Pass imageLayer to PDFPageView

[websirnik]

This pull request allows passing a custom imageLayer when creating a new PDFPageView.

var pdfPageView = new pdfjsViewer.PDFPageView({
    container: container,
    id: PAGE_TO_VIEW,
    scale: SCALE,
    defaultViewport: pdfPage.getViewport(SCALE),
    imageLayer: {
        beginLayout: function (){},
        endLayout: function (){},
        appendImage: function(img){}
    }
});

[timvandermeij]

Could you elaborate a bit on the use case for this? I'm not really seeing why we should have this as a parameter in the library (it sounds like something that may be useful for a custom version, but not really for the library itself).

[timvandermeij]

Missing trailing comma.

[timvandermeij]

The documentation for PDFPageViewOptions above needs to be updated too.

[Snuffleupagus]

Could you elaborate a bit on the use case for this? I'm not really seeing why we should have this as a parameter in the library (it sounds like something that may be useful for a custom version, but not really for the library itself).

Isn't another problem also that the imageLayer functionality is both completely unused and untested as-is. Before surfacing this functionality more prominently, shouldn't e.g. unit-tests be added first such that the relevant code-paths are actually exercised!?

(Also, if a new option is added in PDFPageView, it really should be added to BaseViewer as well.)

[websirnik]

imageLayer implementation was partly already in the codebase but was never finished. The use case for me was to collect images on a page via appendImage(img) and create a custom image zoom-in experience after.

Since the is no API call to get the images on a page, imageLayer feels like a good solution. I can add documentation & tests. Should I proceed?

[timvandermeij]

Thank you for sharing the use case. I'm personally fine with this as long as there are (unit) tests for it so that we can make sure that it doesn't break in a future update.

[timvandermeij]

I'm going to close this since it cannot be merged in the current state and there was no more activity. If you want to add tests and documentation and fix the linting issues, please open a new pull request for the patch so it can be reviewed again. Thank you.