Don't add an EOL after a superscript

Author: calixteman

src/core/evaluator.js

@@ -2458,6 +2458,7 @@ class PartialEvaluator {
       height: 0,
       vertical: false,
       prevTransform: null,
+      prevTextRise: 0,
       textAdvanceScale: 0,
       spaceInFlowMin: 0,
       spaceInFlowMax: 0,
@@ -2906,7 +2907,19 @@ class PartialEvaluator {
         return true;
       }
 
-      if (Math.abs(advanceY) > textContentItem.height) {
+      // Compensate for a textRise change (e.g. superscript/subscript dropping
+      // back to baseline): textRise is baked into posY/lastPosY via tsm[5] in
+      // getCurrentTextTransform(), scaled by the Y component of the CTM×TM
+      // product, which equals currentTransform[3] / textState.fontSize.
+      // Without this correction a superscript whose textRise exceeds the line
+      // height triggers a spurious EOL when the rise returns to 0.
+      const textRiseDelta = textState.textRise - textContentItem.prevTextRise;
+      const advanceYCorrected =
+        textRiseDelta === 0
+          ? advanceY
+          : advanceY -
+            (currentTransform[3] / textState.fontSize) * textRiseDelta;
+      if (Math.abs(advanceYCorrected) > textContentItem.height) {
         appendEOL();
         return true;
       }
@@ -3068,6 +3081,7 @@ class PartialEvaluator {
         if (scaledDim) {
           // Save the position of the last visible character.
           textChunk.prevTransform = getCurrentTextTransform();
+          textChunk.prevTextRise = textState.textRise;
         }
 
         const glyphUnicode = glyph.unicode;

test/pdfs/.gitignore

@@ -890,3 +890,4 @@
 !acroform_calculation_order.pdf
 !extractPages_null_in_array.pdf
 !issue20930.pdf
+!text_rise_eol_bug.pdf

test/pdfs/text_rise_eol_bug.pdf

@@ -3985,6 +3985,27 @@ Caron Broadcasting, Inc., an Ohio corporation (“Lessee”).`)
       await loadingTask.destroy();
     });
 
+    it("gets text content without spurious EOL after a superscript (text_rise_eol_bug.pdf)", async function () {
+      const loadingTask = getDocument(
+        buildGetDocumentParams("text_rise_eol_bug.pdf")
+      );
+      const pdfDoc = await loadingTask.promise;
+      const pdfPage = await pdfDoc.getPage(1);
+      const { items } = await pdfPage.getTextContent({
+        disableNormalization: true,
+      });
+
+      // No item should carry a hasEOL flag between the superscript and the
+      // text that follows it.
+      expect(items.every(i => !i.hasEOL)).toEqual(true);
+
+      // Full sentence must be reconstructable without a newline.
+      const text = mergeText(items);
+      expect(text).toEqual("E = mc2 is the mass-energy equivalence.");
+
+      await loadingTask.destroy();
+    });
+
     it("gets text content with a specific view box", async function () {
       const loadingTask = getDocument(buildGetDocumentParams("issue16316.pdf"));
       const pdfDoc = await loadingTask.promise;