SkPDF: Optionally output PDF/A-2b archive format.
Note: this format does not yet pass validation tests.
Add skia_pdf_generate_pdfa GYP flag. Default to off for now.
PDF/A files are not reproducable, so they make correctness
testing harder.
Turn the Metadata struct into te SkPDFMetadata struct. This
splits out a lot of functionality around both kinds of metadata.
When PDF/A is used, add an ID entry to the trailer.
Add SkPDFObjNumMap::addObjectRecursively.
Test with
GYP_DEFINES=skia_pdf_generate_pdfa=1 bin/sync-and-gyp
ninja -C out/Release dm
out/Release/dm --config pdf --src skp gm -w /tmp/dm
With skia_pdf_generate_pdfa=0, all PDFs generated from GMs and
SKPs are identical. With skia_pdf_generate_pdfa=1, all PDFs
generated from GMs and SKPs render identically in Pdfium.
BUG=skia:3110
Review URL: https://codereview.chromium.org/1394263003
diff --git a/src/pdf/SkPDFMetadata.cpp b/src/pdf/SkPDFMetadata.cpp
new file mode 100644
index 0000000..4865deb
--- /dev/null
+++ b/src/pdf/SkPDFMetadata.cpp
@@ -0,0 +1,350 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkPDFMetadata.h"
+#include "SkPDFTypes.h"
+
+#ifdef SK_PDF_GENERATE_PDFA
+#include "SkMD5.h"
+#endif
+
+static SkString pdf_date(const SkTime::DateTime& dt) {
+ int timeZoneMinutes = SkToInt(dt.fTimeZoneMinutes);
+ char timezoneSign = timeZoneMinutes >= 0 ? '+' : '-';
+ int timeZoneHours = SkTAbs(timeZoneMinutes) / 60;
+ timeZoneMinutes = SkTAbs(timeZoneMinutes) % 60;
+ return SkStringPrintf(
+ "D:%04u%02u%02u%02u%02u%02u%c%02d'%02d'",
+ static_cast<unsigned>(dt.fYear), static_cast<unsigned>(dt.fMonth),
+ static_cast<unsigned>(dt.fDay), static_cast<unsigned>(dt.fHour),
+ static_cast<unsigned>(dt.fMinute),
+ static_cast<unsigned>(dt.fSecond), timezoneSign, timeZoneHours,
+ timeZoneMinutes);
+}
+
+SkPDFObject* SkPDFMetadata::createDocumentInformationDict() const {
+ SkAutoTUnref<SkPDFDict> dict(new SkPDFDict);
+ static const char* keys[] = {
+ "Title", "Author", "Subject", "Keywords", "Creator"};
+ for (const char* key : keys) {
+ for (const SkDocument::Attribute& keyValue : fInfo) {
+ if (keyValue.fKey.equals(key)) {
+ dict->insertString(key, keyValue.fValue);
+ }
+ }
+ }
+ dict->insertString("Producer", "Skia/PDF");
+ if (fCreation) {
+ dict->insertString("CreationDate", pdf_date(*fCreation.get()));
+ }
+ if (fModified) {
+ dict->insertString("ModDate", pdf_date(*fModified.get()));
+ }
+ return dict.detach();
+}
+
+#ifdef SK_PDF_GENERATE_PDFA
+SkPDFMetadata::UUID SkPDFMetadata::uuid() const {
+ // The main requirement is for the UUID to be unique; the exact
+ // format of the data that will be hashed is not important.
+ SkMD5 md5;
+ const char uuidNamespace[] = "org.skia.pdf\n";
+ md5.write(uuidNamespace, strlen(uuidNamespace));
+ SkMSec msec = SkTime::GetMSecs();
+ md5.write(&msec, sizeof(msec));
+ SkTime::DateTime dateTime;
+ SkTime::GetDateTime(&dateTime);
+ md5.write(&dateTime, sizeof(dateTime));
+ if (fCreation) {
+ md5.write(fCreation.get(), sizeof(fCreation));
+ }
+ if (fModified) {
+ md5.write(fModified.get(), sizeof(fModified));
+ }
+ for (const auto& kv : fInfo) {
+ md5.write(kv.fKey.c_str(), kv.fKey.size());
+ md5.write("\037", 1);
+ md5.write(kv.fValue.c_str(), kv.fValue.size());
+ md5.write("\036", 1);
+ }
+ SkMD5::Digest digest;
+ md5.finish(digest);
+ // See RFC 4122, page 6-7.
