Improve text-selection for Type3 fonts with bogus /FontBBox-entries (…

…issue 14999)

This extends PR 13461, by also building a fallback bounding box for Type3 fonts that contain a much too small /FontBBox-entry.

*Please note:* While this patch improves things overall, copy-and-pasting still doesn't work perfectly for this document. In particular the lowercase letter "c" cannot be selected/copied, however this can be reproduced in both Adobe Reader and PDFium (in Google Chrome) too, which is caused by a lack of proper /ToUnicode-data in the PDF document.

src/core/evaluator.js

@@ -4404,8 +4404,10 @@ class TranslatedFont {
  const fontResources = this.dict.get("Resources") || resources;
  const charProcOperatorList = Object.create(null);
 
- const isEmptyBBox =
- !translatedFont.bbox || isArrayEqual(translatedFont.bbox, [0, 0, 0, 0]);
+ const fontBBox = Util.normalizeRect(translatedFont.bbox || [0, 0, 0, 0]),
+ width = fontBBox[2] - fontBBox[0],
+ height = fontBBox[3] - fontBBox[1];
+ const fontBBoxSize = Math.hypot(width, height);
 
  for (const key of charProcs.getKeys()) {
  loadCharProcsPromise = loadCharProcsPromise.then(() => {
@@ -4426,7 +4428,7 @@ class TranslatedFont {
  // colour-related parameters) in the graphics state;
  // any use of such operators shall be ignored."
  if (operatorList.fnArray[0] === OPS.setCharWidthAndBounds) {
- this._removeType3ColorOperators(operatorList, isEmptyBBox);
+ this._removeType3ColorOperators(operatorList, fontBBoxSize);
  }
  charProcOperatorList[key] = operatorList.getIR();
 
@@ -4454,7 +4456,7 @@ class TranslatedFont {
  /**
  * @private
  */
- _removeType3ColorOperators(operatorList, isEmptyBBox = false) {
+ _removeType3ColorOperators(operatorList, fontBBoxSize = NaN) {
  if (
  typeof PDFJSDev === "undefined" ||
  PDFJSDev.test("!PRODUCTION || TESTING")
@@ -4467,12 +4469,19 @@ class TranslatedFont {
  const charBBox = Util.normalizeRect(operatorList.argsArray[0].slice(2)),
  width = charBBox[2] - charBBox[0],
  height = charBBox[3] - charBBox[1];
+ const charBBoxSize = Math.hypot(width, height);
 
  if (width === 0 || height === 0) {
  // Skip the d1 operator when its bounds are bogus (fixes issue14953.pdf).
  operatorList.fnArray.splice(0, 1);
  operatorList.argsArray.splice(0, 1);
- } else if (isEmptyBBox) {
+ } else if (
+ fontBBoxSize === 0 ||
+ Math.round(charBBoxSize / fontBBoxSize) >= 10
+ ) {
+ // 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];
  }

test/pdfs/.gitignore

@@ -121,6 +121,7 @@
 !issue13916.pdf
 !issue14023.pdf
 !issue14438.pdf
+!issue14999_reduced.pdf
 !bad-PageLabels.pdf
 !decodeACSuccessive.pdf
 !issue13003.pdf
@@ -328,6 +329,7 @@
 !bug903856.pdf
 !issue14618.pdf
 !bug850854.pdf
+!issue14999_reduced.pdf
 !issue12810.pdf
 !bug866395.pdf
 !issue12010_reduced.pdf

test/test_manifest.json

@@ -2848,6 +2848,12 @@
  "link": false,
  "type": "text"
  },
+ { "id": "issue14999",
+ "file": "pdfs/issue14999_reduced.pdf",
+ "md5": "a4e664e734f6869aa66245e72d448874",
+ "rounds": 1,
+ "type": "text"
+ },
  { "id": "issue6901-eq",
  "file": "pdfs/issue6901.pdf",
  "md5": "1a0604b1a7a3aaf2162b425a9a84230b",