Magnifying a portion of the X screen - Xwindows

This is a discussion on Magnifying a portion of the X screen - Xwindows ; The "standard" program `xmag` allows static capturing a portion of an X-window screen and magnifying it. But, compared to the programs available for Microsoft Windows, it's badly crippled. There are relatively simple programs available -- and some even ship with ...

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Thread: Magnifying a portion of the X screen

  1. Magnifying a portion of the X screen

    The "standard" program `xmag` allows static capturing a portion of an
    X-window screen and magnifying it. But, compared to the programs available
    for Microsoft Windows, it's badly crippled. There are relatively simple
    programs available -- and some even ship with the base Windows
    installation -- that allow
    (a) dynamic changing magnification with a mouse-click
    (b) live capturing the region surrounding the mouse as it's dragged
    around
    (c) live display as the area being magnified changes.

    PLEASE don't think that this is a troll. I'm a long-time and committed user
    and developer of both Windows and Linux and I find that right now for a
    program that I'm working on I need some of the functionality that I have in
    windows under Linux too.

    One problem with the development of a really capable X window app is the
    multiplicity of standards and toolkits so a developer has to either program
    to a least common denominator system or supply enough in the way of
    libraries to make his/her app work on "any" system.

    As I see it right now, a reasonable target (though hardly inclusive) is
    what's provided with something like a RedHat 7.x or 8.x distribution which
    is, I think, X + Xt + Lesstif.

    If there's a Windows-like screen region magnifier available, then it doesn't
    ship with my "target" systems -- or at least doesn't get installed by
    default in them.

    1. If there is a program that does (most of) what I need, please tell me so
    I won't start reinventing round objects. If the app needs extensions to do
    some things, I just might do that instead of starting from scratch.

    2. If there is no (readily available) program of this type, please tell me
    a) is my target reasonable
    b) what features should be included or excluded from the app

    TIA
    Norm


  2. Re: Magnifying a portion of the X screen

    "Norm Dresner" writes:

    > The "standard" program `xmag` allows static capturing a portion of an
    > X-window screen and magnifying it. But, compared to the programs available
    > for Microsoft Windows, it's badly crippled. There are relatively simple
    > programs available -- and some even ship with the base Windows
    > installation -- that allow
    > (a) dynamic changing magnification with a mouse-click
    > (b) live capturing the region surrounding the mouse as it's dragged
    > around


    That seems easy to implement. XSelectInput(PointerMotionMask) on the
    root window, and do XShmGetImage, magnify, XShmPutImage.

    > (c) live display as the area being magnified changes.


    Slightly trickier. The problem is to be notified when some area
    changes. With a suitable graphics card (anything modern), it is
    possible to set the overlay unit to read from the framebuffer. This
    would give instant update of whatever region was configured, without
    using a single CPU cycle. The source rectangle would need to be
    reconfigured on mouse motion, of course, but it's a cheap operation.
    The only catch is that X provides no means for implementing this.

    --
    Måns Rullgård
    mru@inprovide.com

  3. Re: Magnifying a portion of the X screen

    > (a) dynamic changing magnification with a mouse-click
    This should require only a small enhancement to xmag.

    > (b) live capturing the region surrounding the mouse as it's dragged
    > around

    This should require only a small enhancement to xmag.

    > (c) live display as the area being magnified changes.

    "100% live" probably requires a proxy X11 server (or an X11 protocol
    extension) to filter and "tee" the protocol stream for the windows that
    are subject to the magnification (currently are mapped to the portion
    of the screen that is being magnified). Otherwise, this effect might
    be simulated by repetitive re-read and re-magnify (say, at 10 Hz).

    --

  4. Re: Magnifying a portion of the X screen

    "Norm Dresner" writes:

    > The "standard" program `xmag` allows static capturing a portion of an
    > X-window screen and magnifying it. But, compared to the programs available
    > for Microsoft Windows, it's badly crippled. There are relatively simple
    > programs available -- and some even ship with the base Windows
    > installation -- that allow
    > (a) dynamic changing magnification with a mouse-click
    > (b) live capturing the region surrounding the mouse as it's dragged
    > around
    > (c) live display as the area being magnified changes.
    >
    > PLEASE don't think that this is a troll.


    Sure sounds like a troll. Are you sure you didn't do a google
    search for:

    x windows screen magnifier

    This site is good:

    http://www.magnifiers.org/links/Scre...rs/UNIX_Linux/

    As a result of your post I installed kmag, pretty neat.


