SkPDF: Memory improvements for PDF Streams

    ΔMEM = -15%
    ΔCPU = -7%

BUG=skia:3030

Review URL: https://codereview.chromium.org/1227913008

4 files changed, 104 insertions, 41 deletions

diff --git a/src/pdf/SkPDFFont.cpp b/src/pdf/SkPDFFont.cpp
index 17623c7c3b..25ffc0b851 100644
--- a/src/pdf/SkPDFFont.cpp
+++ b/src/pdf/SkPDFFont.cpp
@@ -584,6 +584,7 @@ static void sk_delete_array(const void* ptr, void*) {
 }
 #endif
 
+#if defined(SK_SFNTLY_SUBSETTER)
 static size_t get_subset_font_stream(const char* fontName,
                                      const SkTypeface* typeface,
                                      const SkTDArray<uint32_t>& subset,
@@ -594,7 +595,6 @@ static size_t get_subset_font_stream(const char* fontName,
 
     size_t fontSize = fontData->getLength();
 
-#if defined (SK_SFNTLY_SUBSETTER)
     // Read font into buffer.
     SkPDFStream* subsetFontStream = NULL;
     SkTDArray<unsigned char> originalFont;
@@ -624,15 +624,12 @@ static size_t get_subset_font_stream(const char* fontName,
         return fontSize;
     }
     fontData->rewind();
-#else
-    sk_ignore_unused_variable(fontName);
-    sk_ignore_unused_variable(subset);
-#endif
 
     // Fail over: just embed the whole font.
     *fontStream = new SkPDFStream(fontData.get());
     return fontSize;
 }
+#endif
 
 ///////////////////////////////////////////////////////////////////////////////
 // class SkPDFGlyphSet
@@ -1061,40 +1058,43 @@ bool SkPDFCIDFont::addFontDescriptor(int16_t defaultWidth,
 
     switch (getType()) {
         case SkAdvancedTypefaceMetrics::kTrueType_Font: {
-            SkAutoTUnref<SkPDFStream> fontStream;
             size_t fontSize = 0;
-            if (canSubset()) {
+#if defined(SK_SFNTLY_SUBSETTER)
+            if (this->canSubset()) {
+                SkAutoTUnref<SkPDFStream> fontStream;
                 SkPDFStream* rawStream = NULL;
                 fontSize = get_subset_font_stream(fontInfo()->fFontName.c_str(),
                                                   typeface(),
                                                   *subset,
                                                   &rawStream);
-                fontStream.reset(rawStream);
-            } else {
-                int ttcIndex;
-                SkAutoTDelete<SkStream> fontData(
-                        typeface()->openStream(&ttcIndex));
-                fontStream.reset(new SkPDFStream(fontData.get()));
-                fontSize = fontData->getLength();
+                if (rawStream) {
+                    fontStream.reset(rawStream);
+                    fontStream->insertInt("Length1", fontSize);
+                    descriptor->insertObjRef("FontFile2", fontStream.detach());
+                    break;
+                }
             }
-            SkASSERT(fontSize);
-            SkASSERT(fontStream.get());
-
-            fontStream->insertInt("Length1", fontSize);
+#endif
+            SkAutoTUnref<SkPDFSharedStream> fontStream;
+            SkAutoTDelete<SkStreamAsset> fontData(
+                    this->typeface()->openStream(NULL));
+            SkASSERT(fontData);
+            fontSize = fontData->getLength();
+            SkASSERT(fontSize > 0);
+            fontStream.reset(new SkPDFSharedStream(fontData.detach()));
+            fontStream->dict()->insertInt("Length1", fontSize);
             descriptor->insertObjRef("FontFile2", fontStream.detach());
             break;
         }
         case SkAdvancedTypefaceMetrics::kCFF_Font:
         case SkAdvancedTypefaceMetrics::kType1CID_Font: {
-            int ttcIndex;
-            SkAutoTDelete<SkStream> fontData(typeface()->openStream(&ttcIndex));
-            SkAutoTUnref<SkPDFStream> fontStream(
-                new SkPDFStream(fontData.get()));
+            SkAutoTUnref<SkPDFSharedStream> fontStream(
+                    new SkPDFSharedStream(this->typeface()->openStream(NULL)));
 
