I created a uitable (new version using appdesigner) in MATLAB and wanted to support right clicking on cells and showing a cell specific context menu. Much to my surprise there seemed to be no way to support this.
The context menu only seems to trigger with right click on the uitable, but there is no way of knowing which cell was selected (I think, maybe not?). I created a workaround where I left clicked to select a cell, and during that selection I right clicked using a Java Mouse robot to trigger the context menu. This is super ugly but sort of works. Except, if you need to bring up the menu twice on the same cell. Apparently the cell selected callback only fires once for the cell, until a new cell is selected. I tried literally putting two tables in the same spot and upon selecting one toggling to the other, but the memory of cell selection is table specific, so this only worked for two clicks before both tables had been clicked on the same cell, and toggling visibility back to the first resulted in the cell selection callback not firing (since the cell had not changed) . I tried various approaches to try and deselect the cell (disable/enable, visibility change, data change, etc.), but the cell selection callback never changed.
I even tried having duplicate columns, where the goal was to hide a column, where normally columns 1 and 2 would be visible (column 3 out of view due to size), and then on clicking on column 2, column 2 would hide itself (0 width) and column 3 (an exact duplicate) would move into its place, thus seeming to the user like multi-clicking was supported. Unfortunately I can't set the column width to 0 -- or rather, setting it to 0 doesn't completely hide the column. Instead there seems to be some minimal width to the column and the whole thing looked awful.
I wanted to do something similar with a listbox (right click support), but again I couldn't figure out how to identify where I was right clicking. I eventually settled on left clicking on a listbox and using the mouse robot approach to right click to bring up the context menu. Unlike the uitable, it was fairly easy to clear the selection on the listbox (set listbox.Value = {}). However, I strongly dislike the left click instead of right click approach and I'd rather have multiple columns.
Any suggestions would be much appreciated!!!
Edit, for R2023b and newer you should use InteractionInformation from the event object passed to when a menu is launched. See here for more info:
https://www.mathworks.com/help/matlab/ref/uicontextmenu.html#mw_c3c8080d-01ad-48ab-9c13-416405690017
Old Solution
So I found an approach that is better than using a robot. I had tried this but was missing a critical portion which I will describe below.
Upon selecting a row in the table, the open command can be used to launch a context menu. My problem was that I didn't know where to launch the menu. I tried CurrentPoint for the figure, but it was 0,0 (or in general not valid)
Here's the current documentation for CurrentPoint:
Current point, returned as a two-element vector. The vector contains the (x, y) coordinates of the mouse pointer, measured from the lower-left corner of the figure. The values are in units specified by the Units property.
The coordinates update when you do any of the following:
Press the mouse button within the figure.
Release the mouse button after pressing it within the figure.
Press the mouse button within the figure, and then release it outside the figure.
Rotate the scroll wheel within the figure.
Move the mouse within the figure (without pressing any buttons), provided that the WindowButtonMotionFcn property is not empty.
If the figure has a callback that responds to mouse interactions, and you trigger that callback faster than the system can execute the code, the coordinates might not reflect the actual location of the pointer. Instead, they are the location when the callback began execution.
If you use the CurrentPoint property to plot points, the coordinate values might contain rounding error.
Here's the critical line again:
"Move the mouse within the figure (without pressing any buttons), provided that the WindowButtonMotionFcn property is not empty."
So when a selection of a cell happens, the CurrentPoint is not valid. However, if we simply define a WindowButtonMotionFcn, then it is!
So the general idea is to have a callback for the table when a cell is selected (SelectionChangedFcn) and to set a dummy callback for WindowButtonMotionFcn
The final point is that a context menu can be launched with the open function if you specify a given location to launch it at. This is different from attaching it to an object and having it automatically launch on right click.
Here's some example code. If you comment out the callback for windows motion then the whole thing doesn't work! Unfortunately it is a left click for targeting the cell but at least it avoids the non-sense I was using with a java robot right click.
classdef wtf < handle
properties
h %struct, this was an appdesigner handle
cm %context menu
end
methods
function obj = wtf()
h = struct;
h.UIFigure = uifigure();
h.UITable = uitable(h.UIFigure);
obj.h = h;
obj.h.UITable.CellSelectionCallback = @obj.tableCall;
%obj.h.UITable.SelectionChangedFcn = @obj.tableCall;
%Some data ...
s = struct;
s.a = (1:4)';
s.b = (5:8)';
obj.h.UITable.Data = struct2table(s);
%Our context menu
cm = uicontextmenu(obj.h.UIFigure);
m = uimenu(cm,'Text','Menu1');
obj.cm = cm;
%WTF ... without this we don't get a valid CurrentPoint
obj.h.UIFigure.WindowButtonMotionFcn = @obj.mouseMove;
end
function tableCall(obj,x,y)
%y - event info
%x - impacted object
cp = get (obj.h.UIFigure, 'CurrentPoint');
open(obj.cm,cp(1),cp(2));
selected_cell = y.Indices;
%selected_cell = y.Selection;
x.Selection = []; %allows reselecting same cell without
%needing to select another cell first
%Now we can run something on the context menu
%that targets the selected cell
end
function mouseMove(obj,x,y)
%we could store a point here
end
end
end