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fix: gracefully resolve fonts missing variants (#1921)

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This commit is contained in:
Uri Tauber
2026-05-10 21:11:11 +03:00
committed by GitHub
parent 3ac1ab13a0
commit 181ed6c488
1 changed files with 34 additions and 3 deletions
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lib/GfxRenderer/GfxRenderer.cpp
+34 -3
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@@ -10,6 +10,35 @@
#include "FontCacheManager.h"
namespace {
const char* resolveVisualText(const char* text, std::string& visualBuffer, int paragraphLevel);
/**
* Resolves the requested style to the best available style in the given SD card font.
* Falls back gracefully when the font lacks the requested variant.
*/
uint8_t resolveSdCardStyle(const SdCardFont& font, const EpdFontFamily::Style style) {
// Indexed by styleBits (0=REGULAR, 1=BOLD, 2=ITALIC, 3=BOLD_ITALIC)
static const uint8_t kFallbacks[4][4] = {
// REGULAR: REGULAR → BOLD → ITALIC → BOLD_ITALIC
{EpdFontFamily::REGULAR, EpdFontFamily::BOLD, EpdFontFamily::ITALIC, EpdFontFamily::BOLD_ITALIC},
// BOLD: BOLD → BOLD_ITALIC → REGULAR → ITALIC
{EpdFontFamily::BOLD, EpdFontFamily::BOLD_ITALIC, EpdFontFamily::REGULAR, EpdFontFamily::ITALIC},
// ITALIC: ITALIC → REGULAR → BOLD → BOLD_ITALIC (REGULAR before BOLD!)
{EpdFontFamily::ITALIC, EpdFontFamily::REGULAR, EpdFontFamily::BOLD, EpdFontFamily::BOLD_ITALIC},
// BOLD_ITALIC: BOLD_ITALIC → BOLD → ITALIC → REGULAR
{EpdFontFamily::BOLD_ITALIC, EpdFontFamily::BOLD, EpdFontFamily::ITALIC, EpdFontFamily::REGULAR},
};
const uint8_t styleBits = static_cast<uint8_t>(style) & 0x03;
for (uint8_t candidate : kFallbacks[styleBits]) {
if (font.hasStyle(candidate)) return candidate;
}
return EpdFontFamily::REGULAR; // no-variant-at-all safety net
}
} // namespace
const uint8_t* GfxRenderer::getGlyphBitmap(const EpdFontData* fontData, const EpdGlyph* glyph) const {
if (fontData->groups != nullptr) {
auto* fd = fontCacheManager_ ? fontCacheManager_->getDecompressor() : nullptr;
@@ -1074,7 +1103,8 @@ int GfxRenderer::getSpaceWidth(const int fontId, const EpdFontFamily::Style styl
// Advance table fast-path for SD card fonts during layout
auto sdIt = sdCardFonts_.find(fontId);
if (sdIt != sdCardFonts_.end() && sdIt->second->hasAdvanceTable()) {
return fp4::toPixel(sdIt->second->getAdvance(' ', static_cast<uint8_t>(style)));
const uint8_t resolvedStyle = resolveSdCardStyle(*sdIt->second, style);
return fp4::toPixel(sdIt->second->getAdvance(' ', resolvedStyle));
}
const auto fontIt = fontMap.find(fontId);
@@ -1094,7 +1124,8 @@ int GfxRenderer::getSpaceAdvance(const int fontId, const uint32_t leftCp, const
// so we return just the space advance without kerning.
auto sdIt = sdCardFonts_.find(fontId);
if (sdIt != sdCardFonts_.end() && sdIt->second->hasAdvanceTable()) {
return fp4::toPixel(sdIt->second->getAdvance(' ', static_cast<uint8_t>(style)));
const uint8_t resolvedStyle = resolveSdCardStyle(*sdIt->second, style);
return fp4::toPixel(sdIt->second->getAdvance(' ', resolvedStyle));
}
const auto fontIt = fontMap.find(fontId);
@@ -1124,7 +1155,7 @@ int GfxRenderer::getTextAdvanceX(const int fontId, const char* text, EpdFontFami
auto sdIt = sdCardFonts_.find(fontId);
if (sdIt != sdCardFonts_.end() && sdIt->second->hasAdvanceTable()) {
int32_t widthFP = 0;
const uint8_t styleIdx = static_cast<uint8_t>(style);
const uint8_t styleIdx = resolveSdCardStyle(*sdIt->second, style);
while (uint32_t cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&text))) {
widthFP += sdIt->second->getAdvance(cp, styleIdx);
}