  5. Re: Magnifying a portion of the X screen

    "Norm Dresner" writes:

    > 1. If there is a program that does (most of) what I need, please tell me so
    > I won't start reinventing round objects. If the app needs extensions to do
    > some things, I just might do that instead of starting from scratch.


    Xzoom updates its display automatically with a timer, and its
    magnification ratio can be changed with keypresses, but
    apparently not with the mouse. I don't think it can follow the
    mouse automatically while you're using other programs.

    There is also KMagnifier for KDE, and gnome-mag for GNOME.
    I haven't used those myself.

  6. Re: Magnifying a portion of the X screen

    "Norm Dresner" writes:

    > The "standard" program `xmag` allows static capturing a portion of an
    > X-window screen and magnifying it. But, compared to the programs available
    > for Microsoft Windows, it's badly crippled. There are relatively simple
    > programs available -- and some even ship with the base Windows
    > installation -- that allow
    > (a) dynamic changing magnification with a mouse-click
    > (b) live capturing the region surrounding the mouse as it's dragged
    > around
    > (c) live display as the area being magnified changes.


    There do exist screen magnifyiers; of the ones listed in Dans link I
    have tried UnWindows and Gnopernicus (these are actually collections
    av accessability tools). Both these support your demands (well I don't
    remember the possibility to change magnified area by mouse *click*),
    but in different ways. This makes Gnopernicus easier to use, but
    UnWindows is probably faster and might also run on a bigger variety of
    systems. Both can also automatically focus on changes in the display
    making it possible to--for example--follow the text you are writing in
    Emacs.

    Both of these (and all other screen magnifiers I've heard) of have the
    problem that you can't magnify the area of the screen covered by the
    magnifier. The problem is due to technical limitations in the X
    servers. A way around this is using a system capable of managing
    several screens and having the the magnifier on one a screen separate
    from the applications you want to magnify. I haven't seen any sleek
    solution for doing this while having only one monitor, though it would
    be possible to make.

    When I was about to help a visually impaired person some years ago we
    ended up with letting him use a computer with the XFree86 server and
    utilised the possiblity to adjust the screen resolution with key
    strikes. See here
    http://www.tldp.org/HOWTO/Accessibil...al.html#AEN177 Since
    the system he should mainly use was Solaris (itself using the Xsun
    server) he used a Linux system running XFree86 to log in to a
    Solaris system using XDMCP. Worked fine, though not that good security
    wise (the X protocol is sent unencrypted over the network in this
    case).

    --
    - Mårten

    mail: msv@kth.se *** ICQ: 4356928 *** mobile: +46 (0)707390385

  7. Re: Magnifying a portion of the X screen

    "Dan Espen" wrote in message
    news:icekisqxg1.fsf@home-1.localdomain...
    > "Norm Dresner" writes:
    >
    > > The "standard" program `xmag` allows static capturing a portion of an
    > > X-window screen and magnifying it. But, compared to the programs

    available
    > > for Microsoft Windows, it's badly crippled. There are relatively

    simple
    > > programs available -- and some even ship with the base Windows
    > > installation -- that allow
    > > (a) dynamic changing magnification with a mouse-click
    > > (b) live capturing the region surrounding the mouse as it's dragged
    > > around
    > > (c) live display as the area being magnified changes.
    > >
    > > PLEASE don't think that this is a troll.

    >
    > Sure sounds like a troll. Are you sure you didn't do a google
    > search for:
    >
    > x windows screen magnifier
    >
    > This site is good:
    >
    > http://www.magnifiers.org/links/Scre...rs/UNIX_Linux/
    >
    > As a result of your post I installed kmag, pretty neat.
    >


    Not everyone thinks of every keyword when googling.

    Also, I looked at the site you suggest and there are several that look
    promising.

    BUT ... You said that you installed "kmag" -- where did you get it from ?
    Certainly not from the site you cited.

