pinvoke-wkhtmltox - lab with C# .NET Core and wkhtmltox C library

Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;

namespace pinvoke_wkhtmltox
{
    class Program
    {
        static void Main(string[] args)
        {
            var pageIndex = 0;
            var pageName = string.Empty;
            var pages = new Dictionary<string, Dictionary<string, string>>
            {
                { "http://www.google.com.br", new Dictionary<string, string>() },
                { "sample1.html", new Dictionary<string, string> {{ "load.windowStatus", "ready" }} },
                { "http://www.uol.com.br", new Dictionary<string, string>() },
                { "sample2.html", new Dictionary<string, string> {{ "load.windowStatus", "ready" }} }
            };

            bool initialized = WkLib.wkhtmltopdf_init(false);
            Console.WriteLine("initialized: " + initialized);
            
            foreach (var page in pages)
            {
                pageIndex++;
                pageName = $"page_{pageIndex}.pdf";
                Console.WriteLine($">>> target {pageIndex}");

                IntPtr global_settings = WkLib.wkhtmltopdf_create_global_settings();
                Console.WriteLine("global_settings: " + global_settings);

                // int sgs = WkLib.wkhtmltopdf_set_global_setting(global_settings, "out", "google.pdf");
                // Console.WriteLine("wkhtmltopdf_set_global_setting: " + sgs);

                IntPtr converter = WkLib.wkhtmltopdf_create_converter(global_settings);
                Console.WriteLine("converter: " + converter);

                IntPtr object_settings = WkLib.wkhtmltopdf_create_object_settings();
                Console.WriteLine("object_settings: " + object_settings);

                int sos = WkLib.wkhtmltopdf_set_object_setting(object_settings, "page", page.Key);
                Console.WriteLine($"wkhtmltopdf_set_object_setting (page = {page.Key}): {sos}");

                foreach (var prop in page.Value)
                {
                    sos = WkLib.wkhtmltopdf_set_object_setting(object_settings, prop.Key, prop.Value);
                    Console.WriteLine($"wkhtmltopdf_set_object_setting ({prop.Key} = {prop.Value}): {sos}");
                }

                WkLib.wkhtmltopdf_add_object(converter, object_settings, null);
                Console.WriteLine("wkhtmltopdf_add_object");

                bool converted = WkLib.wkhtmltopdf_convert(converter);
                Console.WriteLine("converted: " + converted);

                if (converted)
                {
                    IntPtr data;
                    int data_length = WkLib.wkhtmltopdf_get_output(converter, out data);
                    Console.WriteLine("data_length: " + data_length);
                    Console.WriteLine("data: " + data);

                    var raw = new byte[data_length];
                    Marshal.Copy(data, raw, 0, data_length);

                    File.WriteAllBytes(pageName, raw);
                    Console.WriteLine(pageName);
                }

                WkLib.wkhtmltopdf_destroy_converter(converter);
                Console.WriteLine("wkhtmltopdf_destroy_converter");

                WkLib.wkhtmltopdf_destroy_object_settings(object_settings);
                Console.WriteLine("wkhtmltopdf_destroy_object_settings");

                WkLib.wkhtmltopdf_destroy_global_settings(global_settings);
                Console.WriteLine("wkhtmltopdf_destroy_global_settings");

                Console.WriteLine($"<<< target {pageIndex}");
            }

            bool deinitialized = WkLib.wkhtmltopdf_deinit();
            Console.WriteLine("deinitialized: " + deinitialized);
        }
    }

    static class WkLib
    {
        const string DLLNAME = "wkhtmltox";
        const CharSet CHARSET = CharSet.Unicode;

        const short LPUTF8Str = 48; // custom extension to UnmanagedType

        #region PDF

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern bool wkhtmltopdf_init(bool useGraphics);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern bool wkhtmltopdf_deinit();

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern IntPtr wkhtmltopdf_create_global_settings();

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern void wkhtmltopdf_destroy_global_settings(IntPtr global_settings);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern int wkhtmltopdf_set_global_setting(IntPtr settings,
            [MarshalAs(LPUTF8Str)] string name,
            [MarshalAs(LPUTF8Str)] string value);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern IntPtr wkhtmltopdf_create_converter(IntPtr global_settings);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern void wkhtmltopdf_destroy_converter(IntPtr converter);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern IntPtr wkhtmltopdf_create_object_settings();

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern void wkhtmltopdf_destroy_object_settings(IntPtr object_settings);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern int wkhtmltopdf_set_object_setting(IntPtr object_settings,
            [MarshalAs(LPUTF8Str)] string name,
            [MarshalAs(LPUTF8Str)] string value);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern void wkhtmltopdf_add_object(IntPtr converter, IntPtr object_settings, string data);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern bool wkhtmltopdf_convert(IntPtr converter);

        [DllImport(DLLNAME, CharSet = CHARSET)]
        public static extern int wkhtmltopdf_get_output(IntPtr converter, out IntPtr data);

        #endregion
    }
}

sample1.html

<html>
<head>
    <title>Sample Page 1</title>
</head>
<body>
    <h1>Sample Page 1</h1>
    <h2 id="htwo"></h2>
    <h3 id="wtime"></h3>

    <script>
        var start = Date.now();
        setTimeout(function () {
            var end = Date.now();
            document.getElementById("htwo").innerText = "Boooom! After " + (end-start)/1000 + " secs waiting";
            document.getElementById("wtime").innerText = Date.now()
            window.status = "ready";
        }, 5 * 1000);
    </script>
</body>
</html>

sample2.html

<html>
<head>
    <title>Sample Page 2</title>
</head>
<body>
    <h1>Sample Page 1</h1>
    <h2 id="htwo"></h2>
    <h3 id="wtime"></h3>

    <script>
        var start = Date.now();
        setTimeout(function () {
            var end = Date.now();
            document.getElementById("htwo").innerText = "Boooom! After " + (end-start)/1000 + " secs waiting";
            document.getElementById("wtime").innerText = Date.now()
            window.status = "ready";
        }, 3 * 1000);
    </script>
</body>
</html>