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// 15 july 2014
package ui
import (
"fmt"
"syscall"
"unsafe"
)
type widgetbase struct {
hwnd uintptr
}
var emptystr = syscall.StringToUTF16Ptr("")
func newWidget(class *uint16, style uintptr, extstyle uintptr) *widgetbase {
hwnd, err := f_CreateWindowExW(
extstyle,
class, emptystr,
style | c_WS_CHILD | c_WS_VISIBLE,
c_CW_USEDEFAULT, c_CW_USEDEFAULT,
// c_CW_USEDEFAULT, c_CW_USEDEFAULT,
100,100,
// the following has the consequence of making the control message-only at first
// this shouldn't cause any problems... hopefully not
// but see the msgwndproc() for caveat info
// also don't use low control IDs as they will conflict with dialog boxes (IDCANCEL, etc.)
msgwin, 100, hInstance, nil)
if hwnd == hNULL {
panic(fmt.Errorf("creating control of class %q failed: %v", class, err))
}
return &widgetbase{
hwnd: hwnd,
}
}
// these few methods are embedded by all the various Controls since they all will do the same thing
func (w *widgetbase) unparent() {
res, err := f_SetParent(w.hwnd, msgwin)
if res == hNULL { // result type is HWND
panic(fmt.Errorf("error unparenting control: %v", err))
}
}
func (w *widgetbase) parent(win *window) {
res, err := f_SetParent(w.hwnd, win.hwnd)
if res == hNULL { // result type is HWND
panic(fmt.Errorf("error parenting control: %v", err))
}
}
// don't embed these as exported; let each Control decide if it should
func (w *widgetbase) text() *Request {
c := make(chan interface{})
return &Request{
op: func() {
c <- getWindowText(w.hwnd)
},
resp: c,
}
}
func (w *widgetbase) settext(text string, results ...t_LRESULT) *Request {
c := make(chan interface{})
return &Request{
op: func() {
setWindowText(w.hwnd, text, append([]t_LRESULT{c_FALSE}, results...))
c <- struct{}{}
},
resp: c,
}
}
// all controls that have events receive the events themselves through subclasses
// to do this, all windows (including the message-only window; see http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q104069) forward WM_COMMAND to each control with this function
func forwardCommand(hwnd uintptr, uMsg t_UINT, wParam t_WPARAM, lParam t_LPARAM) t_LRESULT {
control := uintptr(lParam)
// don't generate an event if the control (if there is one) is unparented (a child of the message-only window)
if control != hNULL && f_IsChild(msgwin, control) == 0 {
return f_SendMessageW(control, msgCOMMAND, wParam, lParam)
}
return f_DefWindowProcW(hwnd, uMsg, wParam, lParam)
}
type button struct {
*widgetbase
clicked *event
}
var buttonclass = syscall.StringToUTF16Ptr("BUTTON")
func newButton(text string) *Request {
c := make(chan interface{})
return &Request{
op: func() {
w := newWidget(buttonclass,
c_BS_PUSHBUTTON | c_WS_TABSTOP,
0)
setWindowText(w.hwnd, text, []t_LRESULT{c_FALSE})
b := &button{
widgetbase: w,
clicked: newEvent(),
}
res, err := f_SetWindowSubclass(w.hwnd, buttonsubprocptr, 0, t_DWORD_PTR(uintptr(unsafe.Pointer(b))))
if res == c_FALSE {
panic(fmt.Errorf("error subclassing Button to give it its own event handler: %v", err))
}
c <- b
},
resp: c,
}
}
func (b *button) OnClicked(e func(c Doer)) *Request {
c := make(chan interface{})
return &Request{
op: func() {
b.clicked.set(e)
c <- struct{}{}
},
resp: c,
}
}
func (b *button) Text() *Request {
return b.text()
}
func (b *button) SetText(text string) *Request {
return b.settext(text)
}
var buttonsubprocptr uintptr
// to avoid recursive initialization loop
func init() {
buttonsubprocptr = syscall.NewCallback(buttonSubProc)
}
func buttonSubProc(hwnd uintptr, uMsg t_UINT, wParam t_WPARAM, lParam t_LPARAM, id t_UINT_PTR, data t_DWORD_PTR) t_LRESULT {
b := (*button)(unsafe.Pointer(uintptr(data)))
switch uMsg {
case msgCOMMAND:
if wParam.HIWORD() == c_BN_CLICKED {
b.clicked.fire()
println("button clicked")
return 0
}
return f_DefSubclassProc(hwnd, uMsg, wParam, lParam)
case c_WM_NCDESTROY:
res, err := f_RemoveWindowSubclass(b.hwnd, buttonsubprocptr, id)
if res == c_FALSE {
panic(fmt.Errorf("error removing Button subclass (which was for its own event handler): %v", err))
}
return f_DefSubclassProc(hwnd, uMsg, wParam, lParam)
default:
return f_DefSubclassProc(hwnd, uMsg, wParam, lParam)
}
panic(fmt.Errorf("Button message %d does not return a value (bug in buttonSubProc())", uMsg))
}
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