Fix #30.

internal/win/kernel32.go

@@ -44,4 +44,6 @@ func GetSystemDirectory() (string, error) { return windows.GetSystemDirectory()
 //sys GenerateConsoleCtrlEvent(ctrlEvent uint32, processGroupId int) (err error) = kernel32.GenerateConsoleCtrlEvent
 //sys GetConsoleWindow() (ret HWND) = kernel32.GetConsoleWindow
 //sys GetModuleHandle(moduleName *uint16) (ret Handle, err error) = kernel32.GetModuleHandleW
+//sys GlobalAlloc(flags uint32, bytes uintptr) (ret Handle, err error) = kernel32.GlobalAlloc
+//sys GlobalFree(mem Handle) (err error) [failretval!=0] = kernel32.GlobalFree
 //sys ReleaseActCtx(actCtx Handle) = kernel32.ReleaseActCtx

internal/win/user32.go

@@ -281,30 +281,21 @@ func SendMessagePointer(wnd HWND, msg uint32, wparam uintptr, lparam unsafe.Poin
 	return
 }
 
-func GetDpiForWindow(wnd HWND) (ret int, err error) {
-	if err := procGetDpiForWindow.Find(); err != nil {
-		return 0, err
-	}
-	return getDpiForWindow(wnd), nil
-}
-
-func SetThreadDpiAwarenessContext(dpiContext uintptr) (ret uintptr, err error) {
-	if err := procSetThreadDpiAwarenessContext.Find(); err != nil {
-		return 0, err
-	}
-	return setThreadDpiAwarenessContext(dpiContext), nil
-}
-
 // https://docs.microsoft.com/en-us/windows/win32/winmsg/using-messages-and-message-queues
 func MessageLoop(wnd HWND) error {
+	msg, err := GlobalAlloc(0, unsafe.Sizeof(MSG{}))
+	if err != nil {
+		return err
+	}
+	defer GlobalFree(msg)
+
 	getMessage := procGetMessageW.Addr()
 	translateMessage := procTranslateMessage.Addr()
 	dispatchMessage := procDispatchMessageW.Addr()
 	isDialogMessage := procIsDialogMessageW.Addr()
 
 	for {
-		var msg MSG
+		s, _, err := syscall.Syscall6(getMessage, 4, uintptr(msg), 0, 0, 0, 0, 0)
-		s, _, err := syscall.Syscall6(getMessage, 4, uintptr(unsafe.Pointer(&msg)), 0, 0, 0, 0, 0)
 		if int32(s) == -1 {
 			return err
 		}
@@ -312,10 +303,10 @@ func MessageLoop(wnd HWND) error {
 			return nil
 		}
 
-		s, _, _ = syscall.Syscall(isDialogMessage, 2, uintptr(wnd), uintptr(unsafe.Pointer(&msg)), 0)
+		s, _, _ = syscall.Syscall(isDialogMessage, 2, uintptr(wnd), uintptr(msg), 0)
 		if s == 0 {
-			syscall.Syscall(translateMessage, 1, uintptr(unsafe.Pointer(&msg)), 0, 0)
+			syscall.Syscall(translateMessage, 1, uintptr(msg), 0, 0)
-			syscall.Syscall(dispatchMessage, 1, uintptr(unsafe.Pointer(&msg)), 0, 0)
+			syscall.Syscall(dispatchMessage, 1, uintptr(msg), 0, 0)
 		}
 	}
 }
@@ -398,8 +389,8 @@ type CWPRETSTRUCT struct {
 //sys EnableWindow(wnd HWND, enable bool) (ok bool) = user32.EnableWindow
 //sys EnumWindows(enumFunc uintptr, lparam unsafe.Pointer) (err error) = user32.EnumChildWindows
 //sys GetDlgItem(dlg HWND, dlgItemID int) (ret HWND, err error) = user32.GetDlgItem
-//sys getDpiForWindow(wnd HWND) (ret int) = user32.GetDpiForWindow
+//sys GetDpiForWindow(wnd HWND) (ret int, err error) [false] = user32.GetDpiForWindow?
-//sys GetMessage(msg *MSG, wnd HWND, msgFilterMin uint32, msgFilterMax uint32) (ret uintptr) = user32.GetMessageW
+//sys GetMessage(msg *MSG, wnd HWND, msgFilterMin uint32, msgFilterMax uint32) (ret uintptr, err error) [int32(failretval)==-1] = user32.GetMessageW
 //sys GetSystemMetrics(index int) (ret int) = user32.GetSystemMetrics
 //sys GetWindowDC(wnd HWND) (ret Handle) = user32.GetWindowDC
 //sys GetWindowRect(wnd HWND, cmdShow *RECT) (err error) = user32.GetWindowRect
@@ -415,7 +406,7 @@ type CWPRETSTRUCT struct {
 //sys SetDlgItemText(dlg HWND, dlgItemID int, str *uint16) (err error) = user32.SetDlgItemTextW
 //sys SetFocus(wnd HWND) (ret HWND, err error) = user32.SetFocus
 //sys SetForegroundWindow(wnd HWND) (ok bool) = user32.SetForegroundWindow
-//sys setThreadDpiAwarenessContext(dpiContext uintptr) (ret uintptr) = user32.SetThreadDpiAwarenessContext
+//sys SetThreadDpiAwarenessContext(dpiContext uintptr) (ret uintptr, err error) [false] = user32.SetThreadDpiAwarenessContext?
 //sys SetWindowLong(wnd HWND, index int, newLong int) (ret int, err error) = user32.SetWindowLongW
 //sys SetWindowPos(wnd HWND, wndInsertAfter HWND, x int, y int, cx int, cy int, flags int) (err error) = user32.SetWindowPos
 //sys SetWindowsHookEx(idHook int, fn uintptr, mod Handle, threadID uint32) (ret Handle, err error) = user32.SetWindowsHookExW

