How much overlap to require clipped text to have before it is
defined as visible.
If text is partially clipped then one needs to decide whether
each character is visible or not. The default way this is done is
by finding the center of each character and seeing if that is
visible. This affects text retrieval when the ShowClippedText property is set to false
and also when passing an area of interest via GetText.
Sometimes you may wish to be more selective about whether text
is returned or not. The ClippedTextTolerance property allows you to
define a rectangular area in the center of the character, the
entire of which must be visible for the character to be visible.
The width and height of the rectangular area are determined by the
value of this property.
For example a value of zero represents a point in the center. A
value of a half represents a centered rectangle half the linear
dimensions of the character bounding box. A value of one represents
the entire of the character bounding box from the bottom of any
possible descenders to the top of any possible ascenders.