Restructuring the codebase to make things neater. First off: each window now has its own class; the sysData knows about children. This updates the window class to become a generator and rewrites the WndProc as well.

init_windows.go

@@ -67,9 +67,9 @@ func doWindowsInit() (err error) {
 	if err != nil {
 		return fmt.Errorf("error getting WinMain nCmdShow: %v", err)
 	}
-	err = registerStdWndClass()
+	err = initWndClassInfo()
 	if err != nil {
-		return fmt.Errorf("error registering standard window class: %v", err)
+		return fmt.Errorf("error initializing standard window class auxiliary info: %v", err)
 	}
 	// TODO others
 	return nil		// all ready to go

stdwndclass_windows.go

@@ -5,29 +5,34 @@ import (
 	"fmt"
 	"syscall"
 	"unsafe"
+	"sync"
+)
+
+const (
+	stdWndClassFormat = "gouiwnd%X"
 )
 
 var (
-	stdWndClass = "gouiwndclass"
+	curWndClassNum uintptr
+	curWndClassNumLock sync.Mutex
 )
 
 var (
 	defWindowProc = user32.NewProc("DefWindowProcW")
 )
 
-func stdWndProc(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRESULT {
-	sysData := getSysData(hwnd)
-	if sysData == nil {	// not ready for events yet
-		goto defwndproc
-	}
+func stdWndProc(s *sysData) func(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRESULT {
+	return func(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRESULT {
 		switch uMsg {
 		case _WM_COMMAND:
 			id := _HMENU(wParam.LOWORD())
-		sysData = getSysDataID(id)
-		switch sysData.ctype {
+			s.childrenLock.Lock()
+			defer s.childrenLock.Unlock()
+			ss = s.children[id]
+			switch ss.ctype {
 			case c_button:
 				if wParam.HIWORD() == _BN_CLICKED {
-				sysData.clicked <- struct{}{}
+					sysData.event <- struct{}{}
 				}
 			}
 			return 0
@@ -45,16 +50,15 @@ func stdWndProc(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRESUL
 			}
 			return 0
 		default:
-		goto defwndproc
-	}
-	panic(fmt.Sprintf("stdWndProc message %d did not return: internal bug in ui library", uMsg))
-defwndproc:
 			r1, _, _ := defWindowProc.Call(
 				uintptr(hwnd),
 				uintptr(uMsg),
 				uintptr(wParam),
 				uintptr(lParam))
 			return _LRESULT(r1)
+		}
+		panic(fmt.Sprintf("stdWndProc message %d did not return: internal bug in ui library", uMsg))
+	}
 }
 
 type _WNDCLASS struct {
@@ -70,7 +74,37 @@ type _WNDCLASS struct {
 	lpszClassName		uintptr
 }
 
-func registerStdWndClass() (err error) {
+var (
+	icon, cursor _HANDLE
+)
+
+var (
+	_registerClass = user32.NewProc("RegisterClassW")
+)
+
+func registerStdWndClass(s *sysData) (newClassName string, err error) {
+	curWndClassNumLock.Lock()
+	newClassName = fmt.Sprintf(stdWndClassFormat, curWndClassNum)
+	curWndClassNum++
+	curWndClassNumLock.Unlock()
+
+	wc := &_WNDCLASS{
+		lpszClassName:	uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(newClassName))),
+		lpfnWndProc:		syscall.NewCallback(stdWndProc(s)),
+		hInstance:		hInstance,
+		hIcon:			icon,
+		hCursor:			cursor,
+		hbrBackground:	_HBRUSH(_COLOR_BTNFACE + 1),
+	}
+
+	r1, _, err = user32.NewProc("RegisterClassW").Call(uintptr(unsafe.Pointer(wc)))
+	if r1 == 0 {		// failure
+		return "", err
+	}
+	return newClassName, nil
+}
+
+func initWndClassInfo() (err error) {
 	const (
 		_IDI_APPLICATION = 32512
 		_IDC_ARROW = 32512
@@ -82,7 +116,7 @@ func registerStdWndClass() (err error) {
 	if r1 == 0 {		// failure
 		return fmt.Errorf("error getting window icon: %v", err)
 	}
-	icon := _HANDLE(r1)
+	icon = _HANDLE(r1)
 
 	r1, _, err = user32.NewProc("LoadCursorW").Call(
 		uintptr(_NULL),
@@ -90,20 +124,7 @@ func registerStdWndClass() (err error) {
 	if r1 == 0 {		// failure
 		return fmt.Errorf("error getting window cursor: %v", err)
 	}
-	cursor := _HANDLE(r1)
+	cursor = _HANDLE(r1)
 
-	wc := &_WNDCLASS{
-		lpszClassName:	uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(stdWndClass))),
-		lpfnWndProc:		syscall.NewCallback(stdWndProc),
-		hInstance:		hInstance,
-		hIcon:			icon,
-		hCursor:			cursor,
-		hbrBackground:	_HBRUSH(_COLOR_BTNFACE + 1),
-	}
-
-	r1, _, err = user32.NewProc("RegisterClassW").Call(uintptr(unsafe.Pointer(wc)))
-	if r1 == 0 {		// failure
-		return fmt.Errorf("error registering class: %v", err)
-	}
 	return nil
 }