;setting window transparency example by carlos hernandez/coconut

format PE GUI 4.0
entry start

ID_SCROLLBAR = 1000
ID_STATIC = 1001

include '%fasminc%\win32w.inc'

section '.data' data readable writeable

  _class TCHAR 'FASMWIN32',0
  _title TCHAR 'Layered window example',0
  _error TCHAR 'Startup failed.',0
  _scrollbar TCHAR 'scrollbar',0
  _static TCHAR 'static',0
  _conv TCHAR '%i',0

  hwndstatic dd ?
  hwndscroll dd ?

  buffer rb 32

  wc WNDCLASS 0,WindowProc,0,0,NULL,NULL,NULL,COLOR_BTNFACE+1,NULL,_class

  lpsi SCROLLINFO sizeof.SCROLLINFO,SIF_ALL,5,255,1,255,0

  msg MSG

section '.code' code readable executable

  start:
	invoke	GetModuleHandle,0
	mov	[wc.hInstance],eax
	invoke	LoadIcon,0,IDI_APPLICATION
	mov	[wc.hIcon],eax
	invoke	LoadCursor,0,IDC_ARROW
	mov	[wc.hCursor],eax
	invoke	RegisterClass,wc
	or	eax,eax
	jz	error
	invoke	CreateWindowEx,WS_EX_LAYERED,_class,_title,WS_VISIBLE+WS_SYSMENU,128,128,256,192,NULL,NULL,[wc.hInstance],NULL
	test	eax,eax
	jz	error
  msg_loop:
	invoke	GetMessage,msg,NULL,0,0
	or	eax,eax
	jz	end_loop
	invoke	TranslateMessage,msg
	invoke	DispatchMessage,msg
	jmp	msg_loop
  error:
	invoke	MessageBox,NULL,_error,NULL,MB_ICONERROR+MB_OK
  end_loop:
	invoke	ExitProcess,[msg.wParam]

proc WindowProc hwnd,wmsg,wparam,lparam
	push	ebx esi edi
	cmp	[wmsg],WM_HSCROLL
	je	wmhscroll
	cmp	[wmsg],WM_CREATE
	je	wmcreate
	cmp	[wmsg],WM_DESTROY
	je	wmdestroy
  defwndproc:
	invoke	DefWindowProc,[hwnd],[wmsg],[wparam],[lparam]
	jmp	finish
  wmhscroll:
	mov	eax,[wparam]
	cmp	ax,SB_THUMBPOSITION			 ;received when thumb stops dragging
	je	thumbposition
	cmp	ax,SB_THUMBTRACK			 ;received while thumb is dragging
	je	thumbposition
	cmp	ax,SB_LINELEFT				 ;left arrow clicked
	je	lineleft
	cmp	ax,SB_LINERIGHT 			 ;right arrow clicked
	je	lineright
	cmp	ax,SB_PAGELEFT				 ;left space between arrow and thumb clicked
	je	pageleft
	cmp	ax,SB_PAGERIGHT 			 ;right space between arrow and thumb clicked
	je	pageright
	jmp	defwndproc
  thumbposition:					 ;for our purposes we'll handle both drag/stop events here
	mov	[lpsi.fMask],SIF_TRACKPOS
	invoke	GetScrollInfo,[hwndscroll],SB_CTL,lpsi
	push	[lpsi.nTrackPos]
	pop	[lpsi.nPos]
	mov	[lpsi.fMask],SIF_ALL
	jmp	update_window
  lineleft:
	cmp	[lpsi.nPos],6				;transparency under 5 will make window invisible/useless
	jb	defwndproc
	dec	[lpsi.nPos]
	jmp	update_window
  lineright:
	cmp	[lpsi.nPos],254 			;transparency over 255 will make window invisible/useless
	jg	defwndproc
	inc	[lpsi.nPos]
	jmp	update_window
  pageleft:
	mov	eax,[lpsi.nPage]
	sub	[lpsi.nPos],eax
	jmp	update_window
  pageright:
	mov	eax,[lpsi.nPage]
	add	[lpsi.nPos],eax
  update_window:
	mov	ecx,[lpsi.nPos]
	push	ecx
	cinvoke wsprintf,buffer,_conv,ecx
	invoke	SendMessage,[hwndstatic],WM_SETTEXT,0,buffer
	pop	ecx
	invoke	SetLayeredWindowAttributes,[hwnd],0,ecx,LWA_ALPHA
	invoke	SetScrollInfo,[hwndscroll],SB_CTL,lpsi,1
	xor	eax,eax
	jmp	finish
  wmcreate:							    ;x,y,width,height
	invoke	CreateWindowEx,0,_static,_title,WS_VISIBLE+WS_CHILD,25,20,195,25,[hwnd],ID_STATIC,[wc.hInstance],NULL
	mov	[hwndstatic],eax
	invoke	CreateWindowEx,0,_scrollbar,NULL,WS_VISIBLE+WS_CHILD+SBS_HORZ,25,55,195,15,[hwnd],ID_SCROLLBAR,[wc.hInstance],NULL
	mov	[hwndscroll],eax
	invoke	SetScrollInfo,[hwndscroll],SB_CTL,lpsi,0
	invoke	SetLayeredWindowAttributes,[hwnd],0,255,LWA_ALPHA
	xor	eax,eax
	jmp	finish
  wmdestroy:
	invoke	PostQuitMessage,0
	xor	eax,eax
  finish:
	pop	edi esi ebx
	ret
endp

section '.idata' import data readable writeable

  library kernel32,'KERNEL32.DLL',\
	  user32,'USER32.DLL'

  include '%fasminc%\api\kernel32.inc'
  include '%fasminc%\api\user32.inc'