Tutorial 34: RichEdit Control: More Text Operations

You'll learn more about text operations under RichEdit control. Specifically, you'll know how to search for/replace text, jumping to specific line number.

Download the example.

Theory

Searching for Text

There are several text operations under RichEdit control. Searching for text is one such operation. Searching for text is done by sending EM_FINDTEXT or EM_FINDTEXTEX. These messages has a small difference.

EM_FINDTEXT
wParam == Search options. Can be any combination of the values in the table below.These options are identical for both 
			EM_FINDTEXT and EM_FINDTEXTEX
FR_DOWN If this flag is specified, the search starts from the end of the current selection to the end of the text in the control (downward). This flag has effect only for RichEdit 2.0 or later: This behavior is the default for RichEdit 1.0. The default behavior of RichEdit 2.0 or later is to search from the end of the current selection to the beginning of the text (upward).
In summary, if you use RichEdit 1.0, you can't do anything about the search direction: it always searches downward. If you use RichEdit 2.0 and you want to search downward, you must specify this flag else the search would be upward.
FR_MATCHCASE If this flag is specified, the search is case-sensitive.
FR_WHOLEWORD If this flag is set, the search finds the whole word that matches the specified search string.
Actually, there are a few more flags but they are relevant to non-English languages.
lParam == pointer to the FINDTEXT structure.

			FINDTEXT STRUCT
			  chrg          CHARRANGE  <>
			  lpstrText     DWORD      ?
			FINDTEXT ENDS

chrg is a CHARRANGE structure which is defined as follows:

			CHARRANGE STRUCT
			  cpMin  DWORD      ?
			  cpMax  DWORD      ?
			CHARRANGE ENDS

cpMin contains the character index of the first character in the character array (range).
cpMax contains the character index of the character immediately following the last character in the character array.

In essence, to search for a text string, you have to specify the character range in which to search. The meaning of cpMin 
and cpMax differ according to whether the search is downward or upward. If the search is downward, cpMin 
specifies the starting character index to search in and cpMax the ending character index. If the search is upward, the 
reverse is true, ie. cpMin contains the ending character index while cpMax the starting character index.

lpstrText is the pointer to the text string to search for.

EM_FINDTEXT returns the character index of the first character in the matching text string in the richedit control. It returns -1 if
no match is found.

EM_FINDTEXTEX
wParam == the search options. Same as those of EM_FINDTEXT.
lParam == pointer to the FINDTEXTEX structure.

			FINDTEXTEX STRUCT
			  chrg          CHARRANGE  <>
			  lpstrText     DWORD      ?
			  chrgText	CHARRANGE <>
			FINDTEXTEX ENDS

The first two members of FINDTEXTEX are identical to those of FINDTEXT structure. chrgText is a CHARRANGE structure that will
be filled with the starting/ending characterindices if a match is found.

The return value of EM_FINDTEXTEX is the same as that of EM_FINDTEXT.

The difference between EM_FINDTEXT and EM_FINDTEXTEX is that the FINDTEXTEX structure has an additional member, 
chrgText, which will be filled with the starting/ending character indices if a match is found. This is convenient if we want to do 
more text operations on the string.

Replace/Insert Text

RichEdit control provides EM_SETTEXTEX for replacing/inserting text. This message combines the functionality of WM_SETTEXT and EM_REPLACESEL. It has the following syntax:

	EM_SETTEXTEX
	wParam == pointer to SETTEXTEX structure.

			SETTEXTEX STRUCT
			  flags          DWORD      ?
			  codepage       DWORD      ?
			SETTEXTEX ENDS

	flags can be the combination of the following values:
ST_DEFAULT Deletes the undo stack, discards rich-text formatting, replaces all text.
ST_KEEPUNDO Keeps the undo stack
ST_SELECTION Replaces selection and keeps rich-text formatting
	codepage is the constant that specifies the code page you want to text to be. Usually, we simply use CP_ACP.

Text Selection

We can select the text programmatically with EM_SETSEL or EM_EXSETSEL. Either one works fine. Choosing which message to use depends on the available format of the character indices. If they are already stored in a CHARRANGE structure, it's easier to use EM_EXSETSEL.

	EM_EXSETSEL
	wParam == not used. Must be 0
	lParam == pointer to a CHARRANGE structure that contains the character range to be selected.

Event Notification

In the case of a multiline edit control, you have to subclass it in order to obtain the input messages such as mouse/keyboard events. RichEdit control provides a better scheme that will notify the parent window of such events. In order to register for notifications, the parent window sends EM_SETEVENTMASK message to the RichEdit control, specifying which events it's interested in. EM_SETEVENTMASK has the following syntax:

