TextAlignment

Proposed Solution

Considering the thoughts of the previous chapter the following solution has been worked out:

• Internally keep OOo's text alignment values LEFT and RIGHT with the current meaning and impact. The intention to keep these text alignment values is that they are only used for ODF documents which are created by former OOo versions which still have issue 105270 and for the support of the existing UNO-APIs in order not to break existing extensions, macros, etc. which are using these UNO-APIs.
• Internally introduce new text alignment values START and END corresponding to ODF's left/start and right/end text alignment values. Additionally, the text formatting has to be adjusted to support these new text alignment values accordingly.
• Adjustment of the user interface.
  • Keep the terms left and right for the text alignment:
    • Format dialogs for paragraphs, table cells and styles have to be made aware of the writing direction of the to be formatted object/objects or of the document. By this it can be assured that the text alignment values START and END are mapped to the right terms left, right, left/top and right/bottom and vice versa.
    • This has the drawback that for certain use cases the writing direction of the to be formatted objects is ambiguous. To be deterministic in all use cases the following solutions are implemented:
      • In text documents the writing direction of the paragraph in which the cursor is in is taken.
      • In drawing objects and in table cells of Calc sheets OOo does not support different writing directions for its paragraphs table cells -> no drawbacks here.
      • For two or more table cells with different writing directions in a Calc sheet the sheet's default writing direction is taken.
  • Formatting Toolbar buttons "Align left" and "Align right": Keep the actual terms and its visualization in its icons in order to visual reflect the behavior of these buttons. Internally, the correct text alignment values START respectively END need to be applied at the paragraph/table cell in order to corresponding the visualized behavior. E.g., if toolbar button "Align left" is clicked and the cursor is placed in a paragraph with right-to-left writing direction text alignment value END needs to be applied.
  • Formatting Toolbar buttons "Left-to-Right" and "Right-to-Left" (visible, if enhanced support for complex text layout (CTL) has been enabled): Internally, the actual behavior of these functions are that the writing direction is set to left-to-right respectively right-to-left and the text alignment is set to LEFT respectively RIGHT. The setting of the text alignment needs to be adjusted to START for both functions.
• Introduce a new UNO-API for the text alignment of paragraphs - com::sun::star::style::ParagraphProperties::ParaTextAlign with the possible values START, END, BLOCK, CENTER and STRETCH. Values START and END correspond to the internally newly introduced text alignment values. The values BLOCK, CENTER and STRETCH are the same as the ones from the existing UNO-API com::sun::star::style::ParagraphProperties::ParaAdjust.
• Introduce a new UNO-API for the text alignment of paragraphs in table cells - com::sun::star::table::CellProperties::CellTextAlign with the possible values STANDARD, START, CENTER, END, BLOCK and REPEAT. Values START and END correspond to the internally newly introduced text alignment values. The values STANDARD, CENTER, BLOCK and REPEAT are the same as the ones from the existing UNO-API com::sun::star::table::CellProperties::HoriJustify.
• The ODF import filter has to distinguish two cases

Import of ODF documents which has been created by OOo versions which still have issue 105270. In this case ODF attribute fo:text-align is mapped using the existing UNO-APIs. This assures that such ODF documents are displayed as they are displayed in the OOo versions which still have issue 105270. We will get the following mapping:

fo:text-align value	maps to text alignment value
"left"	LEFT
"start"	LEFT
"right"	RIGHT
"end"	RIGHT

Import of other ODF documents. In this case the new UNO-APIs are used. We will get the following mapping:

fo:text-align value	maps to text alignment value
"left"	START
"start"	START
"right"	END
"end"	END

• The new UNO-APIs have to return START respectively END when the text alignment attribute has text alignment value LEFT respectively RIGHT set. For this conversion two cases need to be distinguished.

Conversion for a certain style:

text alignment value	writing direction of the style (*1)	maps to UNO-API text alignment value
LEFT	left-to-right	START
RIGHT	left-to-right	END
LEFT	right-to-left	END
RIGHT	right-to-left	START

Conversion for a certain paragraph or table cell:

text alignment value	writing direction of paragraph/table cell	writing direction of style (*1)	maps to UNO-API text alignment value
LEFT	left-to-right	left-to-right OR right-to-left	START
LEFT inherited from a style	left-to-right	right-to-left	START
RIGHT	left-to-right	left-to-right OR right-to-left	END
RIGHT inherited from a style	left-to-right	right-to-left	END
LEFT	right-to-left	left-to-right OR right-to-left	END
LEFT inherited from a style	right-to-left	left-to-right	END
RIGHT	right-to-left	left-to-right OR right-to-left	START
RIGHT inherited from a style	right-to-left	left-to-right	START

(*1) If the style has no writing direction set and does not inherit a writing direction from its parent style, the writing direction of the document is taken.

• Deprecate the existing UNO-APIs com::sun::star::style::ParagraphProperties::ParaAdjust and com::sun::star::table::CellProperties::HoriJustify. Document that these UNO-APIs are deprecated in favor of the new ones. Assure that at these deprecated UNO-APIs text alignment values LEFT and RIGHT are returned, when the newly introduced text alignment values START and END are set at the internal text alignment attribute. The conversion will be documented in the UNO-API documentation and has to distinguish two cases:

Conversion for a certain style:

text alignment value	writing direction of style (*2)	maps to UNO-API text alignment value
START	left-to-right	LEFT
END	left-to-right	RIGHT
START	right-to-left	RIGHT
END	right-to-left	LEFT

Conversion for a certain paragraph or table cell:

text alignment value	writing direction of paragraph/table cell	writing direction of style (*2)	maps to UNO-API text alignment value
START	left-to-right	left-to-right OR right-to-left	LEFT
START inherited from a style	left-to-right	right-to-left	LEFT
END	left-to-right	left-to-right OR right-to-left	RIGHT
END inherited from a style	left-to-right	right-to-left	RIGHT
START	right-to-left	left-to-right OR right-to-left	RIGHT
START inherited from a style	right-to-left	left-to-right	RIGHT
END	right-to-left	left-to-right OR right-to-left	LEFT
END inherited from a style	right-to-left	left-to-right	LEFT

(*2) If the style has no writing direction set and does not inherit a writing direction from its parent style, the writing direction of the document is taken.

• The ODF export filter will only use the newly introduced UNO-APIs. Thus, written ODF attribute fo:text-align="left"/"start" respectively fo:text-align="right"/"end" will be according to the ODF specification.
• Each export and import filter for foreign file formats needs to be reviewed and adjusted according to the above given conversions. In order to keep the current behavior of these filters in the first step they can rely on the existing text alignment values. In a follow-up task considering that in a future version the deprecated UNO-APIs will be removed and considering the foreign file format's text alignment definition further adjustments to the export and import filters can be made.

Import filters can continue to use the existing internal APIs or the existing UNO-APIs to set the text alignment values.

Export filters can also use the existing internal APIs or the existing, but deprecated UNO-APIs to retrieve the text alignment values. In the case that the existing internal APIs are used the new text alignment values START and END need to be converted as given above for the existing, but deprecated UNO-APIs.

Test cases for the proposed solution

Format Paragraph Dialog, Tab pane "Alignment"

• Test functionality of setting alignment and text direction
  • for one paragraph
    • no hard-set attribute values
    • hard-set attribute values equal to the default ones
    • hard-set attribute values different to the default ones
  • for two or more paragraphs with the same alignment/text direction attribute values
  • for two or more paragraphs with different alignment/text direction attribute values

Format Paragraph Style Dialog, Tab pane "Alignment"

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