quoc-ho
commented
3 months ago I wanted to add that the popular vscode-pdf also does not flicker when the pdf reloads. See this commit https://github.com/tomoki1207/vscode-pdfviewer/commit/6c4c96d5f380e8c8130b9e58138867d6036f291f.
This snippet in the commit seems to do it:
async function reload() {
// Prevents flickering of page when PDF is reloaded
const oldResetView = PDFViewerApplication.pdfViewer._resetView
PDFViewerApplication.pdfViewer._resetView = function () {
this._firstPageCapability = (0, pdfjsLib.createPromiseCapability)()
this._onePageRenderedCapability = (0, pdfjsLib.createPromiseCapability)()
this._pagesCapability = (0, pdfjsLib.createPromiseCapability)()
this.viewer.textContent = ""
}
// Changing the fingerprint fools pdf.js into keeping scroll position
const doc = await pdfjsLib.getDocument(config.path).promise
doc._pdfInfo.fingerprints = [config.path]
PDFViewerApplication.load(doc)
PDFViewerApplication.pdfViewer._resetView = oldResetView
}
James-Yu
Pre-checks
The Missed
After each compilation, the PDF viewer reloads the PDF with a flicker. Namely, instead of displaying the content of the new PDF seamlessly, a blank page briefly appears before being replaced by the new content.
It would be great to remove the flicker.
The Solution*
The PDF viewer of Overleaf-Workshop is also built on top of pdf.js but doesn't flicker when reloading the PDF. I think the main difference between what they do and LaTeX-Workshop is that when reloading, pdf.js object is not recreated (though I'm not familiar with the code base of LaTeX-Workshop enough to say). Moreover, they also read the content of the PDF file into a byte array before handing it to pdf.js, which might have reduced the latency.
Anything Else?
The amount of code related to PDF viewing in Overleaf-Workshop is quite small. So probably/hopefully, the amount of work needed to implement this in LaTeX-Workshop is also small. I tried to look into this myself, but I found the PDF viewing code in LaTeX-Workshop a bit complicated for me to do it quickly since I'm not very familiar with the codebase.
Even if the maintainers of LaTeX-Workshop decide that it's not worth the trouble, having this available here might help others who want to do this themselves.
Thank you!