internal/win/zsyscall_windows.go

@@ -61,6 +61,8 @@ var (
 	procGenerateConsoleCtrlEvent     = modkernel32.NewProc("GenerateConsoleCtrlEvent")
 	procGetConsoleWindow             = modkernel32.NewProc("GetConsoleWindow")
 	procGetModuleHandleW             = modkernel32.NewProc("GetModuleHandleW")
+	procGlobalAlloc                  = modkernel32.NewProc("GlobalAlloc")
+	procGlobalFree                   = modkernel32.NewProc("GlobalFree")
 	procReleaseActCtx                = modkernel32.NewProc("ReleaseActCtx")
 	procCoCreateInstance             = modole32.NewProc("CoCreateInstance")
 	procSHBrowseForFolder            = modshell32.NewProc("SHBrowseForFolder")
@@ -203,6 +205,23 @@ func GetModuleHandle(moduleName *uint16) (ret Handle, err error) {
 	return
 }
 
+func GlobalAlloc(flags uint32, bytes uintptr) (ret Handle, err error) {
+	r0, _, e1 := syscall.Syscall(procGlobalAlloc.Addr(), 2, uintptr(flags), uintptr(bytes), 0)
+	ret = Handle(r0)
+	if ret == 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func GlobalFree(mem Handle) (err error) {
+	r1, _, e1 := syscall.Syscall(procGlobalFree.Addr(), 1, uintptr(mem), 0, 0)
+	if r1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
 func ReleaseActCtx(actCtx Handle) {
 	syscall.Syscall(procReleaseActCtx.Addr(), 1, uintptr(actCtx), 0, 0)
 	return
@@ -332,15 +351,25 @@ func GetDlgItem(dlg HWND, dlgItemID int) (ret HWND, err error) {
 	return
 }
 
-func getDpiForWindow(wnd HWND) (ret int) {
+func GetDpiForWindow(wnd HWND) (ret int, err error) {
-	r0, _, _ := syscall.Syscall(procGetDpiForWindow.Addr(), 1, uintptr(wnd), 0, 0)
+	err = procGetDpiForWindow.Find()
+	if err != nil {
+		return
+	}
+	r0, _, e1 := syscall.Syscall(procGetDpiForWindow.Addr(), 1, uintptr(wnd), 0, 0)
 	ret = int(r0)
+	if false {
+		err = errnoErr(e1)
+	}
 	return
 }
 
-func GetMessage(msg *MSG, wnd HWND, msgFilterMin uint32, msgFilterMax uint32) (ret uintptr) {
+func GetMessage(msg *MSG, wnd HWND, msgFilterMin uint32, msgFilterMax uint32) (ret uintptr, err error) {
-	r0, _, _ := syscall.Syscall6(procGetMessageW.Addr(), 4, uintptr(unsafe.Pointer(msg)), uintptr(wnd), uintptr(msgFilterMin), uintptr(msgFilterMax), 0, 0)
+	r0, _, e1 := syscall.Syscall6(procGetMessageW.Addr(), 4, uintptr(unsafe.Pointer(msg)), uintptr(wnd), uintptr(msgFilterMin), uintptr(msgFilterMax), 0, 0)
 	ret = uintptr(r0)
+	if int32(ret) == -1 {
+		err = errnoErr(e1)
+	}
 	return
 }
 
@@ -454,9 +483,16 @@ func SetForegroundWindow(wnd HWND) (ok bool) {
 	return
 }
 
-func setThreadDpiAwarenessContext(dpiContext uintptr) (ret uintptr) {
+func SetThreadDpiAwarenessContext(dpiContext uintptr) (ret uintptr, err error) {
-	r0, _, _ := syscall.Syscall(procSetThreadDpiAwarenessContext.Addr(), 1, uintptr(dpiContext), 0, 0)
+	err = procSetThreadDpiAwarenessContext.Find()
+	if err != nil {
+		return
+	}
+	r0, _, e1 := syscall.Syscall(procSetThreadDpiAwarenessContext.Addr(), 1, uintptr(dpiContext), 0, 0)
 	ret = uintptr(r0)
+	if false {
+		err = errnoErr(e1)
+	}
 	return
 }