SkDeflateWStream: support gzip output

src/pdf/SkDeflate.cpp

 
 /*
  * Copyright 2010 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkData.h"
@@ skipping 47 matching lines @@
 }
 
 // Hide all zlib impl details.
 struct SkDeflateWStream::Impl {
     SkWStream* fOut;
     unsigned char fInBuffer[SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE];
     size_t fInBufferIndex;
     z_stream fZStream;
 };
 
-SkDeflateWStream::SkDeflateWStream(SkWStream* out) : fImpl(new SkDeflateWStream::Impl) {
+SkDeflateWStream::SkDeflateWStream(SkWStream* out,
+                                   int compressionLevel,
+                                   bool gzip)
+    : fImpl(new SkDeflateWStream::Impl) {
     fImpl->fOut = out;
     fImpl->fInBufferIndex = 0;
     if (!fImpl->fOut) {
         return;
     }
+    fImpl->fZStream.next_in = nullptr;
     fImpl->fZStream.zalloc = &skia_alloc_func;
     fImpl->fZStream.zfree = &skia_free_func;
     fImpl->fZStream.opaque = nullptr;
-    SkDEBUGCODE(int r =) deflateInit(&fImpl->fZStream, Z_DEFAULT_COMPRESSION);
+    SkASSERT(compressionLevel <= 9 && compressionLevel >= -1);
+    SkDEBUGCODE(int r =) deflateInit2(&fImpl->fZStream, compressionLevel,
+                                      Z_DEFLATED, gzip ? 0x1F : 0x0F,
+                                      8, Z_DEFAULT_STRATEGY);
     SkASSERT(Z_OK == r);
 }
 
 SkDeflateWStream::~SkDeflateWStream() { this->finalize(); }
 
 void SkDeflateWStream::finalize() {
     if (!fImpl->fOut) {
         return;
     }
     do_deflate(Z_FINISH, &fImpl->fZStream, fImpl->fOut, fImpl->fInBuffer,
@@ skipping 22 matching lines @@
                        fImpl->fInBuffer, fImpl->fInBufferIndex);
             fImpl->fInBufferIndex = 0;
         }
     }
     return true;
 }
 
 size_t SkDeflateWStream::bytesWritten() const {
     return fImpl->fZStream.total_in + fImpl->fInBufferIndex;
 }