /PrintArea
+writer.viewer_preferences.print_area = "/CropBox"
+# /PrintClip
+writer.viewer_preferences.print_clip = "/CropBox"
+
+# /PrintScaling
+writer.viewer_preferences.print_scaling = "/None"
+writer.viewer_preferences.print_scaling = "/AppDefault"  # default according to PDF spec
+
+# /Duplex
+writer.viewer_preferences.duplex = "/Simplex"
+writer.viewer_preferences.duplex = "/DuplexFlipShortEdge"
+writer.viewer_preferences.duplex = "/DuplexFlipLongEdge"
+
+# /PickTrayByPDFSize
+writer.viewer_preferences.pick_tray_by_pdfsize = True
+# /PrintPageRange
+writer.viewer_preferences.print_pagerange = ArrayObject(
+    [NumberObject("1"), NumberObject("10"), NumberObject("20"), NumberObject("30")]
+)
+# /NumCopies
+writer.viewer_preferences.num_copies = 2
+
+for i in range(40):
+    writer.add_blank_page(10, 10)
+
+with open("output.pdf", "wb") as output_stream:
+    writer.write(output_stream)
+```

pypdf/_writer.py

@@ -384,7 +384,7 @@ def viewer_preferences(self) -> Optional[ViewerPreferences]:
                 self._root_object[NameObject(CD.VIEWER_PREFERENCES)] = o
         return o
 
-    def create_viewer_preference(self) -> ViewerPreferences:
+    def create_viewer_preferences(self) -> ViewerPreferences:
         o = ViewerPreferences()
         self._root_object[NameObject(CD.VIEWER_PREFERENCES)] = self._add_object(o)
         return o

pypdf/generic/_viewerpref.py

@@ -140,8 +140,6 @@ def _add_prop_int(key: str, deft: Optional[int]) -> property:
         cls.print_pagerange = _add_prop_arr("/PrintPageRange", None)
         cls.num_copies = _add_prop_int("/NumCopies", None)
 
-        # still to be done /PrintPageRange and /NumCopies
-
         return DictionaryObject.__new__(cls)
 
     def __init__(self, obj: Optional[DictionaryObject] = None) -> None:

tests/test_writer.py

@@ -1774,10 +1774,7 @@ def test_damaged_pdf_length_returning_none():
 
 @pytest.mark.enable_socket()
 def test_viewerpreferences():
-    """
-    Add Tests for ViewerPreferences
-    https://github.com/py-pdf/pypdf/issues/140#issuecomment-1685380549
-    """
+    """Add Tests for ViewerPreferences"""
     url = "https://github.com/py-pdf/pypdf/files/9175966/2015._pb_decode_pg0.pdf"
     name = "2015._pb_decode_pg0.pdf"
     reader = PdfReader(BytesIO(get_data_from_url(url, name=name)))
@@ -1828,8 +1825,10 @@ def test_viewerpreferences():
     v.print_pagerange = ArrayObject()
     assert len(v.print_pagerange) == 0
 
-    writer.create_viewer_preference()
+    writer.create_viewer_preferences()
     assert len(writer._root_object["/ViewerPreferences"]) == 0
+    writer.viewer_preferences.direction = "/R2L"
+    assert len(writer._root_object["/ViewerPreferences"]) == 1
 
     del reader.trailer["/Root"]["/ViewerPreferences"]
     assert reader.viewer_preferences is None