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XZOOM(1X)							       XZOOM(1X)

NAME
     xzoom - magnify part of the screen, with fast updates

SYNOPSIS
     xzoom [ -display displayname ] [ -mag mag [ mag ] ] [ -x ] [ -y ] [ -xy ] [
     -geometry geometry ] [ -source geometry ]

OPTIONS
     -display displayname | -d displayname
	  The name of the display to use (not very useful).

     -mag mag [ mag ]
	  What	magnification  to  use. If two number arguments are supplied the
	  first is used for X magniications and the second is used for Y  magni-
	  fication.  Magnification should be greater than 0.

     -x   Mirror horizontally.

     -y   Mirror vertically.

     -xy | -z
	  Exchange X and Y axes before any magnification is performed.

     -geometry geometry | =geometry
	  Size and position xzoom's window.

     -source geometry
	  Size and position the initial source area which is magnified.  The di-
	  mensions  of	this area are multiplied by the magnification to get the
	  size of xzoom's window. If these dimensions are given  separately  (by
	  use of -geometry ) then an error is reported.

DESCRIPTION
     Xzoom displays in its window a magnified area of the X11 display.	The user
     can  interactively  change  the zoomed area, the window size, magnification
     (optionally different magnification for X and Y axes) or rotate  or  mirror
     the image.

COMMANDS
     Once  xzoom  has  started the user can enter simple commands using the key-
     board.

     q	  quit.

     +	  increase magnification value by 1.

     -	  decrease magnification value by 1.

     w	  next + or - command only affect X magnification.

     h	  next + or - command only affect Y magnification.

     x	  mirror the display image horizontally.

     y	  mirror the display image vertically.

     z	  rotate the displayed image 90 degrees counter-clockwise.

     arrow keys
	  scroll the zoomed area 1 pixel in the direction of the arrow.  if  the
	  control key is pressed the zoomed area will scroll 10 pixels.

     d	  sets	the  delay between frame updates.  Built-in delays are 200, 100,
	  50, 10 and 0 ms.

     g	  toggle grid on and off.

     Mouse buttons
	  To set the location of the magnified are click the left  mouse  button
	  inside  xzoom's  window  and then move it (keep the button pressed) to
	  the place which you want to see magnified.

	  Xzoom allow you to resize it's window at any time.

	  When xzoom is iconified it simply waits to get deiconified.

DISPLAYS
     Xzoom uses the window's title bar to inform the  user  about  it's  status.
     Normally  the title says something like xzoom x2 which means the magnifica-
     tion is 2 both in X and Y axes.  If the image is stretched  differently  on
     the  X and Y axes the title will say xzoom X 2; Y 4.  Negative numbers mean
     reflection.  If the image is rotated by 90 or 270 degrees	the  title  will
     show <=> between the X and Y values.

     When d is depressed the title will display the new delay value for approxi-
     mately  2	seconds  and then revert to the default display of magnification
     values.

PERFORMANCE
     Xzoom is fast enough to display enlarged or mirrored  animations  in  small
     windows. On my 486 DX2-66 and Cirrus Logic CL-GD5428 display card (attached
     to  Vesa  local  bus) update of a 256x256 window magnified by 2 (ie, source
     rect is 128x128) takes approximately 30 ms. This time  varies,  off  course
     when  a  different  size  window or different magnification is used.  If we
     chose 50 ms between updates we can get about 12.5	frames	per  second  and
     still  let  an  animation	program do it's work.  It is possible to compile
     xzoom without X shared memory support.  In that case window update  may  be
     about  3 times slower (if we are using a local display, using LAN is a dif-
     ferent story).

SEE ALSO
     xmag.1x.
     I got the motivation for writing xzoom after I saw a similar WindowsNT pro-
     gram, zoomin working. It started just as a  test  for  X11  performance.  I
     don't  have  the  fancy  menus  and scrollbar like zoomin but I do have all
     their features (and more) accessible from the keyboard.

BUGS
     <*> The maximum internal built in delay (see command d above)  was  set  to
     200  ms. Xzoom completes the delay before polling the X event queue for the
     next command. Larger delays would feel like poor response to user commands.

     <*> For best performance the shared memory extension for X11 is used. Xzoom
     will fail if it is compiled to use XSHM and its display is not on the local
     host.

     <*> The Ximage data is accessed  directly,  in  a	way  which  may  not  be
     portable.	Xzoom  will  not  run  with  display depth other than 8 bits per
     pixel.

     <*> Xzoom is given with no warranty. It was tested only  under  Linux  with
     Xfree86 release 3.1.2 (X11R6).

     <*>  Some	strange behavior may occur if the requested magnified area falls
     beyond the borders of the screen. Example is when you have magnification of
     1 and a window whose width is greater than the height of the screen and you
     want 90 degrees rotation. In that case part of the window will not get  up-
     dated.

     <*>  The  frame  used  to	mark the zoomed area may corrupt the contents of
     other windows if they are modified when the frame is visible.  If you don't
     like it disable the -DFRAME option when compiling xzoom.

AUTHOR
     Itai Nahshon

								       XZOOM(1X)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=xzoom&sektion=1&manpath=FreeBSD+15.1-RELEASE+and+Ports.quarterly>

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