本人做了一个GUI界面，目标是实现在axes坐标中导入一张照片，然后可以在照片上用鼠标画圈，然后就可以计算出画圈部分占照片总面积的比例；同时也可以用白色覆盖多余部分(可以看成橡皮擦功能吧？)

但目前：画圈，橡皮擦功能的代码是基于axes坐标轴实现的，也就是说，实际上照片本身并没有改变，画的圈只是和照片在一个坐标中同时显示出来而已，如果保存照片的话，画的圈和擦掉的部分都不会在保存的照片中体现。。。我该怎么改？先谢过了！下面是画圈，和橡皮擦的功能的代码。。。其实本质是一样的

function figure_EasyPaint_WindowButtonDownFcn(hObject, eventdata, handles)

% hObject    handle to figure_EasyPaint (see GCBO)

% eventdata  reserved - to be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

global flag x0 y0 x y PaintFlag Eflag;

flag = 1;     %鼠标单击

cp = get(handles.axes_before, 'CurrentPoint');         %axes_before 为坐标轴Tag

x = cp(1,1);

y = cp(1,2);

if PaintFlag    % 选择画圈按钮

plot(handles.axes_before, x, y, 'Color', [1 0 0]);

end

if Eflag       %选择橡皮擦按钮

set(gcf, 'CurrentAxes', handles.axes_before);

plot(handles.axes_before, x, y, 'Color', [1 1 1]);

end

x0 = x;

y0 = y;

guidata(hObject, handles);

% --- Executes on mouse motion over figure - except title and menu.

function figure_EasyPaint_WindowButtonMotionFcn(hObject, eventdata, handles)

% hObject    handle to figure_EasyPaint (see GCBO)

% eventdata  reserved - to be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

global flag x0 y0 x y PaintFlag Eflag;

x0 = x;

y0 = y;

cp = get(handles.axes_before, 'CurrentPoint');

x = cp(1,1);

y = cp(1,2);

if flag && PaintFlag

temp = get(handles.slider1, 'Value');

LineWidth = temp + 2;

plot(handles.axes_before, [x0 x], [y0 y], 'LineWidth', LineWidth, 'Color', [1 0 0]);

end

if flag && Eflag

set(gcf, 'CurrentAxes', handles.axes_before);

temp = get(handles.slider1, 'Value');

LineWidth = temp + 2;

plot(handles.axes_before, [x0 x], [y0 y], 'LineWidth', LineWidth, 'Color', [1 1 1]);

end

guidata(hObject, handles);

% --- Executes on mouse press over figure background, over a disabled or

% --- inactive control, or over an axes background.

function figure_EasyPaint_WindowButtonUpFcn(hObject, eventdata, handles)

% hObject    handle to figure_EasyPaint (see GCBO)

% eventdata  reserved - to be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

global flag PaintFlag Eflag;

flag = 0;

PaintFlag = 0;

Eflag = 0;

guidata(hObject, handles);