interface ICoreWebView2Experimental18
Note
This reference is no longer being maintained. For the latest API reference, see WebView2 API Reference.
Note
This an experimental API that is shipped with our prerelease SDK. See WebView2 release notes.
interface ICoreWebView2Experimental18
: public IUnknown
This is the ICoreWebView Experimental interface for shared buffer based on file mapping.
Summary
Members | Descriptions |
---|---|
PostSharedBufferToScript | Share a shared buffer object with script of the main frame in the WebView. |
Applies to
Product | Introduced |
---|---|
WebView2 Win32 | N/A |
WebView2 Win32 Prerelease | 1.0.1466 |
Members
PostSharedBufferToScript
Share a shared buffer object with script of the main frame in the WebView.
public HRESULT PostSharedBufferToScript(ICoreWebView2ExperimentalSharedBuffer * sharedBuffer, COREWEBVIEW2_SHARED_BUFFER_ACCESS access, LPCWSTR additionalDataAsJson)
The script will receive a sharedbufferreceived
event from chrome.webview. The event arg for that event will have the following methods and properties: getBuffer()
: return an ArrayBuffer object with the backing content from the shared buffer. additionalData
: an object as the result of parsing additionalDataAsJson
as JSON string. This property will be undefined
if additionalDataAsJson
is nullptr or empty string. source
: with a value set as chrome.webview
object. If a string is provided as additionalDataAsJson
but it is not a valid JSON string, the API will fail with E_INVALIDARG
. If access
is COREWEBVIEW2_SHARED_BUFFER_ACCESS_READ_ONLY, the script will only have read access to the buffer. If the script tries to modify the content in a read only buffer, it will cause an access violation in WebView renderer process and crash the renderer process. If the shared buffer is already closed, the API will fail with RO_E_CLOSED
.
The script code should call chrome.webview.releaseBuffer
with the shared buffer as the parameter to release underlying resources as soon as it does not need access to the shared buffer any more.
The application can post the same shared buffer object to multiple web pages or iframes, or post to the same web page or iframe multiple times. Each PostSharedBufferToScript
will create a separate ArrayBuffer object with its own view of the memory and is separately released. The underlying shared memory will be released when all the views are released.
For example, if we want to send data to script for one time read only consumption.
wil::com_ptr<ICoreWebView2ExperimentalEnvironment10> environment;
CHECK_FAILURE(
m_appWindow->GetWebViewEnvironment()->QueryInterface(IID_PPV_ARGS(&environment)));
wil::com_ptr<ICoreWebView2ExperimentalSharedBuffer> sharedBuffer;
CHECK_FAILURE(environment->CreateSharedBuffer(bufferSize, &sharedBuffer));
// Set data into the shared memory via IStream.
wil::com_ptr<IStream> stream;
CHECK_FAILURE(sharedBuffer->OpenStream(&stream));
CHECK_FAILURE(stream->Write(data, sizeof(data), nullptr));
PCWSTR additionalDataAsJson = L"{\"myBufferType\":\"bufferType1\"}";
if (fromFrame)
{
m_webviewFrame4->PostSharedBufferToScript(
sharedBuffer.get(), COREWEBVIEW2_SHARED_BUFFER_ACCESS_READ_ONLY,
additionalDataAsJson);
}
else
{
m_webView18->PostSharedBufferToScript(
sharedBuffer.get(), COREWEBVIEW2_SHARED_BUFFER_ACCESS_READ_ONLY,
additionalDataAsJson);
}
// Explicitly close the one time shared buffer to ensure that the resource is released.
sharedBuffer->Close();
In the HTML document,
window.chrome.webview.addEventListener("sharedbufferreceived", e => {
SharedBufferReceived(e);});
let readOnlySharedBuffer;
function ShowReadOnlySharedBuffer() {
if (readOnlySharedBuffer) {
DisplaySharedBufferData(readOnlySharedBuffer);
} else {
// Post a web message to ask host to share the one time read only buffer.
chrome.webview.postMessage("RequestOneTimeShareBuffer");
}
}
function DisplaySharedBufferData(buffer) {
document.getElementById("shared-buffer-data").value =
new TextDecoder().decode(new Uint8Array(buffer));
}
function SharedBufferReceived(e) {
if (e.additionalData && e.additionalData.myBufferType == "bufferType1") {
readOnlySharedBuffer = e.getBuffer();
} else {
sharedBuffer = e.getBuffer();
}
DisplaySharedBufferData(e.getBuffer());
}
function ReleaseBuffer(buffer) {
window.chrome.webview.releaseBuffer(buffer);
}
Sharing a buffer to script has security risk. You should only share buffer with trusted site. If a buffer is shared to a untrusted site, possible sensitive information could be leaked. If a buffer is shared as modifiable by the script and the script modifies it in an unexpected way, it could result in corrupted data that might even crash the application.