GTRACK

Track mouse position and show coordinates in figure title.

Description

GTRACK Track mouse position and show coordinates in figure title.

Once GTRACK is active the mouse position is constantly tracked and printed on the current figure title. A left-click will print the coordinates in the command line and store them. Clicking the mouse right button deactivates GTRACK.

USAGE
gtrack() tracks the mouse and prints coordinates in the command line.

clickData = gtrack() will return the click positions in clickData using UIWAIT. Matlab will be in wait mode until the user finishes clicking.

gtrack('newVar') tracks the mouse and creates a new variable in the base workspace called 'newVar' with the click coordinates. This mode does not use UIWAIT.

gtrack([],titleFormat) uses titleFormat as the format string for printing the mouse coordinates in the title.

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
MATLAB Plot Tracing Utility

• MATLAB release: MATLAB 7.1.0 (R14SP3)

[John D'Errico]

Pretty good. A couple of minor quibbles from me.

The author uses global variables here, where a cleaner coding strategy would be to use nested functions, so there was never any real need for globals.

Next, the code returns its result using assignin, which defines a variable called clickData in the base workspace. Sorry, but this a bit of a kludge, and totally unnecessary. What if there just happens to be a variable with that name in your base workspace? (Perhaps from the last time you used this code.) It gets overwritten. What if you wanted to use this function from within another function? Sorry, but this always writes to the base workspace. Instead, the author could have used uiwait and uiresume to allow the function to return a standard matlab argument.

On the good side, this has an H1 line. It has readable help. It offers attribution to a previous code. It looks for when the cursor exceeds the plot limits. The coding style is reasonable, although I'd have liked to see more internal comments.

[José Pina]

Thanks for the suggestions. I hope to submit a new improved entry soon.
I wanted to ask you about the nested function idea. I'm not sure it is possible to use. The point is I'm setting the 'windowbuttonmotionfcn' property of the current figure to 'gtrack(''OnMouseMove'')'. So GTRACK will be called repeatedly by the figure. Between independent calls I'll loose the data. I could alway use persistent instead of global or save the data in the figure handles, but I can't fix it with nested functions. Any suggestion?
Regarding the uiwait, I didn't use it because I wanted to keep the command line active. I know the assignin is dangerous but with the uiwait I might as well just call ginput.
Thanks for the comments once again.

[John D'Errico]

This version allows the user to choose how it will return its results. No more globals, nested functions are cleaner. It now has useful internal comments. Well done - my thanks to José.

[Tom Pilutti]

Beats my own version of this feature that used ginput. I never figured out how to allow user to zoom while function was active. Any possibility for gtrack?

[José Pina]

Tom,
When you use GTRACK, you loose the toolbar zoom button. But if go to the Tools menu and select zoom in, it does work. Zoom as you wish and then go back to the tools menu to disable zooming and reactivate tracking.

[Wendy Luo]

Good work. The program is clear and tidy. Thanks Jose.

[ShyamSundar Baidya]

Thanks for the program.can u help me ?

I want to display some data (left or right) according to the movement of the cursor with respect to current position i.e if the cursor moves left from the current postion i want to display left and same for the right movement.

I thought of storing the value of the previous co-ordinate and compare the X-co ordinate of the current position but i cant store the previous value.Please help me !!

[Furi Andi Karnapi]

Dear Jose, nice work. Thanks for your acknowledgement.

[Tom Richardson]

Hi José.
I have the same challenge as ShyamSundar: classifying the movement of the mouse as left/right. However i also wish to record the times that the cursor moved.
Any ideas?
Cheers!

[PopV Visitkul]

I'm an idiot! Forgot to read the instruction above :-) Nevermind Many thanks again