Implemented transparent gradients

src/pdf/SkPDFGraphicState.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPDFFormXObject.h"
 #include "SkPDFGraphicState.h"
 #include "SkPDFUtils.h"
@@ skipping 120 matching lines @@
         invertFunction = new SkPDFStream(psInvertStream.get());
         invertFunction->insertInt("FunctionType", 4);
         invertFunction->insert("Domain", domainAndRange.get());
         invertFunction->insert("Range", domainAndRange.get());
     }
     return invertFunction;
 }
 
 // static
 SkPDFGraphicState* SkPDFGraphicState::GetSMaskGraphicState(
-        SkPDFFormXObject* sMask, bool invert) {
+        SkPDFFormXObject* sMask, bool invert, SkPDFSMaskMode sMaskMode) {
     // The practical chances of using the same mask more than once are unlikely
     // enough that it's not worth canonicalizing.
     SkAutoMutexAcquire lock(CanonicalPaintsMutex());
 
     SkAutoTUnref<SkPDFDict> sMaskDict(new SkPDFDict("Mask"));
-    sMaskDict->insertName("S", "Alpha");
+    if (sMaskMode == kAlpha_SMaskMode) {
+        sMaskDict->insertName("S", "Alpha");
+    } else if (sMaskMode == kLuminosity_SMaskMode) {
+        sMaskDict->insertName("S", "Luminosity");
+    }
     sMaskDict->insert("G", new SkPDFObjRef(sMask))->unref();
 
     SkPDFGraphicState* result = new SkPDFGraphicState;
     result->fPopulated = true;
     result->fSMask = true;
     result->insertName("Type", "ExtGState");
     result->insert("SMask", sMaskDict.get());
     result->fResources.push(sMask);
     sMask->ref();
 
@@ skipping 118 matching lines @@
     }
     if (bXfermodeName < 0 || bXfermodeName > SkXfermode::kLastMode ||
             blend_mode_from_xfermode(bXfermodeName) == NULL) {
         bXfermodeName = SkXfermode::kSrcOver_Mode;
     }
     const char* bXfermodeString = blend_mode_from_xfermode(bXfermodeName);
     SkASSERT(bXfermodeString != NULL);
 
     return strcmp(aXfermodeString, bXfermodeString) == 0;
 }