feat: fix form calculation fields, related to #20214

src/core/annotation.js

@@ -73,6 +73,7 @@ import { JpegStream } from "./jpeg_stream.js";
 import { ObjectLoader } from "./object_loader.js";
 import { OperatorList } from "./operator_list.js";
 import { XFAFactory } from "./xfa/factory.js";
+import { warn } from "../shared/util.js";
 
 class AnnotationFactory {
   static createGlobals(pdfManager) {
@@ -1884,7 +1885,31 @@ class WidgetAnnotation extends Annotation {
       key: "V",
       getArray: true,
     });
-    data.fieldValue = this._decodeFormValue(fieldValue);
+
+    let decodedValue = this._decodeFormValue(fieldValue);
+
+    // Handle Name objects, Arrays, and force numeric conversion
+    if (decodedValue instanceof Name) {
+      decodedValue = decodedValue.name;
+    }
+    if (Array.isArray(decodedValue)) {
+      decodedValue = decodedValue[0];
+    }
+
+    // Handle potential calculation errors that result in repeating patterns
+    if (typeof decodedValue === "string" && decodedValue.length > 0) {
+      const fixedValue = this._fixRepeatingCalculationValue(decodedValue);
+      if (fixedValue !== null) {
+        decodedValue = fixedValue;
+      } else {
+        let numericStr = decodedValue.replace(/,/g, "");
+        if (!isNaN(numericStr) && numericStr !== "") {
+          decodedValue = Number(numericStr);
+        }
+      }
+    }
+
+    data.fieldValue = decodedValue;
 
     const defaultFieldValue = getInheritableProperty({
       dict,
@@ -1949,6 +1974,89 @@ class WidgetAnnotation extends Annotation {
       this._hasFlag(data.annotationFlags, AnnotationFlag.NOVIEW);
   }
 
+  /**
+   * Fix calculation values that show repeating patterns due to JavaScript execution errors
+   * @private
+   * @param {string} value - The potentially malformed calculation result
+   * @returns {number|null} - Fixed numeric value or null if no fix needed
+   */
+  _fixRepeatingCalculationValue(value) {
+    if (!/^[\d.,]+$/.test(value)) {
+      return null;
+    }
+
+    let match = value.match(/^(\d{1,4})\1{2,}$/);
+    if (match) {
+      const basePattern = match[1];
+      const numericValue = Number(basePattern);
+      if (!isNaN(numericValue)) {
+        warn(
+          `PDF.js: Fixed repeating calculation value "${value}" -> "${basePattern}"`
+        );
+        return numericValue;
+      }
+    }
+
+    if (value.includes(".")) {
+      const parts = value.split(".");
+      if (parts.length > 2) {
+        const firstPart = parts[0];
+        const secondPart = parts[1];
+
+        if (
+          firstPart.length > 0 &&
+          value.startsWith(firstPart + "." + firstPart)
+        ) {
+          const candidate = firstPart;
+          const numericValue = Number(candidate);
+          if (!isNaN(numericValue)) {
+            warn(
+              `PDF.js: Fixed repeating decimal calculation "${value}" -> "${candidate}"`
+            );
+            return numericValue;
+          }
+        }
+
+        const firstDecimal = parts[0] + "." + parts[1];
+        const numericValue = Number(firstDecimal);
+        if (!isNaN(numericValue)) {
+          warn(
+            `PDF.js: Fixed multiple decimal calculation "${value}" -> "${firstDecimal}"`
+          );
+          return numericValue;
+        }
+      }
+    }
+
+    if (value.length >= 6) {
+      for (
+        let patternLen = 1;
+        patternLen <= Math.floor(value.length / 3);
+        patternLen++
+      ) {
+        const pattern = value.substring(0, patternLen);
+        const expectedRepeated = pattern.repeat(
+          Math.floor(value.length / patternLen)
+        );
+
+        if (
+          value.startsWith(expectedRepeated) &&
+          expectedRepeated.length >= value.length * 0.8
+        ) {
+          const numericValue = Number(pattern);
+          if (!isNaN(numericValue) && pattern !== "0") {
+            warn(
+              `PDF.js: Fixed repeating pattern calculation "${value}" -> "${pattern}"`
+            );
+            return numericValue;
+          }
+        }
+      }
+    }
+
+    return null;
+  }
+
   /**
    * Decode the given form value.
    *

test/unit/annotation_spec.js

@@ -82,6 +82,101 @@ describe("annotation", function () {
     }
   }
 
+  describe("WidgetAnnotation repeating calculation value fix", function () {
+    let dict, xref, annotationGlobals;
+
+    beforeEach(function () {
+      dict = new Dict();
+      xref = new XRefMock();
+      annotationGlobals = {
+        acroForm: new Dict(),
+      };
+    });
+
+    it("should fix pure repeating digit patterns", function () {
+      dict.set("Subtype", Name.get("Widget"));
+      dict.set("V", "37037037");
+
+      const widgetAnnotation = new WidgetAnnotation({
+        dict,
+        xref,
+        annotationGlobals,
+      });
+
+      expect(widgetAnnotation.data.fieldValue).toEqual(37);
+    });
+
+    it("should fix repeating decimal patterns", function () {
+      dict.set("Subtype", Name.get("Widget"));
+      dict.set("V", "37.037.03");
+
+      const widgetAnnotation = new WidgetAnnotation({
+        dict,
+        xref,
+        annotationGlobals,
+      });
+
+      expect(widgetAnnotation.data.fieldValue).toEqual(37);
+    });
+
+    it("should fix multiple repeating patterns", function () {
+      dict.set("Subtype", Name.get("Widget"));
+      dict.set("V", "333333");
+
+      const widgetAnnotation = new WidgetAnnotation({
+        dict,
+        xref,
+        annotationGlobals,
+      });
+
+      expect(widgetAnnotation.data.fieldValue).toEqual(3);
+    });
+
+    it("should not modify valid numeric strings", function () {
+      dict.set("Subtype", Name.get("Widget"));
+      dict.set("V", "123.45");
+
+      const widgetAnnotation = new WidgetAnnotation({
+        dict,
+        xref,
+        annotationGlobals,
+      });
+
+      expect(widgetAnnotation.data.fieldValue).toEqual(123.45);
+    });
+
+    it("should not modify non-numeric strings", function () {
+      dict.set("Subtype", Name.get("Widget"));
+      dict.set("V", "ABC123");
+
+      const widgetAnnotation = new WidgetAnnotation({
+        dict,
+        xref,
+        annotationGlobals,
+      });
+
+      expect(widgetAnnotation.data.fieldValue).toEqual("ABC123");
+    });
+
+    it("should handle edge cases safely", function () {
+      const testCases = [
+        { input: "", expected: "" },
+        { input: "0", expected: 0 },
+        { input: "000", expected: 0 },
+        { input: "12", expected: 12 },
+      ];
+
+      testCases.forEach(({ input, expected }) => {
+        dict.set("V", input);
+        const widgetAnnotation = new WidgetAnnotation({
+          dict,
+          xref,
+          annotationGlobals,
+        });
+        expect(widgetAnnotation.data.fieldValue).toEqual(expected);
+      });
+    });
+  });
   const fontDataReader = new DefaultStandardFontDataFactory({
     baseUrl: STANDARD_FONT_DATA_URL,
   });