How to get pointer location as grid point of an axes in matlab guide?

In MATLAB GUIDE, i have a application to place a imgae object on the exact grid point loaction of an axes.

I have a solution to place the object on random loaction on the axes through getting the pointer location from the command " get(0,'PointerLocation')".

For the current application, the pointer location need to be exact grid point of the axes.

Suggest me a solution.

[Jan]

What is an "grid point of the axes"? Which kind of grid do you mean here?

What about using the 'CurrentPoint' of the axes?

[Vinothkumar Sethurasu]

I have prepared a grid mesh on an axes where i need to place number of image objects on the grid intersection point. So i need get the co-ordinates for the grid intersection points.

Or

Do i need to place a data points at the grid intersection locations?

[Jan]

Sorry, I do not understand the explanations. Please post some code or a screen shot, which clarifies, what you need. What does "placing data points" mean? How do you "prepare a gridmesh"?

[Vinothkumar Sethurasu]

>>The grid mesh prepared on create function with these commands.

xlim([0 1]);
ylim([0 0.5]);
set(gca,'Xtick', 0:0.01:1);
set(gca,'Ytick', 0:0.0355:0.5);

>> The blue star is the image object need to be placed on the grid point. the image object is created by buttondown function with these commands,

handles.componentAxis(end)=axes('parent',handles.Sketch_window, ...
    'position',[alpha-0.05 beta-0.04 0.1 0.1]);
matlabImage = imread('D:\Vinoth\star.png');

the alpha & beta values will be calculated from getting the pointer location from - get(0,'PointerLocation') command.

Now, i need to pick the exact grid intersection point to place the star image in a particular interval from the pre-specified grid mesh.

[Vinothkumar Sethurasu]

Hello jan,

Got my explanations?

Is it understandable now?

Answer 1

[Jan]

It is hard to convert the global mouse position on the screen to a position in the axes. Therefore get(0,'PointerLocation') is not useful. The axes contain a 'CurrentPoint' property already, which can be used directly.

I do not understand, why or where you create new axes objects.

what about this example:

function [] = kkkj
AxesH = axes('XLim', [0 1], 'YLim', [0 0.5], ...
             'Xtick', 0:0.01:1, 'Ytick', 0:0.0355:0.5, ...
             'XGrid', 'on', 'YGrid', 'on', ...
             'NextPlot', 'add', ...   % as: hold on
             'ButtonDownFcn', @myAxesClick);
end

function myAxesClick(AxesH, EventData)
P     = get(AxesH, 'CurrentPoint');   % Mouse click position in Axes
XTick = get(AxesH, 'XTick');          % X and Y grid
YTick = get(AxesH, 'YTick');

[~, xm] = min(abs(P(1, 1) - XTick));  % Find nearest X and Y grid point
X = XTick(xm);
[~, ym] = min(abs(P(1, 2) - YTick));
Y = YTick(ym);

plot(X, Y, 'pb', 'MarkerSize', 20);  % Plot a star
end

[Jonas]

nice solution. the part with nearest grid value can also be replaced with the interp1() function with the 'nearest' option

[Jan]

interp1 is not implemented efficiently. This is not a problem, if the code involves a GUI interaction with a user, because waiting for the mouse click is still the bottleneck.

[Vinothkumar Sethurasu]

Thanks a lot.

Its working well for my application.