Fix parent-element “exact” preemption

lib/KOReaderSync/ProgressMapper.cpp

@@ -7,6 +7,44 @@
 
 #include "ChapterXPathIndexer.h"
 
+namespace {
+bool resolveFromPercentage(const std::shared_ptr<Epub>& epub, const float percentage, const int spineCount,
+                           int& outSpineIndex, float& outIntraSpineProgress) {
+  if (!std::isfinite(percentage) || !epub || spineCount <= 0) {
+    return false;
+  }
+
+  const size_t bookSize = epub->getBookSize();
+  if (bookSize == 0) {
+    return false;
+  }
+
+  const float sanitizedPercentage = std::clamp(percentage, 0.0f, 1.0f);
+  const size_t targetBytes = static_cast<size_t>(bookSize * sanitizedPercentage);
+
+  outSpineIndex = spineCount - 1;
+  for (int i = 0; i < spineCount; i++) {
+    const size_t cumulativeSize = epub->getCumulativeSpineItemSize(i);
+    if (cumulativeSize >= targetBytes) {
+      outSpineIndex = i;
+      break;
+    }
+  }
+
+  outIntraSpineProgress = 0.0f;
+  const size_t prevCumSize = (outSpineIndex > 0) ? epub->getCumulativeSpineItemSize(outSpineIndex - 1) : 0;
+  const size_t currentCumSize = epub->getCumulativeSpineItemSize(outSpineIndex);
+  const size_t spineSize = currentCumSize - prevCumSize;
+  if (spineSize > 0) {
+    const size_t bytesIntoSpine = (targetBytes > prevCumSize) ? (targetBytes - prevCumSize) : 0;
+    outIntraSpineProgress = static_cast<float>(bytesIntoSpine) / static_cast<float>(spineSize);
+    outIntraSpineProgress = std::clamp(outIntraSpineProgress, 0.0f, 1.0f);
+  }
+
+  return true;
+}
+}  // namespace
+
 KOReaderPosition ProgressMapper::toKOReader(const std::shared_ptr<Epub>& epub, const CrossPointPosition& pos) {
   KOReaderPosition result;
 
@@ -58,6 +96,7 @@ CrossPointPosition ProgressMapper::toCrossPoint(const std::shared_ptr<Epub>& epu
   float resolvedIntraSpineProgress = -1.0f;
   bool xpathExactMatch = false;
   bool usedXPathMapping = false;
+  bool usedPercentageReconcile = false;
 
   int xpathSpineIndex = -1;
   if (ChapterXPathIndexer::tryExtractSpineIndexFromXPath(koPos.xpath, xpathSpineIndex) && xpathSpineIndex >= 0 &&
@@ -68,6 +107,30 @@ CrossPointPosition ProgressMapper::toCrossPoint(const std::shared_ptr<Epub>& epu
       result.spineIndex = xpathSpineIndex;
       resolvedIntraSpineProgress = intraFromXPath;
       usedXPathMapping = true;
+
+      // KOReader's text-node indexing can differ across renderers/parsers in some
+      // XHTML shapes. When an XPath-resolved position disagrees materially with
+      // KOReader's percentage but points to the same spine, use percentage-derived
+      // intra-spine progress as a safer tie-breaker.
+      if (std::isfinite(koPos.percentage) && resolvedIntraSpineProgress >= 0.0f) {
+        const float sanitizedPercentage = std::clamp(koPos.percentage, 0.0f, 1.0f);
+        const float mappedPercentage = epub->calculateProgress(result.spineIndex, resolvedIntraSpineProgress);
+        const float delta = std::fabs(mappedPercentage - sanitizedPercentage);
+
+        constexpr float kReconcileThreshold = 0.01f;  // 1% absolute book progress
+        if (delta > kReconcileThreshold) {
+          int percentageSpineIndex = -1;
+          float percentageIntraSpine = -1.0f;
+          if (resolveFromPercentage(epub, koPos.percentage, spineCount, percentageSpineIndex, percentageIntraSpine) &&
+              percentageSpineIndex == result.spineIndex && percentageIntraSpine >= 0.0f) {
+            LOG_DBG("ProgressMapper",
+                    "Reconciling XPath position with percentage: spine=%d xpath=%.3f pct=%.3f delta=%.3f -> %.3f",
+                    result.spineIndex, resolvedIntraSpineProgress, sanitizedPercentage, delta, percentageIntraSpine);
+            resolvedIntraSpineProgress = percentageIntraSpine;
+            usedPercentageReconcile = true;
+          }
+        }
+      }
     }
     // Extract paragraph index from XPath for direct page lookup via section cache
     uint16_t pIndex = 0;
@@ -78,43 +141,14 @@ CrossPointPosition ProgressMapper::toCrossPoint(const std::shared_ptr<Epub>& epu
   }
 
