Prepares the image to receive drawing commands.
Original signature is '- (void)lockFocus'
Available in Mac OS X v10.0 and later.

C# | Visual Basic | Visual C++ |
public virtual void LockFocus()
Public Overridable Sub LockFocus
public: virtual void LockFocus()

- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)