	EM_SETEVENTMASK
	wParam == not used. Must be 0
	lParam == event mask value. It can be the combination of the flags in the table below.
ENM_CHANGE Sends EN_CHANGE notifications
ENM_CORRECTTEXT Sends EN_CORRECTTEXT notifications
ENM_DRAGDROPDONE Sends EN_DRAGDROPDONE notifications
ENM_DROPFILES Sends EN_DROPFILES notifications.
ENM_KEYEVENTS Sends EN_MSGFILTER notifications for keyboard events
ENM_LINK Rich Edit 2.0 and later: Sends EN_LINK notifications when the mouse pointer is over text that has the CFE_LINK and one of several mouse actions is performed.
ENM_MOUSEEVENTS Sends EN_MSGFILTER notifications for mouse events
ENM_OBJECTPOSITIONS Sends EN_OBJECTPOSITIONS notifications
ENM_PROTECTED Sends EN_PROTECTED notifications
ENM_REQUESTRESIZE Sends EN_REQUESTRESIZE notifications
ENM_SCROLL Sends EN_HSCROLL and EN_VSCROLL notifications
ENM_SCROLLEVENTS Sends EN_MSGFILTER notifications for mouse wheel events
ENM_SELCHANGE Sends EN_SELCHANGE notifications
ENM_UPDATE

Sends EN_UPDATE notifications.
Rich Edit 2.0 and later: this flag is ignored and the EN_UPDATE notifications are always sent. However, if Rich Edit 3.0 emulates Rich Edit 1.0, you must use this flag to send EN_UPDATE notifications

All the above notifications will be sent as WM_NOTIFY message: you have to check the code member of NMHDR structure for the notification message. For example, if you want to register for mouse events (eg. you want to provide a context sensitive popup menu), you must do something like this:

	invoke SendMessage,hwndRichEdit,EM_SETEVENTMASK,0,ENM_MOUSEEVENTS
	.....
	.....
	WndProc proc hWnd:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD
	.....
	....
		.elseif uMsg==WM_NOTIFY
			push esi
			mov esi,lParam
			assume esi:ptr NMHDR
			.if [esi].code==EN_MSGFILTER
				....
				[ do something here]
				....
			.endif
			pop esi

Example:

The following example is the update of IczEdit in tutorial no. 33. It adds search/replace functionality and accelerator keys to the program. It also processes the mouse events and provides a popup menu on right mouse click.

.386
.model flat,stdcall
option casemap:none
include \masm32\include\windows.inc
include \masm32\include\user32.inc
include \masm32\include\comdlg32.inc
include \masm32\include\gdi32.inc
include \masm32\include\kernel32.inc
includelib \masm32\lib\gdi32.lib
includelib \masm32\lib\comdlg32.lib
includelib \masm32\lib\user32.lib
includelib \masm32\lib\kernel32.lib

WinMain proto :DWORD,:DWORD,:DWORD,:DWORD

.const
IDR_MAINMENU                   equ 101
IDM_OPEN                      equ  40001
IDM_SAVE                       equ 40002
IDM_CLOSE                      equ 40003
IDM_SAVEAS                     equ 40004
IDM_EXIT                       equ 40005
IDM_COPY                      equ  40006
IDM_CUT                       equ  40007
IDM_PASTE                      equ 40008
IDM_DELETE                     equ 40009
IDM_SELECTALL                  equ 40010
IDM_OPTION 			equ 40011
IDM_UNDO			equ 40012
IDM_REDO			equ 40013
IDD_OPTIONDLG                  equ 101
IDC_BACKCOLORBOX               equ 1000
IDC_TEXTCOLORBOX               equ 1001
IDR_MAINACCEL                 equ  105
IDD_FINDDLG                    equ 102
IDD_GOTODLG                    equ 103
IDD_REPLACEDLG                 equ 104
IDC_FINDEDIT                  equ  1000
IDC_MATCHCASE                  equ 1001
IDC_REPLACEEDIT                 equ 1001
IDC_WHOLEWORD                  equ 1002
IDC_DOWN                       equ 1003
IDC_UP                       equ   1004
IDC_LINENO                   equ   1005
IDM_FIND                       equ 40014
IDM_FINDNEXT                  equ  40015
IDM_REPLACE                     equ 40016
IDM_GOTOLINE                   equ 40017
IDM_FINDPREV                  equ  40018
RichEditID 			equ 300

.data
ClassName db "IczEditClass",0
AppName  db "IczEdit version 2.0",0
RichEditDLL db "riched20.dll",0
RichEditClass db "RichEdit20A",0
NoRichEdit db "Cannot find riched20.dll",0
ASMFilterString 		db "ASM Source code (*.asm)",0,"*.asm",0
				db "All Files (*.*)",0,"*.*",0,0
OpenFileFail db "Cannot open the file",0
WannaSave db "The data in the control is modified. Want to save it?",0
FileOpened dd FALSE
BackgroundColor dd 0FFFFFFh		; default to white
TextColor dd 0		; default to black
hSearch dd ?		; handle to the search/replace dialog box
hAccel dd ?

.data?
hInstance dd ?
hRichEdit dd ?
hwndRichEdit dd ?
FileName db 256 dup(?)
AlternateFileName db 256 dup(?)
CustomColors dd 16 dup(?)
FindBuffer db 256 dup(?)
ReplaceBuffer db 256 dup(?)
uFlags dd ?
findtext FINDTEXTEX <>

.code
start:
	mov byte ptr [FindBuffer],0
	mov byte ptr [ReplaceBuffer],0
	invoke GetModuleHandle, NULL
	mov    hInstance,eax
	invoke LoadLibrary,addr RichEditDLL
	.if eax!=0
		mov hRichEdit,eax
		invoke WinMain, hInstance,0,0, SW_SHOWDEFAULT
		invoke FreeLibrary,hRichEdit
	.else
		invoke MessageBox,0,addr NoRichEdit,addr AppName,MB_OK or MB_ICONERROR
	.endif
	invoke ExitProcess,eax
	
