How use the returned "buffer" of Electronjs function "getNativeWindowHandle()" in native functions?

Question

I use the electronjs function getNativeWindowHandle() to find the HWND of electron main window.

I.e. one log was: <Buffer@0x00000293A66F0450 ec 02 07 00 00 00 00 00>

Converted to HEX: ec02070000000000

But the real HWND is: 459500, obtained doing

handleElectron.substring(0, 6).match(/.{1,2}/g), to have the three first couples of the string, then

newhandle = handleElectron[2] + handleElectron[1] + handleElectron[0]; because the handle has the the fist two and the third two chars inverted.

Then I use parseInt(handleElectron, 16) << 8) / 256 to obtain the decimal

Same result doing: user32.FindWindowW(TEXT('Chrome_WidgetWin_1'), null); (native function via node-ffi),

but I need to put it in a while loop because the FindWindowW sometimes gives 0.

Is there a cleaner and correct way to convert the result of getNativeWindowHandle() in HWND usable by FindWindowW or any other native functions?

Answer 1

The following code returns the integer value you're looking for:

const os = require("os")

function getNativeWindowHandle_Int(win) {
    let hbuf = win.getNativeWindowHandle()

    if (os.endianness() == "LE") {
        return hbuf.readInt32LE()
    }
    else {
        return hbuf.readInt32BE()
    }
}

It appears safe to assume that Windows is Little-Endian, but the code nevertheless checks the endianness using Node's os.endianness(). About reading only 32 bits, Microsoft's documentation says the following:

When sharing a handle between 32-bit and 64-bit applications, only the lower 32 bits are significant, so it is safe to truncate the handle (when passing it from 64-bit to 32-bit) [..]

Call the function on a BrowserWindow as such:

let myWin = new BrowserWindow()
console.log(getNativeWindowHandle_Int(myWin))

Answer 2

Add an answer for Mac.

// ts
const handle = window.getNativeWindowHandle();
testNativeWindow(handle);

// mm
auto buffer = info[0].As<Napi::Buffer<uint8_t>>();
void **handle = reinterpret_cast<void **>(buffer);
NSView* electronView = (__bridge NSView *)*handle;