c# Winforms WebBrowser - Clear all cookies

Hello,

I recently search for a method to delete all cookies from the build in .NET WinForms WebBrowser control.

I didn't found any working solution for it, nor working example.

It being told to use InternetSetOption, but nothing found about it.

So, i will write here my solution for clearing and deleting all cookies.

My solution using InternetSetOption with the option flag: INTERNET_OPTION_SUPPRESS_BEHAVIOR, which described as:

A general purpose option that is used to suppress behaviors on a process-wide basis. The lpBuffer parameter of the function must be a pointer to a DWORD containing the specific behavior to suppress. This option cannot be queried with InternetQueryOption.

This option flag should be used together with INTERNET_SUPPRESS_COOKIE_PERSIST options, which means:

Suppresses the persistence of cookies, even if the server has specified them as persistent.

So the example code for it will be:

static void Main()
{
    SuppressWininetBehavior();

    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    Application.Run(new Form1());
}

[System.Runtime.InteropServices.DllImport("wininet.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto, SetLastError = true)]
public static extern bool InternetSetOption(int hInternet, int dwOption, IntPtr lpBuffer, int dwBufferLength);

private static unsafe void SuppressWininetBehavior()
{
    /* SOURCE: http://msdn.microsoft.com/en-us/library/windows/desktop/aa385328%28v=vs.85%29.aspx
        * INTERNET_OPTION_SUPPRESS_BEHAVIOR (81):
        *      A general purpose option that is used to suppress behaviors on a process-wide basis. 
        *      The lpBuffer parameter of the function must be a pointer to a DWORD containing the specific behavior to suppress. 
        *      This option cannot be queried with InternetQueryOption. 
        *      
        * INTERNET_SUPPRESS_COOKIE_PERSIST (3):
        *      Suppresses the persistence of cookies, even if the server has specified them as persistent.
        *      Version:  Requires Internet Explorer 8.0 or later.
        */

    int option = (int)3/* INTERNET_SUPPRESS_COOKIE_PERSIST*/;
    int* optionPtr = &option;

    bool success = InternetSetOption(0, 81/*INTERNET_OPTION_SUPPRESS_BEHAVIOR*/, new IntPtr(optionPtr), sizeof(int));
    if (!success)
    {
        MessageBox.Show("Something went wrong !>?");
    }
}

Please make sure your project is allows unsafe code. (under Properties => Build Tab)

This code is deleting the COOKIES per PROCESS on startup ONLY.
[tested on WIN-7 and working great]


Best Regards,
MDB-BLOG :)

NSIS - Launch a program as user from UAC elevated installer

NSIS - Launch a program as user from UAC elevated installer

==========================================

I noticed that if a program is running as UAC elevated (admin or high user privileges), 

any opening process by this process will get the same privileges as the executing program,

which means, that any process opened by this UAC elevated program will be elevated also.

I found a solution for it, for opening the process UN-ELEVATED from ELEVATED running program.
I show this information as for NSIS installer, but can be used in ANY development environment (C#, NSIS, C++, JAVA, VB, and any).

The idea is to run the process in UN-ELEVATED mode, using windows's file explorer process `explorer.exe` (info).
Lets say the process that we want to launch is on `$TEMP\MyUnElevatedProcess.exe`.
So, for NSIS code, I will just write:

Exec '"$WINDIR\explorer.exe" "$TEMP\MyUnElevatedProcess.exe"'

And this will do the work...
The process `MyUnElevatedProcess.exe` will run with same ELEVATION that have your windows login, as have `$WINDIR\explorer.exe`.


Execute with parameters:
In addition, if the UN-ELEVATED process need to executed with parameters, you will need to create another file that executes the UN-ELEVATED process (for example a BATCH file which just run the process with the command line parameters).
a good example can be:

; assuming that the file `MyUnElevatedProcess.exe` exists on `$TEMP\`

; create shortcut with ARGUMENTS
CreateShortCut "$TEMP\Shortcut.lnk" "$TEMP\MyUnElevatedProcess.exe" "/arg1 /arg2 /arg3"

; execute the file NON elevated
Exec '"$WINDIR\explorer.exe" "$TEMP\Shortcut.lnk"'

Remember,
if your main program (the executing), is not ELEVATED, this logic is not relevant, because then you can just run `Exec` (open-process function in NSIS) which will have the same elevation as your process.

I hope it helps,
MDB-BLOG

C# | How to deskew an image

I found this code on CodeProject site:
http://www.codeproject.com/KB/graphics/Deskew_an_Image.aspx
By mackenb | 25 Apr 2006

The article describes an algorithm to calculate the skew angle of an image.