    Norm


  8. Re: Magnifying a portion of the X screen

    Norm Dresner wrote:
    > The "standard" program `xmag` allows static capturing a portion of an
    > X-window screen and magnifying it. But, compared to the programs available
    > for Microsoft Windows, it's badly crippled. There are relatively simple
    > programs available -- and some even ship with the base Windows
    > installation -- that allow
    > (a) dynamic changing magnification with a mouse-click
    > (b) live capturing the region surrounding the mouse as it's dragged
    > around
    > (c) live display as the area being magnified changes.
    >


    Xdamage extension of the new X.org xserver?

    tom

  9. Re: Magnifying a portion of the X screen

    Norm Dresner wrote:

    > Not everyone thinks of every keyword when googling.
    >
    > Also, I looked at the site you suggest and there are several that look
    > promising.
    >
    > BUT ... You said that you installed "kmag" -- where did you get it from ?
    > Certainly not from the site you cited.


    Surely you can think of the Google keyword "kmag" when wanting to search
    for kmag, couldn't you?

    --
    Erik Max Francis && max@alcyone.com && http://www.alcyone.com/max/
    San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
    Courage is the fear of being thought a coward.
    -- Horace Smith

  10. Re: Magnifying a portion of the X screen

    "Norm Dresner" writes:

    > "Dan Espen" wrote in message
    > news:icekisqxg1.fsf@home-1.localdomain...
    >> "Norm Dresner" writes:
    >>
    >> > The "standard" program `xmag` allows static capturing a portion of an
    >> > X-window screen and magnifying it. But, compared to the programs

    > available
    >> > for Microsoft Windows, it's badly crippled. There are relatively

    > simple
    >> > programs available -- and some even ship with the base Windows
    >> > installation -- that allow
    >> > (a) dynamic changing magnification with a mouse-click
    >> > (b) live capturing the region surrounding the mouse as it's dragged
    >> > around
    >> > (c) live display as the area being magnified changes.
    >> >
    >> > PLEASE don't think that this is a troll.

    >>
    >> Sure sounds like a troll. Are you sure you didn't do a google
    >> search for:
    >>
    >> x windows screen magnifier
    >>
    >> This site is good:
    >>
    >> http://www.magnifiers.org/links/Scre...rs/UNIX_Linux/
    >>
    >> As a result of your post I installed kmag, pretty neat.
    >>

    >
    > Not everyone thinks of every keyword when googling.


    True, but what else could you use? OK, I just used your subject
    line and it didn't work very well. I officially conceed that you
    aren't a troll.

    > Also, I looked at the site you suggest and there are several that look
    > promising.
    >
    > BUT ... You said that you installed "kmag" -- where did you get it from ?
    > Certainly not from the site you cited.


    I'm not sure what you mean. I followed the 5th link down to kmagnifier.
    After I saw that the actual executable was kmag I used URPMI (a Mandrake
    tool) to find the package name and install it.

    I just checked their screenshots. The Mandrake package and KMagnifier
    are the same thing.

    So I used that page...in a way.

  11. Re: Magnifying a portion of the X screen

    "Erik Max Francis" wrote in message
    news:Tsednb-k__Bt6APcRVn-sw@speakeasy.net...
    > Norm Dresner wrote:
    >
    > > Not everyone thinks of every keyword when googling.
    > >
    > > Also, I looked at the site you suggest and there are several that look
    > > promising.
    > >
    > > BUT ... You said that you installed "kmag" -- where did you get it from

    ?
    > > Certainly not from the site you cited.

    >
    > Surely you can think of the Google keyword "kmag" when wanting to search
    > for kmag, couldn't you?
    >

    Why would I ever want to search for "kmag" without knowing it existed in the
    first place?


  12. Re: Magnifying a portion of the X screen

    Tomas Carnecky writes:

    > Norm Dresner wrote:
    >> The "standard" program `xmag` allows static capturing a portion of an
    >> X-window screen and magnifying it. But, compared to the programs available
    >> for Microsoft Windows, it's badly crippled. There are relatively simple
    >> programs available -- and some even ship with the base Windows
    >> installation -- that allow
    >> (a) dynamic changing magnification with a mouse-click
    >> (b) live capturing the region surrounding the mouse as it's dragged
    >> around
    >> (c) live display as the area being magnified changes.
    >>

    >
    > Xdamage extension of the new X.org xserver?


    Gnopernicus magnifier will use that according to
    http://blogs.sun.com/roller/comments...tour_2004_part

    Also other more or less new extension will be utilised: COMPOSITE and
    XFIXES. XEvIE is already used if present.

    As far as I understand COMPOSITE might fix the problem of magnifying
    parts of the screen covered by the magnifier window.

    --
    - Mårten

    mail: msv@kth.se *** ICQ: 4356928 *** mobile: +46 (0)707390385

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