Chapter 8. MATLAB图形用户界面设计

题目来自《MATLAB程序设计与应用》第二版 刘卫国 Chapter 8 MATLAB图形用户界面设计

课后习题解答

1. 图形窗口与坐标轴

课堂讨论 在同一图形窗口建立两个坐标轴

分别用axes函数和axis函数在同一图形窗口建立两个坐标轴。例如，建立水平放置的两个坐标轴如图所示。

要求左边坐标轴用默认属性，坐标轴标题为“坐标轴1”；右边坐标轴的 x 轴范围为 $[-\pi ,\pi ]$，y 轴范围为 $[-1,1]$ ，坐标轴标题为“坐标轴2”。
（1）用axes函数实现。
（2）用axis函数和subplot函数实现。

% (1) axes
figure(811)
ax1 = axes('Position',[0.05 0.1 0.4 0.8]);
ax1.Title.String = '坐标轴1';
ax2 = axes('Position',[0.55 0.1 0.4 0.8], ...
    'XLim', [-pi, pi], 'YLim', [-1, 1]);
ax2.Title.String = '坐标轴2';
% (2) axis, subplot
figure(812)
subplot(1, 2, 1)
title('坐标轴1')
subplot(1, 2, 2)
axis([-pi, pi, -1, 1])
title('坐标轴2')

2. 曲线与曲面对象

课堂讨论1 plot函数和line函数比较

请比较用plot函数和line函数在同一坐标轴绘制多条曲线的方法。在同一坐标轴绘制 $y=\sin x$ 和 $y=\cos x$，其中 $x\in [0,2\pi ]$。要求正弦曲线用蓝色实线，余弦曲线用绿色虚线。

课堂讨论2 surf函数和surface函数比较

请比较用surf函数和surface函数在同一坐标轴绘制多个曲面的方法。在同一坐标轴绘制以下两个曲面。

% (1) plot函数与line函数比较
x = linspace(0, 2*pi);
figure(8211)
plot(x, sin(x), 'b-', x, cos(x), 'g--')
title('plot函数')
figure(8212)
line(x', sin(x'), 'Color', 'b', 'LineStyle', '-')
line(x', cos(x'), 'Color', 'g', 'LineStyle', '--')
title('line函数')
% (2) surf函数与surface函数比较
[u, v] = meshgrid(-2:0.1:2, -3:0.1:3);
[x, y] = meshgrid(-2:0.1:2, -3:0.1:3);
figure(8221)
subplot(1, 2, 1)
surf(u.^2/2, u, v);
title('曲面(1):(u^2/2, u, v)'); xlabel('x'); ylabel('y'); zlabel('z');
subplot(1, 2, 2)
surf(x, y, x.*y.*exp(-x.^2-y.^2));
title('曲面(2):(x, y, xye^{-x^2-y^2})'); xlabel('x'); ylabel('y'); zlabel('z');
figure(8222)
subplot(1, 2, 1)
surface(u.^2/2, u, v);
title('曲面(1):(u^2/2, u, v)'); xlabel('x'); ylabel('y'); zlabel('z');
subplot(1, 2, 2)
surface(x, y, x.*y.*exp(-x.^2-y.^2));
title('曲面(2):(x, y, xye^{-x^2-y^2})'); xlabel('x'); ylabel('y'); zlabel('z');

3. 图形用户界面设计方法

课堂讨论 分析执行结果

建立如图所示的图形窗口。

若在“绘图1”按钮的回调函数体中添加以下代码：

x=0:pi/50:2*pi；
plot(x, sin(x),'r')
hd=line(x, cos(x))；
hd.Color='b';

在“绘图2”按钮的回调函数体中添加以下代码：

x=0:pi/50:2*pi;
hd=line(x, cos(x));
hd.Color='b';
plot(x, sin(x),'r')

