function sendMessage(hwnd, msg, wparam, lparam) : integer
Sends a Windows message to a window.
This function is a low-level helper. It expects that you already know the target window handle, the message id, and the meaning of the wParam and lParam values for the message you are sending.
The message ids are Windows message constants. They are not specific to Cheat Engine.
Function Parameters
| Parameter
|
Type
|
Description
|
| hwnd
|
Integer
|
The window handle that should receive the message.
|
| msg
|
Integer
|
The Windows message id to send.
|
| wparam
|
Integer
|
The wParam value for the message.
|
| lparam
|
Integer
|
The lParam value for the message.
|
Returns
Integer — The result returned by the message handler.
Common Windows Message IDs
| Constant
|
Value
|
Description
|
| WM_NULL
|
0x0000
|
Does nothing.
|
| WM_CREATE
|
0x0001
|
Sent when a window is being created.
|
| WM_DESTROY
|
0x0002
|
Sent when a window is being destroyed.
|
| WM_MOVE
|
0x0003
|
Sent after a window has been moved.
|
| WM_SIZE
|
0x0005
|
Sent after a window size has changed.
|
| WM_ACTIVATE
|
0x0006
|
Sent when a window is activated or deactivated.
|
| WM_SETFOCUS
|
0x0007
|
Sent when a window receives keyboard focus.
|
| WM_KILLFOCUS
|
0x0008
|
Sent when a window loses keyboard focus.
|
| WM_ENABLE
|
0x000A
|
Sent when a window is enabled or disabled.
|
| WM_SETREDRAW
|
0x000B
|
Enables or disables redrawing of a window.
|
| WM_SETTEXT
|
0x000C
|
Sets the text of a window or control.
|
| WM_GETTEXT
|
0x000D
|
Gets the text of a window or control.
|
| WM_GETTEXTLENGTH
|
0x000E
|
Gets the length of the text of a window or control.
|
| WM_PAINT
|
0x000F
|
Requests that a window paints itself.
|
| WM_CLOSE
|
0x0010
|
Requests that a window closes.
|
| WM_SHOWWINDOW
|
0x0018
|
Sent when a window is shown or hidden.
|
| WM_SETCURSOR
|
0x0020
|
Sent when the cursor is set for a window.
|
| WM_NOTIFY
|
0x004E
|
Sent by common controls to notify their parent window.
|
| WM_KEYDOWN
|
0x0100
|
Sent when a key is pressed.
|
| WM_KEYUP
|
0x0101
|
Sent when a key is released.
|
| WM_CHAR
|
0x0102
|
Sent when a character input is generated.
|
| WM_COMMAND
|
0x0111
|
Sent when a menu item, accelerator, or control notification is triggered.
|
| WM_SYSCOMMAND
|
0x0112
|
Sent when a system command is requested.
|
| WM_TIMER
|
0x0113
|
Sent when a timer expires.
|
| WM_HSCROLL
|
0x0114
|
Sent when a horizontal scroll event occurs.
|
| WM_VSCROLL
|
0x0115
|
Sent when a vertical scroll event occurs.
|
| WM_MOUSEMOVE
|
0x0200
|
Sent when the mouse moves over a window.
|
| WM_LBUTTONDOWN
|
0x0201
|
Sent when the left mouse button is pressed.
|
| WM_LBUTTONUP
|
0x0202
|
Sent when the left mouse button is released.
|
| WM_RBUTTONDOWN
|
0x0204
|
Sent when the right mouse button is pressed.
|
| WM_RBUTTONUP
|
0x0205
|
Sent when the right mouse button is released.
|
Common Control Message IDs
| Constant
|
Value
|
Description
|
| BM_CLICK
|
0x00F5
|
Simulates a button click.
|
| EM_SETSEL
|
0x00B1
|
Sets the selection range in an edit control.
|
| EM_REPLACESEL
|
0x00C2
|
Replaces the current selection in an edit control.
|
| CB_ADDSTRING
|
0x0143
|
Adds a string to a combo box.
|
| CB_GETCURSEL
|
0x0147
|
Gets the selected item index of a combo box.
|
| CB_SETCURSEL
|
0x014E
|
Sets the selected item index of a combo box.
|
| LB_ADDSTRING
|
0x0180
|
Adds a string to a list box.
|
| LB_GETCURSEL
|
0x0188
|
Gets the selected item index of a list box.
|
| LB_SETCURSEL
|
0x0186
|
Sets the selected item index of a list box.
|
Examples
local form = createForm()
form.Caption = "sendMessage Example"
form.show()
local hwnd = form.Handle
sendMessage(hwnd, 0x0007, 0, 0) -- WM_SETFOCUS
local form = createForm()
form.Caption = "Close Example"
form.show()
local hwnd = form.Handle
sendMessage(hwnd, 0x0010, 0, 0) -- WM_CLOSE
local form = createForm()
local button = createButton(form)
button.Parent = form
button.Caption = "Click me"
button.OnClick = function(sender)
print("Button clicked")
end
form.show()
sendMessage(button.Handle, 0x00F5, 0, 0) -- BM_CLICK
Notes
- The msg parameter is a Windows message id.
- wParam and lParam depend entirely on the specific message.
- Some messages require pointers, buffers, handles, or packed coordinate values.
- Do not assume that wParam and lParam are always plain integers.
- Prefer Cheat Engine's class properties and methods when they exist.
- sendMessage is mainly useful for advanced Windows GUI interaction.
Core Lua documentation entry points
