/// <summary>
/// Executes a method call over the DevTools protocol.
/// </summary>
/// <param name="webview">The WebView control.</param>
/// <param name="method">The method name.</param>
/// <param name="parameters">
/// The JSON string with method parameters. May be null.
/// See the <see href="https://chromedevtools.github.io/devtools-protocol/">
/// DevTools Protocol documentation</see> for details of supported methods
/// and the expected parameters.
/// </param>
/// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
/// <returns>
/// The JSON string with the response. Structure of the response varies depending
/// on the method name and is defined by the 'RETURN OBJECT' section of
/// the Chrome DevTools Protocol command description.
/// </returns>
/// <remarks>
/// Usage of the ExecuteDevToolsMethodAsync function does not require an active
/// DevTools front-end or remote-debugging session. Other active DevTools sessions
/// will continue to function independently. However, any modification of global
/// browser state by one session may not be reflected in the UI of other sessions.
/// <para/>
/// Communication with the DevTools front-end (when displayed) can be logged
/// for development purposes by passing the `--devtools-protocol-log-
/// file=<path>` command-line flag.
/// </remarks>
public static Task<string> ExecuteDevToolsMethodAsync(this IChromiumWebView webview, string method, string parameters, CancellationToken cancellationToken)
{
CefValue args = null;
if (parameters != null)
{
args = CefApi.CefParseJSON(parameters, CefJsonParserOptions.AllowTrailingCommas, out string errorMessage);
if (args is null)
throw new ArgumentOutOfRangeException(nameof(parameters), errorMessage is null ? "An error occurred during JSON parsing." : errorMessage);
}
return ExecuteDevToolsMethodAsync(webview, method, args is null ? default(CefDictionaryValue) : args.GetDictionary(), cancellationToken);
}
private static async Task<string> ExecuteDevToolsMethodInternalAsync(IChromiumWebView webview, string method, CefDictionaryValue parameters, CancellationToken cancellationToken)
{
CefBrowser browser = webview.BrowserObject;
if (browser is null)
throw new InvalidOperationException();
cancellationToken.ThrowIfCancellationRequested();
CefBrowserHost browserHost = browser.Host;
DevToolsProtocolClient protocolClient = GetProtocolClient(browserHost);
await CefNetSynchronizationContextAwaiter.GetForThread(CefThreadId.UI);
cancellationToken.ThrowIfCancellationRequested();
int messageId = browserHost.ExecuteDevToolsMethod(protocolClient.IncrementMessageId(), method, parameters);
protocolClient.UpdateLastMessageId(messageId);
DevToolsMethodResult r;
if (cancellationToken.CanBeCanceled)
{
Task<DevToolsMethodResult> waitTask = protocolClient.WaitForMessageAsync(messageId, DevToolsCallCompletionSource.ConvertUtf8BufferToJsonString);
await Task.WhenAny(waitTask, Task.Delay(Timeout.Infinite, cancellationToken)).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested();
r = waitTask.Result;
}
else
{
r = await protocolClient.WaitForMessageAsync(messageId, DevToolsCallCompletionSource.ConvertUtf8BufferToJsonString).ConfigureAwait(false);
}
if (r.Success)
{
if (r.Result is byte[] buff)
return Encoding.UTF8.GetString(buff);
return r.Result as string;
}
CefValue errorValue;
if (r.Result is byte[] buffer)
errorValue = CefApi.CefParseJSONBuffer(buffer, CefJsonParserOptions.AllowTrailingCommas);
else
errorValue = CefApi.CefParseJSON(r.Result as string, CefJsonParserOptions.AllowTrailingCommas);
if (errorValue is null)
throw new DevToolsProtocolException($"An unknown error occurred while trying to execute the '{method}' method.");
throw new DevToolsProtocolException(errorValue.GetDictionary().GetString("message"));
}