Bug 220043 – iOS 14.3 Safari can't print vertical-rl content correctly

• Component: Printing
• Status: NEW

[Meng-Yuan Huang]

Created attachment 416578 [details]
Most printing previews are blank pages.

I design an ePub viewer app with CSS "writing-mode: vertical-rl" support.
The app also supports content printing.
Chrome 87 on Windows or macOS can correctly print content in both horizontal-tb and vertical-rl modes.
However, iOS 14.3 Safari can't print them correctly in vertical-rl mode. Most printing previews are blank pages. See the attached screenshot.

For example:
1. Open this link:
https://mrmyhuang.github.io/catalog/juan/T0396/1?settings=rtlVerticalLayout=1
2. Click the top right three dots button.
3. Click the item with a printer icon and a label "列印."
4. Check the printing previews...

Please fix the printing support for vertical-rl content.

If anyone needs the app sources for debugging, please follow these steps:
1. Run the bash script:
git clone [e-mail]:MrMYHuang/cbetar2.git
cd cbetar2
npm i -D
npm run start

2. Open the link:
http://localhost:3000/catalog/juan/T0396/1?settings=rtlVerticalLayout=1

[Smoley]

Thanks for filing, I can reproduce this on iOS 13.6.1 as well as the latest iOS 14.4 beta. 3/4 pages also appear blank in print previews on macOS as well.

[Radar WebKit Bug Importer]

<rdar://problem/72595375>

[Shufei]

Created attachment 469928 [details]
Mongolian botched in rl or lr

I’m really tired of this hive of bugs for CJK or otherwise.  Attachment is for the Mongolian text test page.  It does this with any Mongolian, Phags-pa, Uyighur text, rl or lr, doesn’t matter.  CJK is perpetually b0rked, too.  IpadOS 16.7.5.