MATLAB Central Newsreader - Getting pointer position within axes

Getting pointer position within axes

Michelle — Tue, 26 Feb 2008 17:47:01 -0500

Hello,

Here is what I would like to do:

When my mouse rolls over a plot object in an axes, I want to
plot some text that identifies the object, directly next to
the object. I don't want to have to click on the object to
make this text display in the axes. I just want to roll
over the object.

I have the Image Processing Toolbox installed, and have
tried working with iptPointerManager to accomplish the
desired task. However, the iptPointerManager seems to
maintain only the pointer's current position in the figure,
and in pixels. I don't know how to translate the pointer
position (in pixels, with respect to the figure) to the
location of the plotted object (in data units, with respect
to the axes).

Can anyone suggest a solution?

Thank you,

Michelle Kline

Re: Getting pointer position within axes

Ilya Rozenfeld — Tue, 26 Feb 2008 20:49:02 -0500

Check help for "WindowButtonMotionFcn" and "CurrentPoint".

In the callback for WindowButtonMotionFcn you can query
cursor position (in the figure coordinates) using
CurrentPoint property and if it is close enough to your
object then trigger some event.

"Michelle " <mkline@egi.utah.edu> wrote in message
<fq1jal$jg7$1@fred.mathworks.com>...
> Hello,
>
> Here is what I would like to do:
>
> When my mouse rolls over a plot object in an axes, I
want to
> plot some text that identifies the object, directly next
to
> the object. I don't want to have to click on the object
to
> make this text display in the axes. I just want to roll
> over the object.
>
> I have the Image Processing Toolbox installed, and have
> tried working with iptPointerManager to accomplish the
> desired task. However, the iptPointerManager seems to
> maintain only the pointer's current position in the
figure,
> and in pixels. I don't know how to translate the pointer
> position (in pixels, with respect to the figure) to the
> location of the plotted object (in data units, with
respect
> to the axes).
>
> Can anyone suggest a solution?
>
> Thank you,
>
> Michelle Kline

Re: Getting pointer position within axes

Michelle — Tue, 26 Feb 2008 21:13:02 -0500

Thanks, Ilya.

I now see that I don't have to actually click with my mouse
to trigger the WindowButtonMotionFcn. A big problem still
remains, though. Now that I've got the cursor position, in
figure coordinates, how do I determine (programmatically)
what object my cursor is currently near? The objects are
points that I plotted in a graph axes using the plot
command. I have no way of telling what each point's
position is, in terms of figure units. (Or can I?) I only
know each point's position in my data units (for example age
vs. feet).

- Michelle

"Ilya Rozenfeld" <rozeni.nospam@alum.rpi.edu> wrote in
message <fq1tvu$mr3$1@fred.mathworks.com>...
> Check help for "WindowButtonMotionFcn" and "CurrentPoint".
>
> In the callback for WindowButtonMotionFcn you can query
> cursor position (in the figure coordinates) using
> CurrentPoint property and if it is close enough to your
> object then trigger some event.
>
>
> "Michelle " <mkline@egi.utah.edu> wrote in message
> <fq1jal$jg7$1@fred.mathworks.com>...
> > Hello,
> >
> > Here is what I would like to do:
> >
> > When my mouse rolls over a plot object in an axes, I
> want to
> > plot some text that identifies the object, directly next
> to
> > the object. I don't want to have to click on the object
> to
> > make this text display in the axes. I just want to roll
> > over the object.
> >
> > I have the Image Processing Toolbox installed, and have
> > tried working with iptPointerManager to accomplish the
> > desired task. However, the iptPointerManager seems to
> > maintain only the pointer's current position in the
> figure,
> > and in pixels. I don't know how to translate the pointer
> > position (in pixels, with respect to the figure) to the
> > location of the plotted object (in data units, with
> respect
> > to the axes).
> >
> > Can anyone suggest a solution?
> >
> > Thank you,
> >
> > Michelle Kline
>

Re: Getting pointer position within axes

sourabh bora — Sun, 16 Mar 2008 21:49:03 -0400

Hi Michelle,
I am facing the same problem as you.. how to determine the
location of objects within the axes. I would be glad if you
let me know once you find the solution.
A matlab program called freehanddraw.m can give you some
idea how to work with window mouse button.

another approach you may try is using ginput.
http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=7347&objectType=File
Thanks
Sourabh Bpra

"Michelle " <mkline@egi.utah.edu> wrote in message
<fq1vcu$f80$1@fred.mathworks.com>...
> Thanks, Ilya.
>
> I now see that I don't have to actually click with my mouse
> to trigger the WindowButtonMotionFcn. A big problem still
> remains, though. Now that I've got the cursor position, in
> figure coordinates, how do I determine (programmatically)
> what object my cursor is currently near? The objects are
> points that I plotted in a graph axes using the plot
> command. I have no way of telling what each point's
> position is, in terms of figure units. (Or can I?) I only
> know each point's position in my data units (for example age
> vs. feet).
>
> - Michelle
>

Re: Getting pointer position within axes

Rikki — Thu, 04 Jun 2009 14:24:01 -0400

Look at this link: http://msenux.redwoods.edu/Math4Textbook/Programming/NestedFunctions.pdf

#7 at the end shows you exactly how to do this.