Collabora Online now takes the visible area (viewport) of large Writer documents into account in more cases, leading to better performance & interactivity.

Motivation¶

Collabora Online has two kinds of "visible areas" for a document: on one hand, the entire document is visible, so in case any part of the document changes, the browser client gets notified; on the other hand, there is a viewport in the web browser, and keeping that up to date is a priority, compared to the rest of the document.

There were some cases in the past where we handled the entire document with the same priority, leading to slower than ideal update times on the UI.

Wouldn't it be nice to always update the visible part first, and only then deal with the rest, on idle?

Results so far¶

When looking at this topic, we noticed a cluster of problems:

First, consider the case of a long (~300 pages) document, where you insert a page break at the start and wait for the update of the visible area. The entire document layout (now 301 pages) were calculated, and now we do this for the visible area synchronously (and the rest on idle). This operation is now about 19 times faster.

Second, loading a long document calculated the entire layout before showing the first page. This is now improved, the document loading time itself at a LOK API level for such a long document is now about 5 times faster.

Third, COOL didn't consider the priority of core tasks when interrupting to do its own work (COOL's document editing process and LibreOffice core shares the same main loop). Now we do this, categorizing the core tasks into "high priority" and "low priority" buckets and we only interrupt when core doesn't have high priority tasks any more (this is only in 25.04).

Fourth, there was no easy access to a large Writer document during development. Now make run COOL_WRITER_LARGE=y allows opening a long document in your local browser for development / testing purposes.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

As usual, the high-level problem was addressed by a series of small changes:

• cool#11064 kit: send the client's visible area during file load
• cool#11064 kit: check for callbacks & wsd socket in the anyInput callback
• cool#11064 any input: conditionally consider priority of core tasks
• cool#11064 any input: add page insert testcase
• cool#11064 test: support creating a large Writer document with many pages

The tracking issue was cool#11064.

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition.

Writer has the concept of paragraph margins and page margins, but what happens when you combine the two? It turns out the expectation is that sometimes the top paragraph margin is ignored in this case. We'll see two cases where the behavior of Writer is now improved to better match Word in this regard.

This work is primarily for Collabora Online, but the feature is available in desktop Writer as well.

Motivation¶

As described in a previous bugreport, there was a first problem where Word ignored the top paragraph margin of a document, but Writer did not. A recent bugreport then pointed out that the first implementation went too far and now a wanted top margin was ignored. This lead to a set of conditions which now does a decent emulation of Word's rules in this regard.

Results so far¶

Here is the old Writer render result for a document where the top margin should be ignored:

And here is the new Writer render result for a document where the top margin is ignored:

Finally, the reference render result, showing the ignored top paragraph margin:

As you can see, now the unwanted top paragraph margin is omitted at page top.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

As usual, the high-level problem was addressed by a series of small changes:

• tdf#160952 sw: ignore top margin of para on non-first pages with newer DOCX
• tdf#164095 sw: fix missing top margin on paragraph after changing page style

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition. Collabora intends to continue supporting and contributing to LibreOffice, the code is merged so we expect all of this work will be available in TDF's next release too (25.2).

Impress shape text doesn't have much support for styles, e.g. the default UI in Writer gives you a paragraph style dropdown, and you don't get the same in Impress. Still, a paragraph style is attached to bullets based on their outline level, and Impress has a View → Outline menu item to give you that styled text you can copy. Pasting that to Writer started to lose styles recently and it's now fixed to work again.

This work is primarily for Collabora Online, but the feature is available in desktop Impress as well.

Motivation¶

As described in a previous commit, I had a case where lots of not needed paragraph styles were exported to RTF in case an Impress document had enough master pages. The idea was to only export actually used paragraph styles, to avoid wasting CPU power.

Turns out filtering out paragraph styles has to happen at two locations:

• in the style table to assign an index to a paragraph style
• when referring to those styles

The problem was that unused styles were removed from the style table, but not from the style → index mapping, so as soon as you had both used and unused paragraph styles, the declared and the referred style indexes didn't match anymore.

Results so far¶

Here is a sample paste result in Writer, where you can see that the text doesn't have a custom paragraph style:

And here is the same paste, now with paragraph styles restored:

As you can see, now the pasted text has paragraph styles.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

The bugfix commit was editeng RTF export: fix broken offsets into the para style table.

