Added combo boxes and added some to the main window example.

comboboxes.go

@@ -0,0 +1,83 @@
+// 10 february 2014
+package main
+
+import (
+//	"syscall"
+//	"unsafe"
+)
+
+// Combobox styles.
+const (
+	// from winuser.h
+	CBS_SIMPLE = 0x0001
+	CBS_DROPDOWN = 0x0002
+	CBS_DROPDOWNLIST = 0x0003
+	CBS_OWNERDRAWFIXED = 0x0010
+	CBS_OWNERDRAWVARIABLE = 0x0020
+	CBS_AUTOHSCROLL = 0x0040
+	CBS_OEMCONVERT = 0x0080
+	CBS_SORT = 0x0100
+	CBS_HASSTRINGS = 0x0200
+	CBS_NOINTEGRALHEIGHT = 0x0400
+	CBS_DISABLENOSCROLL = 0x0800
+	CBS_UPPERCASE = 0x2000
+	CBS_LOWERCASE = 0x4000
+)
+
+// Combobox messages.
+// TODO filter out messages not provided in windows 2000
+const (
+	// from winuser.h
+	CB_GETEDITSEL = 0x0140
+	CB_LIMITTEXT = 0x0141
+	CB_SETEDITSEL = 0x0142
+	CB_ADDSTRING = 0x0143
+	CB_DELETESTRING = 0x0144
+	CB_DIR = 0x0145
+	CB_GETCOUNT = 0x0146
+	CB_GETCURSEL = 0x0147
+	CB_GETLBTEXT = 0x0148
+	CB_GETLBTEXTLEN = 0x0149
+	CB_INSERTSTRING = 0x014A
+	CB_RESETCONTENT = 0x014B
+	CB_FINDSTRING = 0x014C
+	CB_SELECTSTRING = 0x014D
+	CB_SETCURSEL = 0x014E
+	CB_SHOWDROPDOWN = 0x014F
+	CB_GETITEMDATA = 0x0150
+	CB_SETITEMDATA = 0x0151
+	CB_GETDROPPEDCONTROLRECT = 0x0152
+	CB_SETITEMHEIGHT = 0x0153
+	CB_GETITEMHEIGHT = 0x0154
+	CB_SETEXTENDEDUI = 0x0155
+	CB_GETEXTENDEDUI = 0x0156
+	CB_GETDROPPEDSTATE = 0x0157
+	CB_FINDSTRINGEXACT = 0x0158
+	CB_SETLOCALE = 0x0159
+	CB_GETLOCALE = 0x015A
+	CB_GETTOPINDEX = 0x015B
+	CB_SETTOPINDEX = 0x015C
+	CB_GETHORIZONTALEXTENT = 0x015D
+	CB_SETHORIZONTALEXTENT = 0x015E
+	CB_GETDROPPEDWIDTH = 0x015F
+	CB_SETDROPPEDWIDTH = 0x0160
+	CB_INITSTORAGE = 0x0161
+	CB_MULTIPLEADDSTRING = 0x0163
+	CB_GETCOMBOBOXINFO = 0x0164
+)
+
+// Combobox WM_COMMAND notificaitons.
+const (
+	// from winuser.h
+	CBN_ERRSPACE = (-1)		// TODO this will blow up the Go compiler if it's used
+	CBN_SELCHANGE = 1
+	CBN_DBLCLK = 2
+	CBN_SETFOCUS = 3
+	CBN_KILLFOCUS = 4
+	CBN_EDITCHANGE = 5
+	CBN_EDITUPDATE = 6
+	CBN_DROPDOWN = 7
+	CBN_CLOSEUP = 8
+	CBN_SELENDOK = 9
+	CBN_SELENDCANCEL = 10
+)

common.go

@@ -3,8 +3,11 @@ package main
 
 import (
 	"syscall"
+	"unsafe"
 )
 
+// TODO filter out commctrl.h stuff because the combobox stuff has values that differ between windows versions and bleh
+
 var (
 	user32 = syscall.NewLazyDLL("user32.dll")
 	kernel32 = syscall.NewLazyDLL("kernel32.dll")
@@ -37,7 +40,30 @@ func (w WPARAM) HIWORD() uint16 {
 	return uint16((w >> 16) & 0xFFFF)
 }
 
+func LPARAMFromString(str string) LPARAM {
+	return LPARAM(unsafe.Pointer(syscall.StringToUTF16Ptr(str)))
+}
+
 // microsoft's header files do this
 func MAKEINTRESOURCE(what uint16) uintptr {
 	return uintptr(what)
 }
+
+// TODO adorn error messages with which step failed?
+func getText(hwnd HWND) (text string, err error) {
+	var tc []uint16
+
+	length, err := SendMessage(hwnd, WM_GETTEXTLENGTH, 0, 0)
+	if err != nil {
+		return "", err
+	}
+	tc = make([]uint16, length + 1)
+	_, err = SendMessage(hwnd,
+		WM_GETTEXT,
+		WPARAM(length + 1),
+		LPARAM(unsafe.Pointer(&tc[0])))
+	if err != nil {
+		return "", err
+	}
+	return syscall.UTF16ToString(tc), nil
+}

main.go

@@ -21,17 +21,47 @@ func fatalf(format string, args ...interface{}) {
 
 const (
 	IDC_BUTTON = 100
+	IDC_VARCOMBO = 101
+	IDC_FIXCOMBO = 102
 )
 
