vtkWebAssemblySessionHelper.h

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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
 
#ifndef vtkWebAssemblySessionHelper_h
#define vtkWebAssemblySessionHelper_h
 
#include <emscripten/val.h>
 
#include "vtkABINamespace.h"
#include "vtkObjectManager.h"
#include "vtkSession.h"
 
VTK_ABI_NAMESPACE_BEGIN
 
// Implement vtkSessionJsonImpl as a wrapper around emscripten::val
struct vtkSessionJsonImpl
{
  emscripten::val JsonValue;
};
 
namespace
{
 
using namespace emscripten;
 
// Initialize JavaScript global objects.
thread_local const val Uint8Array = val::global("Uint8Array");
thread_local const val Uint32Array = val::global("Uint32Array");
thread_local const val JSON = val::global("JSON");
thread_local const val Array = val::global("Array");

vtkSession NewVTKInterfaceForJavaScript()
{
  vtkSessionDescriptor descriptor;
  descriptor.StringifyJson = +[](vtkSessionJson inputJson) -> char*
  {
    const auto jsonString = JSON.call<val>("stringify", inputJson->JsonValue).as<std::string>();
    const auto length = jsonString.length();
    char* result = new char[length + 1];
    snprintf(result, length + 1, "%s", jsonString.c_str());
    return result;
  };
  descriptor.ParseJson = +[](const char* inputString) -> vtkSessionJson
  {
    vtkSessionJsonImpl* result = new vtkSessionJsonImpl{};
    result->JsonValue = JSON.call<val>("parse", std::string(inputString));
    return result;
  };
  descriptor.InteractorManagesTheEventLoop = false;
  return vtkCreateSession(&descriptor);
}
 
}
VTK_ABI_NAMESPACE_END
 
#endif