Matlab - Trace Position of Cursor without Click Mouse GPOS

Author

Trace Position of Cursor without Click Mouse GPOS

Frank Pezzulo

2008-01-30, 8:20 pm

DEAR ALL,

my problem is to use function "gpos" that you can get to
File Exchange.

Can i have an example code to run this function ... I try
with my example but doesn't work. Thanks

My Example is:

t = (0:0.05:1)';
d1 = sin(2*pi*t)*[1 2 3];
d2 = cos(2*pi*t)*[1 2 3];
h=plot(t,[d1 d2]);
gpos(h)
set(h,'WindowButtonMotionFcn',@gpos)

Thank you very much to all have help me until now!!!

Frank

Walter Roberson

2008-01-30, 8:20 pm

Frank Pezzulo

2008-01-30, 11:14 pm

roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) wrote in
message <fnqdnl$ikg$1@canopus.cc.umanitoba.ca>...
> In article <fnqd12$m0c$1@fred.mathworks.com>,
> Frank Pezzulo <john.doe.nospam@mathworks.com> wrote:
>
>
>
> What happens instead of it working? Telling us that something
> "doesn't work" is not usually useful to us; we need to
know what
> you observed when you tried to run it.
> --
> "There are some ideas so wrong that only a very
intelligent person
> could believe in them." --
George Orwell

IT SHOWS ONLY PLOT WITH LINE BUT FUNCTION gpos DOESN'T WORK!
MAYBE I HAVE WRONG TO USE THE LINE
set(h,'WindowButtonMotionFcn',@gpos) ????

Walter Roberson

2008-01-30, 11:14 pm

In article <fnqd12$m0c$1@fred.mathworks.com>,
Frank Pezzulo <john.doe.nospam@mathworks.com> wrote:

>my problem is to use function "gpos" that you can get to
>File Exchange.

>Can i have an example code to run this function ... I try
>with my example but doesn't work. Thanks

>My Example is:

>t = (0:0.05:1)';
>d1 = sin(2*pi*t)*[1 2 3];
>d2 = cos(2*pi*t)*[1 2 3];
>h=plot(t,[d1 d2]);
>gpos(h)
>set(h,'WindowButtonMotionFcn',@gpos)

Looks to me like you failed to read the documentation at the
beginning of the gpos.m source file. I should push you some more
to say what you expected your sample code to *do*, but I don't
have the energy at the moment for enough exchanges to help you
realize for yourself what is going wrong. So here is an adjusted
example that should do something visible, even if it wasn't what
you expected.

Put this in testgpos.m and then invoke
testgpos
from the command line:

function testgpos
%As you move your cursor around, the updated cursor position should
%be displayed in the command window.
t = (0:0.05:1)';
d1 = sin(2*pi*t)*[1 2 3];
d2 = cos(2*pi*t)*[1 2 3];
plot(t,[d1 d2]);
set(gcf, 'WindowButtonMotionFcn', {@displaypos, gca});
end

function displaypos(src, evt, whichaxis)
[x y] = gpos(whichaxis);
disp(sprintf('cursor now at: %g %g\n', x, y));
end

Important hints:

- gpos() requires an axis as input. plot() returns a lineseries,
not an axis, so h=plot() followed by gpos(h) is wrong because
you would be passing a lineseries handle to gpos instead of an axis.

- calling gpos by itself outside of the callback does not
do anything useful for you.

- gpos() returns two values, not an array of two values.

- The gpos.m source indicates,

% 2. It works like GINPUT provided by Matlab,but it traces the position
% of cursor without click and is designed for 2-D axes.

Here, 'traces the position' should be read as meaning
'follows and returns the position', not as
meaning that it will draw anything on the plot.
--
"Any sufficiently advanced bug is indistinguishable from a feature."
-- Rich Kulawiec

Frank Pezzulo

2008-01-31, 8:28 pm

roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) wrote in
message <fnqsb7$679$1@canopus.cc.umanitoba.ca>...
> In article <fnqd12$m0c$1@fred.mathworks.com>,
> Frank Pezzulo <john.doe.nospam@mathworks.com> wrote:
>
>
>
>
>
> Looks to me like you failed to read the documentation at the
> beginning of the gpos.m source file. I should push you
some more
> to say what you expected your sample code to *do*, but I don't
> have the energy at the moment for enough exchanges to help you
> realize for yourself what is going wrong. So here is an
adjusted
> example that should do something visible, even if it
wasn't what
> you expected.
>
> Put this in testgpos.m and then invoke
> testgpos
> from the command line:
>
>
> function testgpos
> %As you move your cursor around, the updated cursor
position should
> %be displayed in the command window.
> t = (0:0.05:1)';
> d1 = sin(2*pi*t)*[1 2 3];
> d2 = cos(2*pi*t)*[1 2 3];
> plot(t,[d1 d2]);
> set(gcf, 'WindowButtonMotionFcn', {@displaypos, gca});
> end
>
> function displaypos(src, evt, whichaxis)
> [x y] = gpos(whichaxis);
> disp(sprintf('cursor now at: %g %g\n', x, y));
> end
>
>
>
> Important hints:
>
> - gpos() requires an axis as input. plot() returns a
lineseries,
> not an axis, so h=plot() followed by gpos(h) is wrong because
> you would be passing a lineseries handle to gpos instead
of an axis.
>
> - calling gpos by itself outside of the callback does not
> do anything useful for you.
>
> - gpos() returns two values, not an array of two values.
>
> - The gpos.m source indicates,
>
> % 2. It works like GINPUT provided by Matlab,but it
traces the position
> % of cursor without click and is designed for 2-D axes.
>
> Here, 'traces the position' should be read as meaning
> 'follows and returns the position', not as
> meaning that it will draw anything on the plot.
> --
> "Any sufficiently advanced bug is indistinguishable
from a feature."
> -- Rich Kulawiec

THANK YOU VERY MUCH ... I'VE RESOLVED.

REGARDS,

FRANCESCO

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