ScreenshotsTests.cs

[Test]
public void TakingHTML2CanvasFullPageScreenshot()
{
    using (var driver = new ChromeDriver())
    {
        driver.Manage().Timeouts().PageLoad = TimeSpan.FromSeconds(5);
        driver.Navigate().GoToUrl(@"https://automatetheplanet.com");
        IJavaScriptExecutor js = driver;
        var html2canvasJs = File.ReadAllText($"{GetAssemblyDirectory()}\\html2canvas.js");
        js.ExecuteScript(html2canvasJs);
        string generateScreenshotJS = @"function genScreenshot () {
	                                        var canvasImgContentDecoded;
	                                        html2canvas(document.body, {
 		                                        onrendered: function (canvas) {                                          
		                                            window.canvasImgContentDecoded = canvas.toDataURL(""image/png"");
	                                        }});
                                        }
                                        genScreenshot();";
        js.ExecuteScript(generateScreenshotJS);

        var wait = new WebDriverWait(driver, TimeSpan.FromSeconds(10));
        wait.IgnoreExceptionTypes(typeof(InvalidOperationException));
        wait.Until(wd => ((IJavaScriptExecutor)wd).ExecuteScript("return canvasImgContentDecoded;") != null);
        var pngContent = (string)js.ExecuteScript("return canvasImgContentDecoded;");

        pngContent = pngContent.Replace("data:image/png;base64,", string.Empty);
        byte[] data = Convert.FromBase64String(pngContent);
        var tempFilePath = Path.GetTempFileName().Replace(".tmp", ".png");
        Image image;
        using (var ms = new MemoryStream(data))
        {
            image = Image.FromStream(ms);
        }
        image.Save(tempFilePath, ImageFormat.Png);
    }
}
        
private string GetAssemblyDirectory()
{
    string codeBase = Assembly.GetExecutingAssembly().CodeBase;
    var uri = new UriBuilder(codeBase);
    string path = Uri.UnescapeDataString(uri.Path);
    return Path.GetDirectoryName(path);
}