1 files changed, 234 insertions, 0 deletions
diff --git a/prevlib/stdwndclass_windows.go b/prevlib/stdwndclass_windows.go
new file mode 100644
index 0000000..f6dd395
--- /dev/null
+++ b/prevlib/stdwndclass_windows.go
@@ -0,0 +1,234 @@
+// 8 february 2014
+
+package ui
+
+import (
+	"fmt"
+	"syscall"
+	"unsafe"
+)
+
+var (
+	stdWndClass = toUTF16("gouiwnd")
+)
+
+var (
+	_defWindowProc = user32.NewProc("DefWindowProcW")
+)
+
+func defWindowProc(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRESULT {
+	r1, _, _ := _defWindowProc.Call(
+		uintptr(hwnd),
+		uintptr(uMsg),
+		uintptr(wParam),
+		uintptr(lParam))
+	return _LRESULT(r1)
+}
+
+// don't worry about error returns from GetWindowLongPtr()/SetWindowLongPtr()
+// see comments of http://blogs.msdn.com/b/oldnewthing/archive/2014/02/03/10496248.aspx
+
+func getWindowLongPtr(hwnd _HWND, what uintptr) uintptr {
+	r1, _, _ := _getWindowLongPtr.Call(
+		uintptr(hwnd),
+		what)
+	return r1
+}
+
+func setWindowLongPtr(hwnd _HWND, what uintptr, value uintptr) {
+	_setWindowLongPtr.Call(
+		uintptr(hwnd),
+		what,
+		value)
+}
+
+// we can store a pointer in extra space provided by Windows
+// we'll store sysData there
+// see http://blogs.msdn.com/b/oldnewthing/archive/2005/03/03/384285.aspx
+
+func getSysData(hwnd _HWND) *sysData {
+	return (*sysData)(unsafe.Pointer(getWindowLongPtr(hwnd, negConst(_GWLP_USERDATA))))
+}
+
+func storeSysData(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRESULT {
+	// we can get the lpParam from CreateWindowEx() in WM_NCCREATE and WM_CREATE
+	// we can freely skip any messages that come prior
+	// see http://blogs.msdn.com/b/oldnewthing/archive/2005/04/22/410773.aspx and http://blogs.msdn.com/b/oldnewthing/archive/2014/02/03/10496248.aspx (note the date on the latter one!)
+	if uMsg == _WM_NCCREATE {
+		// the lpParam to CreateWindowEx() is the first uintptr of the CREATESTRUCT
+		// so rather than create that whole structure, we'll just grab the uintptr at the address pointed to by lParam
+		cs := (*uintptr)(unsafe.Pointer(lParam))
+		saddr := *cs
+		setWindowLongPtr(hwnd, negConst(_GWLP_USERDATA), saddr)
+		// also set s.hwnd here so it can be used by other window messages right away
+		s := (*sysData)(unsafe.Pointer(saddr))
+		s.hwnd = hwnd
+	}
+	// then regardless of what happens, defer to DefWindowProc() (if you trace the execution of the above links, this is what they do)
+	return defWindowProc(hwnd, uMsg, wParam, lParam)
+}
+
+var (
+	_getFocus = user32.NewProc("GetFocus")
+	_isChild  = user32.NewProc("IsChild")
+	// _setFocus in area_windows.go
+)
+
+// this is needed to ensure focus is preserved when switching away from and back to our program
+// from http://blogs.msdn.com/b/oldnewthing/archive/2014/05/21/10527168.aspx
+func (s *sysData) handleFocus(wParam _WPARAM) {
+	// parameter splitting from Microsoft's windowsx.h
+	state := uint32(wParam.LOWORD()) // originally UINT
+	minimized := wParam.HIWORD() != 0
+
+	if minimized { // don't do anything on minimize
+		return
+	}
+	if state == _WA_INACTIVE { // focusing out
+		old, _, _ := _getFocus.Call()
+		if _HWND(old) != _HWND(_NULL) { // if there is one
+			r1, _, _ := _isChild.Call(
+				uintptr(s.hwnd),
+				old)
+			if r1 != 0 {
+				s.lastfocus = _HWND(old)
+			}
+		}
+	} else { // focusing in
+		if s.lastfocus != _HWND(_NULL) { // if we have one
+			// don't bother checking SetFocus()'s error; see http://stackoverflow.com/questions/24073695/winapi-can-setfocus-return-null-without-an-error-because-thats-what-im-see/24074912#24074912