WinMain proc hInst:DWORD,hPrevInst:DWORD,CmdLine:DWORD,CmdShow:DWORD
	LOCAL wc:WNDCLASSEX
	LOCAL msg:MSG
	LOCAL hwnd:DWORD
	mov   wc.cbSize,SIZEOF WNDCLASSEX
	mov   wc.style, CS_HREDRAW or CS_VREDRAW
	mov   wc.lpfnWndProc, OFFSET WndProc
	mov   wc.cbClsExtra,NULL
	mov   wc.cbWndExtra,NULL
	push  hInst
	pop   wc.hInstance
	mov   wc.hbrBackground,COLOR_WINDOW+1
	mov   wc.lpszMenuName,IDR_MAINMENU
	mov   wc.lpszClassName,OFFSET ClassName
	invoke LoadIcon,NULL,IDI_APPLICATION
	mov   wc.hIcon,eax
	mov   wc.hIconSm,eax
	invoke LoadCursor,NULL,IDC_ARROW
	mov   wc.hCursor,eax
	invoke RegisterClassEx, addr wc
	INVOKE CreateWindowEx,NULL,ADDR ClassName,ADDR AppName,\
           WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,\
           CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,NULL,NULL,\
           hInst,NULL
	mov   hwnd,eax
	invoke ShowWindow, hwnd,SW_SHOWNORMAL
	invoke UpdateWindow, hwnd
	invoke LoadAccelerators,hInstance,IDR_MAINACCEL
	mov hAccel,eax
	.while TRUE
		invoke GetMessage, ADDR msg,0,0,0
		.break .if (!eax)
		invoke IsDialogMessage,hSearch,addr msg
		.if eax==FALSE
			invoke TranslateAccelerator,hwnd,hAccel,addr msg
			.if eax==0
				invoke TranslateMessage, ADDR msg
				invoke DispatchMessage, ADDR msg
			.endif
		.endif
	.endw
	mov   eax,msg.wParam
	ret
WinMain endp

StreamInProc proc hFile:DWORD,pBuffer:DWORD, NumBytes:DWORD, pBytesRead:DWORD
	invoke ReadFile,hFile,pBuffer,NumBytes,pBytesRead,0
	xor eax,1
	ret
StreamInProc endp

StreamOutProc proc hFile:DWORD,pBuffer:DWORD, NumBytes:DWORD, pBytesWritten:DWORD
	invoke WriteFile,hFile,pBuffer,NumBytes,pBytesWritten,0
	xor eax,1
	ret
StreamOutProc endp

CheckModifyState proc hWnd:DWORD
	invoke SendMessage,hwndRichEdit,EM_GETMODIFY,0,0
	.if eax!=0
		invoke MessageBox,hWnd,addr WannaSave,addr AppName,MB_YESNOCANCEL
		.if eax==IDYES
			invoke SendMessage,hWnd,WM_COMMAND,IDM_SAVE,0
		.elseif eax==IDCANCEL
			mov eax,FALSE
			ret
		.endif
	.endif
	mov eax,TRUE
	ret
CheckModifyState endp

SetColor proc
	LOCAL cfm:CHARFORMAT
	invoke SendMessage,hwndRichEdit,EM_SETBKGNDCOLOR,0,BackgroundColor
	invoke RtlZeroMemory,addr cfm,sizeof cfm
	mov cfm.cbSize,sizeof cfm
	mov cfm.dwMask,CFM_COLOR
	push TextColor
	pop cfm.crTextColor
	invoke SendMessage,hwndRichEdit,EM_SETCHARFORMAT,SCF_ALL,addr cfm
	ret
SetColor endp

OptionProc proc hWnd:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD
	LOCAL clr:CHOOSECOLOR
	.if uMsg==WM_INITDIALOG
	.elseif uMsg==WM_COMMAND
		mov eax,wParam
		shr eax,16
		.if ax==BN_CLICKED
			mov eax,wParam
			.if ax==IDCANCEL
				invoke SendMessage,hWnd,WM_CLOSE,0,0
			.elseif ax==IDC_BACKCOLORBOX
				invoke RtlZeroMemory,addr clr,sizeof clr
				mov clr.lStructSize,sizeof clr
				push hWnd
				pop clr.hwndOwner
				push hInstance
				pop clr.hInstance
				push BackgroundColor
				pop clr.rgbResult
				mov clr.lpCustColors,offset CustomColors
				mov clr.Flags,CC_ANYCOLOR or CC_RGBINIT
				invoke ChooseColor,addr clr
				.if eax!=0
					push clr.rgbResult
					pop BackgroundColor
					invoke GetDlgItem,hWnd,IDC_BACKCOLORBOX
					invoke InvalidateRect,eax,0,TRUE
				.endif
			.elseif ax==IDC_TEXTCOLORBOX
				invoke RtlZeroMemory,addr clr,sizeof clr
				mov clr.lStructSize,sizeof clr
				push hWnd
				pop clr.hwndOwner
				push hInstance
				pop clr.hInstance
				push TextColor
				pop clr.rgbResult
				mov clr.lpCustColors,offset CustomColors
				mov clr.Flags,CC_ANYCOLOR or CC_RGBINIT
				invoke ChooseColor,addr clr
				.if eax!=0
					push clr.rgbResult
					pop TextColor
					invoke GetDlgItem,hWnd,IDC_TEXTCOLORBOX
					invoke InvalidateRect,eax,0,TRUE
				.endif
			.elseif ax==IDOK
				invoke SendMessage,hwndRichEdit,EM_GETMODIFY,0,0
				push eax
				invoke SetColor
				pop eax
				invoke SendMessage,hwndRichEdit,EM_SETMODIFY,eax,0
				invoke EndDialog,hWnd,0
			.endif
		.endif
	.elseif uMsg==WM_CTLCOLORSTATIC
		invoke GetDlgItem,hWnd,IDC_BACKCOLORBOX
		.if eax==lParam
			invoke CreateSolidBrush,BackgroundColor			
			ret
		.else
			invoke GetDlgItem,hWnd,IDC_TEXTCOLORBOX
			.if eax==lParam
				invoke CreateSolidBrush,TextColor
				ret
			.endif
		.endif
		mov eax,FALSE
		ret
	.elseif uMsg==WM_CLOSE
		invoke EndDialog,hWnd,0
	.else
		mov eax,FALSE
		ret
	.endif
	mov eax,TRUE
	ret
OptionProc endp

