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Add a helper method, in the PartialEvaluator class, for building a transfer map #21816

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Merged
timvandermeij merged 1 commit into from
Aug 23, 2026
+15 −25
Merged

Add a helper method, in the PartialEvaluator class, for building a transfer map #21816

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40 changes: 15 additions & 25 deletions src/core/evaluator.js
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Original file line number Diff line number Diff line change
Expand Up @@ -885,6 +885,16 @@ class PartialEvaluator {
}
}

#createTransferMap(fn) {
const transferFn = this._pdfFunctionFactory.create(fn),
tmp = new Float32Array(1);
return Uint8Array.from({ length: 256 }, (_, i) => {
tmp[0] = i / 255;
transferFn(tmp, 0, tmp, 0);
return (tmp[0] * 255) | 0;
});
}

handleSMask(
smask,
resources,
Expand All @@ -904,15 +914,7 @@ class PartialEvaluator {
// we will build a map of integer values in range 0..255 to be fast.
const transferObj = smask.get("TR");
if (isPDFFunction(transferObj)) {
const transferFn = this._pdfFunctionFactory.create(transferObj);
const transferMap = new Uint8Array(256);
const tmp = new Float32Array(1);
for (let i = 0; i < 256; i++) {
tmp[0] = i / 255;
transferFn(tmp, 0, tmp, 0);
transferMap[i] = (tmp[0] * 255) | 0;
}
smaskOptions.transferMap = transferMap;
smaskOptions.transferMap = this.#createTransferMap(transferObj);
}

return this.buildFormXObject(
Expand All @@ -930,12 +932,9 @@ class PartialEvaluator {
handleTransferFunction(tr) {
let transferArray;
if (Array.isArray(tr)) {
transferArray = tr;
if (tr.length > 1 && tr.every(map => map === tr[0])) {
// All entries in the array are the same, so we can just use one of
// them.
transferArray = [tr[0]];
}
// If all entries in the array are the same, we can just use one of them.
transferArray =
tr.length > 1 && tr.every(map => map === tr[0]) ? [tr[0]] : tr;
} else if (isPDFFunction(tr)) {
transferArray = [tr];
} else {
Expand All @@ -955,16 +954,7 @@ class PartialEvaluator {
} else if (!isPDFFunction(transferObj)) {
return null; // Not a valid transfer function object.
}

const transferFn = this._pdfFunctionFactory.create(transferObj);
const transferMap = new Uint8Array(256),
tmp = new Float32Array(1);
for (let j = 0; j < 256; j++) {
tmp[0] = j / 255;
transferFn(tmp, 0, tmp, 0);
transferMap[j] = (tmp[0] * 255) | 0;
}
transferMaps.push(transferMap);
transferMaps.push(this.#createTransferMap(transferObj));
numEffectfulFns++;
}

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