带有 addlisteners 的多个 GUI 点

Question

我有一个 GUI，用户可以在其中单击一个按钮来创建一个点。此点用于测量（即计算它与另一个静态点之间的距离）。

    function pushbutton1_Callback(hObject, eventdata, handles)

    a = handles.calciter; % This iterates for each time pushbutton is pressed.

    mypoint = drawpoint(handles.axes1);

    handles.el = addlistener(mypoint, 'ROIMoved', @mypointmoved_Callback);

因此，如果我的 pushbutton1 创建另一个点；我怎样才能得到它，所以每个点都有多个 addlistener？

我需要多个 handles.el 吗？

如果有兴趣，我的包含更多信息。

Answer 1

继续我之前的回答...

为每个新点添加一个监听器。
你不需要有多个handles.el，你可以忽略el，因为你根本不用它。
您可以存储创建点的句柄数组（如果需要）。
您可以将点的索引存储在mypoint.UserData中（如果需要的话）。
在监听器的回调中，可以从数组中获取任意一个点，也可以查看触发事件的点的索引。

这里是代码的相关部分（请阅读评论）：

% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
axes(handles.axes1);

mypoint = drawpoint;

%Add event listenr to every point
%if ~isfield(handles, 'el')
addlistener(mypoint, 'ROIMoved', @mypointmoved_Callback);
%end

%Save an array of handles to created points:
if ~isfield(handles, 'mypoints')
    mypoint.Color = [0.7410, 0.2, 0]; %First point has a different color.
    handles.mypoints = mypoint; %Add first point.

    %Distance from the first added point.
    handles.distx = 0;
    handles.disty = 0;
    set(handles.edit1, 'String', '0'); %Display the distance from the first added point.
else    
    handles.mypoints(end+1) = mypoint; %Add a new point to the end of the array
end

points_counter = length(handles.mypoints); %Number of points - use as "Point serial number".
mypoint.UserData = points_counter; %Store the index of the point in UserData property

% Update handles structure
guidata(hObject, handles);


function mypointmoved_Callback(src, eventData)
handles = guidata(src.Parent); %Get the handles using the parent of the point (the axes).

if src.UserData == 1
    %Example for using the index of the point stored in UserData property.
    set(handles.edit1, 'String', '0');
    return;
end

px = src.Position(1);
py = src.Position(2);

%Get the first point that added by the user 
p0 = handles.mypoints(1);

%Get the x,y position of the first point that added by the user
p0x = p0.Position(1);
p0y = p0.Position(2);

%Compute the distance from p0:
distx = abs(px - p0x);
disty = abs(py - p0y);

handles.distx = distx;
handles.disty = disty;

dist = norm([distx, disty]); %Euclidean distance

%Display the euclidean distance from p0.
set(handles.edit1, 'String', num2str(dist));
drawnow

该示例显示用户移动的点到第一个（用户）添加的点的欧式距离。

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