SearchProc proc hWnd:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD
	.if uMsg==WM_INITDIALOG
		push hWnd
		pop hSearch
		invoke CheckRadioButton,hWnd,IDC_DOWN,IDC_UP,IDC_DOWN
		invoke SendDlgItemMessage,hWnd,IDC_FINDEDIT,WM_SETTEXT,0,addr FindBuffer
	.elseif uMsg==WM_COMMAND
		mov eax,wParam
		shr eax,16
		.if ax==BN_CLICKED
			mov eax,wParam
			.if ax==IDOK
				mov uFlags,0
				invoke SendMessage,hwndRichEdit,EM_EXGETSEL,0,addr findtext.chrg
				invoke GetDlgItemText,hWnd,IDC_FINDEDIT,addr FindBuffer,sizeof FindBuffer
				.if eax!=0
					invoke IsDlgButtonChecked,hWnd,IDC_DOWN
					.if eax==BST_CHECKED
						or uFlags,FR_DOWN
						mov eax,findtext.chrg.cpMin
						.if eax!=findtext.chrg.cpMax
							push findtext.chrg.cpMax
							pop findtext.chrg.cpMin
						.endif
						mov findtext.chrg.cpMax,-1
					.else
						mov findtext.chrg.cpMax,0
					.endif
					invoke IsDlgButtonChecked,hWnd,IDC_MATCHCASE
					.if eax==BST_CHECKED
						or uFlags,FR_MATCHCASE
					.endif
					invoke IsDlgButtonChecked,hWnd,IDC_WHOLEWORD
					.if eax==BST_CHECKED
						or uFlags,FR_WHOLEWORD
					.endif
					mov findtext.lpstrText,offset FindBuffer
					invoke SendMessage,hwndRichEdit,EM_FINDTEXTEX,uFlags,addr findtext
					.if eax!=-1
						invoke SendMessage,hwndRichEdit,EM_EXSETSEL,0,addr findtext.chrgText
					.endif
				.endif
			.elseif ax==IDCANCEL
				invoke SendMessage,hWnd,WM_CLOSE,0,0
			.else
				mov eax,FALSE
				ret
			.endif
		.endif
	.elseif uMsg==WM_CLOSE
		mov hSearch,0
		invoke EndDialog,hWnd,0
	.else
		mov eax,FALSE
		ret
	.endif
	mov eax,TRUE
	ret
SearchProc endp

ReplaceProc proc hWnd:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD
	LOCAL settext:SETTEXTEX
	.if uMsg==WM_INITDIALOG
		push hWnd
		pop hSearch
		invoke SetDlgItemText,hWnd,IDC_FINDEDIT,addr FindBuffer
		invoke SetDlgItemText,hWnd,IDC_REPLACEEDIT,addr ReplaceBuffer
	.elseif uMsg==WM_COMMAND
		mov eax,wParam
		shr eax,16
		.if ax==BN_CLICKED
			mov eax,wParam
			.if ax==IDCANCEL
				invoke SendMessage,hWnd,WM_CLOSE,0,0
			.elseif ax==IDOK
				invoke GetDlgItemText,hWnd,IDC_FINDEDIT,addr FindBuffer,sizeof FindBuffer
				invoke GetDlgItemText,hWnd,IDC_REPLACEEDIT,addr ReplaceBuffer,sizeof ReplaceBuffer
				mov findtext.chrg.cpMin,0
				mov findtext.chrg.cpMax,-1
				mov findtext.lpstrText,offset FindBuffer
				mov settext.flags,ST_SELECTION
				mov settext.codepage,CP_ACP
				.while TRUE
					invoke SendMessage,hwndRichEdit,EM_FINDTEXTEX,FR_DOWN,addr findtext
					.if eax==-1
						.break
					.else
						invoke SendMessage,hwndRichEdit,EM_EXSETSEL,0,addr findtext.chrgText
						invoke SendMessage,hwndRichEdit,EM_SETTEXTEX,addr settext,addr ReplaceBuffer
					.endif
				.endw
			.endif
		.endif
	.elseif uMsg==WM_CLOSE
		mov hSearch,0
		invoke EndDialog,hWnd,0
	.else
		mov eax,FALSE
		ret
	.endif
	mov eax,TRUE
	ret
ReplaceProc endp

