SkPDF: SkPDFStream takes only SkStreamAsset

This is possible since https://crrev.com/869763002. Later, I'll clean
up the logic and class constructors.  For now, I assert everywhere I
expect a SkStreamAsset to be well-behaved (duplcate, hasLength).
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2098393002

Review-Url: https://codereview.chromium.org/2098393002

src/pdf/SkPDFFont.cpp

@@ -591,7 +591,7 @@ static size_t get_subset_font_stream(const char* fontName,
                                      const SkTDArray<uint32_t>& subset,
                                      SkPDFStream** fontStream) {
     int ttcIndex;
-    std::unique_ptr<SkStream> fontData(typeface->openStream(&ttcIndex));
+    std::unique_ptr<SkStreamAsset> fontData(typeface->openStream(&ttcIndex));
     SkASSERT(fontData);
     if (!fontData) {
         return 0;

src/pdf/SkPDFFormXObject.cpp

@@ -43,7 +43,7 @@ SkPDFFormXObject::SkPDFFormXObject(SkPDFDevice* device) {
 /**
  * Creates a FormXObject from a content stream and associated resources.
  */
-SkPDFFormXObject::SkPDFFormXObject(SkStream* content, SkRect bbox,
+SkPDFFormXObject::SkPDFFormXObject(SkStreamAsset* content, SkRect bbox,
                                    SkPDFDict* resourceDict) {
     setData(content);
 

src/pdf/SkPDFFormXObject.h

@@ -37,7 +37,7 @@ public:
      * Create a PDF form XObject from a raw content stream and associated
      * resources.
      */
-    explicit SkPDFFormXObject(SkStream* content,
+    explicit SkPDFFormXObject(SkStreamAsset* content,
                               SkRect bbox,
                               SkPDFDict* resourceDict);
     virtual ~SkPDFFormXObject();

src/pdf/SkPDFShader.cpp

@@ -672,7 +672,7 @@ static void populate_tiling_pattern_dict(SkPDFDict* pattern,
  * @param gsIndex A graphics state resource index to apply, or <0 if no
  * graphics state to apply.
  */
-static SkStream* create_pattern_fill_content(int gsIndex, SkRect& bounds) {
+static SkStreamAsset* create_pattern_fill_content(int gsIndex, SkRect& bounds) {
     SkDynamicMemoryWStream content;
     if (gsIndex >= 0) {
         SkPDFUtils::ApplyGraphicState(gsIndex, &content);
@@ -699,7 +699,7 @@ static sk_sp<SkPDFObject> create_smask_graphic_state(
     sk_sp<SkPDFObject> luminosityShader(
             get_pdf_shader_by_state(doc, dpi, &alphaToLuminosityState));
 
-    std::unique_ptr<SkStream> alphaStream(create_pattern_fill_content(-1, bbox));
+    std::unique_ptr<SkStreamAsset> alphaStream(create_pattern_fill_content(-1, bbox));
 
     auto resources =
         get_gradient_resource_dict(luminosityShader.get(), nullptr);
@@ -738,7 +738,7 @@ SkPDFAlphaFunctionShader* SkPDFAlphaFunctionShader::Create(
     auto resourceDict =
             get_gradient_resource_dict(colorShader.get(), alphaGs.get());
 
-    std::unique_ptr<SkStream> colorStream(
+    std::unique_ptr<SkStreamAsset> colorStream(
             create_pattern_fill_content(0, bbox));
     alphaFunctionShader->setData(colorStream.get());
 

src/pdf/SkPDFStream.cpp

@@ -24,7 +24,7 @@ void SkPDFStream::emitObject(SkWStream* stream,
     SkASSERT(fCompressedData);
     this->INHERITED::emitObject(stream, objNumMap, substitutes);
     // duplicate (a cheap operation) preserves const on fCompressedData.
-    std::unique_ptr<SkStreamRewindable> dup(fCompressedData->duplicate());
+    std::unique_ptr<SkStreamAsset> dup(fCompressedData->duplicate());
     SkASSERT(dup);
     SkASSERT(dup->hasLength());
     stream->writeText(" stream\n");
@@ -33,13 +33,14 @@ void SkPDFStream::emitObject(SkWStream* stream,
 }
 
 
-void SkPDFStream::setData(SkStream* stream) {
+void SkPDFStream::setData(SkStreamAsset* stream) {
     SkASSERT(!fCompressedData);  // Only call this function once.
     SkASSERT(stream);
     // Code assumes that the stream starts at the beginning.
 
     #ifdef SK_PDF_LESS_COMPRESSION
-    std::unique_ptr<SkStreamRewindable> duplicate(stream->duplicate());
+    std::unique_ptr<SkStreamAsset> duplicate(stream->duplicate());
+    SkASSERT(duplicate && duplicate->hasLength());
     if (duplicate && duplicate->hasLength()) {
         this->insertInt("Length", duplicate->getLength());
         fCompressedData.reset(duplicate.release());
@@ -53,8 +54,12 @@ void SkPDFStream::setData(SkStream* stream) {
     deflateWStream.finalize();
     size_t length = compressedData.bytesWritten();
 
+    SkASSERT(stream->hasLength());
     if (stream->hasLength()) {
-        std::unique_ptr<SkStreamRewindable> dup(stream->duplicate());
+        std::unique_ptr<SkStreamAsset> dup(stream->duplicate());
+        SkASSERT(stream->hasLength());
+        SkASSERT(stream->getLength() == dup->getLength());
+        SkASSERT(dup && dup->hasLength());
         if (dup && dup->hasLength() &&
             dup->getLength() <= length + strlen("/Filter_/FlateDecode_")) {
             this->insertInt("Length", dup->getLength());

src/pdf/SkPDFStream.h

@@ -30,7 +30,7 @@ public:
      *  stream dictionary.
      *  @param stream The data part of the stream.  Will not take ownership.
      */
-    explicit SkPDFStream(SkStream* stream) { this->setData(stream); }
+    explicit SkPDFStream(SkStreamAsset* stream) { this->setData(stream); }
 
     virtual ~SkPDFStream();
 
@@ -47,14 +47,14 @@ protected:
     SkPDFStream() {}
 
     /** Only call this function once. */
-    void setData(SkStream* stream);
+    void setData(SkStreamAsset* stream);
     void setData(SkData* data) {
         SkMemoryStream memoryStream(data);
         this->setData(&memoryStream);
     }
 
 private:
-    std::unique_ptr<SkStreamRewindable> fCompressedData;
+    std::unique_ptr<SkStreamAsset> fCompressedData;
 
     typedef SkPDFDict INHERITED;
 };