[VB.NET]使用Win32 API擷取滑鼠游標位置的顏色

要使用Win32 API擷取滑鼠游標位置的顏色,主要可分為三個步驟:

  1. 呼叫GetDC API取得畫布
  2. 呼叫GetPixel API取得畫布上指定位置的像素
  3. 呼叫ReleaseDC API釋放畫布

image

使用上可以直接透過下面整理過的函式:

    <DllImport(“User32.dll”, EntryPoint:=”GetDC”, 
CallingConvention:=CallingConvention.StdCall,

CharSet:=CharSet.Auto, exactspelling:=True)>
Public Shared Function GetDC(ByVal hwnd As IntPtr) As IntPtr
End Function
Public Declare Function GetPixel Lib “gdi32” Alias “GetPixel” (ByVal hdc As IntPtr, ByVal X As Int32, ByVal Y As Int32) As Int32
<DllImport(“user32.dll”)>

Private Shared Function ReleaseDC(ByVal hWnd As IntPtr, ByVal hDC As IntPtr) As Integer
End Function

Private Function GetColor() As Color
Return GetColor(Cursor.Position)
End Function

Private Function GetColor(ByVal point As Point) As Color
Return GetColor(point.X, point.Y)
End Function

Private Function GetColor(ByVal x As Integer, ByVal y As Integer) As Color
Dim hdc As IntPtr
hdc = GetDC(IntPtr.Zero) ‘取該Handle值的DC
GetColor = ColorTranslator.FromWin32(GetPixel(hdc, x, y))
ReleaseDC(IntPtr.Zero, hdc) ‘將DC 釋放
End Function


簡易範例如下:

Imports System.Runtime.InteropServices

Public Class Form1
<DllImport(“User32.dll”, EntryPoint:=”GetDC”,
CallingConvention:=CallingConvention.StdCall,

CharSet:=CharSet.Auto, exactspelling:=True)>
Public Shared Function GetDC(ByVal hwnd As IntPtr) As IntPtr
End Function
Public Declare Function GetPixel Lib “gdi32” Alias “GetPixel” (ByVal hdc As IntPtr, ByVal X As Int32, ByVal Y As Int32) As Int32
<DllImport(“user32.dll”)>

Private Shared Function ReleaseDC(ByVal hWnd As IntPtr, ByVal hDC As IntPtr) As Integer
End Function

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Dim x As Integer
Dim y As Integer
Dim p As Point = Cursor.Position
x = p.X
y = p.Y
Me.Text = “位置: x:” & x & “, y:” & y
lblColor.BackColor = GetColor()
lblWin32ColorCode.Text = ColorTranslator.ToWin32(lblColor.BackColor)
lblHtmlColorCode.Text = ColorTranslator.ToHtml(lblColor.BackColor)
lblOLEColorCode.Text = ColorTranslator.ToOle(lblColor.BackColor)
lblColorInfo.Text = lblColor.BackColor.ToString
End Sub

Private Function GetColor() As Color
Return GetColor(Cursor.Position)
End Function

Private Function GetColor(ByVal point As Point) As Color
Return GetColor(point.X, point.Y)
End Function

Private Function GetColor(ByVal x As Integer, ByVal y As Integer) As Color
Dim hdc As IntPtr
hdc = GetDC(IntPtr.Zero) ‘取該Handle值的DC
GetColor = ColorTranslator.FromWin32(GetPixel(hdc, x, y))
ReleaseDC(IntPtr.Zero, hdc) ‘將DC 釋放
End Function

End Class

運行結果:

image

Download

ColorPicker.zip