GoToProc proc hWnd:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD
	LOCAL LineNo:DWORD
	LOCAL chrg:CHARRANGE
	.if uMsg==WM_INITDIALOG
		push hWnd
		pop hSearch
	.elseif uMsg==WM_COMMAND
		mov eax,wParam
		shr eax,16
		.if ax==BN_CLICKED
			mov eax,wParam
			.if ax==IDCANCEL
				invoke SendMessage,hWnd,WM_CLOSE,0,0
			.elseif ax==IDOK
				invoke GetDlgItemInt,hWnd,IDC_LINENO,NULL,FALSE
				mov LineNo,eax
				invoke SendMessage,hwndRichEdit,EM_GETLINECOUNT,0,0
				.if eax>LineNo
					invoke SendMessage,hwndRichEdit,EM_LINEINDEX,LineNo,0
					mov chrg.cpMin,eax
					mov chrg.cpMax,eax
					invoke SendMessage,hwndRichEdit,EM_EXSETSEL,0,addr chrg
					invoke SetFocus,hwndRichEdit
				.endif
			.endif
		.endif
	.elseif uMsg==WM_CLOSE
		mov hSearch,0
		invoke EndDialog,hWnd,0
	.else
		mov eax,FALSE
		ret
	.endif
	mov eax,TRUE
	ret
GoToProc endp

PrepareEditMenu proc hSubMenu:DWORD
	LOCAL chrg:CHARRANGE
	invoke SendMessage,hwndRichEdit,EM_CANPASTE,CF_TEXT,0
	.if eax==0		; no text in the clipboard
		invoke EnableMenuItem,hSubMenu,IDM_PASTE,MF_GRAYED
	.else
		invoke EnableMenuItem,hSubMenu,IDM_PASTE,MF_ENABLED
	.endif
	invoke SendMessage,hwndRichEdit,EM_CANUNDO,0,0
	.if eax==0
		invoke EnableMenuItem,hSubMenu,IDM_UNDO,MF_GRAYED
	.else
		invoke EnableMenuItem,hSubMenu,IDM_UNDO,MF_ENABLED
	.endif
	invoke SendMessage,hwndRichEdit,EM_CANREDO,0,0
	.if eax==0
		invoke EnableMenuItem,hSubMenu,IDM_REDO,MF_GRAYED
	.else
		invoke EnableMenuItem,hSubMenu,IDM_REDO,MF_ENABLED
	.endif
	invoke SendMessage,hwndRichEdit,EM_EXGETSEL,0,addr chrg
	mov eax,chrg.cpMin
	.if eax==chrg.cpMax		; no current selection
		invoke EnableMenuItem,hSubMenu,IDM_COPY,MF_GRAYED
		invoke EnableMenuItem,hSubMenu,IDM_CUT,MF_GRAYED
		invoke EnableMenuItem,hSubMenu,IDM_DELETE,MF_GRAYED
	.else
		invoke EnableMenuItem,hSubMenu,IDM_COPY,MF_ENABLED
		invoke EnableMenuItem,hSubMenu,IDM_CUT,MF_ENABLED
		invoke EnableMenuItem,hSubMenu,IDM_DELETE,MF_ENABLED
	.endif
	ret
PrepareEditMenu endp