The tracking bug was tdf#163883.

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition. Collabora intends to continue supporting and contributing to LibreOffice, the code is merged so we expect all of this work will be available in TDF's next release too (25.2).

Writer TextBoxes provide the user with shapes that can have complex geometry and complex content. There is also a feature to capture shapes inside page boundaries: now the two features interact with each other better.

This work is primarily for Collabora Online, but the feature is available in desktop Writer as well.

Motivation¶

As described in a previous post, Writer implements the TextBox feature with a pair of objects: a Draw shape (with complex geometry) and a (hidden) Writer TextFrame, providing complex content. To avoid wrapping problems, the underlying TextFrame always has its wrap type set to "through", i.e. text may wrap around the Draw shape, but the hidden TextFrame is always ignored during text wrapping.

In most cases this provides the expected behavior, because the user sees one object, so wrapping around at most one object is not surprising.

However, there is also an other feature, that shapes may be captured inside page frames: if their position would be outside the page frame, Writer corrects this, so they are not off-page. This also makes sense, so it can't happen that your document has a shape that is hard to find, due to a silly position.

The trouble comes when these two are combined: the Draw shape's position gets adjusted to be captured inside the page frame, but the TextFrame's wrap type is "through", and objects with this wrap type are an exception from the capturing mechanism, so the position of the two shapes get out of sync.

Results so far¶

The problem is now solved by improving the layout, so in case the TextFrame is actually part of a Draw shape + TextFrame pair (forming a TextBox), then we calculate the effective wrap type of the TextFrame based on the wrap type of its Draw shape, so either both objects are captured or none, which results in consistent render result.

Here is a sample document where all margins are configured to be equal, but capturing corrected the Draw shape (and not the TextFrame):

And here is the same document, with consistent positioning:

As you can see, now the rendered margins actually equal, as wanted.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

The bugfix commit was sw textbox: capture fly when its draw object is captured.

The tracking bug was tdf#138711.

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition. Collabora intends to continue supporting and contributing to LibreOffice, the code is merged so we expect all of this work will be available in TDF's next release too (25.2).

The SVG export in Impress now supports a per-paragraph setting to handle semi-transparent shape text, while previously this was only possible to control at a per-shape level.

This work is primarily for Collabora Online, but the feature is available in desktop Impress as well.

Motivation¶

As described in a previous post, Impress already had the capability to have semi-transparent shape text, but the SVG export of this for the case when not all paragraphs have the same setting was broken.

Transparency in SVG can be described as a property of a group (<g style="opacity: 0.5">...</g>) and it can be also a property of the text (<tspan fill-opacity="0.5">...</tspan>).

The SVG export works with the metafile of the shape, so when looking for meta actions, it tries to guess if the transparency will be for text: if so, it needs to use the tspan markup, otherwise going with the g markup is OK.

What happened here is that meta action for a normal text started, so the SVG export assumed the text is not semi-transparent, but later the second line was still transparent, so we started a group element, and this resulted in a not even well-formed XML output.

Results so far¶

The relevant part of the test document is simple: just 3 paragraphs, the second one is semi-transparent (and also has a bullet, as an extra):

Once this was exported to SVG, this resulted in a non-well-formed XML, so you got this error in a web browser:

Once tweaking the transparency mask writer to check if text started already, we get the correct SVG render:

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

The bugfix commit was SVG export: fix handling of semi-transparent text inside a list.

The tracking bug was tdf#162782.

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition. Collabora intends to continue supporting and contributing to LibreOffice, the code is merged so we expect all of this work will be available in TDF's next release too (25.2).

Writer now has support for doing partial layout passes when LOK clients have pending events, which sometimes improves interactivity a lot.

This work is primarily for Collabora Online, but the feature is useful for any LOK clients.

Motivation¶

I recently worked with a document that has relatively simple structure, but it has 300 pages, and most of the content is part of a numbered list. Pasting a simple string (like an URL) into the end of a paragraph resulted in a short, but annoying hang. It turns out we updated Writer's layout for all the 300 pages before the content was repainted on the single visible page. In theory, you could reorder events, so you first calculate the first page, you paint the first page, then you calculate the remaining 299 pages. Is this possible in practice? Let's try!

