QtCS25 - Rich Text editing in Qt Quick

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Session Summary

Discussion of some past work, work in progress and ideas

Session Owners

Shawn Rutledge

Notes

TextDocument

Existed in Qt 5 (mostly unchanged through 6.6) only to expose TextEdit's document to C++.

A while back we added some QML-facing features: 

TextDocument.source = "mydoc.md"
TextDocument.save()
TextDocument.saveAs("export.html")

But maybe such ad-hoc convenience APIs for I/O are dangerous? Should we go for a standard JS I/O API instead? Nobody expressed being worried, but Andy mentioned https://git.qt.io/annichol/FileAccess

TextSelection

The user can select text, and then we can change things on that single selection: 

TextEdit.cursorSelection.alignment
TextEdit.cursorSelection.color
TextEdit.cursorSelection.font (not a color!)
TextEdit.cursorSelection.text

Proposal for 6.10: programmatic editing https://codereview.qt-project.org/c/qt/qtdeclarative/+/523731

  • declare (or createObject()) one or more non-vlsual selections as you like
  • add some invokables
    • linkTo() was what I needed first...
    • tooltip - qqc? alt text?
    • underlinestyle
    • anchors
    • what else?

Feedback/discussion:

  • this is not the same as QTextCursor API. But can it do everything QTextCursor can do?
    • maybe call it TextCursor to match C++? (I'm not fond of that idea)
  • functionality to test:
    • insertion (what if start == end and you set text = "something")
    • setting tooltips AKA "alt" text in links
    • anchors
    • RTL (probably Igor Khanin will help with that)
    • Try to create a code editor with syntax highlighting, line numbers, background colors etc.
  • this API is not inspired by anything from the JS world. What else is out there?
    • CodeMirror
    • Monaco
    • Scintilla api is also a nice C++ API FWIW.

Other

Other things were on the agenda but we ran out of time.

Igor did a search on sourcegraph.com: found 9 projects where QAbstractTextDocumentLayout was subclassed. But he says there are not good enough docs about how to subclass it.

RTL is one reason to subclass it; but it may not work as well in Qt Quick as in widgets (albeit there are corner-case RTL bugs there too)

qtbase/tests/manual/textrendering/codeeditor was a fine example: got removed during the example-vandalism of last year, and now we don't have a code editor that does line numbers. Except for Creator, of course.

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