Overriding the paragraph font size

[smoores-dev]

Is there any way to set/override a default base font-size for the Navigator? I know of fontSize (a multiplier on the root font size of the document) and typeScale (a more limited multiplier on font size? I'm actually unsure), but neither of these allow the app to set a baseline font size for all books. I'm looking for something that behaves more like fontFamily, overriding the font-size for paragraph-level text.

This is coming up because, even just in the handful of published EPUBs I'm using for testing, there are some wild variations in font size, which makes for a jarring reading experience when switching between books. One publisher in particular seems to like to set p { font-size: small } for some godforsaken reason, so the text is absolutely tiny (13px!) on a phone screen.

[mickael-menu]

There's nothing out of the box for setting the base font size. But looking at Readium CSS's documentation, I think you should be able to set the --RS_baseFontSize property:

https://github.com/readium/readium-css/blob/master/docs/CSS08-defaults.md#typography

For some reason, it looks like I forgot to add it in the constructor of CSSRSProperties, but you can still provide it manually with overrides:

EPUBNavigatorViewController(
    config: EPUBNavigatorViewController.Configuration(
        readiumCSSRSProperties: CSSRSProperties(
            overrides: ["--RS__baseFontSize": "14px"]
        )
    )
)

All the properties in overrides will be added as CSS properties on the root element, so you can add other CSS properties if you find another solution.

But from the problem you described, I think you might be able to fix it just by reducing the typeScale and increasing the fontSize.

[smoores-dev]

Thanks so much for your response! I think this actually led me (indirectly) to what I needed, which was the readium-advanced-on flag. Looking at the code, it seems like I should be able to enable this by setting UserSettings(publisherDefaults: false), but for some reason that doesn't actually set the flag in the webview? Instead I've been just setting it on some arbitrary CSS variable so that it's picked up by the query selector:

readiumCSSRSProperties: CSSRSProperties(
  overrides: ["--ST_view": "readium-advanced-on"]
)

If you happen to know what I'm missing to get this working without the override, that'd be awesome, but for now I think this is fine!

[mickael-menu]

Oh yes, I forgot to mention the readium-advanced-on flag. This can help, as well as the text normalization.

UserSettings is deprecated but kept for backward compatibility. What you want is EPUBDefaults, you can initialize the EPUBNavigatorViewController with:

EPUBNavigatorViewController(
    config: EPUBNavigatorViewController.Configuration(
        defaults: EPUBDefaults(
            publisherStyles: false,
            textNormalization: true
        )
    )
)

If you want to let the user control whether or not the publisherStyles setting is disabled, you can use EPUBPreferences and EPUBNavigatorViewController.submitPreferences instead. EPUBDefaults are the fallback static setting values when no preferences are given.

See the user guide for a detailed explanation.

[smoores-dev]

Ah, this is perfect, thank you! I had somehow missed that user guide, but it's great and I think has everything I need