WndProc proc hWnd:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD
	LOCAL ofn:OPENFILENAME
	LOCAL buffer[256]:BYTE
	LOCAL editstream:EDITSTREAM
	LOCAL hFile:DWORD
	LOCAL hPopup:DWORD
	LOCAL pt:POINT
	LOCAL chrg:CHARRANGE
	.if uMsg==WM_CREATE
		invoke CreateWindowEx,WS_EX_CLIENTEDGE,addr RichEditClass,0,\
                          WS_CHILD or WS_VISIBLE or ES_MULTILINE or WS_VSCROLL or WS_HSCROLL or ES_NOHIDESEL,\
				                  CW_USEDEFAULT,CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,hWnd,RichEditID,hInstance,0
		mov hwndRichEdit,eax
		invoke SendMessage,hwndRichEdit,EM_LIMITTEXT,-1,0
		invoke SetColor
		invoke SendMessage,hwndRichEdit,EM_SETMODIFY,FALSE,0
		invoke SendMessage,hwndRichEdit,EM_SETEVENTMASK,0,ENM_MOUSEEVENTS
		invoke SendMessage,hwndRichEdit,EM_EMPTYUNDOBUFFER,0,0
	.elseif uMsg==WM_NOTIFY
		push esi
		mov esi,lParam
		assume esi:ptr NMHDR
		.if [esi].code==EN_MSGFILTER
			assume esi:ptr MSGFILTER
			.if [esi].msg==WM_RBUTTONDOWN
				invoke GetMenu,hWnd
				invoke GetSubMenu,eax,1
				mov hPopup,eax
				invoke PrepareEditMenu,hPopup
				mov edx,[esi].lParam
				mov ecx,edx
				and edx,0FFFFh
				shr ecx,16
				mov pt.x,edx
				mov pt.y,ecx
				invoke ClientToScreen,hWnd,addr pt
				invoke TrackPopupMenu,hPopup,TPM_LEFTALIGN or TPM_BOTTOMALIGN,pt.x,pt.y,NULL,hWnd,NULL
			.endif
		.endif
		pop esi
	.elseif uMsg==WM_INITMENUPOPUP
		mov eax,lParam
		.if ax==0		; file menu			
			.if FileOpened==TRUE	; a file is already opened
				invoke EnableMenuItem,wParam,IDM_OPEN,MF_GRAYED
				invoke EnableMenuItem,wParam,IDM_CLOSE,MF_ENABLED
				invoke EnableMenuItem,wParam,IDM_SAVE,MF_ENABLED
				invoke EnableMenuItem,wParam,IDM_SAVEAS,MF_ENABLED
			.else
				invoke EnableMenuItem,wParam,IDM_OPEN,MF_ENABLED
				invoke EnableMenuItem,wParam,IDM_CLOSE,MF_GRAYED
				invoke EnableMenuItem,wParam,IDM_SAVE,MF_GRAYED
				invoke EnableMenuItem,wParam,IDM_SAVEAS,MF_GRAYED
			.endif
		.elseif ax==1	; edit menu
			invoke PrepareEditMenu,wParam
		.elseif ax==2		; search menu bar
			.if FileOpened==TRUE
				invoke EnableMenuItem,wParam,IDM_FIND,MF_ENABLED
				invoke EnableMenuItem,wParam,IDM_FINDNEXT,MF_ENABLED
				invoke EnableMenuItem,wParam,IDM_FINDPREV,MF_ENABLED
				invoke EnableMenuItem,wParam,IDM_REPLACE,MF_ENABLED
				invoke EnableMenuItem,wParam,IDM_GOTOLINE,MF_ENABLED
			.else
				invoke EnableMenuItem,wParam,IDM_FIND,MF_GRAYED
				invoke EnableMenuItem,wParam,IDM_FINDNEXT,MF_GRAYED
				invoke EnableMenuItem,wParam,IDM_FINDPREV,MF_GRAYED
				invoke EnableMenuItem,wParam,IDM_REPLACE,MF_GRAYED
				invoke EnableMenuItem,wParam,IDM_GOTOLINE,MF_GRAYED
			.endif
		.endif
	.elseif uMsg==WM_COMMAND
		.if lParam==0		; menu commands
			mov eax,wParam
			.if ax==IDM_OPEN
				invoke RtlZeroMemory,addr ofn,sizeof ofn
				mov ofn.lStructSize,sizeof ofn
				push hWnd
				pop ofn.hwndOwner
				push hInstance
				pop ofn.hInstance
				mov ofn.lpstrFilter,offset ASMFilterString
				mov ofn.lpstrFile,offset FileName
				mov byte ptr [FileName],0
				mov ofn.nMaxFile,sizeof FileName
				mov ofn.Flags,OFN_FILEMUSTEXIST or OFN_HIDEREADONLY or OFN_PATHMUSTEXIST
				invoke GetOpenFileName,addr ofn
				.if eax!=0
					invoke CreateFile,addr FileName,GENERIC_READ,FILE_SHARE_READ,NULL,\
                            OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,0
					.if eax!=INVALID_HANDLE_VALUE
						mov hFile,eax
						;================================================================
						; stream the text into the richedit control
						;================================================================
						mov editstream.dwCookie,eax
						mov editstream.pfnCallback,offset StreamInProc
						invoke SendMessage,hwndRichEdit,EM_STREAMIN,SF_TEXT,addr editstream
						;==========================================================
						; Initialize the modify state to false
						;==========================================================
						invoke SendMessage,hwndRichEdit,EM_SETMODIFY,FALSE,0
						invoke CloseHandle,hFile
						mov FileOpened,TRUE
					.else
						invoke MessageBox,hWnd,addr OpenFileFail,addr AppName,MB_OK or MB_ICONERROR
					.endif
				.endif
			.elseif ax==IDM_CLOSE
				invoke CheckModifyState,hWnd
				.if eax==TRUE
					invoke SetWindowText,hwndRichEdit,0
