Read only text frames in TX Text Control .NET

Blogged by Björn Meyer on March 22, 2007 and tagged with Samples, .NET.

Text frames are a very smart way to position text at a specific position in the document. They are commonly used for a recipient address details area on a letter or any other information that must be at a fixed position in a document.

TX Text Control offers properties to avoid the scaling and the movement of the frame:

Moveable

Sizeable

Sometimes, applications require that such text frames are not editable by the user. In this case, we can use the TextFrameActivated event to set a flag that indicates that a text frame is currently active.

void TX_TextFrameActivated(object sender, TXTextControl.TextFrameEventArgs e)
{
	m_trapKeystrokes = true;
}

On the KeyPress event, we can trap the keystrokes, if the mentioned flag has been set to true.

void m_tx_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
	if (m_trapKeystrokes)
		e.Handled = true;
}

The TextFrameDeactivated event is used to reset the global flag:

void m_tx_TextFrameDeactivated(object sender, TXTextControl.TextFrameEventArgs e)
{
	m_trapKeystrokes = false;
}

The following class is a sample how to inherit from the TextFrame class to create such protected text frames:

class ProtectedTextFrame : TXTextControl.TextFrame
{
	private bool						m_protected;
	private TXTextControl.TextControl   			m_tx;
	private bool						m_trapKeystrokes = false;

	public ProtectedTextFrame(Size Size, bool Protected, TXTextControl.TextControl TX) : base(Size)
	{
		m_protected = Protected;
		m_tx = TX;

		if (m_protected)
		{
			m_tx.TextFrameActivated += new TXTextControl.TextFrameEventHandler(TX_TextFrameActivated);
			m_tx.TextFrameDeactivated += new TXTextControl.TextFrameEventHandler(m_tx_TextFrameDeactivated);
			m_tx.KeyPress += new System.Windows.Forms.KeyPressEventHandler(m_tx_KeyPress);
		}
	}

	void m_tx_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
	{
		if (m_trapKeystrokes)
			e.Handled = true;
	}

	void m_tx_TextFrameDeactivated(object sender, TXTextControl.TextFrameEventArgs e)
	{
		m_trapKeystrokes = false;
	}

	void TX_TextFrameActivated(object sender, TXTextControl.TextFrameEventArgs e)
	{
		m_trapKeystrokes = true;
	}

	public bool Protected
	{
		get { return m_protected; }
		set { m_protected = value; }
	}
}

This class can be instantiated like this:

ProtectedTextFrame newFrame = new ProtectedTextFrame(new Size(1000, 1000), true, textControl1);
newFrame.Protected = true;
textControl1.TextFrames.Add(newFrame, -1);

Feel free to contact me, if you want to discuss this approach or, if you have any questions.