MATLAB制作GUI（6）—GUI中图像座标获取①（ginput）

前几天在用MATLAB写GUI软件的过程中遇到了一些问题，在这里分享一下，今天先讲一下第一个问题就是GUI中图像座标的获取，今天先介绍第一个方法：ginput函数实现座标的获取。

其实ginput函数就是获取鼠标或者光标的图像输入，可以获取图像上的座标位置以及按键属性，具体使用方法见MATLAB公司的帮助文档，里面介绍很详细：

下面是GIF图GUI的实现代码：

function varargout = Getposition(varargin)
% GETPOSITION MATLAB code for Getposition.fig
%      GETPOSITION, by itself, creates a new GETPOSITION or raises the existing
%      singleton*.
%
%      H = GETPOSITION returns the handle to a new GETPOSITION or the handle to
%      the existing singleton*.
%
%      GETPOSITION('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in GETPOSITION.M with the given input arguments.
%
%      GETPOSITION('Property','Value',...) creates a new GETPOSITION or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before Getposition_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to Getposition_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 Getposition

% Last Modified by GUIDE v2.5 08-Apr-2019 13:13:02

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @Getposition_OpeningFcn, ...
                   'gui_OutputFcn',  @Getposition_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 Getposition is made visible.
function Getposition_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 Getposition (see VARARGIN)

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

% Update handles structure
guidata(hObject, handles);

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


% --- Outputs from this function are returned to the command line.
function varargout = Getposition_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)
[pathname filename] = uigetfile({'*.jpg';'*.*'});
if isequal(filename,0)
    warning off
    imshow('trees.tif')
else
    str = [pathname,filename];
    pic = imread(str);
    imshow(pic)
end
axes(handles.axes1)
while(1)
    [x,y] = ginput();
    set(handles.edit1,'string',x);
    set(handles.edit2,'string',y);
end

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

该方法虽然实现简单，但是存在问题：

①十字光标于整个figure界面显示，不美观；

②可以获取图像显示区域以外的座标，不符合使用要求；

③使用死循环进行不断获取座标，而死循环具有一定的风险性；

因此，后面将介绍其他方法获取GUI图像上的座标信息，大家可以根据使用情况选择获取方法~