Node C ++插件-将类型数组作为参数传递时，如何访问类型数组(Float32Array)? [英] Node C++ Addon - How do I access a Typed Array (Float32Array) when it's been passed as an argument?

问题描述

我想利用V8 Float32Array数据结构.如何初始化?

I'd like to make use of the V8 Float32Array data structure. How can I initialise it?

我也对直接内存访问数据感兴趣.那怎么办?

I'd also be interested in direct memory access to the data. How could that be done?

推荐答案

已更新

现在最好的方法是使用帮助器 <代码> Nan :: TypedArrayContents .

The best way now is to use the helper Nan::TypedArrayContents.

assert(args[i]->IsFloat32Array());
Local<Float32Array> myarr = args[i].As<Float32Array>();
Nan::TypedArrayContents<float> dest(myarr);
// Now use dest, e.g. (*dest)[0]

在节点画布.

原始答案，它显示了为什么帮助程序有用

v8 API现在正在快速变化，因此这取决于您的node/io.js版本.要访问作为参数提供的数组中的数据，这应通过io.js< 3.0:节点0.12起作用:

The v8 API is changing rapidly right now so this depends on your version of node/io.js. To access the data from the array provided as an argument, this should work for node 0.12 through io.js <3.0:

assert(args[i]->IsFloat32Array()); // These type-check methods are available.
Local<Float32Array> myarr = args[i].As<Float32Array>();
void* dataPtr = myarr->GetIndexedPropertiesExternalArrayData();

在io.js> = 3.0(v8 4.3)中，您应该改为使用 ArrayBuffer :: GetContents .(我尚未使用过，并且将在3.0发布时进行更新.)文档为

In io.js >=3.0 (v8 4.3) you should instead use ArrayBuffer::GetContents. (I haven't used this yet and will update this when 3.0 is released.) Docs are here.

在节点0.10中，对TypedArrays进行了自制.这是一种实现方式:

In node 0.10, TypedArrays were home-brewed. This was one way of doing it:

Local<Object> buffer = args[i]->Get(NanNew("buffer"))->ToObject();
void* dataPtr = buffer->GetPointerFromInternalField(0);

构造类型数组可以通过以下方式完成:

Constructing a typed array can be done with:

 Float32Array::New(ArrayBuffer::New(Isolate::GetCurrent(), size * 4), 0, size);

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