func (sv *ScrollView) scroll(sb int32, cmd uint16) int {
var pos int32
var si win.SCROLLINFO
si.CbSize = uint32(unsafe.Sizeof(si))
si.FMask = win.SIF_PAGE | win.SIF_POS | win.SIF_RANGE | win.SIF_TRACKPOS
win.GetScrollInfo(sv.hWnd, sb, &si)
pos = si.NPos
switch cmd {
case win.SB_LINELEFT: // == win.SB_LINEUP
pos -= 20
case win.SB_LINERIGHT: // == win.SB_LINEDOWN
pos += 20
case win.SB_PAGELEFT: // == win.SB_PAGEUP
pos -= int32(si.NPage)
case win.SB_PAGERIGHT: // == win.SB_PAGEDOWN
pos += int32(si.NPage)
case win.SB_THUMBTRACK:
pos = si.NTrackPos
}
if pos < 0 {
pos = 0
}
if pos > si.NMax+1-int32(si.NPage) {
pos = si.NMax + 1 - int32(si.NPage)
}
si.FMask = win.SIF_POS
si.NPos = pos
win.SetScrollInfo(sv.hWnd, sb, &si, true)
return -int(pos)
}