   if (!usedXPathMapping) {
-    const size_t bookSize = epub->getBookSize();
-    if (bookSize == 0) {
+    int percentageSpineIndex = -1;
+    float percentageIntraSpine = -1.0f;
+    if (!resolveFromPercentage(epub, koPos.percentage, spineCount, percentageSpineIndex, percentageIntraSpine)) {
       return result;
     }
 
-    if (!std::isfinite(koPos.percentage)) {
-      return result;
-    }
-
-    const float sanitizedPercentage = std::clamp(koPos.percentage, 0.0f, 1.0f);
-    const size_t targetBytes = static_cast<size_t>(bookSize * sanitizedPercentage);
-
-    bool spineFound = false;
-    for (int i = 0; i < spineCount; i++) {
-      const size_t cumulativeSize = epub->getCumulativeSpineItemSize(i);
-      if (cumulativeSize >= targetBytes) {
-        result.spineIndex = i;
-        spineFound = true;
-        break;
-      }
-    }
-
-    if (!spineFound && spineCount > 0) {
-      result.spineIndex = spineCount - 1;
-    }
-
-    if (result.spineIndex < epub->getSpineItemsCount()) {
-      const size_t prevCumSize = (result.spineIndex > 0) ? epub->getCumulativeSpineItemSize(result.spineIndex - 1) : 0;
-      const size_t currentCumSize = epub->getCumulativeSpineItemSize(result.spineIndex);
-      const size_t spineSize = currentCumSize - prevCumSize;
-
-      if (spineSize > 0) {
-        const size_t bytesIntoSpine = (targetBytes > prevCumSize) ? (targetBytes - prevCumSize) : 0;
-        resolvedIntraSpineProgress = static_cast<float>(bytesIntoSpine) / static_cast<float>(spineSize);
-        resolvedIntraSpineProgress = std::max(0.0f, std::min(1.0f, resolvedIntraSpineProgress));
-      }
-    }
+    result.spineIndex = percentageSpineIndex;
+    resolvedIntraSpineProgress = percentageIntraSpine;
   }
 
   // Estimate page number within the selected spine item
@@ -154,9 +188,15 @@ CrossPointPosition ProgressMapper::toCrossPoint(const std::shared_ptr<Epub>& epu
     }
   }
 
-  LOG_DBG("ProgressMapper", "KOReader -> CrossPoint: %.2f%% at %s -> spine=%d, page=%d (%s, exact=%s)",
-          koPos.percentage * 100, koPos.xpath.c_str(), result.spineIndex, result.pageNumber,
-          usedXPathMapping ? "xpath" : "percentage", xpathExactMatch ? "yes" : "no");
+    LOG_DBG("ProgressMapper", "Resolved KOReader position: spine=%d intra=%.3f hasPIdx=%s pIdx=%u",
+      result.spineIndex, resolvedIntraSpineProgress, result.hasParagraphIndex ? "yes" : "no",
+      result.paragraphIndex);
+
+    const char* mappingSource = usedXPathMapping ? (usedPercentageReconcile ? "xpath+percentage" : "xpath")
+                   : "percentage";
+    LOG_DBG("ProgressMapper", "KOReader -> CrossPoint: %.2f%% at %s -> spine=%d, page=%d (%s, exact=%s)",
+      koPos.percentage * 100, koPos.xpath.c_str(), result.spineIndex, result.pageNumber, mappingSource,
+      xpathExactMatch ? "yes" : "no");
 
   return result;
 }