MATLAB制作GUI—GUI中图像坐标的获取③（回调函数实现）

今天，将介绍GUI中获取图像坐标的最后一种方法—通过axes坐标轴的回调函数实现坐标的获取。

今天使用的回调函数是axes中的ButtonDownFcn函数，当鼠标在axes中点击时，MATLAB就会调用ButtonDownFcn函数。

下面是该GUI的gif图：

下面贴出实现代码：

function varargout = Getposition3(varargin)
% GETPOSITION3 MATLAB code for Getposition3.fig
%      GETPOSITION3, by itself, creates a new GETPOSITION3 or raises the existing
%      singleton*.
%
%      H = GETPOSITION3 returns the handle to a new GETPOSITION3 or the handle to
%      the existing singleton*.
%
%      GETPOSITION3('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in GETPOSITION3.M with the given input arguments.
%
%      GETPOSITION3('Property','Value',...) creates a new GETPOSITION3 or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before Getposition3_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to Getposition3_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help Getposition3

% Last Modified by GUIDE v2.5 14-Apr-2019 12:00:42

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @Getposition3_OpeningFcn, ...
                   'gui_OutputFcn',  @Getposition3_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT


% --- Executes just before Getposition3 is made visible.
function Getposition3_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to Getposition3 (see VARARGIN)

% Choose default command line output for Getposition3
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes Getposition3 wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = Getposition3_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;


% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
pic = imread('trees.tif');
handles.im = imshow(pic);
axis on
axes(handles.axes1);
set(handles.im,'Pickableparts','none');
set(handles.axes1,'ButtonDownFcn',@mycallbackfcn);

function mycallbackfcn(hObject,eventdata,handles)
handles = guidata(hObject);
pos = get(hObject,'Currentpoint');
set(handles.edit1,'string',pos(1,1));
set(handles.edit2,'string',pos(1,2));

function edit1_Callback(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit1 as text
%        str2double(get(hObject,'String')) returns contents of edit1 as a double


% --- Executes during object creation, after setting all properties.
function edit1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end



function edit2_Callback(hObject, eventdata, handles)
% hObject    handle to edit2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit2 as text
%        str2double(get(hObject,'String')) returns contents of edit2 as a double


% --- Executes during object creation, after setting all properties.
function edit2_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end


% --- Executes during object creation, after setting all properties.
function pushbutton1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

 一开始实现这个功能的时候，自己没有发现这种方式实现，后面是在师兄的指导下实现的，其中最重要的就是设置图像显示句柄中的Pickableparts参数。

其中Pickableparts参数是确实对象是否捕获鼠标点击，同时HitTest参数是确定对象是否响应鼠标点击或将其传递给最近的父级。

下面是这两个参数设置时实现的功能：

 具体详情请看MATLAB公司的帮助文档：https://ww2.mathworks.cn/help/matlab/creating_plots/capturing-mouse-clicks.html

通过这种方法实现虽然比前两种方法都要好，但是还是存在一些缺点：

①因为使用的是axes的回调函数，因此axis必须打开，当使用imshow函数时，必须使用axis on将axis打开（imshow默认关闭axis），而使用imagesc时axis默认打开；

②从gif图中可以看出当获取图像外的坐标区域时同样也可以获取坐标信息，因为坐标区域仍然也是axes区域。

---------------------------------------------------------------------------------------------------------------------

虽然这三种方法都可以获取GUI图像上的坐标，但是都存在缺点，如果大家有更好的办法，希望能分享，最后祝大家在学习的道路上一帆风顺~