Results so far¶

The relevant part of the test document is simple: just an empty numbered paragraph, so we can paste somewhere:

This is a good sample, because pasting into a numbered list requires invalidating all list items in that list, since possibly the paste operation created a new list item, and then the number portion has to be updated for all items in the rest of the list. So if you paste into a numbered list, you need to re-calculate the entire document if all the document is just a numbered list.

The first problem was that Writer tracks its visible area, but LOK needs two kinds of visible areas. The first kind decides if invalidations are interesting for part of the document area. LOK wants to get all invalidations, so in case we cache some document content in the client that is near the visible area, we need to know when to throw away that cache. On the other hand, we want to still track the actually visible viewport of the client, so we can prioritize visible vs hidden parts of the document. Writer in LOK mode thought that all parts of the document are a priority, but this could improved by taking the client's viewport into account.

The second problem was that even if Writer had two layout passes (first is synchronous, for the visible area; second is async, for the rest of the document), both passes were performed before allowing a LOK client to request tiles for the issued invalidations.

This is now solved by a new registerAnyInputCallback() API, which allows the LOK client to signal if it has pending events (e.g. unprocessed callbacks, tiles to be painted) or it's OK for Writer layout to finish its idle job first.

The end result for pasting a URL into this 300 pages document, when measuring end-to-end (from sending the paste command to getting the first updated tile) is a decrease in response time, from 963 ms to 14 ms.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

As usual, the high-level problem was addressed by a series of small changes:

• cool#9735 sw lok: take LOK vis area into account when deciding idle layout
• Related: cool#9735 vcl lok: add an AnyInput() callback
• Related: cool#9735 sw lok: handle the AnyInput() callback during idle layout
• sfx2: fix crash in SfxObjectShell::IsHelpDocument()

The tracking issue for this problem was cool#9735.

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition. Collabora intends to continue supporting and contributing to LibreOffice, the code is merged so we expect all of this work will be available in TDF's next release too (25.2).

Writer now has improved support for font fallback when you open a DOCX file that refers to fonts which are not available currently.

This work is primarily for Collabora Online, but the feature is fully available in desktop Writer as well.

Motivation¶

Font embedding is meant to solve the problems around missing fonts, but you can also find documents with stub embedded fonts that are to be ignored and our code didn't have any sanity check on such fonts, leading to unexpected glyph-level fallbacks. Additionally, once font-level fallback happened, we didn't take the font style (e.g. sans vs serif) into account, which is expected to work when finding a good replacement for the missing font.

Results so far¶

Here is how to the original rendering looked like:

Once the handler for the embedded fonts in ODT/DOCX was improved to ignore stub fonts where even basic glyphs were not available, the result was a bit more consistent, but still bad. Here is a different document to show the problem:

Note how now we used the same font, but the glyphs are always sans, not serif. So the final step was to import the font type from DOCX and consider that while deciding font fallback:

With this, we ignore stub embedded fonts from DOCX, we import the font type and in general font fallback on Linux takes the font type into account while deciding font fallback.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

As usual, the high-level problem was addressed by a series of small changes:

• tdf#162002 DOCX import: ignore subsetted embedded fonts for editing
• tdf#162002 DOCX import, font embed: only discard subset fonts with few glyphs
• tdf#162072 vcl, fontconfig: consider font-family-generic for substitute
• Related: tdf#162072 DOCX import: handle font family for characters
• tdf#162280 vcl: consider font family type for glyph caching

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition. Collabora intends to continue supporting and contributing to LibreOffice, the code is merged so we expect all of this work will be available in TDF's next release too (24.8).

Writer now has improved support for toplevel line shapes when you import those from DOCX.

This work is primarily for Collabora Online, but the feature is fully available in desktop Writer as well.

Motivation¶

As described in a post from 2014, Writer reads the drawingML markup for shapes in DOCX files, including line shapes. While investigating a simple-looking problem around a horizontal vs vertical line, it turns out that there is a deeper issue here, and it looks like now have proper fix for this bug.

Results so far¶

Imagine that your company template has a nice footer in two columns, and the content in the columns are separated by a vertical line shape, but when you open your DOCX in Writer, it crosses the text of that footer instead:

While researching how line shapes are represented in our document model and how ODT import works, it turned out that the proper way to create a line shape is to only consider size / scaling when it comes to the individual points of the line, everything else (e.g. position / translation) should go to the transform matrix of the shape, then the render result will be as expected:

It was also interesting to see that this also improved other, existing test documents, e.g. core.git sw/qa/extras/ooxmlimport/data/line-rotation.docx looked like this before:

And the same fix makes it perfect:

Just stick to the rule: scaling goes to the points -- translation, rotation and horizontal shear goes to the shape.