+ digest.data[6] = (digest.data[6] & 0x0F) | 0x30;
+ digest.data[8] = (digest.data[6] & 0x3F) | 0x80;
+ static_assert(sizeof(digest) == sizeof(UUID), "uuid_size");
+ SkPDFMetadata::UUID uuid;
+ memcpy(&uuid, &digest, sizeof(digest));
+ return uuid;
+}
+
+SkPDFObject* SkPDFMetadata::CreatePdfId(const UUID& doc, const UUID& instance) {
+ // /ID [ <81b14aafa313db63dbd6f981e49f94f4>
+ // <81b14aafa313db63dbd6f981e49f94f4> ]
+ SkAutoTUnref<SkPDFArray> array(new SkPDFArray);
+ static_assert(sizeof(UUID) == 16, "uuid_size");
+ array->appendString(
+ SkString(reinterpret_cast<const char*>(&doc), sizeof(UUID)));
+ array->appendString(
+ SkString(reinterpret_cast<const char*>(&instance), sizeof(UUID)));
+ return array.detach();
+}
+
+// Improvement on SkStringPrintf to allow for arbitrarily long output.
+// TODO: replace SkStringPrintf.
+static SkString sk_string_printf(const char* format, ...) {
+#ifdef SK_BUILD_FOR_WIN
+ va_list args;
+ va_start(args, format);
+ char buffer[1024];
+ int length = _vsnprintf_s(buffer, sizeof(buffer), _TRUNCATE, format, args);
+ va_end(args);
+ if (length >= 0 && length < (int)sizeof(buffer)) {
+ return SkString(buffer, length);
+ }
+ va_start(args, format);
+ length = _vscprintf(format, args);
+ va_end(args);
+
+ SkString string((size_t)length);
+ va_start(args, format);
+ SkDEBUGCODE(int check = ) _vsnprintf_s(string.writable_str(), length + 1,
+ _TRUNCATE, format, args);
+ va_end(args);
+ SkASSERT(check == length);
+ SkASSERT(string[length] == '\0');
+ return skstd::move(string);
+#else // C99/C++11 standard vsnprintf
+ // TODO: When all compilers support this, remove windows-specific code.
+ va_list args;
+ va_start(args, format);
+ char buffer[1024];
+ int length = vsnprintf(buffer, sizeof(buffer), format, args);
+ va_end(args);
+ if (length < 0) {
+ return SkString();
+ }
+ if (length < (int)sizeof(buffer)) {
+ return SkString(buffer, length);
+ }
+ SkString string((size_t)length);
+ va_start(args, format);
+ SkDEBUGCODE(int check = )
+ vsnprintf(string.writable_str(), length + 1, format, args);
+ va_end(args);
+ SkASSERT(check == length);
+ SkASSERT(string[length] == '\0');
+ return skstd::move(string);
+#endif
+}
+
+static const SkString get(const SkTArray<SkDocument::Attribute>& info,
+ const char* key) {
+ for (const auto& keyValue : info) {
+ if (keyValue.fKey.equals(key)) {
+ return keyValue.fValue;
+ }
+ }
+ return SkString();
+}
+
+#define HEXIFY(INPUT_PTR, OUTPUT_PTR, HEX_STRING, BYTE_COUNT) \
+ do { \
+ for (int i = 0; i < (BYTE_COUNT); ++i) { \
+ uint8_t value = *(INPUT_PTR)++; \
+ *(OUTPUT_PTR)++ = (HEX_STRING)[value >> 4]; \
+ *(OUTPUT_PTR)++ = (HEX_STRING)[value & 0xF]; \
+ } \
+ } while (false)
+static SkString uuid_to_string(const SkPDFMetadata::UUID& uuid) {
