I have a plot of an image, made with imagesc. I'm developing a workflow where a user can click on the image and interactively overlay a curve. My first issue was that the ButtonDownFcn for the figure is blocked by the image. I worked around this by setting the ButtonDownFcn on the image object instead (and walking back up the parents to get to the figure). Now I'm finding that the curve I'm plotting can also block callbacks intended for the image.
My searches have indicated that I should be able to disable the "hittest" property to prevent the problem, but this has been ineffective for both the image and plotted lines. Suggestions?
Example:
file 1
function testCallback(src,data)
disp('Hello')
file 2
fig = imagesc(rand(100,100));
set(fig,'ButtonDownFcn',#testCallback);
hold on
plot([0 100],[0 100],'m-','linewidth',5,'hittest','off')
Unable to trigger callback when clicking on the line.
You could also set the button down function for the line that you add. Change your plot command to this:
plot([0 100],[0 100],'m-','linewidth',5,'ButtonDownFcn',#testCallback)
Related
I have a very simple GUI made in guide where i have a plot function initiated by a pushbutton which plots a scatter plot in axes (called Method1axes1):
handles.plot = scatter(X,Y, 'parent', handles.Method1axes1);
Now I want the user to be able to click the axes (plot) to get en new larger figure. I tried the below code which is working if i DON'T plot in the axes first. As soon as I run the plot function the scatterplot appears in Method1axes1 but I can no longer click the figure.
% --- Executes on mouse press over axes background.
function Method1axes1_ButtonDownFcn(hObject, eventdata, handles)
figure
scatter(X,Y);
What am I doing wrong?
This is a kind of special case for MATLAB, and it is not extremely well documented.
There are 2 things you need to consider:
1) The most obvious part. When you plot something in your axes, the plot is on the foreground. So when you click on your axes, the top plot intercept that click and tries to process it. You need to disable the mouse click capture from the plot/scatter/image objects you have in your axes. For that, you have to set the HitTest property of your scatter object to 'off'. (recent MATLAB version have changed the name of this property, it is now called PickableParts).
2) Much less obvious and documented. It used to be in the doc for the axes ButtonDownFcn callback but it is not explained anymore (although the behaviour persist). This is what I could find on old forums:
When you call PLOT, if the axes NextPlot property is set to 'replace'
(which it is by default) most of the properties of the axes (including
ButtonDownFcn) are reset to their default values.
Change the axes NextPlot property to 'replacechildren' to avoid this,
or set the ButtonDownFcn after calling PLOT, or use the low-level LINE
function instead of the higher-level PLOT function.
This is also discussed and explained here: Why does the ButtonDownFcn callback of my axes object stop working after plotting something?
For your case, I tried set(axe_handle,'NextPlot','replacechildren') and it works ok to let the mouse click reach the ButtonDownFcn, but unfortunately it creates havoc with the axes limits and LimitModes ... so I opted for the second solution, which is to redefine the callback for ButtonDownFcn after every plot in the axes.
So in summary, your code for the pushbutton1_Callback should be:
function pushbutton1_Callback(hObject, eventdata, handles)
% Whatever stuff you do before plotting
% ...
% Plot your data
handles.plot = scatter(X,Y, 'parent', handles.Method1axes1);
% Disable mouse click events for the "scatterplot" object
set(handles.plot,'HitTest','off') ;
% re-set the "ButtonDownFcn" callback
set(handles.Method1axes1,'ButtonDownFcn',#(s,e) Method1axes1_ButtonDownFcn(s,e,handles) )
And for your axes mouse click event, you might as well keep the handle of the new generated objects:
function Method1axes1_ButtonDownFcn(hObject, eventdata, handles)
handles.newfig = figure ;
handles.axes1copy = copyobj( handles.Method1axes1 , handles.newfig ) ;
Note that instead of plotting a new set, I simply use the copyobj function, very handy when you need to reproduce a plot.
Illustration:
If you want to set the figure/graph to enlarge and shrink on mouse
scroll/click, then just set the zoom property of the required axes in
OpeningFcn within the m file.
For example within the OpeningFcn in the GUI's m file, put the below code. Please ensure that you put the below code within the OpeningFcn function.
h1 = zoom(handles.Method1axes1);
h1.Enable = 'on';
Now, on each mouse scroll/click, you would be able to zoom in/out the graphs.
A sample screenshot of openingFcn for a GUI named ZoomAxesDemo is given below.
I have a GUI with two axes. The first one for original image while the second one is for interpolated image.
First in my code, I use imrect to select part of the original image and then I crop that part using imcrop . After that I display the cropped image in both axes.
What I want is to know how to zoom in the first axes (the original image) and it shows the same zooming the second axes ( interpolated image ) automatically.
Thanks a lot in advance.
It is not clear the relationship between the two actions you mention in your question:
using imrect and imcrop to work on the image
zooming on one axes and have the same zoom on the second
A possible solution to automatically apply the zoom made on the first axes to the second one could be using the linkaxes built-in function.
If in your GUI you have two axex with, respectively, tag axes1 and axes2, you can add the following statements in the GUI OpeningFcn
linkaxes([handles.axes1 handles.axes2])
This allows automatically applying the zoom you make on axes1 also to axes2.
Hope this helps.
