From 07f1786ff2f76661f5bef24d5c75eb549ab0fd10 Mon Sep 17 00:00:00 2001
From: Arthur Tazhitdinov <lisnake@gmail.com>
Date: Wed, 7 Jan 2026 03:15:38 +0500
Subject: [PATCH] Enhance hyphenation logic to allow fallback breaks for better
 line breaking in ParsedText

---
 lib/Epub/Epub/ParsedText.cpp | 9 ++++++---
 lib/Epub/Epub/ParsedText.h   | 2 +-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/Epub/Epub/ParsedText.cpp b/lib/Epub/Epub/ParsedText.cpp
index 7dac22ad..305ba1a2 100644
--- a/lib/Epub/Epub/ParsedText.cpp
+++ b/lib/Epub/Epub/ParsedText.cpp
@@ -177,7 +177,9 @@ std::vector<size_t> ParsedText::computeHyphenatedLineBreaks(const GfxRenderer& r
       }
 
       const int availableWidth = pageWidth - lineWidth - spacing;
-      if (availableWidth > 0 && hyphenateWordAtIndex(currentIndex, availableWidth, renderer, fontId, wordWidths)) {
+      const bool allowFallbackBreaks = isFirstWord;  // Only permit fallback splits when even the first word overflows
+      if (availableWidth > 0 &&
+          hyphenateWordAtIndex(currentIndex, availableWidth, renderer, fontId, wordWidths, allowFallbackBreaks)) {
         // Widths updated for the split word; retry with current index
         continue;
       }
@@ -199,7 +201,8 @@ std::vector<size_t> ParsedText::computeHyphenatedLineBreaks(const GfxRenderer& r
 
 // Splits words[wordIndex] into prefix+hyphen and remainder when a legal breakpoint fits the available width.
 bool ParsedText::hyphenateWordAtIndex(const size_t wordIndex, const int availableWidth, const GfxRenderer& renderer,
-                                      const int fontId, std::vector<uint16_t>& wordWidths) {
+                                      const int fontId, std::vector<uint16_t>& wordWidths,
+                                      const bool allowFallbackBreaks) {
   if (availableWidth <= 0 || wordIndex >= words.size()) {
     return false;
   }
@@ -209,7 +212,7 @@ bool ParsedText::hyphenateWordAtIndex(const size_t wordIndex, const int availabl
   std::advance(wordIt, wordIndex);
   std::advance(styleIt, wordIndex);
 
-  const auto breakOffsets = Hyphenator::breakOffsets(*wordIt, true);
+  const auto breakOffsets = Hyphenator::breakOffsets(*wordIt, allowFallbackBreaks);
   if (breakOffsets.empty()) {
     return false;
   }
diff --git a/lib/Epub/Epub/ParsedText.h b/lib/Epub/Epub/ParsedText.h
index e7f53f9c..1089054e 100644
--- a/lib/Epub/Epub/ParsedText.h
+++ b/lib/Epub/Epub/ParsedText.h
@@ -24,7 +24,7 @@ class ParsedText {
   std::vector<size_t> computeHyphenatedLineBreaks(const GfxRenderer& renderer, int fontId, int pageWidth,
                                                   int spaceWidth, std::vector<uint16_t>& wordWidths);
   bool hyphenateWordAtIndex(size_t wordIndex, int availableWidth, const GfxRenderer& renderer, int fontId,
-                            std::vector<uint16_t>& wordWidths);
+                            std::vector<uint16_t>& wordWidths, bool allowFallbackBreaks);
   void extractLine(size_t breakIndex, int pageWidth, int spaceWidth, const std::vector<uint16_t>& wordWidths,
                    const std::vector<size_t>& lineBreakIndices,
                    const std::function<void(std::shared_ptr<TextBlock>)>& processLine);