C# Plugin - Characters missing in message box

[superfestung]

Hello Plugin Community,

im starting fresh with the C# Plugin from: https://github.com/molsonkiko/NppCSharpPluginPack

I want to read the marked characters in the editor, here “Notepad”, and use it later for searching text in a XML file. For testing i used a message box for displaying the string, but every second character is missing. Before that i didnt use the UTF8 conversion and directly passed the result of Win32.SendMessage(PluginBase.GetCurrentScintilla(), SciMsg.SCI_GETSELTEXT, 0, strSearchVariable); to the message box, which than showed some chinese looking like characters.

Any ideas what i am missing?
And yes, i need to learn more C# programming ;-)

My C# Code:

 static void HelpMe()
 {
    
     int start = 0, end = 0;
     int bufferSize = 0;

     IntPtr intSelectionStart = Win32.SendMessage(PluginBase.GetCurrentScintilla(), SciMsg.SCI_GETSELECTIONSTART, 0, 0);
     IntPtr intSelectionEnd = Win32.SendMessage(PluginBase.GetCurrentScintilla(), SciMsg.SCI_GETSELECTIONEND, 0, 0);
   
     start = intSelectionStart.ToInt32();
     end = intSelectionEnd.ToInt32();

     bufferSize = start < end ? end - start : start - end;

     if (bufferSize > 0)
     {
         var strSearchVariable = new StringBuilder(bufferSize + 1);

         Win32.SendMessage(PluginBase.GetCurrentScintilla(), SciMsg.SCI_GETSELTEXT, 0, strSearchVariable);

         byte[] utf8_Bytes = new byte[strSearchVariable.Length];
         
         for (int i = 0; i < strSearchVariable.Length; ++i)
         {
             utf8_Bytes[i] = (byte)strSearchVariable[i];                    
         }
        
         string strTest = Encoding.UTF8.GetString(utf8_Bytes, 0, utf8_Bytes.Length);

         MessageBox.Show(strTest, "Search Variable Display", MessageBoxButtons.OK, MessageBoxIcon.Information);
         
     }
     else
     {
         MessageBox.Show("No Characters selected!", "Search Variable Display", MessageBoxButtons.OK, MessageBoxIcon.Warning);
     }
 }

[Coises]

@superfestung said in C# Plugin - Characters missing in message box:

Any ideas what i am missing?

I don’t know C#, but until someone comes along who does, I can at least point out that somewhere along the line, you are reading UTF-8 into something that expects UTF-16.

I suspect that is happening when you use StringBuilder; it looks like that creates a UTF-16 buffer. You’re then sending a message to Scintilla, which returns UTF-8. Then you’re reading the characters (UTF-16, two bytes each) from StringBuilder into the bytes of UTF-8.

My guess is that there is probably a sensible wrapper for Scintilla included somewhere in the C# plugin pack, so you don’t have to do everything with bare SendMessage calls, but I don’t follow how to read the source.

If not, I think you need to pass the address of the utf8_Bytes buffer to SendMessage, rather than using StringBuilder; but I don’t know how that’s done in C#.

Edit to add:

While this isn’t your immediate problem, you’ll also need to consider that the data returned by Scintilla isn’t necessarily UTF-8; it could also be in the active system codepage. You will need to use SCI_GETCODEPAGE to know that. In C++, I use MultiByteToWideChar to convert between Scintilla’s representation and Windows’ wide characters.

[Mark Olson]

@superfestung
I’m the maintainer of the plugin pack, but I’m out of town and can’t reach my computer until tomorrow evening. If you think this is a bug, consider opening an issue in the GH repo and I’ll look into it.

[Mark Olson]

@superfestung
To convert a StringBuilder to a string, use its ToString method. And don’t cast a char to a byte. This is all basic C#, so read the docs.

[superfestung]

Thank you all for the answers!

I found a working solution for me, much simpler than i thought, when you know it.
@Coises You were right, i do not need the message calls.

        static void HelpMe()
        {       
            int start = Npp.editor.GetSelectionStart();
            int end = Npp.editor.GetSelectionEnd();

            int bufferSize = start < end ? end - start : start - end;

            if (bufferSize > 0)
            {
                string strTest = Npp.editor.GetSelText();
                MessageBox.Show(strTest, "Search Variable Display", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            else
            {
                MessageBox.Show("No Characters selected!", "Search Variable Display", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }
        }

[Alan Kilborn]

@superfestung

I’m not a guru of C#, but I’d think it would be simpler to do:

        static void HelpMe()
        {       
                    string strTest = Npp.editor.GetSelText();
                    if (strTest.Length > 0)
                    {
                        MessageBox.Show(strTest, "Search Variable Display", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                    else
                    {
                        MessageBox.Show("No Characters selected!", "Search Variable Display", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    }
        }

[superfestung]

@Alan-Kilborn
Yes! Now its a beauty…