I have used drawnow to draw the characters of the mnist dataset.. which outputs the following output
when i created GUI with matlab and calling drawnow to display images after loading it draws the figure on the open window giving the following output
my question is how to force it to draw in new window ?
drawnow only asks Matlab to flush the event queue and update figure windows; it doesn't determine how and where things are plotted. It's hard to tell since you don't include any code, but in your case it looks like you just plot the character images and the GUI elements into the same figure.
You can control which figure window a graphics operation refers to by setting the "current figure", whose handle is always contained in the variable gcf (graphics: current figure).
You generate a new figure and make it current by calling
figure
If you want to later make this figure current again, you need to save its handle:
fa = figure;
You then make a figure with a given handle current again by
figure(fa)
Some rough sketch of a possible program:
% generate figure windows
fa = figure;
fb = figure;
% plot something in figure a and make the screen update
figure(fa)
plot(...)
drawnow
% put a UI element into figure b and make the screen update
figure(fb)
uicontrol(...)
drawnow
I have a piece of code that is 300 lines long. There is 3 different instances of imshow throughout the code that displays figures as the code is run..
The GUI I am creating will be very simple. Currently I have a push button that initiates the m file.
I am trying to get the images to be displayed within the GUI that I am creating and not in separate Figure windows.
I have being looking at tutorials online but cant get a quick fix for my problem, they all get a bit convoluted and I cant figure out what exactly to do.
I have 3 axis inserted onto the GUI, In the "view callbacks" for each axis I can createfcn, deletefcn and buttonDownFcn. When I createFcn it gives me a hint to "place code in OpeningFcn to populate axes1" in the auto generated code.
I have tried to do this but I am not able to find the correct place to write the code.
Can somebody tell me if I am going in the correct direction or if I have it wrong.
Thanks
In order to display these images, you need to declare the parent in imshow. The parent is what you want to act as the canvas for your image, and in your case will be an axes.
I created a very simple gui with three axes and a push button. MATLAB named my axes axes1, axes2 and axes3. Guide saves the handles to these axes so that you can interact with them throughout your gui code. For example, you mentioned the opening function... here is mine with a call to imshow (the only lines I added were the last three ones):
% --- Executes just before myGUI is made visible.
function myGUI_OpeningFcn(hObject, eventdata, handles, varargin)
% Choose default command line output for myGUI
handles.output = hObject;
% Update handles structure
guidata(hObject, handles);
% UIWAIT makes myGUI wait for user response (see UIRESUME)
% uiwait(handles.figure1);
imshow('myImage1.png', 'Parent', handles.axes1)
imshow('myImage2.png', 'Parent', handles.axes2)
imshow('myImage3.png', 'Parent', handles.axes3)
Notice that I can grab the handles of my axes and then declare them to be the parents for the results of my imshow call.
If you're not sure what the names of your handles are, you can check in the GUI editor by right clicking, looking at the property inspector, and the tag property.
If you want to perform a similar operation for when you click on your pushbutton, right click on the button in the editor, and click on View Callbacks -> Callback, and you can add your imshow code there.
Good luck.
If I understand correctly you just want your images to appear in the axes instead of a figure. Try setting the focus to the axes itself before showing the image.
axes(1);%you may need to change the one to your axes handle.
imagesc(imageToBeDisplayed);
axes(2);
imagesc(secondImage);
axes(3);
imagesc(thirdImage);
This way before you call imagesc you make sure your program knows where to send the image. Otherwise it may just create a figure.
I have a project of "Optical Character Recognition" in MATLAB and i need your help:
how do i recognize when the user press the mouse on an image?
i trying to do this with ButtonDownFcn but even when i just printing message
the message is not printed.
i want to allow the user to select the license plate from the image.
how can i do this and save the Pixels of the selected area?
thanks in advance.
Addressing your two questions:
I'm guessing that you are trying to set the 'ButtonDownFcn' of the figure window, which won't work how you expect it to. If you want to do something when the user clicks on an image, you should make sure that you're setting the 'ButtonDownFcn' of the image, and not the figure window or the axes object. Note this line in the figure property documentation (emphasis added by me):
Executes whenever you press a mouse button while the pointer is in the figure window, but not over a child object (i.e., uicontrol, uipanel, axes, or axes child).
This is why you have to set a 'ButtonDownFcn' for each object you want it to work for. Setting it for the figure window won't make it work automatically for each object in the figure. Here's an example that sets the 'ButtonDownFcn' for the figure and an image object:
img = imread('peppers.png'); %# Load a sample image
hFigure = figure; %# Create a figure window
hImage = image(img); %# Plot an image
set(hFigure,'ButtonDownFcn',... %# Set the ButtonDownFcn for the figure
#(s,e) disp('hello'));
set(hImage,'ButtonDownFcn',... %# Set the ButtonDownFcn for the image
#(s,e) disp('world'));
Notice how clicking inside and outside the image displays a different message, since each calls the 'ButtonDownFcn' for a different object. Notice also that if you click on the tick mark label of one of the axes, nothing is displayed. This is because the axes object has its own 'ButtonDownFcn', which wasn't set to anything.
If you have access to the Image Processing Toolbox you can use the function IMFREEHAND to have the user draw an ROI (region of interest) in the image. Then you can use the createMask method to create a binary mask of the image with ones for pixels inside the ROI and zeroes for pixels outside the ROI.