Creating a mouse down event specific to an axes1 component only

I am using the following to allow the user to use the mouse press to draw a marker on an image loaded to an axes component (axes1). There are other axes also on my GUI, and I want to be able to constrain this mouse action only if the mouse is over axes 1. Currently it also draws a marker when over other axes.

I put this in the opening function.

    set(gcf, 'WindowButtonDownFcn', @getMousePositionOnImage);

And then use this function for the mouse click.

function getMousePositionOnImage(src, event)

handles = guidata(src);
cursorPoint = get(handles.axes1, 'CurrentPoint');
curX = cursorPoint(1,1);
curY = cursorPoint(1,2);

%check if mouse clicked outside of axes component
xLimits = get(handles.axes1, 'xlim');
yLimits = get(handles.axes1, 'ylim');

if (curX<min(xLimits)) (curX==min(xLimits))
end
if (curX>max(xLimits)) (curX==max(xLimits))
end
if (curY<min(yLimits)) (curY==min(yLimits))
end
if (curY>max(yLimits)) (curY==max(yLimits))
end

x=round(curX)
y=round(curY)
setappdata(0,'curX',x);
setappdata(0,'curY',y);

%Remove previous marker if present
delete( findobj(gca, 'type', 'line') );
hold on
plot(x,y,'ro','MarkerSize',10,'LineWidth',2)
hold off;

IMG = getimage(handles.axes1);
delta=50;
if (x<delta+1)|| (y<delta+1)
  ROI = IMG(1:delta, 1:delta,:);    % This is the ROI (indexing is (ymin:ymax, xmin:xmax)
else
  ROI = IMG(y-delta:y+delta, x-delta:x+delta,:);    % This is the ROI (indexing is (ymin:ymax, xmin:xmax)
end

%Now take a ROI around the marker position (i.e. where mouse is clicked) 
%and draw in axes 3
axes(handles.axes3)
cla
[high,low]=Autoscaleimage(handles,ROI,3);
imshow(ROI,[low,high]);
hold on
plot(delta+1,delta+1,'ro','MarkerSize',10,'LineWidth',2);
hold off

[Jason]

This seems to work:

if (curX>min(xLimits)&&curX<max(xLimits)&&curY>min(yLimits)&&curY<max(yLimits))

was wondering if there was a more direct way to say if mouse over axes1?

Answer 1

[Geoff Hayes]

Jason - in the OpeningFcn of your GUI, assign the getMousePositionOnImage to the axes and not the figure. Try the following

 set(handles.axes1,'ButtonDownFcn',@getMousePositionOnImage);

When I try the above on OS X 10.9.5 with MATLAB R2014a, the getMousePositionOnImage only fires when I press the mouse button down within the axes.

[Jason]

hmm...I get the following error:

Error using matlab.graphics.axis.Axes/set
There is no WindowButtonDownFcn property on the Axes class.

Error in Generic_Image_Capture>Generic_Image_Capture_OpeningFcn (line 86)
set(handles.axes1, 'WindowButtonDownFcn', @getMousePositionOnImage);

[Geoff Hayes]

Jason - remove Window from WindowButtonDownFcn. The callback that you are assigning to is 'ButtonDownFcn'.

[Jason]

After doing this, there is no action when I click on axes1? do I need to change the arguments on the function:

function getMousePositionOnImage(src,event)

[Geoff Hayes]

Jason - you don't need to change the function inputs. Please see the attached example.

[Jason]

Thanks Geoff, but when I include

cursorPoint = get(handles.axes1, 'CurrentPoint')
curX = cursorPoint(1,1)
curY = cursorPoint(1,2)

in your code, this doesn't work,

Undefined variable "handles" or class "handles.axes1".

Im sorry about this!

[Geoff Hayes]

Jason - isn't hObject the handle to the axes1 since this callback will only fire for this control? If not try getting the handles structure using

 handles = guidata(hObject);
 cursorPoint = get(handles.axes1, 'CurrentPoint')
 curX = cursorPoint(1,1)
 curY = cursorPoint(1,2)

[Jason]

It works whilst there is nothing added to axes 1, as soon as I load a tiff image to it, then it stops working.

[Jason]

I've come across this nice method:

axes(handles.axes1)
imageHandle = imshow('MyImage.tif');
set(imageHandle,'ButtonDownFcn',@ImageClickCallback);

function ImageClickCallback ( objectHandle , eventData )
axesHandle  = get(objectHandle,'Parent');
coordinates = get(axesHandle,'CurrentPoint'); 
coordinates = coordinates(1,1:2);
curX = coordinates(1,1);
curY = coordinates(1,2);

%Now plot a smaller part of the image on another axes:
IMG=getimage(objectHandle);

%  IMG = imageHandle ;
  delta=50;
  if (x<delta+1)|| (y<delta+1)
      ROI = IMG(1:delta, 1:delta,:);    % This is the ROI (indexing is (ymin:ymax, xmin:xmax)
  else
      ROI = IMG(y-delta:y+delta, x-delta:x+delta,:);    
  end

    axes(handles.axes3)
    cla
    imshow(ROI,[]);
    hold on
    plot(delta+1,delta+1,'ro','MarkerSize',10,'LineWidth',2);
    hold off

end

If I want to go and plot something on another axes (i.e. handles.axes3) as shown in the code, Im struggling to get the handles of this component.

How can i make access other axes components within this ImageClickCallback?

[Jason]

it seems If I include handles as an argument in the function above, and then update the handles structure it works:

set(imageHandle,'ButtonDownFcn',@ImageClickCallback, handles);

and

function ImageClickCallback (objectHandle , eventData, handles)
handles = guidata(objectHandle)

[Geoff Hayes]

Jason - when you pass the handles structure as an input to the callback as

 set(imageHandle,'ButtonDownFcn',@ImageClickCallback, handles);

it is the copy of handles at the time of when this callback is assigned that will always be passed into this function. If you wish to get the most up-to-date handles structure every time your callback fires then just do

 function ImageClickCallback (objectHandle , eventData)
 handles = guidata(objectHandles)
 % etc.

[Jason]

But then i cannot make plots on another axes component unless i include handles as an argument

[Geoff Hayes]

Yes you can with

 handles = guidata(objectHandles)

which gives you the structure of handles to all other controls within the GUI. Look closer at what you were doing with your code

 function ImageClickCallback (objectHandle , eventData, handles)
 handles = guidata(objectHandle)

You are passing handles as the third input to the above callback only to overwrite it with the first line of code, so passing in this object is unnecessary.

[Jason]

Yes your right, thanks for all your help. Jason