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How To Create Plug-ins for EmEditor

By Makoto Emura


  1. Getting Started
  2. Start A New Project From Scratch
  3. What Can You Do With a Plug-in?
  4. Potential Problems and How To Fix Them

Prerequisites for this tutorial:

  • Some experience in Visual C++
  • Microsoft Visual Studio
  • EmEditor Professional

Getting Started

The first part of this tutorial is to make sure we can compile a simple program and get it working in EmEditor.

  1. Download the hello world program and open HelloWorld.vcxproj in Visual Studio.
  2. Build the project. Use the default configuration for now - debug on x64 or x86.
  3. Open EmEditor. Go to Tools > Plug-ins > Customize Plug-ins... and click the button that says "Add" and add the DLL that was created.
  4. Click on the funny looking light bulb icon in your plug-ins toolbar. If you don't see the plug-ins toolbar, you can enable it in View > Toolbars > Plug-ins Toolbar. Yes, that is supposed to resemble a light bulb. The plug-in writes "Hello World! " on the editor.
  5. Remove the plug-in by opening the Customize Plug-ins window, selecting the HelloWorld plug-in, and clicking "Remove".

Start A New Project From Scratch

You can use HelloWorld as the starting point for your program, or alternatively, follow these instructions to setup a workspace to develop a new plug-in.

  1. Create a new DLL project. In Visual Studio, make a new project using the "Dynamic-Link Library" template for Visual C++.
  2. Add the three template files to your new project. The template repository contains two header files and one module-definition file that are required to link a plug-in to EmEditor. Treat these files as read-only. The template files are:
    • etlframe.h - helper functions for plug-in.h
    • plug-in.h - handles message passing tasks
    • exports.def - exports functions from the plug-in so that they are callable from EmEditor
  3. Make a couple changes to the project properties:
    1. Change the linker settings to use exports.def as the module definition file. In project properties, go to Linker > Input. At the top of the window, change configuration and platform to all, so that this change affects all builds. Change the value of Module Definition File to "exports.def".
    2. Change the Runtime Library to "Multi-threaded Debug (/MTd)" for debug configuration, and "Multi-threaded (/MT)" for release configuration. This is found under C/C++ > Code Generation > Runtime Library.
    3. Change the debugging command path to EmEditor.exe. This is optional but recommended, so that the debugger opens EmEditor automatically. This setting is found under Debugging. Change the Command value to your installation path which ends with EmEditor.exe, without quotation marks.
  4. Delete the contents of stdafx.h and add the following code:
#pragma once
#include <windows.h>
#include <windowsx.h>
#include <crtdbg.h>
#include <tchar.h>
#pragma comment(lib, "shlwapi.lib")
  1. Create a new header file and add the following code.
    • CETLFrame encapsulates the plug-in. It is constructed only when EmEditor opens, and destroyed only when EmEditor closes.
    • The enum constants contain information about the plug-in, such as the name and icon image of this plug-in. There is more information about these variables in "CETLFrame Member Variables".
    • The functions OnCommand() and OnEvents() are the main entry points for your application.
    • You can learn more about these callback functions, plus some optional ones, in "Messages to Plug-ins" and "Functions to Export".
#pragma once

class MyCFrame : public CETLFrame<MyCFrame>
	enum {
		_IDS_NAME = 0,
		_IDS_MENU = 0,
		_IDS_STATUS = 0,
		_IDS_VER = 0,
		_USE_LOC_DLL = 0,
		_IDB_BITMAP = 0,
		_IDB_16C_24 = 0,
		_IDB_TRUE_16_HOT = 0,
		_IDB_TRUE_16_BW = 0,
		_IDB_TRUE_24_HOT = 0,
		_IDB_TRUE_24_BW = 0,

	void OnCommand(HWND hwnd);

	void OnEvents(HWND hwnd, UINT nEvent, LPARAM lParam)

	BOOL QueryStatus(HWND hwnd, LPBOOL pbChecked)
	{*pbChecked = FALSE; return TRUE;}

	BOOL DisableAutoComplete(HWND hwnd)
	{return FALSE;}

	BOOL UseDroppedFiles(HWND hwnd)
	{return FALSE;}

	BOOL QueryUninstall(HWND hwnd)
	{return FALSE;}

	BOOL SetUninstall(HWND hwnd, LPTSTR command, LPTSTR param)

