How to disable printing in Cefsharp

By FoxLearn 6/29/2024 2:43:42 AM   42
To disable printing in CefSharp, which is a .NET wrapper around the Chromium Embedded Framework (CEF), you typically need to modify the settings of the CefSettings object when initializing CefSharp in your application.

Unfortunately, CefSharp does not provide a direct method to disable printing through properties. However, you can achieve this indirectly by modifying the command line arguments that are passed to Chromium (CEF's core).

Use the CommandLineArgsDisabled property of CefSettings to pass specific arguments to Chromium that disable printing features:

CefSettings settings = new CefSettings();

// Disable printing-related command line arguments
settings.CefCommandLineArgs.Add("disable-print-preview", "1");
settings.CefCommandLineArgs.Add("disable-pdf-extension", "1");

// Initialize CefSharp with modified settings
Cef.Initialize(settings);

Using disable-print-preview to disable print preview functionality.

Using disable-pdf-extension to disable the PDF extension which is used for printing to PDF.

Additionally, you can also interact with it using window.print.

CefSettings settings = new CefSettings();

// Initialize cef with the provided settings
Cef.Initialize(settings);

ChromiumWebBrowser chromeBrowser = new ChromiumWebBrowser("www.foxlearn.com");

In CefSharp, you can attach a listener to every frame using the FrameLoadStart event of the ChromiumWebBrowser control. This event fires when a frame has finished loading.

chromeBrowser.FrameLoadEnd += (sender, args) =>
{
    // Check if the frame has finished loading successfully
    if (args.Frame.IsMain)
    {
        // Add a script to the frame to override window.print
        args.Frame.ExecuteJavaScriptAsync(@"
            window.print = function() {
                // Optionally, you can handle the print function differently here
                console.log('Printing is disabled.');
                // Or you can just prevent any action
                return false;
            };
        ");
    }
};

You can attach a listener to every frame that is launched and remove the JavaScript window.print default function.

/ Assign FrameLoadStart event listener
chromeBrowser.FrameLoadStart += onFrameLoadStart;

private void onFrameLoadStart(object sender, FrameLoadStartEventArgs args)
{
    args.Frame.ExecuteJavaScriptAsync("window.print = function(){};");
}

To disable printing in CefSharp, you can attach a method to the FrameLoadStart event. This method will execute plain JavaScript that overrides window.print with an empty function, effectively disabling printing.