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   <TITLE>Start a program hidden</TITLE>

   <META NAME="Author" CONTENT="Harold Howe">

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<H3>

Start a program hidden<BR>

</H3>

<BR>

<P>

To start a program hidden, you must edit the <TT>WinMain</TT> function and hide the program's main form and the

program's taskbar icon.

</P>

<B>Step 1:</B> Choose View|Project Source from the C++Builder menu so you

can edit the <TT>WinMain</TT> function. Hide the program's taskbar icon by

calling <TT>ShowWindow</TT> for the application's window handle. Set <TT>ShowMainForm</TT> to

<TT>false</TT> to keep the main form from appearing on the screen.

</P>

<pre>

WINAPI WinMain<b>(</b>HINSTANCE<b>,</b> HINSTANCE<b>,</b> LPSTR<b>,</b> <b>int</b><b>)</b>

<b>{</b>

    <b>try</b>

    <b>{</b>

        Application<b>-></b>Initialize<b>(</b><b>)</b><b>;</b>

        Application<b>-></b>CreateForm<b>(</b><b>__classid</b><b>(</b>TForm1<b>)</b><b>,</b> <b>&</b>Form1<b>)</b><b>;</b>

        Application<b>-></b>ShowMainForm <b>=</b> <b>false</b><b>;</b>

        ShowWindow<b>(</b>Application<b>-></b>Handle<b>,</b> SW_HIDE<b>)</b><b>;</b>

        Application<b>-></b>Run<b>(</b><b>)</b><b>;</b>

    <b>}</b>

    <b>catch</b> <b>(</b>Exception <b>&</b>exception<b>)</b>

    <b>{</b>

        Application<b>-></b>ShowException<b>(</b><b>&</b>exception<b>)</b><b>;</b>

    <b>}</b>

    <b>return</b> <font color="blue">0</font><b>;</b>

<b>}</b>

</pre>



<P>

<B>Step 2:</B> Execute these two code statements when you want to show the 

application. Note that <TT>Application-&gt;MainForm-&gt;Visible=true</TT> can be 

shortened to just <TT>Visible=true</TT> if the code is located in a method 

of the main form's class.

</P>

<pre>

ShowWindow<b>(</b>Application<b>-></b>Handle<b>,</b> SW_SHOW<b>)</b><b>;</b>

Application<b>-></b>MainForm<b>-></b>Visible <b>=</b> <b>true</b><b>;</b>

</pre>



<BR>

<p>

<B>Final Note</B> (C++Builder 1.0 only): In C++Builder 1.0, the constructor for the global

<TT>TApplication</TT> object called the <TT>CreateHandle</TT> method. <TT>CreateHandle</TT> executed API

functions to create a window handle for the application. Creating the window handle resulted in a taskbar icon

appearing on the screen. This icon would appear before <TT>WinMain</TT> ran. This icon would appear to flash if

<TT>WinMain</TT> was trying to create a program that started in a hidden state. The rest of this FAQ explains how to

eliminate the taskbar icon flash that occurred in C++Builder 1.0 programs. C++Builder 3.0 contained a fix for the

shortcoming in <TT>TApplication</TT>. If you use C++Builder 3.0, ignore what follows.</P>



<P>

Because of the way the VCL works, the application's icon will flash briefly on the

taskbar before the <TT>ShowWindow</TT> call executes inside of <TT>WinMain</TT>.

</P>

<P>

The VCL creates the global application object before <TT>WinMain</TT> is called. The

<TT>TApplication</TT> constructor executes a function called <TT>CreateHandle</TT> that creates

a window handle and places an icon on the taskbar. The only way to keep the

icon from flashing is to provide a different version of

<TT>CreateHandle</TT>. This isn't too hard if you have the professional

or client/server versions of C++Builder. You can simply copy

<TT>\SOURCE\VCL\FORMS.PAS</TT> to your project directory, add this file to your

project, and fix the flaws in <TT>CreateHandle</TT>. <TT>CreateHandle</TT> contains two statements

that force an icon to appear on the taskbar.

