V8/usr/man/man9/lens.9

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.TH LENS 9.1
.SH NAME
lens \- bitmap
.m magnifier
.SH SYNOPSIS
.B lens
.SH DESCRIPTION
.I Lens
is an interactive screen bitmap magnifier.
When it
starts, it displays an enlarged image of a magnifying glass in
its layer, which becomes a setting sun when
.I lens
wants to confirm a command to exit.
.PP
The first item in the button 2 menu,
which rotates among
.I go,
.I peek
and
.I stop,
determines the activity of the magnifier.
Clicking button 1 serves as an abbreviation for selecting
.I go
or
.I peek.
When the magnifier is going,
a crawling-bordered rectangle is drawn
around the source, and the
.I lens
window contains the magnified image.
The mouse controls
the position of the source rectangle.
.PP
During peeking, the rectangle last selected while
going is re-examined periodically, and the contents
are magnified, whether or not the
.I lens
window is currently selected.
.PP
When stopped, the
.I lens
window is inactive.   
.PP
The button 2 menu also allows changing the magnification factor.
The magnification factors are chosen from the
Fibonacci numbers, and menu items for the next size smaller and larger
are presented as,
.I e.g.,
.I 3x
or
.I 8x.
The current magnification factor is not displayed in the menu, only
the next factors larger and smaller.
The initial magnification factor is two.
.PP
Button 2 may also be used to select the intervals at which peeking
updates occur.
These intervals are selected, in ticks, from among the powers of two, where
a tick is one-sixtieth of a second.
These choices are presented as,
.I e.g.,
.I "32 ticks"
or
.I "128 ticks."
The initial interval between peeks is 64 ticks, approximately one second.
.PP
The image window may be controlled by the button 2 menu item which
toggles between
.I inset
and
.I "full size."
In inset mode, the image is displayed inside the image window of the
magnified lens icon.
In full size mode, the image is displayed in the entire
.I lens
window.
.PP
The final buton 2 menu entry is
.I exit.
A setting sun is displayed, and button 3 must be clicked to confirm.
.SH BUGS
While going, the display is only refreshed when the mouse is moved.
Inconsistent results may be obtained when
.I lens
is used to examine its own image window.
.PP
While peeking, it is assumed that the
.I lens
window contains an accurate magnification of what was on the screen
at the time of the last magnification.  If
.I lens
is used to examine its own image, strange things may occur.
.PP
Due to the bitmap reshaping techniques employed by the magnification
algorithms, high magnification factors will not work with large image
windows.
Precisely, if the product of the vertical magnification factor and
the width of the destination rectangle overflows a signed
short integer, predictable but undesirable results will occur.