运行该图形窗口，分别单击这两个按钮，绘出的图形是否一样？分别是什么曲线？

S.f = figure(83); 
S.ax = axes('Position',[0.2 0.25 0.6 0.6]); 
S.bl = uicontrol('style','push',...
                 'units','normalized',...
                 'position',[0.25 0.05 0.2 0.1],...
                 'fontsize',14,...
                 'string','绘图1',...
                 'callback',{@bl_call,S});
S.br = uicontrol('style','push',...
                 'units','normalized',...
                 'Position',[0.55 0.05 0.2 0.1],...
                 'fontsize',14,...
                 'string','绘图2',...
                 'callback',{@br_call,S});

function bl_call(varargin)
    S = varargin{3};  % Get the structure.
    S.ax();
    x = 0 : pi/50 : 2*pi;
    plot(x, sin(x),'r');
    hd = line(x, cos(x));
    hd.Color='b';
end

function br_call(varargin)
    S = varargin{3};  % Get the structure.
    S.ax();
    x = 0 : pi/50 : 2*pi;
    hd = line(x, cos(x));
    hd.Color='b';
    plot(x, sin(x),'r');
end

4. 用户界面设计工具

课堂讨论 建立图形用户界面的方法

分别用命令和用GUIDE工具建立一个图形用户界面。界面中包含一个坐标轴和一个“绘图”按钮，按钮的Tag属性为BtPlot。运行该用户界面，单击“绘图”按钮，在坐标轴绘制正弦曲线。比较两种方式的回调函数的定义方法。

% (1) 命令工具
S.f = figure; 
S.ax = axes('Position',[0.15 0.25 0.7 0.7]);
S.btplot = uicontrol('style','push',...
                 'units','normalized',...
                 'tag', 'BtPlot',...
                 'position',[0.4 0.05 0.2 0.1],...
                 'fontsize',14,...
                 'string','绘图',...
                 'callback',{@BtPlot_call,S});
% (2) GUIDE 工具
gui_plot;

function varargout = gui_plot(varargin)
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @gui_plot_OpeningFcn, ...
                   'gui_OutputFcn',  @gui_plot_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
 
function gui_plot_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
guidata(hObject, handles);
 
function varargout = gui_plot_OutputFcn(hObject, eventdata, handles)
varargout{1} = handles.output;
 
function BtPlot_Callback(hObject, eventdata, handles)
axes(handles.axes1);
cla;
x = 0 : pi/50 : 2*pi;
plot(x, sin(x),'r');
 
function axes1_CreateFcn(hObject, eventdata, handles)

function axes1_DeleteFcn(hObject, eventdata, handles)

5. APP设计工具

课堂讨论 APP设计

用App Designer工具建立一个图形用户界面，其中包含一个坐标轴、一个旋钮、一个离散旋钮和一个“绘图”按钮，旋钮的值域为 $[0,5]$，离散旋钮的值域为 $[1,4]$。运行该用户界面，单击“绘图”按钮，从旋钮获取 $m$ 的值，从离散旋钮获取 $n$ 的值，在坐标轴绘制曲线，以下是曲线方程：

app85;

classdef app85 < matlab.apps.AppBase
    % Properties that correspond to app components
    properties (Access = public)
        UIFigure  matlab.ui.Figure
        UIAxes    matlab.ui.control.UIAxes
        Knob      matlab.ui.control.Knob
        Knob_2    matlab.ui.control.DiscreteKnob
        Button    matlab.ui.control.Button
    end
    % Callbacks that handle component events
    methods (Access = private)
        % Button pushed function: Button
        function ButtonPushed(app, event)
            m = app.Knob.Value;
            n = app.Knob_2.Value;
            t = linspace(0, 2*pi, 100);
            plot(app.UIAxes, m*sin(t), n*cos(t));
        end
    end
    % Component initialization
    methods (Access = private)
        % Create UIFigure and components
        function createComponents(app)
            % Create UIFigure and hide until all components are created
            app.UIFigure = uifigure('Visible', 'off');
            app.UIFigure.Position = [100 100 550 301];
            app.UIFigure.Name = 'UI Figure';
            % Create UIAxes
            app.UIAxes = uiaxes(app.UIFigure);
            title(app.UIAxes, {'x = m sin(t)'; 'y = n cos(t) '; 't \in [0 2\pi]'})
            xlabel(app.UIAxes, 'X')
            ylabel(app.UIAxes, 'Y')
            app.UIAxes.TitleFontWeight = 'bold';
            app.UIAxes.Position = [137 12 400 275];
            % Create Knob
            app.Knob = uiknob(app.UIFigure, 'continuous');
            app.Knob.Limits = [0 5];
            app.Knob.Position = [47 199 60 60];
            app.Knob.Value = 2.5;
            % Create Knob_2
            app.Knob_2 = uiknob(app.UIFigure, 'discrete');
            app.Knob_2.Items = {'1', '2', '3', '4'};
            app.Knob_2.Position = [47 99 60 60];
            app.Knob_2.Value = '2';
            % Create Button
            app.Button = uibutton(app.UIFigure, 'push');
            app.Button.ButtonPushedFcn = createCallbackFcn(app, @ButtonPushed, true);
            app.Button.FontSize = 18;
            app.Button.Position = [27 40 100 40];
            app.Button.Text = '绘图';
            % Show the figure after all components are created
            app.UIFigure.Visible = 'on';
        end
    end
    % App creation and deletion
    methods (Access = public)
        % Construct app
        function app = app85
            % Create UIFigure and components
            createComponents(app)
            % Register the app with App Designer
            registerApp(app, app.UIFigure)
            if nargout == 0
                clear app
            end
        end
        % Code that executes before app deletion
        function delete(app)
            % Delete UIFigure when app is deleted
            delete(app.UIFigure)
        end
    end
end

