Fixed partial print issue on IE / Edge

[pixelbits-mk]

Fixed partial print issue for IE / Edge as described in issue #3983.

Issue Description
When printing a PDF from the PDF.js viewer, pages are being cutoff near the bottom of the page.

Steps to reproduce

1. Open a PDF from PDF.js viewer
2. Click the "Print" button
3. Select a printer and continue to print
4. On the printed output, observe that the bottom portion of the page is cutoff.

Fix Description
The issue was fixed by changing the rendered size of the canvas to 100%, setting the CSS scale factor to 1 for both the width and height, changing the PRINT_OUTPUT_SCALE to be dependent on DPI, and fixing the PT to PX conversion between the viewport and canvas measurements.

Notes
All tests pass.
Confirmed that the issue has been fixed on IE 11.494, Edge 25.1, FF 47.0.1, Chrome 51.0
The PRINT_OUTPUT_SCALE factor has not been changed.

[timvandermeij]

/botio-linux preview

[pdfjsbot]

From: Bot.io (Linux)

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Received

Command cmd_preview from @timvandermeij received. Current queue size: 0

Live output at: http://107.21.233.14:8877/28fdb624aa3247a/output.txt

[pdfjsbot]

From: Bot.io (Linux)

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Success

Full output at http://107.21.233.14:8877/28fdb624aa3247a/output.txt

Total script time: 1.06 mins

Published

• Viewer: http://107.21.233.14:8877/28fdb624aa3247a/web/viewer.html
• B2G Viewer: http://107.21.233.14:8877/28fdb624aa3247a/extensions/b2g/content/web/viewer.html
• Extension: http://107.21.233.14:8877/28fdb624aa3247a/extensions/firefox/pdf.js.xpi

[pixelbits-mk]

Any status on this PR? Please let me know if any changes are requested to move this forward.

[timvandermeij]

The commit itself looks good to me. We mainly need to do more manual testing before merging this.

[Snuffleupagus]

Is this actually necessary, given that it should already be set with CSS, see

pdf.js/web/viewer.css

Line 1813 in 336b26a

height: 100%;

?

[Snuffleupagus]

The commit itself looks good to me.

Generally I agree, but I've added a couple of questions/comments above.

We mainly need to do more manual testing before merging this.

Agreed; and this is sort of time-consuming to do. We'd need to ensure that this isn't regressing other printing fixes, e.g. PR #7005.
Note: Given that we're close to the release of the next Firefox version, we probably don't want to land this just before the merge to avoid having to create uplift patches if there're any regressions.

[yurydelendik]

The DPI shall be set now to 150%. See #7677. Thanks.