Sheng Jiang 蒋晟

Note: Windows Forms programming in new development is discouraged by Microsoft at this point as Microsoft wants to make full use of hardware accelerated drawing instead of using the CPU-intensive GDI. But maintaining old Windows Forms code in Visual C++ 2012 is still supported, GDI isn’t going anywhere anytime soon.

Visual C++ 2012 removed the Windows Forms project template and I see people scramble to find ways to create a Windows Forms project.  There is a walkaround that’s been around for years, that is, to convert a CLR console application to a Windows one, then add forms related code to the project.

The basic steps are listed at http://support.microsoft.com/kb/317433, conveniently named “How to suppress the console window for a managed extensions to Visual C++ Windows Forms application“. Yes, the need to convert a C++ console application to windows forms is that old, back all the way back in the managed extensions for C++  days.

So what I need to do to add Windows Forms support to a C++/CLI console application? Of course the System.Windows.Forms.dll reference is missing in a new console application, so I need to reference it:

• In code:

#using <System.dll>
#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>

using namespace System::Windows::Forms;

• Or In IDE:
  • Select the project in Solution Explorer
  • On the Project menu or the context menu of the project node, select Properties
  • In the Property Pages dialog box, expand the Common Properties node, select Framework and References, and then click Add New Reference.
  • Find and add System.Windows.Forms in the list of available references.

In reality the Windows Forms Designer generates a lot of layout code that uses System.Drawing types like Point and Size, so I need to repeat the steps for System.Drawing.

Next the console window needs to be suppressed. The C++/CLI console project template in fact does not specify an entry point, so compiler guesses because a main function exists, the project is a console application. A Windows Forma application’s entry point has the same signature with the main function, therefore the /subsystem setting of the project needs to be changed to Windows:

• Go back to the project’s Property Pages dialog box.
• Click the Linker folder on the type.
• Click the System property page.
• Change the SubSystem property to Windows.

Ready? Not yet. The compiler is now trying to find a WinMain function, and throws LNK2028 and  LNK2019 when it can’t find the entry point, which of course isn’t there. I am not interested in writing one as I prefer to keep the nice args command line parameter of an array<String^>^ type , so I need to tell the compiler my entry point function is still main:

• Go back to the the Linker folder.
• Click the Advanced property page.
• Change the Entry Point property to main.

We are almost here. Windows Forms needs an STA thread, so I have to add  [STAThreadAttribute] to the main function:

[STAThreadAttribute]
int main(array<System::String ^> ^args)
{

….. // wait did I add anything here? I guess not yet

Here you go,  a Windows Forms application that does nothing interesting.  Mmm, to make it a little more visual, I create a new Windows Form class named Form1 and run it in the main function:

//before main function
#include “Form1.h”
using namespace ProjectName;

//in the main function
Application::EnableVisualStyles();
Application::SetCompatibleTextRenderingDefault(false);

// Create the main window and run it
Application::Run(gcnew Form1());

Yada! I have a Windows Forms application running now.