+var varCombo, fixCombo HWND
+
 func wndProc(hwnd HWND, msg uint32, wParam WPARAM, lParam LPARAM) LRESULT {
 	switch msg {
 	case WM_COMMAND:
 		if wParam.LOWORD() == IDC_BUTTON {
+			buttonclick := "neither clicked nor double clicked (somehow)"
 			if wParam.HIWORD() == BN_CLICKED {
-				MessageBox(hwnd, "clicked", "", MB_OK)
+				buttonclick = "clicked"
 			} else if wParam.HIWORD() == BN_DOUBLECLICKED {
-				MessageBox(hwnd, "double clicked", "", MB_OK)
+				buttonclick = "double clicked"
 			}
+
+			varText, err := getText(varCombo)
+			if err != nil {
+				fatalf("error getting variable combo box text: %v", err)
+			}
+
+			fixTextWM, err := getText(fixCombo)
+			if err != nil {
+				fatalf("error getting fixed combo box text with WM_GETTEXT: %v", err)
+			}
+
+			fixTextIndex, err := SendMessage(fixCombo, CB_GETCURSEL, 0, 0)
+			if err != nil {
+				fatalf("error getting fixed combo box current selection: %v", err)
+			}
+			// TODO get text from index
+
+			MessageBox(hwnd,
+				fmt.Sprintf("button state: %s\n" +
+					"variable combo box text: %s\n" +
+					"fixed combo box text with WM_GETTEXT: %s\n" +
+					"fixed combo box current index: %d\n",
+					buttonclick, varText, fixTextWM, fixTextIndex),
+				"note",
+				MB_OK)
 		}
 		return 0
 	case WM_CLOSE:
@@ -103,12 +133,48 @@ func main() {
 		0,
 		"BUTTON", "Click Me",
 		BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_TABSTOP,
-		20, 20, 100, 100,
+		20, 20, 100, 20,
 		hwnd, HMENU(IDC_BUTTON), hInstance, NULL)
 	if err != nil {
 		fatalf("error creating button: %v", err)
 	}
 
+	varCombo, err = CreateWindowEx(
+		0,
+		"COMBOBOX", "",
+		CBS_DROPDOWN | CBS_AUTOHSCROLL | WS_CHILD | WS_VISIBLE | WS_TABSTOP,
+		140, 20, 100, 20,
+		hwnd, HMENU(IDC_VARCOMBO), hInstance, NULL)
+	if err != nil {
+		fatalf("error creating variable combo box: %v", err)
+	}
+	vcItems := []string{"a", "b", "c", "d"}
+	for _, v := range vcItems {
+		_, err := SendMessage(varCombo, CB_ADDSTRING, 0,
+			LPARAMFromString(v))
+		if err != nil {
+			fatalf("error adding %q to variable combo box: %v", v, err)
+		}
+	}
+
+	fixCombo, err = CreateWindowEx(
+		0,
+		"COMBOBOX", "",
+		CBS_DROPDOWNLIST | WS_CHILD | WS_VISIBLE | WS_TABSTOP,
+		140, 50, 100, 20,
+		hwnd, HMENU(IDC_FIXCOMBO), hInstance, NULL)
+	if err != nil {
+		fatalf("error creating fixed combo box: %v", err)
+	}
+	fcItems := []string{"e", "f", "g", "h"}
+	for _, v := range fcItems {
+		_, err := SendMessage(fixCombo, CB_ADDSTRING, 0,
+			LPARAMFromString(v))
+		if err != nil {
+			fatalf("error adding %q to fixed combo box: %v", v, err)
+		}
+	}
+
 	_, err = ShowWindow(hwnd, nCmdShow)
 	if err != nil {
 		fatalf("error showing window: %v", err)

messages.go

@@ -6,6 +6,11 @@ import (
 	"unsafe"
 )
 
+// SendMessage constants.
+const (
+	HWND_BROADCAST = HWND(0xFFFF)
+)
+
 type MSG struct {
 	Hwnd	HWND
 	Message	uint32
@@ -19,6 +24,7 @@ var (
 	dispatchMessage = user32.NewProc("DispatchMessageW")
 	getMessage = user32.NewProc("GetMessageW")
 	postQuitMessage = user32.NewProc("PostQuitMessage")
+	sendMessage = user32.NewProc("SendMessageW")
 	translateMessage = user32.NewProc("TranslateMessage")
 )
 
@@ -49,6 +55,16 @@ func PostQuitMessage(nExitCode int) (err error) {
 	return nil
 }
 
+// TODO handle errors
+func SendMessage(hWnd HWND, Msg uint32, wParam WPARAM, lParam LPARAM) (result LRESULT, err error) {
+	r1, _, _ := sendMessage.Call(
+		uintptr(hWnd),
+		uintptr(Msg),
+		uintptr(wParam),
+		uintptr(lParam))
+	return LRESULT(r1), nil
+}
+
 // TODO handle errors
 func TranslateMessage(lpMsg *MSG) (translated bool, err error) {
 	r1, _, _ := translateMessage.Call(uintptr(unsafe.Pointer(lpMsg)))