             if (getType() == SkAdvancedTypefaceMetrics::kCFF_Font) {
-                fontStream->insertName("Subtype", "Type1C");
+                fontStream->dict()->insertName("Subtype", "Type1C");
             } else {
-                fontStream->insertName("Subtype", "CIDFontType0c");
+                fontStream->dict()->insertName("Subtype", "CIDFontType0c");
             }
             descriptor->insertObjRef("FontFile3", fontStream.detach());
             break;
diff --git a/src/pdf/SkPDFStream.cpp b/src/pdf/SkPDFStream.cpp
index 69ce317bb9..b8f2e4e92b 100644
--- a/src/pdf/SkPDFStream.cpp
+++ b/src/pdf/SkPDFStream.cpp
@@ -20,7 +20,7 @@ void SkPDFStream::emitObject(SkWStream* stream,
                              const SkPDFSubstituteMap& substitutes) const {
     SkASSERT(fCompressedData);
     this->INHERITED::emitObject(stream, objNumMap, substitutes);
-    // Note: emitObject isn't marked const, but could be in the future
+    // duplicate (a cheap operation) preserves const on fCompressedData.
     SkAutoTDelete<SkStreamRewindable> dup(fCompressedData->duplicate());
     SkASSERT(dup);
     SkASSERT(dup->hasLength());
diff --git a/src/pdf/SkPDFTypes.cpp b/src/pdf/SkPDFTypes.cpp
index 2fe408b1cc..9bb9dee497 100644
--- a/src/pdf/SkPDFTypes.cpp
+++ b/src/pdf/SkPDFTypes.cpp
@@ -6,15 +6,10 @@
  * found in the LICENSE file.
  */
 
+#include "SkDeflate.h"
 #include "SkPDFTypes.h"
 #include "SkPDFUtils.h"
-#include "SkStream.h"
-
-#ifdef SK_BUILD_FOR_WIN
-    #define SNPRINTF    _snprintf
-#else
-    #define SNPRINTF    snprintf
-#endif
+#include "SkStreamPriv.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -355,6 +350,13 @@ void SkPDFDict::emitObject(SkWStream* stream,
                            const SkPDFObjNumMap& objNumMap,
                            const SkPDFSubstituteMap& substitutes) const {
     stream->writeText("<<");
+    this->emitAll(stream, objNumMap, substitutes);
+    stream->writeText(">>");
+}
+
+void SkPDFDict::emitAll(SkWStream* stream,
+                        const SkPDFObjNumMap& objNumMap,
+                        const SkPDFSubstituteMap& substitutes) const {
     for (int i = 0; i < fRecords.count(); i++) {
         fRecords[i].fKey.emitObject(stream, objNumMap, substitutes);
         stream->writeText(" ");
@@ -363,7 +365,6 @@ void SkPDFDict::emitObject(SkWStream* stream,
             stream->writeText("\n");
         }
     }
-    stream->writeText(">>");
 }
 
 void SkPDFDict::addResources(SkPDFObjNumMap* catalog,
@@ -439,6 +440,41 @@ void SkPDFDict::clear() {
 