+ // 8-4-4-4-12
+ char buffer[36]; // [32 + 4]
+ static const char gHex[] = "0123456789abcdef";
+ SkASSERT(strlen(gHex) == 16);
+ char* ptr = buffer;
+ const uint8_t* data = uuid.fData;
+ HEXIFY(data, ptr, gHex, 4);
+ *ptr++ = '-';
+ HEXIFY(data, ptr, gHex, 2);
+ *ptr++ = '-';
+ HEXIFY(data, ptr, gHex, 2);
+ *ptr++ = '-';
+ HEXIFY(data, ptr, gHex, 2);
+ *ptr++ = '-';
+ HEXIFY(data, ptr, gHex, 6);
+ SkASSERT(ptr == buffer + 36);
+ SkASSERT(data == uuid.fData + 16);
+ return SkString(buffer, 36);
+}
+#undef HEXIFY
+
+namespace {
+class PDFXMLObject : public SkPDFObject {
+public:
+ PDFXMLObject(SkString xml) : fXML(skstd::move(xml)) {}
+ void emitObject(SkWStream* stream,
+ const SkPDFObjNumMap& omap,
+ const SkPDFSubstituteMap& smap) const override {
+ SkPDFDict dict("Metadata");
+ dict.insertName("Subtype", "XML");
+ dict.insertInt("Length", fXML.size());
+ dict.emitObject(stream, omap, smap);
+ static const char streamBegin[] = " stream\n";
+ stream->write(streamBegin, strlen(streamBegin));
+ // Do not compress this. The standard requires that a
+ // program that does not understand PDF can grep for
+ // "<?xpacket" and extracť the entire XML.
+ stream->write(fXML.c_str(), fXML.size());
+ static const char streamEnd[] = "\nendstream";
+ stream->write(streamEnd, strlen(streamEnd));
+ }
+
+private:
+ const SkString fXML;
+};
+} // namespace
+
+static int count_xml_escape_size(const SkString& input) {
+ int extra = 0;
+ for (size_t i = 0; i < input.size(); ++i) {
+ if (input[i] == '&') {
+ extra += 4; // strlen("&") - strlen("&")
+ } else if (input[i] == '<') {
+ extra += 3; // strlen("<") - strlen("<")
+ }
+ }
+ return extra;
+}
+
+const SkString escape_xml(const SkString& input,
+ const char* before = nullptr,
+ const char* after = nullptr) {
+ if (input.size() == 0) {
+ return input;
+ }
+ // "&" --> "&" and "<" --> "<"
+ // text is assumed to be in UTF-8
+ // all strings are xml content, not attribute values.
+ size_t beforeLen = before ? strlen(before) : 0;
+ size_t afterLen = after ? strlen(after) : 0;
+ int extra = count_xml_escape_size(input);
+ SkString output(input.size() + extra + beforeLen + afterLen);
+ char* out = output.writable_str();
+ if (before) {
+ strncpy(out, before, beforeLen);
+ out += beforeLen;
+ }
+ static const char kAmp[] = "&";
+ static const char kLt[] = "<";
+ for (size_t i = 0; i < input.size(); ++i) {
+ if (input[i] == '&') {
+ strncpy(out, kAmp, strlen(kAmp));
+ out += strlen(kAmp);
+ } else if (input[i] == '<') {
+ strncpy(out, kLt, strlen(kLt));
+ out += strlen(kLt);
+ } else {
+ *out++ = input[i];
+ }
+ }
+ if (after) {
+ strncpy(out, after, afterLen);
+ out += afterLen;
+ }
+ // Validate that we haven't written outside of our string.
