Enum FormFontsKey 

pub enum FormFontsKey {
    Form(ObjRef),
    None,
    DirectResources(ObjRef),
    Direct,
}

Which interactive form a set of cached form faces belongs to.

What the faces actually depend on

Not the /AcroForm dictionary: the /DR /Font dictionary inside it, and nothing else. Everything FormFonts builds is either a face named there or one of two constants — the fallback Helvetica and the second face a substitutable charset needs, both from dictionaries written in the source. So that is what the key names, and a form declaring no /DR /Font has faces indistinguishable from a document with no form at all.

The four cases

• an indirect /AcroForm, which is what a real form is written as. The reference is the document-scoped identity every other cache on BuildContext keys on, so the faces are cached under it.
• no /DR /Font to load from — no /AcroForm, or one that declares no default resources. The faces then depend on nothing from the document, so one slot serves every such document a context is threaded through. This is None, and it is the common case: most documents have no form, and an empty <</Fields[]>> written directly into the catalog is common enough that six of this corpus’s 44 files carry one.
• a direct /AcroForm whose /DR /Font is a reference, which is the ordinary spelling of an unusual one. The font dictionary’s reference is as good an identity as the form’s own would have been, so it is cached under that instead.
• a direct /AcroForm with a direct /DR /Font, which is legal and genuinely rare. There is no reference anywhere to key on and the content is document-specific, so it is not cached.

Variants

Form(ObjRef)

The /AcroForm the given object holds.

None

No /DR /Font for the faces to depend on.

DirectResources(ObjRef)

A direct /AcroForm whose /DR /Font is the given object.

Direct

A direct /AcroForm with a direct /DR /Font.

Trait Implementations

impl Clone for FormFontsKey

fn clone(&self) -> FormFontsKey

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for FormFontsKey

impl Debug for FormFontsKey

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for FormFontsKey

impl Hash for FormFontsKey

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for FormFontsKey

fn eq(&self, other: &FormFontsKey) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for FormFontsKey