Tag Archives: snippet
Check if user has administartor rights
In numerous cases it is essential to know if the user has administrator rights or not. A good example for this would be when we want to decide if we want to write a value in HKEY_LOCAL_MACHINE which requires administrator rights or HKEY_CURRENT_USER which doesn’t.
The following method will return true if the application is running under administration rights or false if its not.
1 2 3 4 5 6 | public static bool IsUserAdministrator() { WindowsIdentity user = WindowsIdentity.GetCurrent(); WindowsPrincipal principal = new WindowsPrincipal(user); return principal.IsInRole(WindowsBuiltInRole.Administrator); } |
Create shortcut programmatically in C#
In cases where we need to create a shortcut for our application or for any other reason, the Windows Script Host Object Model library allows us to do just that.
In order to access the classes that will enable us to create shortcuts we need to add the Windows Script Host Object Model library as a reference to our project first.
- Right click on your project
- Click “Add Reference…”
- Select the “COM” tab on the left
- Search for Windows Script Host Object Model and add it as a reference
After you successfully add the reference in your project you should be able to use the snippet bellow to create shortcuts as you please.
Create shortcut:
1 2 3 4 5 6 7 8 9 10 11 | public static void CreateShortcut(string shortcutName, string shortcutPath, string targetFileLocation) { string shortcutLocation = System.IO.Path.Combine(shortcutPath, shortcutName + ".lnk"); WshShell shell = new WshShell(); IWshShortcut shortcut = (IWshShortcut)shell.CreateShortcut(shortcutLocation); shortcut.Description = "My shortcut description"; // The description of the shortcut shortcut.IconLocation = @"c:\myicon.ico"; // The icon of the shortcut shortcut.TargetPath = targetFileLocation; // The path of the file that will launch when the shortcut is run shortcut.Save(); // Save the shortcut } |
Usage:
1 | CreateShortcut("my shortcut", Environment.GetFolderPath(Environment.SpecialFolder.Desktop), Assembly.GetExecutingAssembly().Location); |
Start application at Windows startup with C#
The following snippet will allow you to add your application in the registry so it will launch when Windows start. Alternative you can use Environment.SpecialFolder.Startup to place a shortcut of your application in the startup folder which will have the same effect.
Note that this snippet will add an entry in HKEY_CURRENT_USER which means the program will only launch at startup for the user that is currently logged in when you run the code. If you want your program to run at startup for all users you will need to use HKEY_LOCAL_MACHINE instead but keep in mind that you will require administration rights in order to do that.
Register program to start with Windows:
1 2 3 4 5 6 7 | public static void AddApplicationToStartup() { using (RegistryKey key = Registry.CurrentUser.OpenSubKey("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run", true)) { key.SetValue("My Program", "\"" + Application.ExecutablePath + "\""); } } |
Stop program from starting with Windows:
1 2 3 4 5 6 7 | public static void RemoveApplicationFromStartup() { using (RegistryKey key = Registry.CurrentUser.OpenSubKey("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run", true)) { key.DeleteValue("My Program", false); } } |
How to draw Listbox items with alternative background colors
Some people find it easier to read large amount of data when the rows have an alternative background color instead of always the same. This is called Zebra Striping.
For this example we will look into implementing this technique for our ListBox control so it will look similar to this:
First we need to ensure that the ListBox.DrawMode property is set to DrawMode.OwnerDrawFixed. This can be accomplished by either changing the property in the properties window or by placing listBox1.DrawMode = DrawMode.OwnerDrawFixed; in your form’s constructor or any of the load events.
Then we need to handle the ListBox’s DrawItem event so we can change the colors as we like.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | private void listBox1_DrawItem(object sender, DrawItemEventArgs e) { bool isSelected = ((e.State & DrawItemState.Selected) == DrawItemState.Selected); if (e.Index > -1) { /* If the item is selected set the background color to SystemColors.Highlight or else set the color to either WhiteSmoke or White depending if the item index is even or odd */ Color color = isSelected ? SystemColors.Highlight : e.Index % 2 == 0 ? Color.WhiteSmoke : Color.White; // Background item brush SolidBrush backgroundBrush = new SolidBrush(color); // Text color brush SolidBrush textBrush = new SolidBrush(e.ForeColor); // Draw the background e.Graphics.FillRectangle(backgroundBrush, e.Bounds); // Draw the text e.Graphics.DrawString(listBox1.Items[e.Index].ToString(), e.Font, textBrush, e.Bounds, StringFormat.GenericDefault); // Clean up backgroundBrush.Dispose(); textBrush.Dispose(); } e.DrawFocusRectangle(); } |
And we are done ! Feel free to modify the example to suit your needs.
How to allow only one application instance
The following code will ensure that your application can only have one instance active. If the user tries to open the application again while the application is already running then the application will simply quit (in this case after showing a message).
For this to work we will need to modify the Program.cs to check with the use of Mutex if the application is already running or not before we open the main form. Our check will take place in the Main method.
Your code in Program.cs should look like this:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | using System; using System.Reflection; using System.Runtime.InteropServices; using System.Threading; using System.Windows.Forms; namespace WindowsFormsApplication1 { static class Program { [STAThread] static void Main() { /* Retrieve the application Guid attribute. Alternative you can simply use the application name to initialize the Mutex * but it might be risky as other programs might have similar name and make use of the Mutex class as well. */ GuidAttribute appGuid = (GuidAttribute)Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(GuidAttribute), true)[0]; // The boolean that will store the value if Mutex was successfully created which will mean that our application is not already running. bool createdNew = true; // Initialize the Mutex object. using (Mutex mutex = new Mutex(true, appGuid.Value, out createdNew)) { /* If Mutex was created successfully which means our application is not running run the application as usual * or else display a message and close the application.*/ if (createdNew) { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } else { MessageBox.Show("Application is already running"); } } } } } |
Feel free to modify the example to suit your needs.