+ SkASSERT(out == &output.writable_str()[output.size()]);
+ *out = '\0';
+ return skstd::move(output);
+}
+
+SkPDFObject* SkPDFMetadata::createXMPObject(const UUID& doc,
+ const UUID& instance) const {
+ static const char templateString[] =
+ "<?xpacket begin=\"\" id=\"W5M0MpCehiHzreSzNTczkc9d\"?>\n"
+ "<x:xmpmeta xmlns:x=\"adobe:ns:meta/\"\n"
+ " x:xmptk=\"Adobe XMP Core 5.4-c005 78.147326, "
+ "2012/08/23-13:03:03\">\n"
+ "<rdf:RDF "
+ "xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\">\n"
+ "<rdf:Description rdf:about=\"\"\n"
+ " xmlns:xmp=\"http://ns.adobe.com/xap/1.0/\"\n"
+ " xmlns:dc=\"http://purl.org/dc/elements/1.1/\"\n"
+ " xmlns:xmpMM=\"http://ns.adobe.com/xap/1.0/mm/\"\n"
+ " xmlns:pdf=\"http://ns.adobe.com/pdf/1.3/\"\n"
+ " xmlns:pdfaid=\"http://www.aiim.org/pdfa/ns/id/\">\n"
+ "<pdfaid:part>2</pdfaid:part>\n"
+ "<pdfaid:conformance>B</pdfaid:conformance>\n"
+ "%s" // ModifyDate
+ "%s" // CreateDate
+ "%s" // MetadataDate
+ "%s" // xmp:CreatorTool
+ "<dc:format>application/pdf</dc:format>\n"
+ "%s" // dc:title
+ "%s" // dc:description
+ "%s" // author
+ "%s" // keywords
+ "<xmpMM:DocumentID>uuid:%s</xmpMM:DocumentID>\n"
+ "<xmpMM:InstanceID>uuid:%s</xmpMM:InstanceID>\n"
+ "<pdf:Producer>Skia/PDF</pdf:Producer>\n"
+ "%s" // pdf:Keywords
+ "</rdf:Description>\n"
+ "</rdf:RDF>\n"
+ "</x:xmpmeta>\n" // Note: the standard suggests 4k of padding.
+ "<?xpacket end=\"w\"?>\n";
+
+ SkString creationDate;
+ SkString modificationDate;
+ SkString metadataDate;
+ if (fCreation) {
+ SkString tmp;
+ fCreation->toISO8601(&tmp);
+ SkASSERT(0 == count_xml_escape_size(tmp));
+ // YYYY-mm-ddTHH:MM:SS[+|-]ZZ:ZZ; no need to escape
+ creationDate = sk_string_printf("<xmp:CreateDate>%s</xmp:CreateDate>\n",
+ tmp.c_str());
+ }
+ if (fModified) {
+ SkString tmp;
+ fModified->toISO8601(&tmp);
+ SkASSERT(0 == count_xml_escape_size(tmp));
+ modificationDate = sk_string_printf(
+ "<xmp:ModifyDate>%s</xmp:ModifyDate>\n", tmp.c_str());
+ metadataDate = sk_string_printf(
+ "<xmp:MetadataDate>%s</xmp:MetadataDate>\n", tmp.c_str());
+ }
+
+ SkString title =
+ escape_xml(get(fInfo, "Title"), "<dc:title><rdf:Alt><rdf:li>",
+ "</rdf:li></rdf:Alt></dc:title>\n");
+ SkString author =
+ escape_xml(get(fInfo, "Author"), "<dc:creator><rdf:Bag><rdf:li>",
+ "</rdf:li></rdf:Bag></dc:creator>\n");
+ // TODO: in theory, XMP can support multiple authors. Split on a delimiter?
+ SkString subject = escape_xml(get(fInfo, "Subject"),
+ "<dc:description><rdf:Alt><rdf:li>",
+ "</rdf:li></rdf:Alt></dc:description>\n");
+ SkString keywords1 =
+ escape_xml(get(fInfo, "Keywords"), "<dc:subject><rdf:Bag><rdf:li>",
+ "</rdf:li></rdf:Bag></dc:subject>\n");
+ SkString keywords2 = escape_xml(get(fInfo, "Keywords"), "<pdf:Keywords>",
+ "</pdf:Keywords>\n");
+
+ // TODO: in theory, keywords can be a list too.
+ SkString creator = escape_xml(get(fInfo, "Creator"), "<xmp:CreatorTool>",
+ "</xmp:CreatorTool>\n");
+ SkString documentID = uuid_to_string(doc); // no need to escape
+ SkASSERT(0 == count_xml_escape_size(documentID));
+ SkString instanceID = uuid_to_string(instance);
+ SkASSERT(0 == count_xml_escape_size(instanceID));
+ return new PDFXMLObject(sk_string_printf(
+ templateString, modificationDate.c_str(), creationDate.c_str(),
+ metadataDate.c_str(), creator.c_str(), title.c_str(),
+ subject.c_str(), author.c_str(), keywords1.c_str(),
+ documentID.c_str(), instanceID.c_str(), keywords2.c_str()));
+}
+
+#endif // SK_PDF_GENERATE_PDFA