实现屏幕变暗的效果


		

	

        

 

 

　　想利用VB编程实现屏幕变暗的效果（象关闭Win95时的效果），只要按下面的步骤来做

1、在Form1中加入两个CommandButton和一个PictureBox.

2、在Form1的代码窗口中添加以下代码：

Private Type RECT

Left As Long

Top As Long

Right As Long

Bottom As Long

End Type

 

Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long

Private Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hdc As Long) As Long

Private Declare Function CreatePatternBrush Lib "gdi32" (ByVal hBitmap As Long) As Long

Private Declare Function PatBlt Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal dwRop As Long) As Long

Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long

Private Declare Function CreateBitmap Lib "gdi32" (ByVal nWidth As Long, ByVal nHeight As Long, ByVal nPlanes As Long, ByVal nBitCount As Long, lpBits As Any) As Long

Private Declare Function SelectObject Lib "gdi32" (ByVal hdc As Long, ByVal hObject As Long) As Long

Private Declare Function InvalidateRect Lib "user32" (ByVal hwnd As Long, ByVal lpRect As 

Long, ByVal bErase As Long) As Long

 

Private bybits(1 To 16) As Byte

Private hBitmap As Long, hBrush As Long

Private hDesktopWnd As Long

 

Private Sub Command1_Click()

Dim rop As Long, res As Long

Dim hdc5 As Long, width5 As Long, height5 As Long

 

hdc5 = GetDC(0)

width5 = Screen.Width  Screen.TwipsPerPixelX

height5 = Screen.Height  Screen.TwipsPerPixelY

 

rop = &HA000C9

Call SelectObject(hdc5, hBrush)

res = PatBlt(hdc5, 0, 0, width5, height5, rop)

Call DeleteObject(hBrush)

 

res = ReleaseDC(0, hdc5)

End Sub

 

Private Sub Command2_Click()

Dim aa As Long

 

aa = InvalidateRect(0, 0, 1)

End Sub

 

Private Sub Form_Load()

Dim ary

Dim i As Long

ary = Array(&H55, &H0, &HAA, &H0, &H55, &H0, &HAA, &H0, _

&H55, &H0, &HAA, &H0, &H55, &H0, &HAA, &H0)

For i = 1 To 16

bybits(i) = ary(i - 1)

Next i

hBitmap = CreateBitmap(8, 8, 1, 1, bybits(1))

hBrush = CreatePatternBrush(hBitmap)

Picture1.ForeColor = RGB(0, 0, 0)

Picture1.BackColor = RGB(255, 255, 255)

Picture1.ScaleMode = 3

End Sub

 

　　运行程序，按Command1就可以使屏幕暗下来，按Command2恢复。