Introduce kPerIsolateDataIndex and tidy JS_Define.h

fpdfsdk/src/jsapi/fxjs_v8.cpp

Index: fpdfsdk/src/jsapi/fxjs_v8.cpp
diff --git a/fpdfsdk/src/jsapi/fxjs_v8.cpp b/fpdfsdk/src/jsapi/fxjs_v8.cpp
index d5673e6e87d40b3fc5225b4482230256a31be338..ac7c88b262fbdabc1c1a4f8e6c5a13f9bb919b6b 100644
--- a/fpdfsdk/src/jsapi/fxjs_v8.cpp
+++ b/fpdfsdk/src/jsapi/fxjs_v8.cpp
@@ -5,7 +5,6 @@
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../../../core/include/fxcrt/fx_basic.h"
-#include "../../include/fsdk_define.h"
 #include "../../include/jsapi/fxjs_v8.h"
 
 const wchar_t kFXJSValueNameString[] = L"string";
@@ -19,6 +18,12 @@ const wchar_t kFXJSValueNameUndefined[] = L"undefined";
 
 static unsigned int g_embedderDataSlot = 1u;
 
+// Keep this consistent with the values defined in gin/public/context_holder.h
+// (without actually requiring a dependency on gin itself for the standalone
+// embedders of PDFIum). The value we want to use is:
+//   kPerContextDataStartIndex + kEmbedderPDFium, which is 3.
+static const unsigned int kPerContextDataIndex = 3u;
+
 class CFXJS_PrivateData {
  public:
   CFXJS_PrivateData(int nObjDefID) : ObjDefID(nObjDefID), pPrivate(NULL) {}
@@ -100,6 +105,13 @@ FXJS_PerIsolateData* FXJS_PerIsolateData::Get(v8::Isolate* pIsolate) {
       pIsolate->GetData(g_embedderDataSlot));
 }
 
+void FXJS_Initialize(unsigned int embedderDataSlot) {
+  g_embedderDataSlot = embedderDataSlot;
+}
+
+void FXJS_Release() {
+}
+
 int FXJS_DefineObj(v8::Isolate* pIsolate,
                    const wchar_t* sObjName,
                    FXJSOBJTYPE eObjType,
@@ -269,7 +281,7 @@ void FXJS_InitializeRuntime(v8::Isolate* pIsolate,
 
   FXJS_PerIsolateData::SetUp(pIsolate);
   v8::Local<v8::External> ptr = v8::External::New(pIsolate, pFXRuntime);

[Tom Sepez, 2015/09/25 17:32:18]

Here's the spot where I'd like to use the AlignedPointer methods, but I'm not
sure how to go about this.  Do I need an ordinary v8::Object here that would
hold it in a slot?  Would this object still be set in the context's
kPerContextDataIndex slot?

A code fragment might be illuminating.

[jochen (gone - plz use gerrit), 2015/09/28 11:27:31]

v8Context->SetAlignedPointerInEmbedderData(kPerContextDataIndex, pFXRuntime);
should do the trick

[Tom Sepez, 2015/09/28 16:20:18]

Done. Appears to work (I thought I'd tried this earlier but got segvs, which is
why I asked).

-  v8Context->SetEmbedderData(1, ptr);
+  v8Context->SetEmbedderData(kPerContextDataIndex, ptr);
 
   int maxID = CFXJS_ObjDefinition::MaxID(pIsolate);
   for (int i = 0; i < maxID; ++i) {
@@ -338,11 +350,13 @@ void FXJS_ReleaseRuntime(v8::Isolate* pIsolate,
   delete pData;
 }
 
-void FXJS_Initialize(unsigned int embedderDataSlot) {
-  g_embedderDataSlot = embedderDataSlot;
-}
-
-void FXJS_Release() {
+IFXJS_Runtime* FXJS_GetRuntimeFromIsolate(v8::Isolate* pIsolate) {
+  v8::Local<v8::Context> context = pIsolate->GetCurrentContext();
+  v8::Local<v8::Value> v = context->GetEmbedderData(kPerContextDataIndex);
+  if (v.IsEmpty())
+    return nullptr;
+  v8::Local<v8::External> field = v8::Local<v8::External>::Cast(v);
+  return static_cast<IFXJS_Runtime*>(field->Value());
 }
 
 int FXJS_Execute(v8::Isolate* pIsolate,