					mov FileOpened,FALSE
				.endif
			.elseif ax==IDM_SAVE
				invoke CreateFile,addr FileName,GENERIC_WRITE,FILE_SHARE_READ,NULL,\
                          CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,0
				.if eax!=INVALID_HANDLE_VALUE
@@:				
					mov hFile,eax
					;================================================================
					; stream the text to the file
					;================================================================
					mov editstream.dwCookie,eax
					mov editstream.pfnCallback,offset StreamOutProc
					invoke SendMessage,hwndRichEdit,EM_STREAMOUT,SF_TEXT,addr editstream
					;==========================================================
					; Initialize the modify state to false
					;==========================================================
					invoke SendMessage,hwndRichEdit,EM_SETMODIFY,FALSE,0
					invoke CloseHandle,hFile
				.else
					invoke MessageBox,hWnd,addr OpenFileFail,addr AppName,MB_OK or MB_ICONERROR
				.endif
			.elseif ax==IDM_COPY
				invoke SendMessage,hwndRichEdit,WM_COPY,0,0
			.elseif ax==IDM_CUT
				invoke SendMessage,hwndRichEdit,WM_CUT,0,0
			.elseif ax==IDM_PASTE
				invoke SendMessage,hwndRichEdit,WM_PASTE,0,0
			.elseif ax==IDM_DELETE
				invoke SendMessage,hwndRichEdit,EM_REPLACESEL,TRUE,0
			.elseif ax==IDM_SELECTALL
				mov chrg.cpMin,0
				mov chrg.cpMax,-1
				invoke SendMessage,hwndRichEdit,EM_EXSETSEL,0,addr chrg
			.elseif ax==IDM_UNDO
				invoke SendMessage,hwndRichEdit,EM_UNDO,0,0
			.elseif ax==IDM_REDO
				invoke SendMessage,hwndRichEdit,EM_REDO,0,0
			.elseif ax==IDM_OPTION
				invoke DialogBoxParam,hInstance,IDD_OPTIONDLG,hWnd,addr OptionProc,0
			.elseif ax==IDM_SAVEAS
				invoke RtlZeroMemory,addr ofn,sizeof ofn
				mov ofn.lStructSize,sizeof ofn
				push hWnd
				pop ofn.hwndOwner
				push hInstance
				pop ofn.hInstance
				mov ofn.lpstrFilter,offset ASMFilterString
				mov ofn.lpstrFile,offset AlternateFileName
				mov byte ptr [AlternateFileName],0
				mov ofn.nMaxFile,sizeof AlternateFileName
				mov ofn.Flags,OFN_FILEMUSTEXIST or OFN_HIDEREADONLY or OFN_PATHMUSTEXIST
				invoke GetSaveFileName,addr ofn
				.if eax!=0
					invoke CreateFile,addr AlternateFileName,GENERIC_WRITE,FILE_SHARE_READ,\
                            NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,0
					.if eax!=INVALID_HANDLE_VALUE
						jmp @B
					.endif
				.endif
			.elseif ax==IDM_FIND
				.if hSearch==0
					invoke CreateDialogParam,hInstance,IDD_FINDDLG,hWnd,addr SearchProc,0
				.endif
			.elseif ax==IDM_REPLACE
				.if hSearch==0
					invoke CreateDialogParam,hInstance,IDD_REPLACEDLG,hWnd,addr ReplaceProc,0
				.endif
			.elseif ax==IDM_GOTOLINE
				.if hSearch==0
					invoke CreateDialogParam,hInstance,IDD_GOTODLG,hWnd,addr GoToProc,0
				.endif
			.elseif ax==IDM_FINDNEXT
				invoke lstrlen,addr FindBuffer
				.if eax!=0
					invoke SendMessage,hwndRichEdit,EM_EXGETSEL,0,addr findtext.chrg
					mov eax,findtext.chrg.cpMin
					.if eax!=findtext.chrg.cpMax
						push findtext.chrg.cpMax
						pop findtext.chrg.cpMin
					.endif
					mov findtext.chrg.cpMax,-1
					mov findtext.lpstrText,offset FindBuffer
					invoke SendMessage,hwndRichEdit,EM_FINDTEXTEX,FR_DOWN,addr findtext
					.if eax!=-1
						invoke SendMessage,hwndRichEdit,EM_EXSETSEL,0,addr findtext.chrgText
					.endif
				.endif
			.elseif ax==IDM_FINDPREV
				invoke lstrlen,addr FindBuffer
				.if eax!=0
					invoke SendMessage,hwndRichEdit,EM_EXGETSEL,0,addr findtext.chrg
					mov findtext.chrg.cpMax,0
					mov findtext.lpstrText,offset FindBuffer
					invoke SendMessage,hwndRichEdit,EM_FINDTEXTEX,0,addr findtext
					.if eax!=-1
						invoke SendMessage,hwndRichEdit,EM_EXSETSEL,0,addr findtext.chrgText
					.endif
				.endif
			.elseif ax==IDM_EXIT
				invoke SendMessage,hWnd,WM_CLOSE,0,0
			.endif
		.endif
	.elseif uMsg==WM_CLOSE
		invoke CheckModifyState,hWnd
		.if eax==TRUE
			invoke DestroyWindow,hWnd
		.endif
	.elseif uMsg==WM_SIZE
		mov eax,lParam
		mov edx,eax
		and eax,0FFFFh
		shr edx,16
		invoke MoveWindow,hwndRichEdit,0,0,eax,edx,TRUE		
	.elseif uMsg==WM_DESTROY
		invoke PostQuitMessage,NULL
	.else
		invoke DefWindowProc,hWnd,uMsg,wParam,lParam		
		ret
	.endif
	xor eax,eax
	ret
WndProc endp
end start

