Message::Msg Property
.NET Framework (current version)
Gets or sets the ID number for the message.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
The following code example demonstrates overriding the WndProc method to handle operating system messages identified in the Message. The WM_ACTIVATEAPP operating system message is handled in this example to know when another application is becoming active. For information about the available Message::Msg, Message::LParam, and Message::WParam values, see the MSG Structure documentation. For information about the actual constant values, see Message Constants.
using namespace System; using namespace System::Drawing; using namespace System::Windows::Forms; using namespace System::Security::Permissions; namespace csTempWindowsApplication1 { public ref class Form1: public System::Windows::Forms::Form { private: // Constant value was found in the "windows.h" header file. static const Int32 WM_ACTIVATEAPP = 0x001C; Boolean appActive; public: Form1() { appActive = true; this->Size = System::Drawing::Size( 300, 300 ); this->Text = "Form1"; this->Font = gcnew System::Drawing::Font( "Microsoft Sans Serif",18.0F,System::Drawing::FontStyle::Bold,System::Drawing::GraphicsUnit::Point,((System::Byte)(0)) ); } protected: virtual void OnPaint( PaintEventArgs^ e ) override { // Paint a string in different styles depending on whether the // application is active. if ( appActive ) { e->Graphics->FillRectangle( SystemBrushes::ActiveCaption, 20, 20, 260, 50 ); e->Graphics->DrawString( "Application is active", this->Font, SystemBrushes::ActiveCaptionText, 20, 20 ); } else { e->Graphics->FillRectangle( SystemBrushes::InactiveCaption, 20, 20, 260, 50 ); e->Graphics->DrawString( "Application is Inactive", this->Font, SystemBrushes::ActiveCaptionText, 20, 20 ); } } [SecurityPermission(SecurityAction::Demand, Flags=SecurityPermissionFlag::UnmanagedCode)] virtual void WndProc( Message% m ) override { // Listen for operating system messages. switch ( m.Msg ) { case WM_ACTIVATEAPP: // The WParam value identifies what is occurring. appActive = (int)m.WParam != 0; // Invalidate to get new text painted. this->Invalidate(); break; } Form::WndProc( m ); } }; } [STAThread] int main() { Application::Run( gcnew csTempWindowsApplication1::Form1 ); }
.NET Framework
Available since 1.1
Available since 1.1
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