Fixed Windows Spinbox sizing for now.

basicctrls_windows.c

@@ -161,5 +161,27 @@ void setGroupSubclass(HWND hwnd, void *data)
 		xpanic("error subclassing Group to give it its own event handler", GetLastError());
 }
 
-// provided for cgo's benefit
-LPWSTR xUPDOWN_CLASSW = UPDOWN_CLASSW;
+HWND newUpDown(HWND prevUpDown)
+{
+	HWND hwnd;
+	HWND parent;
+
+	parent = msgwin;		// for the first up-down
+	if (prevUpDown != NULL) {
+		parent = GetParent(prevUpDown);
+		if (parent == NULL)
+			xpanic("error getting parent of old up-down in Spinbox resize for new up-down", GetLastError());
+		if (DestroyWindow(prevUpDown) == 0)
+			xpanic("error destroying previous up-down in Spinbox resize", GetLastError());
+	}
+	hwnd = CreateWindowExW(0,
+		UPDOWN_CLASSW, L"",
+		// no WS_VISIBLE; we set visibility ourselves
+		WS_CHILD | UDS_ALIGNRIGHT | UDS_ARROWKEYS | UDS_HOTTRACK | UDS_NOTHOUSANDS | UDS_SETBUDDYINT,
+		// this is important; it's necessary for autosizing to work
+		0, 0, 0, 0,
+		parent, NULL, hInstance, NULL);
+	if (hwnd == NULL)
+		xpanic("error creating up-down control for Spinbox", GetLastError());
+	return hwnd;
+}

spinbox_windows.go

@@ -14,6 +14,8 @@ import "C"
 type spinbox struct {
 	hwndEdit			C.HWND
 	hwndUpDown		C.HWND
+	// updown state
+	updownVisible		bool
 }
 
 func newSpinbox() Spinbox {
@@ -21,12 +23,8 @@ func newSpinbox() Spinbox {
 	s.hwndEdit = C.newControl(editclass,
 		C.textfieldStyle | C.ES_NUMBER,
 		C.textfieldExtStyle)
-	s.hwndUpDown = C.newControl(C.xUPDOWN_CLASSW,
-		C.UDS_ALIGNRIGHT | C.UDS_ARROWKEYS | C.UDS_HOTTRACK | C.UDS_NOTHOUSANDS | C.UDS_SETBUDDYINT,
-		0)
-	C.SendMessageW(s.hwndUpDown, C.UDM_SETBUDDY, C.WPARAM(uintptr(unsafe.Pointer(s.hwndEdit))), 0)
-	C.SendMessageW(s.hwndUpDown, C.UDM_SETRANGE32, 0, 100)
-	C.SendMessageW(s.hwndUpDown, C.UDM_SETPOS32, 0, 0)
+	s.updownVisible = true		// initially shown
+	s.remakeUpDown()
 	return s
 }
 
@@ -35,6 +33,23 @@ func (s *spinbox) setParent(p *controlParent) {
 	C.controlSetParent(s.hwndUpDown, p.hwnd)
 }
 
+// an up-down control will only properly position itself the first time
+// stupidly, there are no messages to force a size calculation, nor can I seem to reset the buddy window to force a new position
+// alas, we have to make a new up/down control each time :(
+// TODO we'll need to store a copy of the current position and range for this
+func (s *spinbox) remakeUpDown() {
+	// destroying the previous one and setting the parent properly is handled here
+	s.hwndUpDown = C.newUpDown(s.hwndUpDown)
+	// for this to work, hwndUpDown needs to have rect [0 0 0 0]
+	C.moveWindow(s.hwndUpDown, 0, 0, 0, 0)
+	C.SendMessageW(s.hwndUpDown, C.UDM_SETBUDDY, C.WPARAM(uintptr(unsafe.Pointer(s.hwndEdit))), 0)
+	C.SendMessageW(s.hwndUpDown, C.UDM_SETRANGE32, 0, 100)
+	C.SendMessageW(s.hwndUpDown, C.UDM_SETPOS32, 0, 0)
+	if s.updownVisible {
+		C.ShowWindow(s.hwndUpDown, C.SW_SHOW)
+	}
+}
+
 func (s *spinbox) preferredSize(d *sizing) (width, height int) {
 	// TODO
 	return 20, 20
@@ -42,6 +57,7 @@ func (s *spinbox) preferredSize(d *sizing) (width, height int) {
 
 func (s *spinbox) resize(x int, y int, width int, height int, d *sizing) {
 	C.moveWindow(s.hwndEdit, C.int(x), C.int(y), C.int(width), C.int(height))
+	s.remakeUpDown()
 }
 
 func (s *spinbox) nTabStops() int {
@@ -53,10 +69,12 @@ func (s *spinbox) nTabStops() int {
 func (s *spinbox) containerShow() {
 	C.ShowWindow(s.hwndEdit, C.SW_SHOW)
 	C.ShowWindow(s.hwndUpDown, C.SW_SHOW)
+	s.updownVisible = true
 }
 
 // TODO be sure to modify this when we add Show()/Hide()
 func (s *spinbox) containerHide() {
 	C.ShowWindow(s.hwndEdit, C.SW_HIDE)
 	C.ShowWindow(s.hwndUpDown, C.SW_HIDE)
+	s.updownVisible = false
 }

winapi_windows.h

@@ -75,7 +75,7 @@ extern void setTextFieldSubclass(HWND, void *);
 extern void textfieldSetAndShowInvalidBalloonTip(HWND, WCHAR *);
 extern void textfieldHideInvalidBalloonTip(HWND);
 extern void setGroupSubclass(HWND, void *);
-extern LPWSTR xUPDOWN_CLASSW;
+extern HWND newUpDown(HWND);
 
 // init_windows.c
 extern HINSTANCE hInstance;