A fork of https://github.com/crosspoint-reader/crosspoint-reader
fix: Implement guide-based cover image fallback (#830)
This partially fixes #769 but is dependent upon PR #827 being merged
along side this @daveallie. I removed my PNG conversion code after
finding out that PR was already created. Without this PR though that
book in #769 will still fail to load because of how it's stored in the
file
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
authored by
Justin Mitchell
Dave Allie
and committed by
GitHub
67020609
0bc67474
+59
-11
+48
lib/Epub/Epub.cpp
+48
lib/Epub/Epub.cpp
···
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bookMetadata.author = opfParser.author;
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bookMetadata.language = opfParser.language;
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bookMetadata.coverItemHref = opfParser.coverItemHref;
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+
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// Guide-based cover fallback: if no cover found via metadata/properties,
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// try extracting the image reference from the guide's cover page XHTML
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if (bookMetadata.coverItemHref.empty() && !opfParser.guideCoverPageHref.empty()) {
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LOG_DBG("EBP", "No cover from metadata, trying guide cover page: %s", opfParser.guideCoverPageHref.c_str());
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size_t coverPageSize;
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uint8_t* coverPageData = readItemContentsToBytes(opfParser.guideCoverPageHref, &coverPageSize, true);
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if (coverPageData) {
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const std::string coverPageHtml(reinterpret_cast<char*>(coverPageData), coverPageSize);
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free(coverPageData);
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// Determine base path of the cover page for resolving relative image references
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std::string coverPageBase;
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const auto lastSlash = opfParser.guideCoverPageHref.rfind('/');
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if (lastSlash != std::string::npos) {
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coverPageBase = opfParser.guideCoverPageHref.substr(0, lastSlash + 1);
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}
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// Search for image references: xlink:href="..." (SVG) and src="..." (img)
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std::string imageRef;
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for (const char* pattern : {"xlink:href=\"", "src=\""}) {
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auto pos = coverPageHtml.find(pattern);
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while (pos != std::string::npos) {
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pos += strlen(pattern);
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const auto endPos = coverPageHtml.find('"', pos);
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if (endPos != std::string::npos) {
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const auto ref = coverPageHtml.substr(pos, endPos - pos);
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// Check if it's an image file
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if (ref.length() >= 4) {
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const auto ext = ref.substr(ref.length() - 4);
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if (ext == ".png" || ext == ".jpg" || ext == "jpeg" || ext == ".gif") {
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imageRef = ref;
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break;
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}
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}
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}
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pos = coverPageHtml.find(pattern, pos);
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}
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if (!imageRef.empty()) break;
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}
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if (!imageRef.empty()) {
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bookMetadata.coverItemHref = FsHelpers::normalisePath(coverPageBase + imageRef);
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LOG_DBG("EBP", "Found cover image from guide: %s", bookMetadata.coverItemHref.c_str());
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}
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}
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}
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bookMetadata.textReferenceHref = opfParser.textReferenceHref;
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if (!opfParser.tocNcxPath.empty()) {
+10
-11
lib/Epub/Epub/parsers/ContentOpfParser.cpp
+10
-11
lib/Epub/Epub/parsers/ContentOpfParser.cpp
···
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// parse the guide
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if (self->state == IN_GUIDE && (strcmp(name, "reference") == 0 || strcmp(name, "opf:reference") == 0)) {
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std::string type;
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std::string textHref;
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std::string guideHref;
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for (int i = 0; atts[i]; i += 2) {
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if (strcmp(atts[i], "type") == 0) {
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type = atts[i + 1];
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if (type == "text" || type == "start") {
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continue;
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} else {
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LOG_DBG("COF", "Skipping non-text reference in guide: %s", type.c_str());
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break;
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}
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} else if (strcmp(atts[i], "href") == 0) {
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textHref = FsHelpers::normalisePath(self->baseContentPath + atts[i + 1]);
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guideHref = FsHelpers::normalisePath(self->baseContentPath + atts[i + 1]);
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}
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}
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if ((type == "text" || (type == "start" && !self->textReferenceHref.empty())) && (textHref.length() > 0)) {
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LOG_DBG("COF", "Found %s reference in guide: %s.", type.c_str(), textHref.c_str());
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self->textReferenceHref = textHref;
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if (!guideHref.empty()) {
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if (type == "text" || (type == "start" && !self->textReferenceHref.empty())) {
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LOG_DBG("COF", "Found %s reference in guide: %s", type.c_str(), guideHref.c_str());
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self->textReferenceHref = guideHref;
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} else if ((type == "cover" || type == "cover-page") && self->guideCoverPageHref.empty()) {
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LOG_DBG("COF", "Found cover reference in guide: %s", guideHref.c_str());
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self->guideCoverPageHref = guideHref;
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}
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}
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return;
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}
+1
lib/Epub/Epub/parsers/ContentOpfParser.h
+1
lib/Epub/Epub/parsers/ContentOpfParser.h
···
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std::string tocNcxPath;
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std::string tocNavPath; // EPUB 3 nav document path
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std::string coverItemHref;
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std::string guideCoverPageHref; // Guide reference with type="cover" or "cover-page" (points to XHTML wrapper)
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std::string textReferenceHref;
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std::vector<std::string> cssFiles; // CSS stylesheet paths
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