For now, this is only there for toplevel Writer lines, but in-groupshape and Calc/Impress lines could also follow this technique if there is a practical need.

The "after" screenshots show ~no red, which means there is ~no reference output, where the Writer output would be missing.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

The bugfix commit was tdf#161779 DOCX import, drawingML: fix handling of translation for lines.

The tracking bug was tdf#161779.

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition. Collabora intends to continue supporting and contributing to LibreOffice, the code is merged so we expect all of this work will be available in TDF's next release too (24.8).

Writer now has much better support for continuous / inline endnotes (not on a separate page) in Writer, enabled by default for DOCX files.

This work is primarily for Collabora Online, but the feature is fully available in desktop Writer as well.

Motivation¶

As described in a previous post, Writer already had minimal support for not rendering endnotes on a separate endnote page, but it was not mature enough to enable is by default for DOCX files.

Results so far¶

What changed from the previous "continuous endnotes" approach is that instead of trying to map endnotes to footnotes, we now create a special endnotes section, which only exists at a layout level (no section node is backing this one), and this hosts all endnotes at the end of the document. It turns out this is a much more scalable technique, for example a stress-test with 72 endnotes over several pages is now handled just fine.

Here are some screenshots:

As you can see, there were various differences for this document, but the most problematic one was that the entire endnote was missing from the (originally) last page, as it was rendered on a separate page.

Now it's not only on the correct page, but also its position is correct: the endnote is after the body text, while the footnote is at the bottom of the page, as expected. The second screenshot shows ~no red, which means there is ~no reference output, where the Writer output would be missing.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

As usual, the high-level problem was addressed by a series of small changes:

• tdf#160984 sw continuous endnotes: introduce an endnote section
• tdf#160984 sw continuous endnotes: add a way to find the endnote section start
• tdf#160984 sw continuous endnotes: fix testContinuousEndnotesMoveBackwards
• tdf#160984 sw continuous endnotes: fix CppunitTest_sw_layoutwriter3
• tdf#160984 sw continuous endnotes: switch to a section-based layout
• tdf#161083 sw continuous endnotes: fix layout with a section at doc end
• tdf#160984 sw continuous endnotes, DOC import: enable this unconditionally
• tdf#160984 sw continuous endnotes: enable DOCX import
• tdf#160984 sw continuous endnotes: fix the endnote container's top margin
• tdf#160984 sw continuous endnotes: fix the endnote separator position
• tdf#160984 sw continuous endnotes: fix the endnote separator length
• tdf#160984 sw continuous endnotes: fix crash on loading forum-mso-en-7731.docx
• tdf#160984 sw continuous endnotes: DOCX: import <w:endnotePr> pos == sectEnd
• tdf#160984 sw continuous endnotes: DOCX: export of <w:endnotePr> pos == sectEnd
• tdf#160984 sw continuous endnotes: fix the endnote continuation separator len
• tdf#160984 sw continuous endnotes: hide not functional UI in this mode

The tracking bug was tdf#160984.

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition. Collabora intends to continue supporting and contributing to LibreOffice, the code is merged so we expect all of this work will be available in TDF's next release too (24.8).

Collabora Online now uses the Clipboard API if it's available in the used browser, getting rid of many annoying dialogs.

Motivation¶

The paste side was covered by an earlier post, but in short, if you're on Chrome (or Safari), you won't see the "can't paste" dialog:

Also you won't see a "Can't paste special" dialog:

Wouldn't it be nice to improve the copy side in a similar way?

Results so far¶

The primary reason why we needed similar, annoying dialogs for copy in the past is that the clipboard API was synchronous but the network API is async. This means that writing to the clipboard ("copy") is only possible with data that we have in the browser when the copy is executed. This is a problem, since in general we don't have data for your selection in the browser.

With the Clipboard API, the copy side can be improved as well. Instead of always fetching the HTML for a simple selection (even if you don't copy) and having a three step copy for complex selections, async clipboard write is now possible. This gets us rid of the "You need to download" dialog:

Also it eliminates the "Download completed dialog:

Instead, we still need to nominally write to the clipboard in the special keyboard or click context initiating the copy (Chrome doesn't require this, Safari does), but the written object can be a callback that will do the network operation for us.

