Open Bug 1657489 Opened 1 year ago Updated 8 months ago

Zooming print preview in new print UI flickers, clamps at 100%


(Core :: Print Preview, defect, P2)

Firefox 81



Tracking Status
firefox81 --- affected


(Reporter: svoisen, Unassigned)


(Whiteboard: [print2020][old-ui+])


  1. Enable the new print UI via print.tab_modal.enabled
  2. Cmd or Ctrl+P to print.
  3. Focus the print preview and use Cmd or Ctrl+(mousewheel) to zoom in and out.
  4. Note the flickering of the headers/footers. You cannot zoom in larger than fit-to-window.
  5. Enable "Zoom Text Only" and repeat.
  6. When zooming, the text will grow/shrink, but there's no page reflow.


We should probably set a larger max zoom level and disable the "zoom text only" functionality for the print preview. Additionally, we should get UX input on adding buttons or other zoom controls to more easily expose print preview zooming as a feature to users.

Severity: -- → S3
Priority: -- → P1
Whiteboard: [print2020_v81]

Additionally, changing any UI control resets the zoom level. I assume this is the result of bug 1636728 however.

Turns out we get this "for free" in some sense with desktop pinch zooming enabled (apz.allow_zooming).

Priority: P1 → P2
Whiteboard: [print2020_v81] → [print2020_v81][old-ui+]

Do you still experience the flickering aspect of this report? I can't reproduce that.

Flags: needinfo?(svoisen)

Also, I'm not sure where the clamping to 100% comes from, but presumably the frontend code somewhere? Should we move this to Toolkit?

(In reply to Jonathan Watt [:jwatt] from comment #3)

Do you still experience the flickering aspect of this report? I can't reproduce that.

Yes, by simply trying to zoom beyond the 100% clamp with the mousewheel.

Mark: Per comment 4, is the zoom clamping being imposed by the frontend?

Flags: needinfo?(svoisen) → needinfo?(mstriemer)

I see the same behaviour in the print preview with print.tab_modal.enabled set to false, so I don't think this is related to the frontend.

I haven't looked at the code, but since it clamps to the initial sizing of fitting a page to the window size that code seems like a good place to look.

Flags: needinfo?(mstriemer)
Whiteboard: [print2020_v81][old-ui+] → [print2020_v83][old-ui+]
Whiteboard: [print2020_v83][old-ui+] → [print2020_v84][old-ui+]
Whiteboard: [print2020_v84][old-ui+] → [print2020_v85][old-ui+]
Whiteboard: [print2020_v85][old-ui+] → [print2020_v88][old-ui+]
Whiteboard: [print2020_v88][old-ui+] → [print2020][old-ui+]
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