Fast subclassing through compiled code

LarsJ · September 30, 2018

In GUIRegisterMsg20 - Subclassing Made Easy we saw that it's possible to execute too much code in the WM_NOTIFY message handler in ListView1.au3:

Func WM_NOTIFY( $hWnd, $iMsg, $wParam, $lParam, $iSubclassId, $pData ) ; $iSubclassId = 0, $pData = 0
  If $iMsg <> $WM_NOTIFY Then Return DllCall( "comctl32.dll", "lresult", "DefSubclassProc", "hwnd", $hWnd, "uint", $iMsg, "wparam", $wParam, "lparam", $lParam )[0]
  Local Static $tText = DllStructCreate( "wchar[100]" ), $pText = DllStructGetPtr( $tText )
  Local Static $tRect = DllStructCreate( $tagRECT ), $pRect = DllStructGetPtr( $tRect )

  Switch DllStructGetData( DllStructCreate( $tagNMHDR, $lParam ), "Code" )
    Case $LVN_GETDISPINFOW
      ; Fill virtual listview
      Local $tNMLVDISPINFO = DllStructCreate( $tagNMLVDISPINFO, $lParam )
      If Not BitAND( DllStructGetData( $tNMLVDISPINFO, "Mask" ), $LVIF_TEXT ) Then Return
      Local $sItem = $aItems[DllStructGetData($tNMLVDISPINFO,"Item")][DllStructGetData($tNMLVDISPINFO,"SubItem")]
      DllStructSetData( $tText, 1, $sItem )
      DllStructSetData( $tNMLVDISPINFO, "TextMax", StringLen( $sItem ) )
      DllStructSetData( $tNMLVDISPINFO, "Text", $pText )
      Return

    Case $NM_CUSTOMDRAW
      ; Draw back colors
      Local $tNMLVCUSTOMDRAW = DllStructCreate( $tagNMLVCUSTOMDRAW, $lParam )
      Local $dwDrawStage = DllStructGetData( $tNMLVCUSTOMDRAW, "dwDrawStage" ), $iItem
      Switch $dwDrawStage                        ; Holds a value that specifies the drawing stage
        Case $CDDS_PREPAINT                      ; Before the paint cycle begins
          Return $CDRF_NOTIFYITEMDRAW            ; Notify the parent window of any item-related drawing operations
        Case $CDDS_ITEMPREPAINT                  ; Before painting an item
          Return $CDRF_NOTIFYSUBITEMDRAW         ; Notify the parent window of any subitem-related drawing operations
        Case $CDDS_ITEMPREPAINT + $CDDS_SUBITEM  ; Before painting a subitem
          $iItem = DllStructGetData( $tNMLVCUSTOMDRAW, "dwItemSpec" )
          If GUICtrlSendMsg( $idListView, $LVM_GETITEMSTATE, $iItem, $LVIS_SELECTED ) Then Return $CDRF_NOTIFYPOSTPAINT      ; Selected item
          DllStructSetData( $tNMLVCUSTOMDRAW, "ClrTextBk", $aColors[$iItem][DllStructGetData($tNMLVCUSTOMDRAW,"iSubItem")] ) ; Normal item
          Return $CDRF_NEWFONT                   ; $CDRF_NEWFONT must be returned after changing font or colors
        Case $CDDS_ITEMPOSTPAINT + $CDDS_SUBITEM ; After painting a subitem
          Local $hDC = DllStructGetData( $tNMLVCUSTOMDRAW, "hdc" )
          ; Subitem rectangle
          $iItem = DllStructGetData( $tNMLVCUSTOMDRAW, "dwItemSpec" )
          Local $iSubItem = DllStructGetData( $tNMLVCUSTOMDRAW, "iSubItem" )
          DllStructSetData( $tRect, "Left", $LVIR_LABEL )
          DllStructSetData( $tRect, "Top", $iSubItem )
          GUICtrlSendMsg( $idListView, $LVM_GETSUBITEMRECT, $iItem, $pRect )
          DllStructSetData( $tRect, "Left",   DllStructGetData( $tRect, "Left"   ) + 2 )
          DllStructSetData( $tRect, "Top",    DllStructGetData( $tRect, "Top"    ) + 1 )
          DllStructSetData( $tRect, "Right",  DllStructGetData( $tRect, "Right"  ) - 2 )
          DllStructSetData( $tRect, "Bottom", DllStructGetData( $tRect, "Bottom" ) - 1 )
          ; Subitem back color
          Local $hBrush = DllCall( "gdi32.dll", "handle", "CreateSolidBrush", "int", $aColors[$iItem][$iSubItem] )[0] ; _WinAPI_CreateSolidBrush
          DllCall( "user32.dll", "int", "FillRect", "handle", $hDC, "struct*", $tRect, "handle", $hBrush ) ; _WinAPI_FillRect
          DllCall( "gdi32.dll", "bool", "DeleteObject", "handle", $hBrush ) ; _WinAPI_DeleteObject
          ; Draw subitem text
          DllStructSetData( $tRect, "Top", DllStructGetData( $tRect, "Top" ) + 1 )
          DllCall( "gdi32.dll", "int", "SetTextColor", "handle", $hDC, "int", 0 ) ; _WinAPI_SetTextColor
          DllCall( "gdi32.dll", "int", "SetBkMode", "handle", $hDC, "int", $TRANSPARENT ) ; _WinAPI_SetBkMode
          DllCall( "user32.dll", "int", "DrawTextW", "handle", $hDC, "wstr", $aItems[$iItem][$iSubItem], "int", -1, "struct*", $tRect, "uint", $DT_CENTER ) ; _WinAPI_DrawText
          Return $CDRF_NEWFONT                   ; $CDRF_NEWFONT must be returned after changing font or colors
      EndSwitch
  EndSwitch

  Return DllCall( "comctl32.dll", "lresult", "DefSubclassProc", "hwnd", $hWnd, "uint", $iMsg, "wparam", $wParam, "lparam", $lParam )[0]
  #forceref $hWnd, $iMsg, $wParam, $iSubclassId, $pData
EndFunc

The code here is a full subclass implementation (not based on the UDF).

You can provoke the error this way: Click a row in the listview (not one of the very top rows). Press Shift+Down arrow to select multiple rows. The problem will arise after just a few rows. Press Ctrl+Break in SciTE to stop the code.

One way to make the code faster is to use compiled code. Let's take a closer look at the subclass implementation:

Local $pWM_NOTIFY = DllCallbackGetPtr( DllCallbackRegister( "WM_NOTIFY", "lresult", "hwnd;uint;wparam;lparam;uint_ptr;dword_ptr" ) )
DllCall( "comctl32.dll", "bool", "SetWindowSubclass", "hwnd", $hGui, "ptr", $pWM_NOTIFY, "uint_ptr", 0, "dword_ptr", 0 ) ; $iSubclassId = 0, $pData = 0

$pWM_NOTIFY is a pointer to the message handler function.

To replace the AutoIt message handler with compiled code, we can implement the message handler in C/C++ code in a dll-file and replace $pWM_NOTIFY with a pointer to the compiled code. The C/C++ function definition looks like this:

LRESULT CALLBACK __stdcall MsgHandler( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData )

We can get a pointer to the message handler this way:

Local $hModule = _WinAPI_LoadLibrary( "Subclass.dll" )
Local $pMsgHandler = _WinAPI_GetProcAddress( $hModule, "MsgHandler" )

Now we can simply replace $pWM_NOTIFY with $pMsgHandler in SetWindowSubclass function. And of course we need to pass the $aItems and $aColors arrays to the compiled code in the dll-file. But we already know how to do that.

Note that because $pMsgHandler is used directly in SetWindowSubclass function, we can avoid both the DllCall and DllCallAddress commands. Thus, we avoid a severe overhead in relation to these commands (that the AutoIt code interpreter should interpret a code line for each message (for a huge number of messages), and that DllCall and DllCallAddress are complicated and time-consuming commands).

AutoIt code in ListView2.au3:

#include <GUIConstantsEx.au3>
#include "GuiListViewEx.au3"
#include "AccArrays.au3"

Opt( "MustDeclareVars", 1 )

Global $apsa[2] ; $psaItems, $psaColors

Example()

Func Example()
  ; Rows and columns
  Local $iRows = 10000, $iCols = 8

  ; Create GUI
  Local $hGui = GUICreate( "Virtual and Custom Drawn ListView", 820, 620 )

  ; Create ListView
  Local $idListView = GUICtrlCreateListView( "", 10, 10, 800, 600, $GUI_SS_DEFAULT_LISTVIEW+$LVS_OWNERDATA-$LVS_SINGLESEL )
  _GUICtrlListView_SetExtendedListViewStyle( $idListView, $LVS_EX_DOUBLEBUFFER+$LVS_EX_FULLROWSELECT )
  Local $hListView = GUICtrlGetHandle( $idListView )

  ; Add columns
  For $i = 0 To $iCols - 1
    _GUICtrlListView_AddColumn( $idListView, "Col " & $i, 96, 2 )
  Next

  ; ListView items
  Local $aItems[$iRows][$iCols]
  For $i = 0 To $iRows - 1
    For $j = 0 To $iCols - 1
      $aItems[$i][$j] = $i & "/" & $j
    Next
  Next

  ; ListView colors
  Local $aColors[$iRows][$iCols]
  Local $aLVColors = [ 0xCCCCFF, 0xCCFFFF, 0xCCFFCC, 0xFFFFCC, 0xFFCCCC, 0xFFCCFF ] ; BGR
  For $i = 0 To $iRows - 1
    For $j = 0 To $iCols - 1
      $aColors[$i][$j] = $aLVColors[Random( 0,5,1 )]
    Next
  Next

  ; Load dll-file
  Local $hDll = DllOpen( @AutoItX64 ? "Subclass_x64.dll" : "Subclass.dll" )
  Local $hModule = _WinAPI_LoadLibrary( @AutoItX64 ? "Subclass_x64.dll" : "Subclass.dll" )

  ; $aItems and $aColors
  Local $psaItemsData, $psaColorsData
  AccArrays02( SafeArrays, $aItems, $aColors )
  SafeArrayAccessData( $apsa[0], $psaItemsData )
  SafeArrayAccessData( $apsa[1], $psaColorsData )

  ; Pass data to compiled code
  DllCall( $hDll, "none", "PassData", "hwnd", $hListView, "int", $iCols, "ptr", $psaItemsData, "ptr", $psaColorsData  )

  ; Register WM_NOTIFY message handler
  Local $pMsgHandler = _WinAPI_GetProcAddress( $hModule, "MsgHandler" )
  DllCall( "comctl32.dll", "bool", "SetWindowSubclass", "hwnd", $hGui, "ptr", $pMsgHandler, "uint_ptr", 0, "dword_ptr", 0 ) ; $iSubclassId = 0, $pData = 0

  ; Set number of rows in virtual ListView
  GUICtrlSendMsg( $idListView, $LVM_SETITEMCOUNT, $iRows, 0 )

  ; Adjust height of GUI and ListView to fit 30 rows
  Local $iLvHeight = _GUICtrlListView_GetHeightToFitRows( $idListView, 30 )
  WinMove( $hGui, "", Default, Default, Default, WinGetPos( $hGui )[3] - WinGetClientSize( $hGui )[1] + $iLvHeight + 20 )
  WinMove( GUICtrlGetHandle( $idListView ), "", Default, Default, Default, $iLvHeight )

  ; Show GUI
  GUISetState( @SW_SHOW )

  ; Message loop
  While 1
    Switch GUIGetMsg()
      Case $GUI_EVENT_RESTORE
        ; Adjust height of GUI and ListView to fit 30 rows
        $iLvHeight = _GUICtrlListView_GetHeightToFitRows( $idListView, 30 )
        WinMove( $hGui, "", Default, Default, Default, WinGetPos( $hGui )[3] - WinGetClientSize( $hGui )[1] + $iLvHeight + 20 )
        WinMove( GUICtrlGetHandle( $idListView ), "", Default, Default, Default, $iLvHeight )

      Case $GUI_EVENT_CLOSE
        ExitLoop
    EndSwitch
  WEnd

  ; Cleanup
  DllCall( "comctl32.dll", "bool", "RemoveWindowSubclass", "hwnd", $hGui, "ptr", $pMsgHandler, "uint_ptr", 0 ) ; $iSubclassId = 0
  SafeArrayUnaccessData( $apsa[0] )
  SafeArrayUnaccessData( $apsa[1] )
  _WinAPI_FreeLibrary( $hModule )
  DllClose( $hDLL )
  GUIDelete()
EndFunc

Func SafeArrays( $pvItems, $pvColors )
  SafeArrayCopy( DllStructGetData( DllStructCreate( "ptr", $pvItems  + 8 ), 1 ), $apsa[0] )
  SafeArrayCopy( DllStructGetData( DllStructCreate( "ptr", $pvColors + 8 ), 1 ), $apsa[1] )
EndFunc

C/C++ code in Subclass.cpp:

#include <Windows.h>
#include <CommCtrl.h>
#include <OleAuto.h>

// Globals
HWND      g_hListView;
int        g_iColumns;
VARIANT*  g_psaItems;
VARIANT*  g_psaColors;

void __stdcall PassData( HWND hListView, int iColumns, VARIANT* psaItems, VARIANT* psaColors ) {
  g_hListView = hListView;
  g_iColumns  = iColumns;
  g_psaItems  = psaItems;
  g_psaColors = psaColors;
}

LRESULT CALLBACK __stdcall MsgHandler( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData ) {
  if ( uMsg != WM_NOTIFY ) return DefSubclassProc( hWnd, uMsg, wParam, lParam );

  NMLVDISPINFOW*  plvdi;
  NMLVCUSTOMDRAW* plvcd;
  BSTR            pBstr;
  DWORD_PTR        iItem;
  RECT            r;
  HBRUSH          hBrush;

  switch ( ((LPNMHDR)lParam)->code ) {
    case LVN_GETDISPINFOW:
      // Fill virtual listview
      plvdi = (NMLVDISPINFOW*)lParam;
      if ( ( plvdi->item.mask & LVIF_TEXT ) == 0 ) return TRUE;
      pBstr = g_psaItems[plvdi->item.iItem*g_iColumns+plvdi->item.iSubItem].bstrVal;
      plvdi->item.pszText = pBstr; plvdi->item.cchTextMax = SysStringLen( pBstr );
      return TRUE;

    case NM_CUSTOMDRAW:
      // Draw back colors
      plvcd = (NMLVCUSTOMDRAW*)lParam;
      switch ( plvcd->nmcd.dwDrawStage ) {
        case CDDS_PREPAINT:
          return CDRF_NOTIFYITEMDRAW;
        case CDDS_ITEMPREPAINT:
          return CDRF_NOTIFYSUBITEMDRAW;
        case CDDS_ITEMPREPAINT | CDDS_SUBITEM:
          iItem = plvcd->nmcd.dwItemSpec;
          if ( SendMessageW( g_hListView, LVM_GETITEMSTATE, iItem, LVIS_SELECTED ) ) return CDRF_NOTIFYPOSTPAINT;
          plvcd->clrTextBk = g_psaColors[iItem*g_iColumns+plvcd->iSubItem].intVal;
          return CDRF_NEWFONT;
        case CDDS_ITEMPOSTPAINT | CDDS_SUBITEM:
          // Subitem rectangle
          iItem = plvcd->nmcd.dwItemSpec;
          r.left = LVIR_LABEL; r.top = plvcd->iSubItem;
          SendMessageW( g_hListView, LVM_GETSUBITEMRECT, iItem, (LPARAM)&r );
          r.left += 2; r.right -= 2; r.top += 1; r.bottom -= 1;
          // Subitem back color
          hBrush = CreateSolidBrush( g_psaColors[iItem*g_iColumns+plvcd->iSubItem].intVal );
          FillRect( plvcd->nmcd.hdc, &r, hBrush );
          DeleteObject( hBrush );
          // Draw subitem text
          SetTextColor( plvcd->nmcd.hdc, 0 );
          SetBkMode( plvcd->nmcd.hdc, TRANSPARENT );
          pBstr = g_psaItems[iItem*g_iColumns+plvcd->iSubItem].bstrVal; r.top += 1;
          DrawTextW( plvcd->nmcd.hdc, pBstr, SysStringLen( pBstr ), &r, DT_CENTER );
          return CDRF_NEWFONT;
      }
  }

  return DefSubclassProc( hWnd, uMsg, wParam, lParam );
}

Zip-file
ListView1.au3 is pure AutoIt code. In ListView2.au3 the WM_NOTIFY message handler is replaced with compiled code.

Note that the zip-file contains two small dll-files. If you are using Microsoft SmartScreen or Microsoft Windows Defender, there is a likelihood of fake virus detection, even if the dll-files are created with Microsoft Visual Studio. Most other antivirus products will not detect fake viruses.

You need AutoIt 3.3.12 or later. Tested on Windows 7 and Windows 10.

Comments are welcome. Let me know if there are any issues.

FastSubclassing.7z

Edited September 30, 2018 by LarsJ

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