Control::OnTextChanged Method (EventArgs^)
Raises the TextChanged event.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Raising an event invokes the event handler through a delegate. For more information, see Handling and Raising Events.
The OnTextChanged method also enables derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.
Notes to Inheritors:
When overriding OnTextChanged in a derived class, be sure to call the base class's OnTextChanged method so that registered delegates receive the event.
The following code example changes the ForeColor of a TextBox derived class displaying currency data. The example converts the text to a decimal number and changes the ForeColor to Color::Red if the number is negative and to Color::Black if the number is positive. This example requires that you have a class that derives from the TextBox class.
protected: virtual void OnTextChanged( System::EventArgs^ e ) override { try { // Convert the text to a Double and determine // if it is a negative number. if ( Double::Parse( this->Text ) < 0 ) { // If the number is negative, display it in Red. this->ForeColor = Color::Red; } else { // If the number is not negative, display it in Black. this->ForeColor = Color::Black; } } catch ( Exception^ ) { // If there is an error, display the // text using the system colors. this->ForeColor = SystemColors::ControlText; } TextBox::OnTextChanged( e ); }
Available since 1.1