OpenEuphoria

Re: Setting Icon....

• Posted by Daniel Berstein <daber at PAIR.COM> Feb 28, 1999
• 441 views

At 12:24 PM 28-02-1999 , you wrote:
>The Single window when its created is assign a default icon.
>I do not think you can change it on the fly. So you have to assign your
>own icon as the deault icon when you create it.
>
>But a MDI window I think can change the icon of any of its child
>by sending a message to it because it creates these child windows.
>So are trying to change a single window or a MDI window ?
>If its a single window use your ICON as the default when creating it.
>To change the MDI you have find out the correct message to send.

In fact the icon used in a window is defined on it's window class. You can
send a WM_SETICON message, but the message is only recognized on Win9x, not
NT. If you want to change it at runtime you need to get (or create) a new
icon handle and modify the window class with the SetClassLong() WinAPI
function. In the following code I use the LoadImage() API function to load
from file an icon. The ChangeWindowIcon modifies the small icon associated
with the window (GCL_HICONSM). The small icon is displayed on the left-top
corner of the window and in the taskbar. The large icon (GCL_HICON) is used
when switching task using ALT+TAB. I tested the code and worked fine (on NT
4.0). I modified window.exw (on %EUDIR%\DEMO\WIN32) to call
ChangeWindowIcon when creating the Window (WM_CREATE), tell me if it works
OK on other circumstances. Perhaps it requieres a repaint before displaying
the new icon.


--[CHANGEICON.EW]--
include dll.e

-- Class field offsets for GetClassLong()
global constant
GCL_MENUNAME = -8,                      -- Pointer to the menu name string
GCL_HBRBACKGROUND = -10,        -- Handle to the default background brush
GCL_HCURSOR = -12,                      -- Handle to the window class cursor

GCL_HICON = -14,                                -- Handle to the window class
icon
GCL_HMODULE = -16,                      -- Handle of the module that registered
the class
GCL_CBWNDEXTRA = -18,           -- Size of extra memory associated with each
--window
                                                                        of this class, in bytes.
GCL_CBCLSEXTRA = -20,           -- Size of the extra memory associated with this
--class,
                                                                        in bytes.
GCL_WNDPROC = -24,                      -- Pointer to the window procedure for
this class.
--If a
                                                                        developer replaces the window procedure
--using
                                                                        this index, it must conform to the window
--procedure callback definition as outlined in the
--RegisterClass function. This subclass will affect
--all
                                                                        windows subsequently created with this class.
--An
                                                                        application should not subclass a window created
--by
                                                                        another process.
GCL_STYLE = -26,                                -- 32-bit style bits for this
class
GCW_ATOM = -32,                         -- Atom that uniquely identifies this
class. This
--is the
                                                                        same atom returned by the RegisterClass
--and
                                                                        RegisterClassEx functions
GCL_HICONSM = -34                       --Handle to the window class small icon

-- LoadImage() constants
global constant
        IMAGE_BITMAP = 0,
        IMAGE_ICON = 1,
        IMAGE_CURSOR = 2,
        IMAGE_ENHMETAFILE = 3,

  LR_DEFAULTCOLOR = #0000,
  LR_MONOCHROME = #0001,
  LR_COLOR = #0002,
  LR_COPYRETURNORG = #0004,
  LR_COPYDELETEORG = #0008,
  LR_LOADFROMFILE = #0010,
  LR_LOADTRANSPARENT = #0020,
  LR_DEFAULTSIZE = #0040,
  LR_VGACOLOR = #0080,
  LR_LOADMAP3DCOLORS = #1000,
  LR_CREATEDIBSECTION = #2000,
  LR_COPYFROMRESOURCE = #4000,
  LR_SHARED = #8000

atom user32, ApiSetClassLong, ApiLoadImage

procedure init()
        user32 = open_dll("user32.dll")
        ApiSetClassLong = define_c_func(user32, "SetClassLongA", {C_INT, C_INT,
C_LONG}, C_LONG)
        ApiLoadImage = define_c_func(user32, "LoadImageA", {C_INT, C_POINTER,
C_UINT, C_INT, C_INT, C_UINT}, C_LONG)
end procedure

global function LoadImage(integer hinst, sequence name, integer utype,
integer cxDesired, integer cyDesired, integer fuLoad)
        atom lpszname
        lpszname = allocate_string(name)
return c_func(ApiLoadImage, {hinst, lpszname, utype, cxDesired,
        cyDesired,
fuLoad})
        free(lpszname)
end function

global function SetClassLong(integer hwnd, integer nIndex, integer NewVal)
        return c_func(ApiSetClassLong, {hwnd, nIndex, NewVal})
end function

global function ChangeWindowIcon(integer hwnd, sequence icon_file)
        integer hicon
        hicon = LoadImage(0, icon_file, IMAGE_ICON, 0, 0, LR_LOADFROMFILE)
        return SetClassLong(hwnd, GCL_HICONSM, hicon)
end

init()

--[TEST.EXW]--
include changeicon.ew

--TO DO: Create and populate window

-- hwnd = window handle
ChangeWindowIcon(hwnd, "path\\icon_file.ico")



Regards,
         Daniel  Berstein
         [daber at pair.com]