Add some new methods to INotepadPPGateway

Rewrite the GetCurrentFilePath method using the new GetString method.

Author: alex-ilin

Visual Studio Project Template C#/PluginInfrastructure/NotepadPPGateway.cs

@@ -1,5 +1,7 @@
 // NPP plugin platform for .Net v0.94.00 by Kasper B. Graversen etc.
 using System;
+using System.Drawing;
+using System.Runtime.InteropServices;
 using System.Text;
 using NppPluginNET.PluginInfrastructure;
 
@@ -9,9 +11,14 @@ public interface INotepadPPGateway
 	{
 		void FileNew();
 
+		void AddToolbarIcon(int funcItemsIndex, toolbarIcons icon);
+		void AddToolbarIcon(int funcItemsIndex, Bitmap icon);
+		string GetNppPath();
+		string GetPluginConfigPath();
 		string GetCurrentFilePath();
 		unsafe string GetFilePath(int bufferId);
 		void SetCurrentLanguage(LangType language);
+		bool OpenFile(string path);
 	}
 
 	/// <summary>
@@ -27,16 +34,73 @@ public void FileNew()
 			Win32.SendMessage(PluginBase.nppData._nppHandle, (uint) NppMsg.NPPM_MENUCOMMAND, Unused, NppMenuCmd.IDM_FILE_NEW);
 		}
 
+		public void AddToolbarIcon(int funcItemsIndex, toolbarIcons icon)
+		{
+			IntPtr pTbIcons = Marshal.AllocHGlobal(Marshal.SizeOf(icon));
+			try {
+				Marshal.StructureToPtr(icon, pTbIcons, false);
+				_ = Win32.SendMessage(
+					PluginBase.nppData._nppHandle,
+					(uint) NppMsg.NPPM_ADDTOOLBARICON,
+					PluginBase._funcItems.Items[funcItemsIndex]._cmdID,
+					pTbIcons);
+			} finally {
+				Marshal.FreeHGlobal(pTbIcons);
+			}
+		}
+
+		public void AddToolbarIcon(int funcItemsIndex, Bitmap icon)
+		{
+			var tbi = new toolbarIcons();
+			tbi.hToolbarBmp = icon.GetHbitmap();
+			AddToolbarIcon(funcItemsIndex, tbi);
+		}
+
 		/// <summary>
 		/// Gets the path of the current document.
 		/// </summary>
 		public string GetCurrentFilePath()
+			=> GetString(NppMsg.NPPM_GETFULLCURRENTPATH);
+
+		/// <summary>
+		/// This method incapsulates a common pattern in the Notepad++ API: when
+		/// you need to retrieve a string, you can first query the buffer size.
+		/// This method queries the necessary buffer size, allocates the temporary
+		/// memory, then returns the string retrieved through that buffer.
+		/// </summary>
+		/// <param name="message">Message ID of the data string to query.</param>
+		/// <returns>String returned by Notepad++.</returns>
+		public string GetString(NppMsg message)
 		{
-			var path = new StringBuilder(2000);
-			Win32.SendMessage(PluginBase.nppData._nppHandle, (uint) NppMsg.NPPM_GETFULLCURRENTPATH, 0, path);
-			return path.ToString();
+			int len = Win32.SendMessage(
+					PluginBase.nppData._nppHandle,
+					(uint) message, Unused, Unused).ToInt32()
+				+ 1;
+			var res = new StringBuilder(len);
+			_ = Win32.SendMessage(
+				PluginBase.nppData._nppHandle, (uint) message, len, res);
+			return res.ToString();
 		}
 
+		/// <returns>The path to the Notepad++ executable.</returns>
+		public string GetNppPath()
+			=> GetString(NppMsg.NPPM_GETNPPDIRECTORY);
+
+		/// <returns>The path to the Config folder for plugins.</returns>
+		public string GetPluginConfigPath()
+			=> GetString(NppMsg.NPPM_GETPLUGINSCONFIGDIR);
+
+		/// <summary>
+		/// Open a file for editing in Notepad++, pretty much like using the app's
+		/// File - Open menu.
+		/// </summary>
+		/// <param name="path">The path to the file to open.</param>
+		/// <returns>True on success.</returns>
+		public bool OpenFile(string path)
+			=> Win32.SendMessage(
+				PluginBase.nppData._nppHandle, (uint) NppMsg.NPPM_DOOPEN, Unused, path).ToInt32()
+			!= 0;
+
 		/// <summary>
 		/// Gets the path of the current document.
 		/// </summary>