BCB中如何实现控件半透明

    下面以Button为例来实现 

    窗体半透明实现简单直接设置属性或者用api来设置层属性来实现，但一般控件设置层属性，却得不到半透明效果。实际上做一下小改动就可以了。

响应窗体的OnActivate事件，代码如下。

void __fastcall TForm1::FormActivate(TObject *Sender)
{
        long wsex = ::GetWindowLongPtr(Handle, GWL_EXSTYLE );
        wsex |= WS_EX_TOOLWINDOW ;
        wsex &= ~WS_EX_APPWINDOW;
        ::SetWindowLongPtr(Button1->Handle, GWL_EXSTYLE, wsex );
        ::SetParent(Button1->Handle ,GetDesktopWindow());
        SetWindowLong(Button1->Handle, GWL_EXSTYLE, GetWindowLong(Button1->Handle, GWL_EXSTYLE ) ^ WS_EX_LAYERED ^ WS_EX_TRANSPARENT );
        ::SetLayeredWindowAttributes(Button1->Handle, RGB( 0, 0, 0 ), 255 - 100, LWA_ALPHA );
        Button1->Refresh() ; // 一定要呼叫，否则失败
        ::SetParent(Button1->Handle,Form1->Handle);
        Button1->Repaint() ; // 一定要呼叫，否则失败
}

    半透明实现了，但发现button不响应事件了，实际上把button的消息也“透明”了。别急，语句换为

      SetWindowLong(Button1->Handle, GWL_EXSTYLE, GetWindowLong(Button1->Handle, GWL_EXSTYLE ) ^ WS_EX_LAYERED );

就好了。

   但依然存在一个问题就是窗体移动时，button不会跟着移动，这个好办添加WM_MOVE消息映射自己调整即可。

    全部源代码如下：

h文件

//---------------------------------------------------------------------------

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include
#include
#include
#include
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published: // IDE-managed Components
        TButton *Button1;
        void __fastcall FormActivate(TObject *Sender);
        void __fastcall Button1Click(TObject *Sender);
private: // User declarations
        void  __fastcall  CMMove(TMessage  &msg);    //消息接收处理函数
public:  // User declarations
        __fastcall TForm1(TComponent* Owner);
BEGIN_MESSAGE_MAP
    VCL_MESSAGE_HANDLER(WM_MOVE,TMessage,CMMove)
    //决定WM_MOVE消息交给CMMove  函数处理
END_MESSAGE_MAP(TForm)
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

cpp文件

#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------

void __fastcall TForm1::FormActivate(TObject *Sender)
{
        long wsex = ::GetWindowLongPtr(Handle, GWL_EXSTYLE );
        wsex |= WS_EX_TOOLWINDOW ;
        wsex &= ~WS_EX_APPWINDOW;
        ::SetWindowLongPtr(Button1->Handle, GWL_EXSTYLE, wsex );
        ::SetParent(Button1->Handle ,GetDesktopWindow());
        SetWindowLong(Button1->Handle, GWL_EXSTYLE, GetWindowLong(Button1->Handle, GWL_EXSTYLE ) ^ WS_EX_LAYERED ^ WS_EX_TRANSPARENT );
        ::SetLayeredWindowAttributes(Button1->Handle, RGB( 0, 0, 0 ), 255 - 100, LWA_ALPHA );
        Button1->Refresh() ; // 一定要呼叫，否则失败
        ::SetParent(Button1->Handle,Form1->Handle);
        Button1->Repaint() ; // 一定要呼叫，否则失败
}
//---------------------------------------------------------------------------
void  __fastcall  TForm1::CMMove(TMessage  &msg)   //消息接收处理函数
{
        this->Button1->Left=this->Left+0.33*this->Width;
        this->Button1->Top=this->Top+0.33*this->Height;
}
void __fastcall TForm1::Button1Click(TObject *Sender)
{
        ShowMessage("hao");
}
//---------------------------------------------------------------------------