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Improve text-selection for Type3 fonts, using d0 operators, with empty /FontBBox-entries (issue 19624)

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For Type3 glyphs with `d1` operators it's easy to compute a fallback bounding box, however for `d0` the situation is more difficult.
Given that we nowadays compute the min/max of basic path-rendering operators on the worker-thread, we can utilize that by parsing these Type3 operatorLists to guess a more suitable fallback bounding box.
This commit is contained in:
Jonas Jenwald 2025-03-07 15:13:31 +01:00
parent b9e8844541
commit 0edfd29a3e
3 changed files with 51 additions and 9 deletions
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50
src/core/evaluator.js
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@ -4679,8 +4679,15 @@ class TranslatedFont {
// not execute any operators that set the colour (or other
// colour-related parameters) in the graphics state;
// any use of such operators shall be ignored."
if (operatorList.fnArray[0] === OPS.setCharWidthAndBounds) {
this.#removeType3ColorOperators(operatorList, fontBBoxSize);
switch (operatorList.fnArray[0]) {
case OPS.setCharWidthAndBounds:
this.#removeType3ColorOperators(operatorList, fontBBoxSize);
break;
case OPS.setCharWidth:
if (!fontBBoxSize) {
this.#guessType3FontBBox(operatorList);
}
break;
}
charProcOperatorList[key] = operatorList.getIR();
@ -4728,13 +4735,7 @@ class TranslatedFont {
// Override the fontBBox when it's undefined/empty, or when it's at least
// (approximately) one order of magnitude smaller than the charBBox
// (fixes issue14999_reduced.pdf).
if (!this._bbox) {
this._bbox = [Infinity, Infinity, -Infinity, -Infinity];
}
this._bbox[0] = Math.min(this._bbox[0], charBBox[0]);
this._bbox[1] = Math.min(this._bbox[1], charBBox[1]);
this._bbox[2] = Math.max(this._bbox[2], charBBox[2]);
this._bbox[3] = Math.max(this._bbox[3], charBBox[3]);
this.#computeCharBBox(charBBox);
}
let i = 0,
@ -4787,6 +4788,37 @@ class TranslatedFont {
i++;
}
}
#guessType3FontBBox(operatorList) {
if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
assert(
operatorList.fnArray[0] === OPS.setCharWidth,
"Type3 glyph shall start with the d0 operator."
);
}
let i = 1;
const ii = operatorList.length;
while (i < ii) {
switch (operatorList.fnArray[i]) {
case OPS.constructPath:
const minMax = operatorList.argsArray[i][2];
// Override the fontBBox when it's undefined/empty (fixes 19624.pdf).
this.#computeCharBBox(minMax);
break;
}
i++;
}
}
#computeCharBBox(bbox) {
this._bbox ||= [Infinity, Infinity, -Infinity, -Infinity];
this._bbox[0] = Math.min(this._bbox[0], bbox[0]);
this._bbox[1] = Math.min(this._bbox[1], bbox[1]);
this._bbox[2] = Math.max(this._bbox[2], bbox[2]);
this._bbox[3] = Math.max(this._bbox[3], bbox[3]);
}
}
class StateManager {