Analysis

The search-for-text capability is implemented with EM_FINDTEXTEX. When the user clicks on Find menuitem, IDM_FIND message is sent and the Find dialog box is displayed.


	invoke GetDlgItemText,hWnd,IDC_FINDEDIT,addr FindBuffer,sizeof FindBuffer
	.if eax!=0

When the user types the text to search for and then press OK button, we get the text to be searched for into FindBuffer.

		mov uFlags,0 
		invoke SendMessage,hwndRichEdit,EM_EXGETSEL,0,addr findtext.chrg

If the text string is not null, we continue to initialize uFlags variable to 0.This variable is used to store the search flags used with EM_FINDTEXTEX. After that, we obtain the current selection with EM_EXGETSEL because we need to know the starting point of the search operation.

	invoke IsDlgButtonChecked,hWnd,IDC_DOWN
		.if eax==BST_CHECKED
			or uFlags,FR_DOWN
			mov eax,findtext.chrg.cpMin
			.if eax!=findtext.chrg.cpMax
				push findtext.chrg.cpMax
				pop findtext.chrg.cpMin
			.endif
			mov findtext.chrg.cpMax,-1
		.else
			mov findtext.chrg.cpMax,0
		.endif

The next part is a little tricky. We check the direction radio button to ascertain which direction the search should go. If the downward search is indicated, we set FR_DOWN flag to uFlags. After that, we check whether a selection is currently in effect by comparing the values of cpMin and cpMax. If both values are not equal, it means there is a current selection and we must continue the search from the end of that selection to the end of text in the control. Thus we need to replace the value of cpMax with that of cpMin and change the value of cpMax to -1 (0FFFFFFFFh). If there is no current selection, the range to search is from the current caret position to the end of text.

If the user chooses to search upward, we use the range from the start of the selection to the beginning of the text in the control. That's why we only modify the value of cpMax to 0. In the case of upward search, cpMin contains the character index of the last character in the search range and cpMax the character index of the first char in the search range. It's the inverse of the downward search.

		invoke IsDlgButtonChecked,hWnd,IDC_MATCHCASE
		.if eax==BST_CHECKED
			or uFlags,FR_MATCHCASE
		.endif
		invoke IsDlgButtonChecked,hWnd,IDC_WHOLEWORD
		.if eax==BST_CHECKED
			or uFlags,FR_WHOLEWORD
		.endif
		mov findtext.lpstrText,offset FindBuffer

We continue to check the checkboxes for the search flags, ie, FR_MATCHCASE and FR_WHOLEWORD. Lastly, we put the offset of the text to search for in lpstrText member.

		invoke SendMessage,hwndRichEdit,EM_FINDTEXTEX,uFlags,addr findtext
		.if eax!=-1
			invoke SendMessage,hwndRichEdit,EM_EXSETSEL,0,addr findtext.chrgText
		.endif
	.endif

We are now ready to issue EM_FINDTEXTEX. After that, we examine the search result returned by SendMessage. If the return value is -1, no match is found in the search range. Otherwise, chrgText member of FINDTEXTEX structure is filled with the character indices of the matching text. We thus proceed to select it with EM_EXSETSEL.

The replace operation is done in much the same manner.

	invoke GetDlgItemText,hWnd,IDC_FINDEDIT,addr FindBuffer,sizeof FindBuffer
	invoke GetDlgItemText,hWnd,IDC_REPLACEEDIT,addr ReplaceBuffer,sizeof ReplaceBuffer

We retrieve the text to search for and the text used to replace.

	mov findtext.chrg.cpMin,0
	mov findtext.chrg.cpMax,-1
	mov findtext.lpstrText,offset FindBuffer

To make it easy, the replace operation affects all the text in the control. Thus the starting index is 0 and the ending index is -1.

	mov settext.flags,ST_SELECTION
	mov settext.codepage,CP_ACP

We initialize SETTEXTEX structure to indicate that we want to replace the current selection and use the default system code page.

	.while TRUE
		invoke SendMessage,hwndRichEdit,EM_FINDTEXTEX,FR_DOWN,addr findtext
		.if eax==-1
			.break
		.else
			invoke SendMessage,hwndRichEdit,EM_EXSETSEL,0,addr findtext.chrgText
			invoke SendMessage,hwndRichEdit,EM_SETTEXTEX,addr settext,addr ReplaceBuffer
		.endif
	.endw

We enter an infinite loop, searching for the matching text. If one is found, we select it with EM_EXSETSEL and replace it with EM_SETTEXTEX. When no more match is found, we exit the loop.

Find Next and Find Prev. features use EM_FINDTEXTEX message in the similar manner to the find operation.

We will examine the Go to Line feature next. When the user clicks Go To Line menuitem, we display a dialog box below:

When the user types a line number and presses Ok button, we begin the operation.

	invoke GetDlgItemInt,hWnd,IDC_LINENO,NULL,FALSE
	mov LineNo,eax

Obtain the line number from the edit control

	invoke SendMessage,hwndRichEdit,EM_GETLINECOUNT,0,0
	.if eax>LineNo

Obtain the number of lines in the control. Check whether the user specifies the line number that is out of the range.

		invoke SendMessage,hwndRichEdit,EM_LINEINDEX,LineNo,0

If the line number is valid, we want to move the caret to the first character of that line. So we send EM_LINEINDEX message to the richedit control. This message returns the character index of the first character in the specified line. We send the line number in wParam and in return, we has the character index.

		invoke SendMessage,hwndRichEdit,EM_SETSEL,eax,eax

To set the current selection, this time we use EM_SETSEL because the character indices are not already in a CHARRANGE structure thus it saves us two instructions (to put those indices into a CHARRANGE structure).

		invoke SetFocus,hwndRichEdit
	.endif

The caret will not be displayed unless the richedit control has the focus. So we call SetFocus on it.


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