This is converted to C#: (tested and working)
The Code:

using System.Drawing;
using System.Drawing.Imaging;
using System;
using System.Diagnostics;


public class gmseDeskew
{
    // Representation of a line in the image.
    public class HougLine
    {
        //' Count of points in the line.
        public int Count;
        //' Index in Matrix.
        public int Index;
        //' The line is represented as all x,y that solve y*cos(alpha)-x*sin(alpha)=d
        public double Alpha;
        public double d;
    }

    // The Bitmap
    Bitmap cBmp;
    // The range of angles to search for lines
    double cAlphaStart = -20;
    double cAlphaStep = 0.2;
    int cSteps = 40 * 5;
    // Precalculation of sin and cos.
    double[] cSinA;
    double[] cCosA;
    // Range of d
    double cDMin;
    double cDStep = 1;
    int cDCount;
    // Count of points that fit in a line.
    int[] cHMatrix;

    // calculate the skew angle of the image cBmp

    public double GetSkewAngle()
    {
        HougLine[] hl;
        int i;
        double sum = 0;
        int count = 0;

        //' Hough Transformation
        Calc();
        //' Top 20 of the detected lines in the image.
        hl = GetTop(20);
        //' Average angle of the lines
        for (i = 0; i < 19; i++)      
        {          
             sum += hl[i].Alpha;
             count += 1;
         }
         return sum / count;
     }

     //    ' Calculate the Count lines in the image with most points.
    private HougLine[] GetTop(int Count)
     {
         HougLine[] hl;
         int j;
         HougLine tmp;
         int AlphaIndex, dIndex;
         hl = new HougLine[Count];
         for (int i = 0; i < Count; i++)
         {
             hl[i] = new HougLine();
         }
         for (int i = 0; i < cHMatrix.Length - 1; i++)
         {
             if (cHMatrix[i] > hl[Count - 1].Count)
            {
                hl[Count - 1].Count = cHMatrix[i];
                hl[Count - 1].Index = i;
                j = Count - 1;
                while (j > 0 && hl[j].Count > hl[j - 1].Count)
                {
                    tmp = hl[j];
                    hl[j] = hl[j - 1];
                    hl[j - 1] = tmp;
                    j -= 1;
                }
            }
        }
        for (int i = 0; i < Count; i++)
         {
             dIndex = hl[i].Index / cSteps;
             AlphaIndex = hl[i].Index - dIndex * cSteps;
             hl[i].Alpha = GetAlpha(AlphaIndex);
             hl[i].d = dIndex + cDMin;
         }
         return hl;
     }
     public void New(Bitmap bmp)
     {
         cBmp = bmp;
     }

     //    ' Hough Transforamtion:
     private void Calc()
     {
         int x;
         int y;
         int hMin = cBmp.Height / 4;
         int hMax = cBmp.Height * 3 / 4;
         Init();
         for (y = hMin; y < hMax; y++)
         {
             for (x = 1; x < cBmp.Width - 2; x++)
             {
                 //' Only lower edges are considered.
                 if (IsBlack(x, y) == true)
                 {
                     if (IsBlack(x, y + 1) == false)
                     {
                         Calc(x, y);
                     }
                 }
             }
         }
     }

     //    ' Calculate all lines through the point (x,y).
     private void Calc(int x, int y)
     {
         double d;
         int dIndex;
         int Index;
         for (int alpha = 0; alpha < cSteps - 1; alpha++)
         {
             d = y * cCosA[alpha] - x * cSinA[alpha];
             dIndex = (int)CalcDIndex(d);
             Index = dIndex * cSteps + alpha;

             try
             {
                 cHMatrix[Index] += 1;
             }
             catch (Exception ex)
             {
                 Debug.WriteLine(ex.ToString());
             }
         }
     }
     private double CalcDIndex(double d)
     {
         return Convert.ToInt32(d - cDMin);
     }
     private bool IsBlack(int x, int y)
     {
         Color c;
         double luminance;
         c = cBmp.GetPixel(x, y);
         luminance = (c.R * 0.299) + (c.G * 0.587) + (c.B * 0.114);
         return luminance < 140;
     }
     private void Init()
     {
         double angle;
         //' Precalculation of sin and cos.
         cSinA = new double[cSteps - 1];
         cCosA = new double[cSteps - 1];
         for (int i = 0; i < cSteps - 1; i++)
         {
             angle = GetAlpha(i) * Math.PI / 180.0;
             cSinA[i] = Math.Sin(angle);
             cCosA[i] = Math.Cos(angle);
         }
         //' Range of d
:         cDMin = -cBmp.Width;
         cDCount = (int)(2 * (cBmp.Width + cBmp.Height) / cDStep);
         cHMatrix = new int[cDCount * cSteps];
     }
     public double GetAlpha(int Index)
     {
         return cAlphaStart + Index * cAlphaStep;
     }     public static Bitmap RotateImage(Bitmap bmp, double angle)
     {
         Graphics g;
         Bitmap tmp = new Bitmap(bmp.Width, bmp.Height, PixelFormat.Format32bppRgb);
         tmp.SetResolution(bmp.HorizontalResolution, bmp.VerticalResolution);
         g = Graphics.FromImage(tmp);
         try       
         {
             g.FillRectangle(Brushes.White, 0, 0, bmp.Width, bmp.Height);
             g.RotateTransform((float)angle);
             g.DrawImage(bmp, 0, 0);
         }
         finally
         {
             g.Dispose();
         }
         return tmp;
     }
 }

enjoy...

Windows Mobile | Get current displayed window

Find which window is running right now.
Used for determining if OUR window is on background or not.

[DllImport("coredll.dll", SetLastError = true)]
public static extern IntPtr GetForegroundWindow();