	BOOL QueryProperties(HWND hwnd)
	{return FALSE;}

	BOOL SetProperties(HWND hwnd)
	{return FALSE;}

	BOOL PreTranslateMessage(HWND hwnd, MSG* pMsg)
	{return FALSE;}

	LRESULT UserMessage(HWND hwnd, WPARAM wParam, LPARAM lParam)
	{return NULL;}
  1. Clear the main .cpp file and add the following code. In this code snippet, change main.h to the name of the header file that you have created previously.
    • _ETL_IMPLEMENT enables etlframe.h to call necessary construct and destroy tasks, and must come after the definition for CETLFrame.
#include "stdafx.h"
#include "etlframe.h"
#include "main.h"

void MyCFrame::OnCommand(HWND hwnd)
	// TODO
  1. Give the plug-in a name and an icon. EmEditor retrieves this information through resource files.
    1. Add a new resource file to your project. It should have the extension ".rc".
    2. Add a String Table to the resource file. Double click on your resource file to open the Resource View. Now right click on the resource folder and click Add Resource and add a String Table. Change the Caption value to the plug-in name.
    3. Import a 16 bit color, 16x16 pixel bitmap image to the resource file. If EmEditor is unable to load the icon, try opening and saving it in Paint, as a .bmp with 256 colors.
    4. In the enum on the main .cpp file, change the value of _IDS_MENU, _IDS_STATUS, and _IDS_NAME to the ID name of the name string, and _IDB_BITMAP to the bitmap ID.
  2. Additional info
    • To add another .cpp file to the project, you must define EE_EXTERN_ONLY before including etlframe.h. (Do that for all .cpp files except the main one.) Thus, the first couple rows of the new file should look like this:
    #include "stdafx.h"
    #define EE_EXTERN_ONLY
    #define ETL_FRAME_CLASS_NAME CMyFrame
    #include "etlframe.h"
    • There is a helpful function called GetFrame() which returns a pointer to your current CETLFrame.

What Can You Do With a Plug-in?

A plug-in is best suited for an application that will be used across many projects, and that requires a graphical interface to be shown. EmEditor also allows you to write macros using Javascript, and this may be an easier option for tasks that don't require C++ or a GUI. This section will outline what you can do with the plug-in API. Refer to the API Documentation for detailed explanations.

  1. A plug-in is able to receive events. Most plug-ins are activated when its button is clicked in the Plug-ins toolbar. When this happens, OnCommand() is called. You can also capture various other events in EmEditor such as selection change, using OnEvents().
  2. A plug-in can retrieve or write text in the editor. To get the text shown in the editor, use Editor_GetLineW() or Editor_GetSelTextW(). (There is currently no function to retrieve the entire document in one call.) You can write text using Editor_InsertW(), Editor_InsertFileW() and other related functions. There is an option to run a macro as well, with Editor_RunMacro(). Most commands will require a window handle to your plug-in, which is obtained through CETLFrame::m_hWnd.
  3. You can send commands that are available in the menu bar using 'Editor_ExecCommand()'.
  4. You can search for a string using Editor_FindW() and Editor_FindRegex().
  5. Manipulate CSV documents with Editor_GetCell(), Editor_GetColumn(), Editor_AutoFill().
  6. Get information about the current workspace with Editor_Info(), Editor_GetClip(), Editor_GetVersion(), etc.
  7. To display a graphical interface, you first must get a handle to the DLL using EEGetLocaleInstanceHandle(). Dialogs are simple to make, but to be able to use the editor while interacting with the plug-in, a better option might be to make a sidebar or a toolbar, such as what Projects and HTMLBar employs. For debugging or for outputting simple data, you can write to the status bar of the editor using Editor_SetStatusW().

Potential Problems and How To Fix Them

Here are some problems that I came across while making HelloWorld and CharacterCount:

  • "... is not a member of 'CMyFrame'." You did not implement this required function or variable.
  • "C:...\NewPlugin.dll is not a valid Win32 application." Read step 3.3 of "Start A New Project From Scratch".
  • Linking issues related to the plug-in library: "error C2027: use of undefined type 'CMyFrame'", "error LNK2019: unresolved external symbol ... _ETLCreateFrame", "error C2027: use of undefined type 'ETL_FRAME_CLASS_NAME'", "error LNK2005: "void __cdecl DeleteAllFrames(void)" ... already defined in NewPlugin.obj". Make sure all required header includes are added, in the correct order. Read steps 6 and 8 of "Start A New Project From Scratch".
  • "'_USE_LOC_DLL': undeclared identifier." You must either define the variable _USE_LOC_DLL or #define EE_EXTERN_ONLY. See step 8 of "Start A New Project From Scratch".
  • My new plug-in does not show on the plug-in list after adding it. Make sure you are importing the correct 32 or 64 bit version of your plug-in.
  • My plug-in icon on the toolbar looks like the Internet Explorer icon (or some other icon). The BMP image was not readable. Read step 7.3 of "Start A New Project From Scratch".

The Emurasoft organization page contains several source codes for plug-ins that you may reference.


This document is licensed under a Creative Commons Attribution 4.0 International License.




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