 ////////////////////////////////////////////////////////////////////////////////
 
+void SkPDFSharedStream::emitObject(
+        SkWStream* stream,
+        const SkPDFObjNumMap& objNumMap,
+        const SkPDFSubstituteMap& substitutes) const {
+    SkDynamicMemoryWStream buffer;
+    SkDeflateWStream deflateWStream(&buffer);
+    // Since emitObject is const, this function doesn't change the dictionary.
+    SkAutoTDelete<SkStreamAsset> dup(fAsset->duplicate());  // Cheap copy
+    SkASSERT(dup);
+    SkStreamCopy(&deflateWStream, dup.get());
+    deflateWStream.finalize();
+    size_t length = buffer.bytesWritten();
+    stream->writeText("<<");
+    fDict->emitAll(stream, objNumMap, substitutes);
+    stream->writeText("\n");
+    SkPDFUnion::Name("Length").emitObject(stream, objNumMap, substitutes);
+    stream->writeText(" ");
+    SkPDFUnion::Int(length).emitObject(stream, objNumMap, substitutes);
+    stream->writeText("\n");
+    SkPDFUnion::Name("Filter").emitObject(stream, objNumMap, substitutes);
+    stream->writeText(" ");
+    SkPDFUnion::Name("FlateDecode").emitObject(stream, objNumMap, substitutes);
+    stream->writeText(">>");
+    stream->writeText(" stream\n");
+    buffer.writeToStream(stream);
+    stream->writeText("\nendstream");
+}
+
+void SkPDFSharedStream::addResources(
+        SkPDFObjNumMap* catalog, const SkPDFSubstituteMap& substitutes) const {
+    fDict->addResources(catalog, substitutes);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 SkPDFSubstituteMap::~SkPDFSubstituteMap() {
     fSubstituteMap.foreach(
             [](SkPDFObject*, SkPDFObject** v) { (*v)->unref(); });
diff --git a/src/pdf/SkPDFTypes.h b/src/pdf/SkPDFTypes.h
index 56e534bd5e..85aa0132ed 100644
--- a/src/pdf/SkPDFTypes.h
+++ b/src/pdf/SkPDFTypes.h
@@ -11,6 +11,7 @@
 
 #include "SkRefCnt.h"
 #include "SkScalar.h"
+#include "SkStream.h"
 #include "SkString.h"
 #include "SkTDArray.h"
 #include "SkTHash.h"
@@ -19,7 +20,6 @@
 class SkPDFObjNumMap;
 class SkPDFObject;
 class SkPDFSubstituteMap;
-class SkWStream;
 
 /** \class SkPDFObject
 
@@ -30,8 +30,6 @@ class SkWStream;
 */
 class SkPDFObject : public SkRefCnt {
 public:
-    
-
     /** Subclasses must implement this method to print the object to the
      *  PDF file.
      *  @param catalog  The object catalog to use.
@@ -77,7 +75,7 @@ public:
 
     static SkPDFUnion Int(int32_t);
 
-    static SkPDFUnion Int(size_t);
+    static SkPDFUnion Int(size_t v) { return SkPDFUnion::Int(SkToS32(v)); }
 
     static SkPDFUnion Bool(bool);
 
@@ -188,8 +186,6 @@ private:
 */
 class SkPDFArray : public SkPDFObject {
 public:
-    
-
     static const int kMaxLen = 8191;
 
     /** Create a PDF array. Maximum length is 8191.
@@ -239,8 +235,6 @@ private:
 */
 class SkPDFDict : public SkPDFObject {
 public:
-    
-
     /** Create a PDF dictionary. Maximum number of entries is 4095.
      */
     SkPDFDict();
@@ -290,6 +284,12 @@ public:
      */
     void clear();
 
+    /** Emit the dictionary, without the "<<" and ">>".
+     */
+    void emitAll(SkWStream* stream,
+                 const SkPDFObjNumMap& objNumMap,
+                 const SkPDFSubstituteMap& substitutes) const;
+
 private:
     struct Record {
         SkPDFUnion fKey;
@@ -303,6 +303,33 @@ private:
     typedef SkPDFObject INHERITED;
 };
 
+/** \class SkPDFSharedStream
+
+    This class takes an asset and assumes that it is backed by
+    long-lived shared data (for example, an open file
+    descriptor). That is: no memory savings can be made by holding on
+    to a compressed version instead.
+ */
+class SkPDFSharedStream : public SkPDFObject {
+public:
+    // Takes ownership of asset.
+    SkPDFSharedStream(SkStreamAsset* data)
+        : fAsset(data), fDict(SkNEW(SkPDFDict)) {
+        SkASSERT(data);
+    }
+    SkPDFDict* dict() { return fDict; }
+    void emitObject(SkWStream*,
+                    const SkPDFObjNumMap&,
+                    const SkPDFSubstituteMap&) const override;
+    void addResources(SkPDFObjNumMap*,
+                      const SkPDFSubstituteMap&) const override;
+
+private:
+    SkAutoTDelete<SkStreamAsset> fAsset;
+    SkAutoTUnref<SkPDFDict> fDict;
+    typedef SkPDFObject INHERITED;
+};
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /** \class SkPDFObjNumMap