SyncTeX binary precedence over synctex.js?

[James-Yu]

[Internal Discussion]

As per #4181 (comment) and #4168, I did not find the column-locating code for synctexjs we have been using. I also backtrace a few years code in the past and did not find that. Strangely both you @jlelong and I seem to have an impression on the feature.

I also checked (roughly) the code on invoking SyncTeX binary and figured that the binary indeed returns with a column index:

LaTeX-Workshop/src/locate/synctex.ts

Lines 98 to 101 in 6c63cc3

	if (key === 'line' || key === 'column') {
	record[key] = Number(value)
	continue
	}

instead of the 0-column of synctexjs:

LaTeX-Workshop/src/locate/synctex/worker.ts

Line 236 in 6c63cc3

return input ? { input, line: record.line, column: 0 } : undefined

But now we have latex-workshop.synctex.synctexjs.enabled defaults to true:

LaTeX-Workshop/package.json

Lines 1682 to 1687 in 6c63cc3

	"latex-workshop.synctex.synctexjs.enabled": {
	"scope": "window",
	"type": "boolean",
	"default": true,
	"markdownDescription": "Enable using a builtin synctex function. The command set in latex-workshop.synctex.path will not be used."
	},

What about we return to first try the binary, if anything went wrong (not found, non-zero return), we fallback to the javascript implementation to balance the utility and availability? We may also remove this config if so, or change the purpose of it to be overriding this new logic. May I� have your thoughts? @jlelong

[jlelong]

I have good news: we are not crazy yet! I have managed to trace back to the column-locating code. It was introduced in #1161. It is still alive

LaTeX-Workshop/src/locate/synctex.ts

Lines 471 to 492 in ee13477

	function getRowAndColumn(doc: vscode.TextDocument, row: number, textBeforeSelectionFull: string, textAfterSelectionFull: string) {
	let tempCol = getColumnBySurroundingText(doc.lineAt(row).text, textBeforeSelectionFull, textAfterSelectionFull)
	if (tempCol !== null) {
	return [row, tempCol]
	}
	if (row - 1 >= 0) {
	tempCol = getColumnBySurroundingText(doc.lineAt(row - 1).text, textBeforeSelectionFull, textAfterSelectionFull)
	if (tempCol !== null) {
	return [row - 1, tempCol]
	}
	}
	if (row + 1 < doc.lineCount) {
	tempCol = getColumnBySurroundingText(doc.lineAt(row + 1).text, textBeforeSelectionFull, textAfterSelectionFull)
	if (tempCol !== null) {
	return [row + 1, tempCol]
	}
	}
	return [row, 0]
	}

Ctrl-clicking inside the pdf calls

LaTeX-Workshop/src/preview/viewer.ts

Line 300 in 614eec1

void lw.locate.synctex.toTeX(data, uri.fsPath)

If I understand correctly, synctex does provide a column number but it can be quite inaccurate. The function getRowAndColumn tries to fix it.

[James-Yu]

Thats awesome! I will look into the implementation c.f. #4181 #4168