Unfortunately it's hard to screenshot the new code, since part of the result is that all these dialogs are now eliminated, copy & paste just works. :-)

Note that this can be used also in Firefox, but first you need to set dom.events.asyncClipboard.clipboardItem to true in about:config.

The last part was to adapt tests to this new world, because previously it was handy to just create a selection and assert what would be copied to the clipboard as HTML, but now we don't download the HTML anymore every time you create a selection.

How is this implemented?¶

If you would like to know a bit more about how this works, continue reading... :-)

As usual, the high-level problem was addressed by a series of small changes:

• Related: cool#8648 clipboard: extract parseClipboard() from Control.DownloadProgress.js
• Related: cool#8648 clipboard: use JSON when requesting HTML only
• cool#8648 clipboard: try to use navigator.clipboard.write()
• cool#8648 clipboard: fix desktop/writer/copy_paste_spec.js
• cool#8648 clipboard: fix desktop/calc/clipboard_spec.js
• cool#8648 clipboard: fix desktop/writer/undo_redo_spec.js
• cool#8648 clipboard: fix desktop/writer/track_changes_spec.js
• cool#8648 clipboard: fix most of desktop/writer/top_toolbar_spec.js
• cool#8648 clipboard: fix insert hyperlink dialog
• cool#8648 clipboard: fix desktop/writer/table_operation_spec.js
• cool#8648 clipboard: fix desktop/writer/searchbar_spec.js
• cool#8648 clipboard: fix desktop/writer/notebookbar_spec.js
• cool#8648 clipboard: fix desktop/writer/editable_area_spec.js
• cool#8648 clipboard: fix desktop/impress/undo_redo_spec.js
• cool#8648 clipboard: fix desktop/impress/delete_objects_spec.js
• cool#8648 clipboard: fix desktop/calc/undo_redo_spec.js
• cool#8648 clipboard: fix desktop/calc/top_toolbar_spec.js
• cool#8648 clipboard: fix desktop/calc/searchbar_spec.js
• cool#8648 clipboard: fix desktop/calc/searchbar_spec.js
• cool#8648 clipboard: fix desktop/calc/focus_spec.js
• cool#8648 clipboard: fix desktop/calc/delete_objects_spec.js
• cool#8648 clipboard: fix desktop/calc/autofilter_spec.js
• cool#8648 clipboard: fix desktop/calc/cell_appearance_spec.js
• cool#8648 clipboard: fix mobile/calc/apply_font_spec.js
• cool#8648 clipboard: fix mobile/calc/autofilter_spec.js
• cool#8648 clipboard: fix mobile/calc/bottom_toolbar_spec.js
• cool#8648 clipboard: fix mobile/calc/cell_appearance_spec.js
• cool#8648 clipboard: fix mobile/calc/delete_objects_spec.js
• cool#8648 clipboard: fix mobile/calc/insertion_wizard_spec.js
• cool#8648 clipboard: fix mobile/calc/searchbar_spec.js
• cool#8648 clipboard: fix mobile/calc/spellchecking_spec.js
• cool#8648 clipboard: fix mobile/impress/delete_objects_spec.js
• cool#8648 clipboard: fix mobile/impress/impress_focus_spec.js
• cool#8648 clipboard: fix mobile/impress/insertion_wizard_spec.js
• cool#8648 clipboard: fix mobile/impress/spellchecking_spec.js
• cool#8648 clipboard: fix mobile/writer/apply_font_spec.js
• cool#8648 clipboard: fix mobile/writer/delete_objects_spec.js
• cool#8648 clipboard: fix mobile/writer/insert_formatting_mark_spec.js
• cool#8648 clipboard: fix mobile/impress/insertion_wizard_spec.js
• cool#8648 clipboard: fix mobile/writer/track_changes_spec.js
• cool#8648 clipboard: fix mobile/writer/table_properties_spec.js
• cool#8648 clipboard: stop fetching the clipboard on text selection create in tests
• cool#8648 clipboard: fix idle tests

The tracking issue was cool#8648.

Want to start using this?¶

You can get a development edition of Collabora Online 24.04 and try it out yourself right now: try the development edition.