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pdfTransparencyTyped

AGPL-3.0-onlyRelease 2L4

Transparency Group (§11.6.6), Soft Mask (§11.6.5.2), blend modes (§11.3.5) — ISO 32000-2.

Module pdfTransparencyTyped | Source packages/front/office/pdf/src/extra/transparency-typed.js | Deps pdfErrors, pdfParser | Worker-safe yes

Types the group attributes /Group /S /Transparency (§11.6.6), the soft masks /Luminosity / /Alpha with /TR transfer (§11.6.5.2), and exposes the frozen catalog of standard blend modes (§11.3.5 Table 136).

Resolve

const ext = runtime.resolve('pdfTransparencyTyped');
// Returns: { typeTransparencyGroup, typeSoftMask, resolveBlendMode, BLEND_MODES }

API

Member Signature Returns
typeTransparencyGroup (dict) => Group { s, cs, isolated, knockout, raw, _extras }.
typeSoftMask (dict) => SoftMask { kind, g, backdrop, transfer, raw, _extras }.
resolveBlendMode (value) => string | null Decodes a name or the first recognized name in an array.
BLEND_MODES frozen array 17 standard modes (includes Compatible).

Examples

Group

const ext = runtime.resolve('pdfTransparencyTyped');
const g = ext.typeTransparencyGroup(groupDict);
g.s;         // 'Transparency'
g.cs;        // raw /CS entry
g.isolated;  // true
g.knockout;  // false

Blend mode resolution

ext.resolveBlendMode({ type: 'name', value: 'Multiply' }); // 'Multiply'
ext.resolveBlendMode({ type: 'array', items: [
    { type: 'name', value: 'Saturation' },
    { type: 'name', value: 'Normal' }
]}); // 'Saturation' (first recognized name)

Errors

Code Class When
pdf/extra/transparency-group/not-dict ParseError Group is not a dict.
pdf/extra/transparency-group/bad-type ParseError /Type present and not /Group.
pdf/extra/transparency-group/bad-s ParseError /S is not /Transparency.
pdf/extra/soft-mask/not-dict ParseError SoftMask is not a dict.
pdf/extra/soft-mask/bad-type ParseError /Type is not /Mask.
pdf/extra/soft-mask/bad-s ParseError /S is not Luminosity/Alpha.
pdf/extra/soft-mask/missing-g ParseError /G (transparency group XObject) absent.
pdf/extra/blend-mode/bad-type ParseError Value is neither a name nor an array.

See also