fix: fixes an issue with font scaling on iOS

[wongk]

#260

Allow font scaling to be disabled for header button text.

[vonovak]

Thanks for the PR!

I'd like to ask you for a few small changes, thank you!

[vonovak]

Suggested change

allowFontScaling?: boolean;

[vonovak]

these are props for defaultRenderVisibleButton - I want them to stay relatively minimal. allowFontScaling prop doesn't feel like it really belongs in here.

People don't need to rely on defaultRenderVisibleButton - they can provide their own like this (taking the example from readme) - so they are not limited by this lib:

const MaterialHeaderButton = (props: HeaderButtonProps) => (
  // the `props` here come from <Item ... />
  // you may access them and pass something else to `HeaderButton` if you like
  <HeaderButton IconComponent={MaterialIcons} iconSize={23} {...props}
                renderButton={(itemProps) => {
                  // return whatever you want
                }}
  />
);

[wongk]

in our case, we're using this property like so: <Item {...props} allowFontScaling={Platform.OS !== "ios"} />, because the font scaling actually looks decent on Android but not iOS. we don't want to provide our own renderButton, because that would defeat the purpose of using this library (for us).

[vonovak]

Thanks for the comment @wongk. This is the default implementation of renderButton:

export function defaultRenderVisibleButton(
  visibleButtonProps: VisibleButtonProps
): React.ReactElement {
  const { IconComponent, iconSize, color, iconName, title, buttonStyle } =
    visibleButtonProps;

  return IconComponent && iconName ? (
    <IconComponent
      name={iconName}
      color={color}
      size={iconSize}
      style={buttonStyle}
    />
  ) : (
    <Text style={[styles.text, { color }, buttonStyle]}>{title}</Text>
  );
}

So, it's rather simple. What I'm trying to say is that rather than providing a dozen props to customize this, it's preferable users copy-paste this into their project and customize to their liking - if needed. Ideally this wouldn't be needed but the lib isn't preventing users from doing that.

Let's please change the default impl to use allowFontScaling={Platform.OS !== "ios"} - that fixes the default impl for everyone and if they're not happy with it, they'll provide their own renderButton.

[vonovak]

Suggested change

	allowFontScaling,
	allowFontScaling,

[vonovak]

Suggested change

	allowFontScaling={allowFontScaling}
	allowFontScaling={false} // to fix #260