CODEWITHSUNDEEP
javascriptarraysgoogle-chrome-appgoogle-nativeclientchrome-native-messaging
Ananthi Thangavel
Ananthi Thangavel

Reputation: 91

how to send array buffer from and to in Native client and javascript

I want to send an array buffer from Javascript to a Native Client module and then I want to convert the array buffer to an integer pointer. I saw the earth example in the nacl-sdk directory. They are passing image data and convert it like so: 

    //javascript

    var imageData = context.getImageData(0, 0, img.width, img.height);
// Send NaCl module the raw image data obtained from canvas.
common.naclModule.postMessage({'message' : 'texture',
                               'name' : name,
                               'width' : img.width,
                               'height' : img.height,
                               'data' : imageData.data.buffer});

    //nativeclient
    std::string name = dictionary.Get("name").AsString();
    int width = dictionary.Get("width").AsInt();
    int height = dictionary.Get("height").AsInt();
    pp::VarArrayBuffer array_buffer(dictionary.Get("data"));
    if (!name.empty() && !array_buffer.is_null()) {
      if (width > 0 && height > 0) {
        uint32_t* pixels = static_cast<uint32_t*>(array_buffer.Map());
        SetTexture(name, width, height, pixels);
        array_buffer.Unmap();

I am using eclipse debugging and I don't know how to check whether the array buffer was received correctly and whether I can pass pixels as a parameter to some function or I have to create them with pixels = new uint32_t[size] before passing. More importantly, I need to know how to convert uint32_t* pixels to VarArrayBuffer and send it to Javascript using a dictionary and post the message and how to receive that in Javascript and handle the message as an ArrayBuffer value.

Upvotes: 3

Views: 1001

Answers (1)

binji
binji

Reputation: 1860

The simplest example of this is the ArrayBuffer example in the SDK (examples/api/var_array_buffer).

The memory for the ArrayBuffer is owned by the pp::VarArrayBuffer, so as long as you have a reference to that (and you haven't called pp::VarArrayBuffer::Unmap) you don't have to make a copy of the memory.

pp::Var variables are automatically reference counted, so you don't need to explicitly call AddRef.

Upvotes: 2

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