LIB-PM-ColorWheel

Version 1.2 of the OS/2 PM ColorWheel color-picker dialog library by Alessandro Cantatore. Wraps the undocumented OS/2 ColorSelectClass control from WPCONFIG.DLL into a ready-to-use modal dialog with R/G/B spin buttons.

Features

• Modal "Edit Color" dialog built around the OS/2 Workplace Shell color wheel control
• R, G, B spin buttons (0–255) stay in sync with the wheel
• OK / Undo / Cancel buttons; Close button and system-menu Close behave like Cancel
• Live color-change notifications to the owner window via WM_COLORWHEELCHANGED
• Caller-supplied dialog title (defaults to "Edit Color")
• Supports OS/2 Warp 3 and Warp 4 (selects the correct undocumented message numbers at runtime)

API

LONG APIENTRY WinEditColorDlg(
    HWND  hwndParent,   /* parent window — dialog centers over this */
    HWND  hwndOwner,    /* owner — receives WM_COLORWHEELCHANGED    */
    COLOR color,        /* initial RGB color (LONG)                 */
    PSZ   pszTitle      /* dialog title; NULL -> "Edit Color"       */
);

Returns the selected RGB color as a LONG, or CLR_ERROR on failure.

Notifications

While the dialog is open the owner window receives:

Message	mp1	mp2
WM_COLORWHEELCHANGED (0x0601)	new LONG RGB color	MPVOID

(On Warp 3 the message number is 0x130C instead.)

See h/editcol.h for the full constant and structure reference.

Runtime Requirements

• EDITCOL.DLL must be in a directory listed in LIBPATH.
• WPCONFIG.DLL (part of the OS/2 Workplace Shell) must be present — it is loaded at dialog-open time to register the ColorSelectClass window class.

Using the Library in Your Project

1. Add h\ to your compiler's include path and #include <editcol.h>.
2. Link against lib\EDITCOL.LIB.
3. Ship EDITCOL.DLL with your application.

Open Watcom example

wcc386 -bt=os2 -bm -Ih myapp.c
wlink system os2v2_pm name myapp.exe file myapp.obj lib lib\EDITCOL.LIB option stack=65536

Building from Source

Run from the project root:

wmake -f Makefile.wat 2>&1 | tee compile.log

Outputs:

File	Description
dll\EDITCOL.DLL	Rebuilt DLL
lib\EDITCOL.LIB	Import library (generated by wlink)
sample\TEST.EXE	Test application

The build produces zero errors and zero warnings with Open Watcom 2.0.

Sample Program

Click any mouse button on the client window to open the "Edit Color" dialog. The window background updates live as you drag the color wheel, and the title bar shows the current RGB values. After dismissing, the title bar shows the returned color for 5 seconds before reverting to the window title.

File Layout

Makefile.wat         Open Watcom 2.0 build file (run from project root)
README.md            This file
readme.TXT           Original distribution readme (v1.1)
file_id.diz          BBS description

dll\
  EDITCOL.DLL        Rebuilt dialog DLL

lib\
  EDITCOL.LIB        Import library for EDITCOL.DLL

h\
  editcol.h          Public header — WinEditColorDlg, CLR, constants

src\
  editcol.c          DLL implementation
  editcol.rc         Dialog resource template
  editcol.def        Original module definition (reference)
  editcol.mak        Original IBM VisualAge C++ makefile (reference)

sample\
  test.c             Sample PM application
  test.rc            Resource script (icon)
  test.ICO           Application icon
  test.mak           Original IBM VisualAge C++ makefile (reference)

License

BSD 3-Clause — see readme.TXT for the original terms.

Authors

• Alessandro Cantatore — original library (v1.0–1.1)
• Paul Ratcliffe — original color wheel concept

Open Watcom 2.0 port (v1.2, 2026)

Links

• Paul Ratcliffe's OS/2 page