用VB编写一个屏幕颜色拾取器

设计状态下窗口中添加两个Frame控件做为容器，加入二个PictureBox控件，一个PictureClip控件（其中装入一个设计好的鼠标指针Mask图片），两个文本框控件，几个Label控件，两个Command控件，一个CheckBox控件。



代码如下：

Option Explicit

Private Declare Function GetWindowDC Lib "user32" (ByVal hWnd As Long) As Long
Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Declare Function StretchBlt Lib "gdi32" (ByVal hDC As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal Height As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal nSrcWidth As Long, ByVal nSrcHeight As Long, ByVal dwRop As Long) As Long
Private Declare Function GetPixel Lib "gdi32" (ByVal hDC As Long, ByVal X As Long, ByVal Y As Long) As Long
Private Declare Sub SetWindowPos Lib "user32" (ByVal hWnd As Long, ByVal hWndInsertAfter As Long, ByVal X As Long, ByVal Y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long)
Private Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer

Private Const HWND_TOPMOST = -1
Private Const HWND_NOTOPMOST = -2
Private Const SWP_NOSIZE = &H1
Private Const SWP_NOMOVE = &H2
Private Const SWP_NOACTIVATE = &H10
Private Const SWP_SHOWWINDOW = &H40

Private Type POINTAPI
X As Long
Y As Long
End Type

Private Const SRCCOPY = &HCC0020
Private Const SRCAND = &H8800C6
Private Const SRCPAINT = &HEE0086

Dim MousePos As POINTAPI
Dim oldMousePos As POINTAPI

Private Sub Check1_Click()
'设置顶层窗口
If Check1.Value = 1 Then
SetWindowPos Me.hWnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOACTIVATE Or SWP_SHOWWINDOW Or SWP_NOMOVE Or SWP_NOSIZE
Else
SetWindowPos Me.hWnd, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOACTIVATE Or SWP_SHOWWINDOW Or SWP_NOMOVE Or SWP_NOSIZE
End If
End Sub

Private Sub Command1_Click()
'开始停止捕捉屏幕
If Command1.Caption = "停止" Then
Command1.Caption = "开始"
Timer1.Enabled = False
Else
Command1.Caption = "停止"
Timer1.Enabled = True
End If
End Sub

Private Sub Command2_Click()
'退出程序
Unload Me
End Sub

Private Sub Form_Activate()
'程序启动后自动设置顶层窗口
Check1.Value = 1
End Sub

Private Sub Timer1_Timer()
Dim WindowDC As Long
Dim Color As Long
Dim r As Integer, b As Integer, g As Integer
GetCursorPos MousePos '获取鼠标当前坐标
'If MousePos.X = oldMousePos.X And MousePos.Y = oldMousePos.Y Then Exit Sub '若未移动则返回
Frame1.Caption = "坐标(" & MousePos.X & "," & MousePos.Y & ")"
oldMousePos = MousePos
WindowDC = GetWindowDC(0) '获取屏幕的设备场景
Color = GetPixel(WindowDC, MousePos.X, MousePos.Y) '获取鼠标所指点的颜色
'分解RGB颜色值
r = (Color Mod 256)
b = (Int(Color \ 65536))
g = ((Color - (b * 65536) - r) \ 256)
Label1.BackColor = RGB(r, g, b)
Text1.Text = r & "," & g & "," & b
Text2.Text = WebColor(r, g, b)
'将以鼠标位置为中心的9*9的屏幕图像放大
StretchBlt Picture1.hDC, 0, 0, 73, 73, WindowDC, MousePos.X - 4, MousePos.Y - 4, 9, 9, SRCCOPY
'将一个鼠标指针用Mask的方法透明的画到放大的图像中
Picture2.Picture = PictureClip1.GraphicCell(1)
BitBlt Picture1.hDC, 37, 37, 12, 21, Picture2.hDC, 0, 0, SRCAND
Picture2.Picture = PictureClip1.GraphicCell(0)
BitBlt Picture1.hDC, 37, 37, 12, 21, Picture2.hDC, 0, 0, SRCPAINT
'获得是否按了热键F12
If GetAsyncKeyState(vbKeyF12) <> 0 Then
Timer1.Enabled = False
Command1.Caption = "开始"
End If
End Sub

Private Function WebColor(r As Integer, g As Integer, b As Integer) As String
'将10进制RGB值转为Web颜色值
WebColor = "#" & INT2HEX(r) & INT2HEX(g) & INT2HEX(b)
End Function

Private Function INT2HEX(Value As Integer) As String
'10进制转16进制
INT2HEX = Hex(Value)
If Len(INT2HEX) = 1 Then
INT2HEX = "0" & INT2HEX
End If
End Function

……