Undo stack is lost after theme change #51
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cengels
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Dec 21, 2020
There should now be no char formats in the document (apart from char formats for bold and italics) at any point. Everything is done either by the document's default font options, the TextFormatter class, or updatePaintNode() directly. When pasting, the pasted HTML is now dissected and all non-bold non-italics formats cleanly removed before it is passed on to the QTextDocument. When changing themes, we unfortunately still have to go through the whole document and set the new block formats on each block one-by-one. This is unavoidable due to the way QTextDocument is structured and the fact that there is no way to access its individual block formats (methods like QTextDocument::allFormats() only return copies). This also results in some issues with the undo/redo system since you can't exclude block format changes from the undo/redo system (see #51).
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This is a limitation of the Qt framework. At the moment it is not possible to temporarily disable the
QTextDocument's undo manager, nor is it possible for changes to block formats to not be recorded into the current undo command (unlike char formats, which can useQSyntaxHighlighterorQTextLayout::setFormats()to accomplish this).As a result, the function
FormattableTextArea::updateDocumentDefaults()deliberately clears the undo stack after a theme change so that it is not possible to corrupt the document by undoing the new theme's block formats.There is no easy way to work around this. The only solution I can see is to disable
QTextDocument's undo manager entirely and implement a custom undo manager, but that's an enormous amount of work for comparably little payoff. Hm...The text was updated successfully, but these errors were encountered: