unit winalloc;
{$mode delphi}{$ifndef win32}{$error This unit is for 32 bit Windows only}{$endif}
interface
uses windows, messages;
type
TWndMethod = procedure(var Message: TMessage) of object;
function MakeObjectInstance(Method: TWndMethod): Pointer;
procedure FreeObjectInstance(ObjectInstance: Pointer);
function AllocateHWnd(Method: TWndMethod): HWND;
procedure DeallocateHWnd(Wnd: HWND);
implementation
type
PObjectInstance = ^TObjectInstance;
TObjectInstance = packed record
Code: Byte;
Offset: Integer;
case Integer of
0: (Next: PObjectInstance);
1: (Method: TWndMethod);
end;
type
PInstanceBlock = ^TInstanceBlock;
TInstanceBlock = packed record
Next: PInstanceBlock;
Code: array[1..2] of Byte;
WndProcPtr: Pointer;
Instances: array[0..100] of TObjectInstance;
end;
var
InstBlockList: PInstanceBlock;
InstBlockCount: integer;
InstFreeList: PObjectInstance;
{ Standard window procedure }
{ In ECX = Address of method pointer }
{ Out EAX = Result }
function StdWndProc(Window: HWND; Message, WParam: Longint;
LParam: Longint): Longint; stdcall; assembler;
asm
XOR EAX,EAX
PUSH EAX
PUSH LParam
PUSH WParam
PUSH Message
MOV EDX,ESP
MOV EAX,[ECX].Longint[4]
CALL [ECX].Pointer
ADD ESP,12
POP EAX
end;
{ Allocate an object instance }
function CalcJmpOffset(Src, Dest: Pointer): Longint;
begin
Result := Longint(Dest) - (Longint(Src) + 5);
end;
function MakeObjectInstance(Method: TWndMethod): Pointer;
const
BlockCode: array[1..2] of Byte = (
$59, { POP ECX }
$E9); { JMP StdWndProc }
PageSize = 4096;
var
Block: PInstanceBlock;
Instance: PObjectInstance;
begin
if InstFreeList = nil then
begin
Block := VirtualAlloc(nil, PageSize, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
Block^.Next := InstBlockList;
Move(BlockCode, Block^.Code, SizeOf(BlockCode));
Block^.WndProcPtr := Pointer(CalcJmpOffset(@Block^.Code[2], @StdWndProc));
Instance := @Block^.Instances;
repeat
Instance^.Code := $E8; { CALL NEAR PTR Offset }
Instance^.Offset := CalcJmpOffset(Instance, @Block^.Code);
Instance^.Next := InstFreeList;
InstFreeList := Instance;
Inc(Longint(Instance), SizeOf(TObjectInstance));
until Longint(Instance) - Longint(Block) >= SizeOf(TInstanceBlock);
InstBlockList := Block;
end;
Result := InstFreeList;
Instance := InstFreeList;
InstFreeList := Instance^.Next;
Instance^.Method := Method;
inc(InstBlockCount);
end;
{ Free an object instance }
procedure FreeObjectInstance(ObjectInstance: Pointer);
begin
if (ObjectInstance <> nil) and (InstBlockCount > 0) then
begin
PObjectInstance(ObjectInstance)^.Next := InstFreeList;
InstFreeList := ObjectInstance;
Dec(InstBlockCount);
if InstBlockCount = 0 then begin
VirtualFree(InstBlockList, 0, MEM_RELEASE);
InstBlockList := nil;
ObjectInstance := nil;
end;
end;
end;
var
UtilWindowClass: TWndClass = (
style: 0;
lpfnWndProc: @DefWindowProc;
cbClsExtra: 0;
cbWndExtra: 0;
hInstance: 0;
hIcon: 0;
hCursor: 0;
hbrBackground: 0;
lpszMenuName: nil;
lpszClassName: 'KOLFakeUtilWindow');
function AllocateHWnd(Method: TWndMethod): HWND;
var
TempClass: TWndClass;
ClassRegistered: Boolean;
begin
UtilWindowClass.hInstance := HInstance;
ClassRegistered := GetClassInfo(HInstance, UtilWindowClass.lpszClassName,
TempClass);
if not ClassRegistered or (TempClass.lpfnWndProc <> @DefWindowProc) then
begin
if ClassRegistered then
Windows.UnregisterClass(UtilWindowClass.lpszClassName, HInstance);
Windows.RegisterClass(UtilWindowClass);
end;
Result := CreateWindowEx(WS_EX_TOOLWINDOW, UtilWindowClass.lpszClassName,
'', WS_POPUP {!0}, 0, 0, 0, 0, 0, 0, HInstance, nil);
if Assigned(Method) then
SetWindowLong(Result, GWL_WNDPROC, Longint(MakeObjectInstance(Method)));
end;
procedure DeallocateHWnd(Wnd: HWND);
var
Instance: Pointer;
begin
Instance := Pointer(GetWindowLong(Wnd, GWL_WNDPROC));
DestroyWindow(Wnd);
if Instance <> @DefWindowProc then FreeObjectInstance(Instance);
end;
end.