delphi - SendMessage 的问题（Delphi）

Question

我向外部程序发送消息：

SendMessage(Handle, WM_CHAR, Ord('A'), 0);

但我不知道如何在另一个程序中收到此消息？（使用 WndProc 或类似的东西）有人可以为我解释一下吗？

谢谢

Answer 1

Read How to send and handle a custom Windows message

Untested Code:

const

  WM_REFRESHSOMETHING = WM_USER + 6;

On the Form which should catch the Message you need something like:

...
procedure WMRefreshsomething(var ppbMsg : TMessage); message WM_REFRESHSOMETHING;
...

procedure YourForm.WMRefreshsomething(var ppbMsg : TMessage);
begin
  //Actions...
end;

And then you can send a message like:

SendMessageToAll(Handle, WM_REFRESHSOMETHING, 0, 0);

To all Forms which have the message WM_REFRESHSOMETHING;

See this compilable Example

Answer 2

我在一系列程序中使用以下代码；一个程序启动程序，当每个程序完成时，它们会向启动器发送一条消息，表明它们已完成。该程序的关键是使用 HWND_BROADCAST 参数：消息被发送到计算机上所有正在运行的程序，但当然它只由具有正确消息处理程序的人处理。在必须发送消息的程序中，写

SendMessage (HWND_BROADCAST, RegisterWindowMessage ('message'), 0, 0);

显然，您可以用某个字符串替换“消息”，该字符串在两个程序中都是常量（发送的和接收的）。

我不推荐使用 SendMessage 的 lparam 参数来将数据传递给接收程序；这应该是一个指针，当然程序1中指向数据的指针将指向程序2中的垃圾。可以将longint转换为指针并发送它，然后必须在接收端取消引用

在接收程序中，

type
 TWMMYMessage = record
 Msg: Cardinal;   // ( first is the message ID )
 Handle: HWND;    // ( this is the wParam, Handle of sender)
 Info: Longint;   // ( this is lParam, pointer to our data)
 Result: Longint;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 wm_Launcher:= RegisterWindowMessage ('message')  
 // wm_launcher is a private member of TForm
 .
 .
 .
end;

procedure TForm1.DefaultHandler(var Message);
var
 ee: TWMMYMessage;

begin
 with TMessage (Message) do
  begin
   if (Msg = wm_Launcher) then
    begin
     ee.Msg:= Msg;
     ee.Handle:= wParam;
     ee.Info:= lParam;
     // Checking if this message is not from us
     if ee.Handle <> Handle then WmMyMessage(ee);
    end
   else inherited DefaultHandler(Message);
  end;
end;

procedure TForm1.WmMyMessage(var Msg: TWMMYMessage);
begin
 startbtnclick (nil)   // here we actually do something when the message is received
end;