Option Explicit
Private Type RECT
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type
Private Declare Function LineTo Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long) As Long
Private Declare Function CreatePen Lib "gdi32" (ByVal nPenStyle As Long, ByVal nWidth As Long, ByVal crColor As Long) As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hdc As Long, ByVal hObject As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function GetDesktopWindow Lib "user32" () As Long
Private Declare Function GetWindowDC Lib "user32" (ByVal hWnd As Long) As Long
Private Declare Function MoveToEx Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal lpPoint As Long) As Long
Private Declare Function GetSystemMetrics Lib "user32" (ByVal nIndex As Long) As Long
Private Declare Function InvalidateRect Lib "user32" (ByVal hWnd As Long, lpRect As RECT, ByVal bErase As Long) As Long
Private Declare Function InvalidateRectBynum& Lib "user32" Alias "InvalidateRect" (ByVal hWnd As Long, ByVal lpRect As Long, ByVal bErase As Long)
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Const PS_SOLID = 0
Private Const WM_KEYDOWN = &H100
Private Sub Command1_Click()
Dim cx As Integer
Dim cy As Integer
Dim old As Long '存储旧画笔
Dim p As Long '存储新画笔
Dim a As Long '桌面句柄
Dim b As Long '桌面设备环境
cx = GetSystemMetrics(0)
cy = GetSystemMetrics(1)
a = GetDesktopWindow() '获得桌面句柄
b = GetWindowDC(a) '获得桌面设备环境
p = CreatePen(PS_SOLID, 3, vbRed) '创建画笔
old = SelectObject(b, p) '选择画笔
MoveToEx b, cx / 2, 0, 0 '设置起点坐标
LineTo b, cx / 2, cy '划竖线
MoveToEx b, 0, cy / 2, 0 '设置起点坐标
LineTo b, cx, cy / 2 '划线
SelectObject b, old '恢复画笔
DeleteObject p '删除创建的画笔
End Sub
Private Sub Timer1_Timer()
InvalidateRectBynum& GetDesktopWindow(), 0, True
End Sub
上面的代码是在屏幕中央画一个十字线。问题是刷新屏幕或者移动窗口就没了，要怎么改？
如何实现屏幕刷新即重绘时，不闪烁？