The first is the <TT>CreateWindow</TT> call, which looks like this:

</P>

<PRE>

    FHandle := CreateWindow(WindowClass.lpszClassName, PChar(FTitle),

      WS_POPUP or WS_CAPTION or WS_VISIBLE or WS_CLIPSIBLINGS or

      WS_SYSMENU or WS_MINIMIZEBOX,

      GetSystemMetrics(SM_CXSCREEN) div 2,

      GetSystemMetrics(SM_CYSCREEN) div 2,

      0, 0, 0, 0, HInstance, nil);

</PRE>

<P>

The second call is the call to <TT>ShowWinNoAnimate</TT>. <TT>ShowWinNoAnimate</TT> is a

VCL function whose arguments reflect a <TT>ShowWindow</TT> API call.

</P>

<PRE>

    ShowWinNoAnimate(FHandle, SW_RESTORE);

</PRE>

<P>

In the <TT>CreateWindow</TT> call, the <TT>WS_VISIBLE</TT> style causes the taskbar icon

to appear. You can fix this by simply deleting the <TT>WS_VISIBLE</TT> style.

The <TT>ShowWinNoAnimate</TT> call ends up passing <TT>SW_RESTORE</TT> to the API <TT>ShowWindow</TT>

function. <TT>SW_RESTORE</TT> shows and restores a window, and showing the form

places the icon on the taskbar. You can prevent this by changing

<TT>SW_RESTORE</TT> to <TT>SW_HIDE</TT>, or by commenting out the call altogether. The

new version of <TT>CreateHandle</TT> should look like this:

</P>

<PRE>

    procedure TApplication.CreateHandle;

    var

      TempClass: TWndClass;

      SysMenu: HMenu;

    begin

      if not FHandleCreated then

      begin

        FObjectInstance := MakeObjectInstance(WndProc);

        if not GetClassInfo(HInstance, WindowClass.lpszClassName, TempClass)

        then

        begin

          WindowClass.hInstance := HInstance;

          if Windows.RegisterClass(WindowClass) = 0 then

            raise EOutOfResources.CreateRes(SWindowClass);

        end;

        FHandle := CreateWindow(WindowClass.lpszClassName, PChar(FTitle),

          WS_POPUP or WS_CAPTION or WS_CLIPSIBLINGS or

          WS_SYSMENU or WS_MINIMIZEBOX,

          GetSystemMetrics(SM_CXSCREEN) div 2,

          GetSystemMetrics(SM_CYSCREEN) div 2,

          0, 0, 0, 0, HInstance, nil);

        FTitle := '';

        FHandleCreated := True;

        ShowWinNoAnimate(FHandle, SW_HIDE);

        SetWindowLong(FHandle, GWL_WNDPROC, Longint(FObjectInstance));

        if NewStyleControls then

          SendMessage(FHandle, WM_SETICON, 1, GetIconHandle);

        SysMenu := GetSystemMenu(FHandle, False);

        DeleteMenu(SysMenu, SC_MAXIMIZE, MF_BYCOMMAND);

        DeleteMenu(SysMenu, SC_SIZE, MF_BYCOMMAND);

        if NewStyleControls then DeleteMenu(SysMenu, SC_MOVE, MF_BYCOMMAND);

      end;

    end;

</PRE>

<P>

<B>Important:</B> Make sure you modify the version of <TT>FORMS.PAS</TT> that you

copied to your project directory and added to your project. Do not

modify the file in <TT>\SOURCE\VCL</TT>.

</P>

<P>

So what if you have the standard version of C++Builder and don't have access

to the VCL source? You can code your own version of <TT>TApplication::CreateHandle</TT>

in your project source file using C++. The linker will utilize your updated

version of the function instead of the function in the VCL library files. The

C++ function should look like this (insert this just before the <TT>WinMain</TT>

function).

<pre>

<b>void</b> <b>__fastcall</b> TApplication<b>:</b><b>:</b>CreateHandle<b>(</b><b>void</b><b>)</b>

