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, bool alpha) {
     // 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 (alpha) {
+        sMaskDict->insertName("S", "Alpha");
+    } else {
+        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 38 matching lines @@
       fPopulated(false),
       fSMask(false) {
 }
 
 // populateDict and operator== have to stay in sync with each other.
 void SkPDFGraphicState::populateDict() {
     if (!fPopulated) {
         fPopulated = true;
         insertName("Type", "ExtGState");
 
+        // do a SMask if paint involves a gradient alpha

[vandebo (ex-Chrome), 2013/07/03 17:07:01]

How would paint involve a gradient alpha?  We have a todo style:
// TODO(uername): Thing to do in full sentence form, referring to a bug if
possible.

[ducky, 2013/07/03 23:32:09]

That wasn't supposed to be there. I somehow missed that going through the
presubmit git diff...

+        //TODO ADD STUFF HERE
         SkAutoTUnref<SkPDFScalar> alpha(
             new SkPDFScalar(SkScalarDiv(fPaint.getAlpha(), 0xFF)));
         insert("CA", alpha.get());
         insert("ca", alpha.get());
 
         SK_COMPILE_ASSERT(SkPaint::kButt_Cap == 0, paint_cap_mismatch);
         SK_COMPILE_ASSERT(SkPaint::kRound_Cap == 1, paint_cap_mismatch);
         SK_COMPILE_ASSERT(SkPaint::kSquare_Cap == 2, paint_cap_mismatch);
         SK_COMPILE_ASSERT(SkPaint::kCapCount == 3, paint_cap_mismatch);
         SkASSERT(fPaint.getStrokeCap() >= 0 && fPaint.getStrokeCap() <= 2);
@@ skipping 60 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;
 }