+			_setFocus.Call(uintptr(s.lastfocus))
+		}
+	}
+}
+
+func stdWndProc(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRESULT {
+	s := getSysData(hwnd)
+	if s == nil { // not yet saved
+		return storeSysData(hwnd, uMsg, wParam, lParam)
+	}
+	switch uMsg {
+	case _WM_COMMAND:
+		id := _HMENU(wParam.LOWORD())
+		s.childrenLock.Lock()
+		ss := s.children[id]
+		s.childrenLock.Unlock()
+		switch ss.ctype {
+		case c_button:
+			if wParam.HIWORD() == _BN_CLICKED {
+				ss.event()
+			}
+		case c_checkbox:
+			// we opt into doing this ourselves because http://blogs.msdn.com/b/oldnewthing/archive/2014/05/22/10527522.aspx
+			if wParam.HIWORD() == _BN_CLICKED {
+				state, _, _ := _sendMessage.Call(
+					uintptr(ss.hwnd),
+					uintptr(_BM_GETCHECK),
+					uintptr(0),
+					uintptr(0))
+				if state == _BST_CHECKED {
+					state = _BST_UNCHECKED
+				} else if state == _BST_UNCHECKED {
+					state = _BST_CHECKED
+				}
+				_sendMessage.Call(
+					uintptr(ss.hwnd),
+					uintptr(_BM_SETCHECK),
+					state, // already uintptr
+					uintptr(0))
+			}
+		}
+		return 0
+	case _WM_ACTIVATE:
+		s.handleFocus(wParam)
+		return 0
+	case _WM_GETMINMAXINFO:
+		mm := lParam.MINMAXINFO()
+		// ... minimum size
+		_ = mm
+		return 0
+	case _WM_SIZE:
+		if s.allocate != nil {
+			var r _RECT
+
+			r1, _, err := _getClientRect.Call(
+				uintptr(hwnd),
+				uintptr(unsafe.Pointer(&r)))
+			if r1 == 0 {
+				panic("GetClientRect failed: " + err.Error())
+			}
+			// top-left corner of a client rect is always (0,0) so no need for left/top
+			s.resizeWindow(int(r.right), int(r.bottom))
+			// TODO use the Defer movement functions here?
+			// TODO redraw window and all children here?
+		}
+		return 0
+	case _WM_CLOSE:
+		if s.close() {
+			// TODO destroy
+			s.hide()
+		}
+		return 0
+	default:
+		return defWindowProc(hwnd, uMsg, wParam, lParam)
+	}
+	panic(fmt.Sprintf("stdWndProc message %d did not return: internal bug in ui library", uMsg))
+}
+
+type _WNDCLASS struct {
+	style         uint32
+	lpfnWndProc   uintptr
+	cbClsExtra    int32 // originally int
+	cbWndExtra    int32 // originally int
+	hInstance     _HANDLE
+	hIcon         _HANDLE
+	hCursor       _HANDLE
+	hbrBackground _HBRUSH
+	lpszMenuName  *uint16
+	lpszClassName uintptr
+}
+
+var (
+	icon, cursor _HANDLE
+)
+
+var (
+	_registerClass = user32.NewProc("RegisterClassW")
+)
+
+func registerStdWndClass() (err error) {
+	wc := &_WNDCLASS{
+		lpszClassName: utf16ToArg(stdWndClass),
+		lpfnWndProc:   syscall.NewCallback(stdWndProc),
+		hInstance:     hInstance,
+		hIcon:         icon,
+		hCursor:       cursor,
+		hbrBackground: _HBRUSH(_COLOR_BTNFACE + 1),
+	}
+	r1, _, err := _registerClass.Call(uintptr(unsafe.Pointer(wc)))
+	if r1 == 0 { // failure
+		return err
+	}
+	return nil
+}
+
+// no need to use/recreate MAKEINTRESOURCE() here as the Windows constant generator already took care of that because Microsoft's headers do already
+func initWndClassInfo() (err error) {
+	r1, _, err := user32.NewProc("LoadIconW").Call(
+		uintptr(_NULL),
+		uintptr(_IDI_APPLICATION))
+	if r1 == 0 { // failure
+		return fmt.Errorf("error getting window icon: %v", err)
+	}
+	icon = _HANDLE(r1)
+
+	r1, _, err = user32.NewProc("LoadCursorW").Call(
+		uintptr(_NULL),
+		uintptr(_IDC_ARROW))
+	if r1 == 0 { // failure
+		return fmt.Errorf("error getting window cursor: %v", err)
+	}
+	cursor = _HANDLE(r1)
+
+	return nil
+}