Keeping track of Webkit-specific bugs and resolutions

[JayPanoz]

This issue is meant to keep track of the multiple bugs that are specific to WebKit, that were resolved, but that may benefit from additional debugging, especially as we may not have minimal reproductible testcases for some of them.

iOS Patch

To sum things up, on rotate to landscape in scroll on iOS, the text-adjustment algorithm is mapping 100%, 1rem, etc. to 25px when it is set to 16px. It will never go back to its original value and will also counteracts any zoom value applied (so 25px can become 31.25px if a zoom value of 80% is applied, etc.).

• The issue is handled in Readium/css: Webkit scaling bug on rotate css#189
• The resolution in Readium/css: iOS patch css#190
• The PR to add the flag in ts-toolkit: Implement ReadiumCSS iOS patch #146

We do not know the root cause of the issue, therefore do not have a minimum reproductible test case.

iPadOS Patch

On iPadOS, there is a specific issue when the website is required as desktop (which is the default). With zoom interventions creating nasty rendering issues when text is styled (e.g. font-style, font-variant, etc.)

• The issue was handled in Readium/css: Font-size/zoom issues on iPadOS (desktop-class) + Firefox css#172
• The resolution in Readium/css: Beta 11 css#173
• The issue in Webkit Tracker: https://bugs.webkit.org/show_bug.cgi?id=293617
• The minimal reproductible test case: https://codepen.io/JayPanoz/pen/qEEWEQm
• The PR to add the flag in ts-toolkit: Preferences API #106

Scroll is not scrollable

In Webkit, scroll mode is not scrollable until there is a recalc/reflow happening. We consequently have to force a recalc. This issue was previously resolved as a side effect of adding custom properties after load, or injecting elements in the DOM (scroll affordances).

• The issue was handled here: Scroll is not scrollable in Webkit when loading the resource directly in scroll #136
• The resolution: Fix Webkit scroll issue #138

We do not know the root cause of the issue, therefore do not have a minimum reproductible test case.

[JayPanoz]

Re Scroll is not scrollable, I can now confirm it is not because of Readium CSS, as it could have been Webkit being stuck on a rendering path that has not completed properly when switching from columns to no columns.

This means it can either be an issue with blobs, or the rendering (showing/hiding, positioning), or attributes, etc.