<b>{</b>

    WNDCLASS WindowClass <b>;</b>

    WindowClass<b>.</b>style<b>=</b><font color="blue">0</font><b>;</b>

    WindowClass<b>.</b>lpfnWndProc<b>=</b>DefWindowProc<b>;</b>

    WindowClass<b>.</b>cbClsExtra<b>=</b><font color="blue">0</font><b>;</b>

    WindowClass<b>.</b>cbWndExtra<b>=</b><font color="blue">0</font><b>;</b>

    WindowClass<b>.</b>hInstance <b>=</b><font color="blue">0</font><b>;</b>

    WindowClass<b>.</b>hIcon<b>=</b> <font color="blue">0</font><b>;</b>

    WindowClass<b>.</b>hCursor<b>=</b> <font color="blue">0</font><b>;</b>

    WindowClass<b>.</b>hbrBackground<b>=</b> <font color="blue">0</font><b>;</b>

    WindowClass<b>.</b>lpszMenuName <b>=</b> NULL<b>;</b>

    WindowClass<b>.</b>lpszClassName<b>=</b> <font color="blue">"TApplication"</font><b>;</b>



    TWndClass TempClass<b>;</b>

    HMENU     SysMenu<b>;</b>



    <b>if</b><b>(</b><b>!</b>FHandleCreated<b>)</b>

    <b>{</b>

        FObjectInstance <b>=</b> MakeObjectInstance<b>(</b>WndProc<b>)</b><b>;</b>

        <b>if</b> <b>(</b><b>!</b>GetClassInfo<b>(</b>HInstance<b>,</b> WindowClass<b>.</b>lpszClassName<b>,</b> <b>&</b>TempClass<b>)</b><b>)</b>

        <b>{</b>

            WindowClass<b>.</b>hInstance <b>=</b> HInstance<b>;</b>

            <b>if</b> <b>(</b>RegisterClass<b>(</b><b>&</b>WindowClass<b>)</b> <b>==</b> <font color="blue">0</font><b>)</b>

                <b>throw</b> EOutOfResources<b>(</b><font color="blue">"Error registering window class"</font><b>)</b><b>;</b>

        <b>}</b>

        FHandle <b>=</b> CreateWindow<b>(</b>WindowClass<b>.</b>lpszClassName<b>,</b> FTitle<b>.</b>c_str<b>(</b><b>)</b><b>,</b>

                               WS_POPUP <b>|</b> WS_CAPTION <b>|</b> WS_CLIPSIBLINGS <b>|</b>

                               WS_SYSMENU <b>|</b> WS_MINIMIZEBOX<b>,</b>

                               GetSystemMetrics<b>(</b>SM_CXSCREEN<b>)</b> <b>/</b> <font color="blue">2</font><b>,</b>

                               GetSystemMetrics<b>(</b>SM_CYSCREEN<b>)</b> <b>/</b> <font color="blue">2</font><b>,</b>

                               <font color="blue">0</font><b>,</b> <font color="blue">0</font><b>,</b> <font color="blue">0</font><b>,</b> <font color="blue">0</font><b>,</b> HInstance<b>,</b> NULL<b>)</b><b>;</b>

        FTitle <b>=</b> <font color="blue">""</font><b>;</b>

        FHandleCreated <b>=</b> True<b>;</b>

        <font color="navy">// ShowWinNoAnimate(FHandle, SW_HIDE);</font>

        SetWindowLong<b>(</b>FHandle<b>,</b> GWL_WNDPROC<b>,</b> Longint<b>(</b>FObjectInstance<b>)</b><b>)</b><b>;</b>

        <b>if</b> <b>(</b>NewStyleControls<b>)</b>

            SendMessage<b>(</b>FHandle<b>,</b> WM_SETICON<b>,</b> <font color="blue">1</font><b>,</b> <b>(</b>LPARAM<b>)</b>GetIconHandle<b>(</b><b>)</b><b>)</b><b>;</b>

        SysMenu <b>=</b> GetSystemMenu<b>(</b>FHandle<b>,</b> False<b>)</b><b>;</b>

        DeleteMenu<b>(</b>SysMenu<b>,</b> SC_MAXIMIZE<b>,</b> MF_BYCOMMAND<b>)</b><b>;</b>

        DeleteMenu<b>(</b>SysMenu<b>,</b> SC_SIZE<b>,</b> MF_BYCOMMAND<b>)</b><b>;</b>

        <b>if</b> <b>(</b>NewStyleControls<b>)</b>

            DeleteMenu<b>(</b>SysMenu<b>,</b> SC_MOVE<b>,</b> MF_BYCOMMAND<b>)</b><b>;</b>

    <b>}</b>

<b>}</b>



</pre>



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