Append text to an edit control text buffer? [Archive]

homersux

August 5th, 2004, 18:33

Other than getwindowtext, append text, then setwindowtext, is there a easy way to append text
to a multi-line edit control? This could be used as a convenient log window for verbose information output.

Kayaker

August 5th, 2004, 21:53

Hi,

Are you meaning in your own code, as opposed to this is a reversing trick question?

Unless you WANT to use a multiline edit control, using a listbox and LB_ADDSTRING might be a bit more convenient for log output like this. It's dead easy to control, add, modify... Also has the nice feature of being able to associate a dword value to any item you add using LB_SETITEMDATA, for whatever use you might make of that.

Unless you go to RichEdit, multiline edit controls somehow don't seem as useful for *appending* text without having to fiddle around with carets, line breaks, scrolling and such. Assuming you don't want user input you could use WM_SETTEXT, but it seems you'd need to copy the existing text to a buffer, append it, then write it back, too much overhead.

I find listboxes handy for displaying results from GetLastError / FormatMessage output, which I try to use routinely. Not that this has anything to do with your question, but for the sake of code an example and couple of macros:

Code:



...

.else     ; CreateService fails



     invoke GetLastError

     ; most likely error is ERROR_SERVICE_EXISTS equ 431h



     OutputLBText hListBox_Log, \

               CTEXT("ERROR: CreateService failed with System Message:"

 

    OutputSystemErrorMsg hListBox_Log

         

.endif    ; CreateService endif





;=======================================================

;    Listbox handling Macros to deal with display issues

;=======================================================



;--------------------------------------------------------------------

; MACRO to format FormatMessage string for display in Listbox

; CarriageFeed/LineReturn is not handled well by Listboxes. 

; This macro finds the CF/LR added by FormatMessage and 

;       null terminates the string.

; Usage: pass system error message in eax, i.e.

; invoke GetLastError 

; OutputSystemErrorMsg, hListBox

;--------------------------------------------------------------------

 OutputSystemErrorMsg MACRO _hWnd

     LOCAL lpFormatMsg

     .data?

          lpFormatMsg    db 64 dup(?)   ; max buffer for FormatMessage

     .code

     invoke FormatMessage, FORMAT_MESSAGE_FROM_SYSTEM, NULL, eax,\

           NULL, offset lpFormatMsg, sizeof lpFormatMsg, NULL



     cld

     push ecx

     push edi

     mov eax, 0Dh

 	or ecx, -1

 	lea edi, offset lpFormatMsg

 	repne scasb

     dec edi

     mov byte ptr [edi], 0    ; null terminate the string

     pop edi

     pop ecx

 

     invoke SendMessage, _hWnd, LB_ADDSTRING, 0, offset lpFormatMsg

     invoke SendMessage, _hWnd, LB_ADDSTRING, 0, CTEXT(" "

     invoke SendMessage, _hWnd, LB_GETCOUNT, 0, 0

     sub eax, 1

     invoke SendMessage, _hWnd, LB_SETTOPINDEX, eax, 0

 ENDM

;--------------------------------------------------------------------



;--------------------------------------------------------------------

; MACRO to output Listbox text, may include CF/LR and/or variable formatting arguments

; Usage: pass CF/LR as "\n", leave blank if desired if including Args

; OutputLBText hWnd, CTEXT("text"

; OutputLBText hWnd, CTEXT("text", \n

; OutputLBText hWnd, CTEXT("text %04X", \n, eax

; OutputLBText hWnd, CTEXT("text %04X %04d", ,eax, eax

;--------------------------------------------------------------------

 OutputLBText MACRO _hWnd, Text, CFLR, Args:VARARG

     LOCAL StringBuff

     .data?

          StringBuff    db MAX_PATH dup(?)

     .code

     push eax

     IFNB <Args>    ; if 'Args' argument is not blank, format according to Text syntax

          invoke wsprintf, offset StringBuff, Text, Args

          invoke SendMessage, _hWnd, LB_ADDSTRING, 0,\

                           offset StringBuff

          IFNB <CFLR>    ; if 'CFLR' argument is not blank, add a blank line

               invoke SendMessage, _hWnd, LB_ADDSTRING, 0, CTEXT(" "

          ENDIF         

     ENDIF



     IFB <Args>    ; if 'Args' argument is blank, output Text as passed

          invoke SendMessage, _hWnd, LB_ADDSTRING, 0, Text

          IFNB <CFLR>

               invoke SendMessage, _hWnd, LB_ADDSTRING, 0, CTEXT(" "

          ENDIF     

     ENDIF         

     invoke SendMessage, _hWnd, LB_GETCOUNT, 0, 0

     sub eax, 1

     invoke SendMessage, _hWnd, LB_SETTOPINDEX, eax, 0



     pop eax

 ENDM

;--------------------------------------------------------------------

;=======================================================

Kayaker

homersux

August 6th, 2004, 08:26

well unfortunately, i need to use a simple logging edit control in user land app.
The problem with list control is it cannot be easily copy/pasted. RichEdit is not
a basic gdi32 control object. I may have to fall back to the copy/append/reset
approach since the amount of text information is not huge.

cr.ap

August 6th, 2004, 19:58

according to msdn you can get/set a handle to the EditControl TextBuffer with EM_GETHANDLE/EM_SETHANDLE, however last time i played with it for the exact same reason, i couldnt get it to work correctly an do so dianlly ended up with the same old circular buffer and Get/SetWindowText, maybe you have more luck.

cr.ap

PS: another option for appending may be EM_SETSEL/EM_REPLACESEL.