6. 图形用户界面应用举例

课堂讨论 GUIDE和App Designer工具的应用

分别用GUIDE和App Designer工具建立一个图形用户界面。界面中包含一个坐标轴和一个“绘图”按钮，按钮的Tag属性为BtPlot。运行该用户界面，单击“绘图”按钮，在坐标轴用plot函数绘制一个圆。比较两种方法的回调函数的定义方法以及plot函数的调用方法。

% (1) GUIDE
gui86;	

function varargout = gui86(varargin)
gui_Singleton = 0;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @gui86_OpeningFcn, ...
                   'gui_OutputFcn',  @gui86_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
 
function gui86_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
guidata(hObject, handles);

function varargout = gui86_OutputFcn(hObject, eventdata, handles) 
varargout{1} = handles.output;

function BtPlot_Callback(hObject, eventdata, handles)
axes(handles.axes1);
cla;
t = 0 : pi/50 : 2*pi;
plot(sin(t), cos(t));

% (2) App Designer
app86;	 

classdef app86 < matlab.apps.AppBase
    % Properties that correspond to app components
    properties (Access = public)
        UIFigure  matlab.ui.Figure
        UIAxes    matlab.ui.control.UIAxes
        BtPlot    matlab.ui.control.Button
    end
    % Callbacks that handle component events
    methods (Access = private)
        % Button pushed function: BtPlot
        function BtPlotPushed(app, event)
            t = 0 : pi/50 : 2*pi;
            plot(app.UIAxes, sin(t), cos(t));
        end
    end
    % Component initialization
    methods (Access = private)
        % Create UIFigure and components
        function createComponents(app)
            % Create UIFigure and hide until all components are created
            app.UIFigure = uifigure('Visible', 'off');
            app.UIFigure.Position = [100 100 234 265];
            app.UIFigure.Name = 'UI Figure';
            % Create UIAxes
            app.UIAxes = uiaxes(app.UIFigure);
            title(app.UIAxes, '')
            xlabel(app.UIAxes, '')
            ylabel(app.UIAxes, '')
            app.UIAxes.Box = 'on';
            app.UIAxes.TitleFontWeight = 'bold';
            app.UIAxes.Position = [18 55 200 200];
            % Create BtPlot
            app.BtPlot = uibutton(app.UIFigure, 'push');
            app.BtPlot.ButtonPushedFcn = createCallbackFcn(app, @BtPlotPushed, true);
            app.BtPlot.FontSize = 14;
            app.BtPlot.Position = [68 17 100 28];
            app.BtPlot.Text = '绘图';
            % Show the figure after all components are created
            app.UIFigure.Visible = 'on';
        end
    end
    % App creation and deletion
    methods (Access = public)
        % Construct app
        function app = app86
            % Create UIFigure and components
            createComponents(app)
            % Register the app with App Designer
            registerApp(app, app.UIFigure)
            if nargout == 0
                clear app
            end
        end
        % Code that executes before app deletion
        function delete(app)
            % Delete UIFigure when app is deleted
            delete(app.UIFigure)
        end
    end
end

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