半透明で完全に透明なWindowsフォームを使用できますか？

Question

私は真ん中の長方形で半透明の形を想像して、半透明であるが、そうより透明（または完全に透明、すなわち「見えない」）

というセクションを持つフォームをしたいのですがそれは完全に透明です（ちょっとドーナッツのような）

Answer 1

VB6の場合は、this thread from VBForumsをご覧ください。

は、便宜上、私はここにコードを貼り付けています

Option Explicit 
Private Declare Function CreateRectRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long 
Private Declare Function CombineRgn Lib "gdi32" (ByVal hDestRgn As Long, ByVal hSrcRgn1 As Long, ByVal hSrcRgn2 As Long, ByVal nCombineMode As Long) As Long 
Private Declare Function SetWindowRgn Lib "user32" (ByVal hWnd As Long, ByVal hRgn As Long, ByVal bRedraw As Long) As Long 
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long 
Private Sub Form_Resize() 
Const RGN_DIFF = 4 
Dim outer_rgn As Long 
Dim inner_rgn As Long 
Dim combined_rgn As Long 
Dim wid As Single 
Dim hgt As Single 
Dim border_width As Single 
Dim title_height As Single 
If WindowState = vbMinimized Then Exit Sub 

' Create the regions. 
wid = ScaleX(Width, vbTwips, vbPixels) 
hgt = ScaleY(Height, vbTwips, vbPixels) 
outer_rgn = CreateRectRgn(0, 0, wid, hgt) 

border_width = (wid - ScaleWidth)/2 
title_height = hgt - border_width - ScaleHeight 
inner_rgn = CreateRectRgn(_ 
    wid * 0.25, hgt * 0.25, _ 
    wid * 0.75, hgt * 0.75) 
' Subtract the inner region from the outer. 
combined_rgn = CreateRectRgn(0, 0, 0, 0) 
CombineRgn combined_rgn, outer_rgn, _ 
    inner_rgn, RGN_DIFF 

' Restrict the window to the region. 
SetWindowRgn hWnd, combined_rgn, True 
DeleteObject combined_rgn 
DeleteObject inner_rgn 
DeleteObject outer_rgn 
End Sub