fix: Correct word width and space calculations (#963)

## Summary

**What is the goal of this PR?**

This change fixes an issue I noticed while reading where occasionally,
especially in italics, some words would have too much space between
them. The problem was that word width calculations were including any
negative X overhang, and combined with a space before the word, that can
lead to an inconsistently large space.

## Additional Context

Screenshots of some problematic text:

| In CrossPoint 1.0 | With this change |
| -- | -- |
| <img
src="https://github.com/user-attachments/assets/87bf0e4b-341f-4ba9-b3ea-38c13bd26363"
width="400" /> | <img
src="https://github.com/user-attachments/assets/bf11ba20-c297-4ce1-aa07-43477ef86fc2"
width="400" /> |

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**NO**_

lib/Epub/Epub/ParsedText.cpp

@@ -28,15 +28,17 @@ void stripSoftHyphensInPlace(std::string& word) {
   }
 }
 
-// Returns the rendered width for a word while ignoring soft hyphen glyphs and optionally appending a visible hyphen.
+// Returns the advance width for a word while ignoring soft hyphen glyphs and optionally appending a visible hyphen.
+// Uses advance width (sum of glyph advances) rather than bounding box width so that italic glyph overhangs
+// don't inflate inter-word spacing.
 uint16_t measureWordWidth(const GfxRenderer& renderer, const int fontId, const std::string& word,
                           const EpdFontFamily::Style style, const bool appendHyphen = false) {
   if (word.size() == 1 && word[0] == ' ' && !appendHyphen) {
-    return renderer.getSpaceWidth(fontId);
+    return renderer.getSpaceWidth(fontId, style);
   }
   const bool hasSoftHyphen = containsSoftHyphen(word);
   if (!hasSoftHyphen && !appendHyphen) {
-    return renderer.getTextWidth(fontId, word.c_str(), style);
+    return renderer.getTextAdvanceX(fontId, word.c_str(), style);
   }
 
   std::string sanitized = word;
@@ -46,7 +48,7 @@ uint16_t measureWordWidth(const GfxRenderer& renderer, const int fontId, const s
   if (appendHyphen) {
     sanitized.push_back('-');
   }
-  return renderer.getTextWidth(fontId, sanitized.c_str(), style);
+  return renderer.getTextAdvanceX(fontId, sanitized.c_str(), style);
 }
 
 }  // namespace

lib/Epub/Epub/blocks/TextBlock.cpp

@@ -30,7 +30,7 @@ void TextBlock::render(const GfxRenderer& renderer, const int fontId, const int
       if (w.size() >= 3 && static_cast<uint8_t>(w[0]) == 0xE2 && static_cast<uint8_t>(w[1]) == 0x80 &&
           static_cast<uint8_t>(w[2]) == 0x83) {
         const char* visiblePtr = w.c_str() + 3;
-        const int prefixWidth = renderer.getTextAdvanceX(fontId, "\xe2\x80\x83");
+        const int prefixWidth = renderer.getTextAdvanceX(fontId, "\xe2\x80\x83", currentStyle);
         const int visibleWidth = renderer.getTextWidth(fontId, visiblePtr, currentStyle);
         startX = wordX + prefixWidth;
         underlineWidth = visibleWidth;

lib/GfxRenderer/GfxRenderer.cpp

@@ -808,17 +808,17 @@ int GfxRenderer::getScreenHeight() const {
   return HalDisplay::DISPLAY_WIDTH;
 }
 
-int GfxRenderer::getSpaceWidth(const int fontId) const {
+int GfxRenderer::getSpaceWidth(const int fontId, const EpdFontFamily::Style style) const {
   const auto fontIt = fontMap.find(fontId);
   if (fontIt == fontMap.end()) {
     LOG_ERR("GFX", "Font %d not found", fontId);
     return 0;
   }
 
-  return fontIt->second.getGlyph(' ', EpdFontFamily::REGULAR)->advanceX;
+  return fontIt->second.getGlyph(' ', style)->advanceX;
 }
 
-int GfxRenderer::getTextAdvanceX(const int fontId, const char* text) const {
+int GfxRenderer::getTextAdvanceX(const int fontId, const char* text, const EpdFontFamily::Style style) const {
   const auto fontIt = fontMap.find(fontId);
   if (fontIt == fontMap.end()) {
     LOG_ERR("GFX", "Font %d not found", fontId);
@@ -829,7 +829,7 @@ int GfxRenderer::getTextAdvanceX(const int fontId, const char* text) const {
   int width = 0;
   const auto& font = fontIt->second;
   while ((cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&text)))) {
-    width += font.getGlyph(cp, EpdFontFamily::REGULAR)->advanceX;
+    width += font.getGlyph(cp, style)->advanceX;
   }
   return width;
 }

lib/GfxRenderer/GfxRenderer.h

@@ -105,8 +105,8 @@ class GfxRenderer {
                         EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
   void drawText(int fontId, int x, int y, const char* text, bool black = true,
                 EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
-  int getSpaceWidth(int fontId) const;
+  int getSpaceWidth(int fontId, EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
-  int getTextAdvanceX(int fontId, const char* text) const;
+  int getTextAdvanceX(int fontId, const char* text, EpdFontFamily::Style style) const;
   int getFontAscenderSize(int fontId) const;
   int getLineHeight(int fontId) const;
   std::string truncatedText(int fontId, const char* text, int maxWidth,