Matlab 实现GUI界面相应鼠标事件

和C++平台一样，MATLAB也能在GUI设计中写入鼠标事件

**功能：**拖动鼠标左键时，在Axes区域画线，松开时不画，再次点击时画线…

少数几个需要用到的函数和属性
·WindowButtonDownFcn回调函数
·Selectiontype属性（判断单击/双击，左键/右键）
·Normal左键单击
·Alt右键单击（Ctrl+左键）
·Open双击
·Extend中键（Shift+左键）

由于Line对象的父对象为Axes，故而在GUI界面中添加一个Axes对象。

首先需要判断：
1：我们是否按下了鼠标左键
:2：然后在WindowsButtonMotionFcn回调函数中来选择是否绘制曲线。

由于WindowButtonFcn和WindowButtonMotionFcn是两个不同的回调函数，它们之间的信息需要共享（如判断鼠标是否按下），可以使用全局变量global …

打开WindowButtonFcn的回调函数，判断是否按下了鼠标左键，通过窗口的SelectionType属性判断鼠标左键的行为，以全局变量global将（是否按下了鼠标左键）的信息传递出去。

按下鼠标左键，SelectionType值为normal

为了下一次在移动鼠标时可以绘制坐标曲线，因此需要将当前鼠标左键移动的位置记录下来，可以使用Axes的CurrentPoint属性，并将该句柄pos1保存到全局变量（后续也会用到）

pos1 = get(handles.axes1,'CurrentPoint');

该回调函数的代码为：

function figure1_WindowButtonDownFcn(hObject, eventdata, handles)
% hObject    handle to figure1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global ButtonDown  ;
if strcmp(get(gcf,'SelectionType'),'normal')
    ButtonDown = 1;
    pos1 = get(handles.axes1,'CurrentPoint');
end

然后添加界面的鼠标移动响应函数

通过全局变量ButtonDown判断是否按下了鼠标左键，按下了为1，并记录当前鼠标的位置。

然后绘制一一条线宽为4的曲线

如下为绘图的第一个点：

linr([pos1(1,1) pos(1,1)],[pos1(1,2) pos(1,2)],'LineWidth',4);

在下一次响应鼠标的移动函数时，上次响应时鼠标所处的位置为绘画位置的初始点

pos1 = pos ;

然后在OpeningFcn中定义全局变量并且初始化为空

function Mouse_line_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 Mouse_line (see VARARGIN)
  
global ButtonDown ps1
ButtonDown=[];
ps1=[];

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

% Update handles structure
guidata(hObject, handles);

运行结果：

能绘图，但是无法停下，鼠标移动，曲线跟着到处跑

原因：
没有设置松开鼠标时的回调函数

解决方法：
设置松开鼠标左键WindowButtonUpFcn的操作的回调函数

松开鼠标的回调函数：

function figure1_WindowButtonUpFcn(hObject, eventdata, handles)
% hObject    handle to figure1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global ButtonDown
ButtonDown = 0;

运行结果：

附上全代码：

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

% Last Modified by GUIDE v2.5 22-Oct-2020 15:06:51

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @Mouse_line_OpeningFcn, ...
                   'gui_OutputFcn',  @Mouse_line_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 Mouse_line is made visible.
function Mouse_line_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 Mouse_line (see VARARGIN)
  
global ButtonDown ps1
ButtonDown=[];
ps1=[];

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

% Update handles structure
guidata(hObject, handles);

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


% --- Outputs from this function are returned to the command line.
function varargout = Mouse_line_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 mouse press over figure background, over a disabled or
% --- inactive control, or over an axes background.
function figure1_WindowButtonDownFcn(hObject, eventdata, handles)
% hObject    handle to figure1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global ButtonDown  pos1;
if strcmp(get(gcf,'SelectionType'),'normal')
    ButtonDown = 1;
    pos1 = get(handles.axes1,'CurrentPoint');
end


% --- Executes on mouse motion over figure - except title and menu.
function figure1_WindowButtonMotionFcn(hObject, eventdata, handles)
% hObject    handle to figure1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global ButtonDown  pos1;

if ButtonDown==1
    pos=get(handles.axes1,'CurrentPoint');
    line([pos1(1,1) pos(1,1)],[pos1(1,2) pos(1,2)],'LineWidth',4);
    pos1 =pos;
end


% --- Executes on mouse press over figure background, over a disabled or
% --- inactive control, or over an axes background.
function figure1_WindowButtonUpFcn(hObject, eventdata, handles)
% hObject    handle to figure1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global ButtonDown
ButtonDown = 0;

===OVER

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