Handle graph is the general name of the underlying graph function set , It actually does the work of generating graphics . It can be used to control the appearance of an image or picture .

1 Object handle

Each image has a unique name , Call handle （ Is an integer or real number ）.

Create handle Hnd1：

% Data preparation 
x=-pi:0.1:pi;
y=sin(x);
% Create a curve 
Hnd1=plot(x,y, 'LineWidth', 2)

1.1 Detect the properties of any object

value = get(handle, 'PropertyName'); 
value = get(handle); 

Return the property name of this object , The domain value is the attribute value .

for example Hnd1 Properties of ：get(Hnd1)

>> get(Hnd1)

Hnd1 = 

  Line -  attribute :

              Color: [0 0.4470 0.7410]
          LineStyle: '-'
          LineWidth: 2
             Marker: 'none'
         MarkerSize: 6
    MarkerFaceColor: 'none'
              XData: [1×63 double]
              YData: [1×63 double]
              ZData: [1×0 double]

   Show   All attributes 

    AlignVertexCenters: 'off'
            Annotation: [1×1 matlab.graphics.eventdata.Annotation]
          BeingDeleted: 'off'
            BusyAction: 'queue'
         ButtonDownFcn: ''
              Children: [0×0 GraphicsPlaceholder]
              Clipping: 'on'
                 Color: [0 0.4470 0.7410]
             CreateFcn: ''
             DeleteFcn: ''
           DisplayName: ''
      HandleVisibility: 'on'
               HitTest: 'on'
         Interruptible: 'on'
              LineJoin: 'round'
             LineStyle: '-'
             LineWidth: 2
                Marker: 'none'
       MarkerEdgeColor: 'auto'
       MarkerFaceColor: 'none'
         MarkerIndices: [1×63 uint64]
            MarkerSize: 6
                Parent: [1×1 Axes]
         PickableParts: 'visible'
              Selected: 'off'
    SelectionHighlight: 'on'
                   Tag: ''
                  Type: 'line'
         UIContextMenu: [0×0 GraphicsPlaceholder]
              UserData: []
               Visible: 'on'
                 XData: [1×63 double]
             XDataMode: 'manual'
           XDataSource: ''
                 YData: [1×63 double]
           YDataSource: ''
                 ZData: [1×0 double]
           ZDataSource: ''

1.2 Setting object properties

set(handle,'PropertyName1', value1, ...); 

For example setting Hnd1 Properties of ：

%set Function to modify properties 
set(Hnd1,'LineWidth',4,'LineStyle','--');

1.3 Start the Attribute Editor

propedit(Hnd1); 
propedit; 

result ：

 1.4 use set Function lists possible attribute values

The function is used to provide a list of all possible attribute values .

for example ：

% adopt set Function lists possible attribute values 
set(Hnd1,'LineStyle')

result ：

 5×1 cell  Array 

    {'-'   }
    {'--'  }
    {':'   }
    {'-.'  }
    {'none'}

1.5 Custom data

         In addition to a GUI Beyond the standard attributes defined by the object , The program can define special properties of the data to be controlled . Programmers can use additional attributes to add any type of data to GUI In the object . Any amount of data can be stored , And used for various purposes .

（1） Custom data ：setappdata

setappdata(Hndl, 'DataName', DataValue); 

"DateName" Is the name of this data ;

”DateValue“ Is the value given to the name , It could be a number , It could be a string ;

for example ：

 % Custom data ,DataValue Data values can be numbers , It could be a string 
setappdata(Hnd1,'plot_name','plot(sinex)')

（2） Retrieve user-defined data getappdata

value = getappdata(Hndl, 'DataName'); 
struct = getappdata(Hndl); 

"DateName" Is the name of the data to be called

for example ：

 % Call custom data , return 'plot(sinex)'
value_set=getappdata(Hnd1,'plot_name')
struct=getappdata(Hnd1)

result ：

value_set =

    'plot(sinex)'


struct = 

   That contains the following fields  struct:

    ScribeProxyValue: 7.3863e+05
           plot_name: 'plot(sinex)'

Custom data correlation function ：

 2 Object search

If you plan to modify the properties of the object you create , Then please save the handle of the object , Calling function for base note get and set To prepare for .

But if you lose the handle for some reason , Sure i Retrieve by function ：

- gcf Returns the handle of the current image , If this image does not exist ,gcf Will create a
- gca Returns the handle of the current coordinate system in the current image , If the image does not exist , Or there is no coordinate system in the current image
- gco Returns a handle to the current object
- findobj Find the graphic object with the specified attribute value , Limiting the number of search objects can speed up the operation of the function

form ：

H_obj = gco; 
type = get(H_obj, 'Type') 
Hndls = findobj('PropertyName1',value1, ...) 

give an example ：

% For some reason , The handle to the object is missing , You can find by function 
% Gets the handle of the current image . If this image does not exist ,gcf  Will create a 
Hnd1_gcf=gcf
% Returns the handle of the current coordinate system in the current image , If the image does not exist , Or there is no coordinate system in the current image ,
% So the function  gca  A coordinate system is created , And return its handle 
Hnd1_gca=gca
% Returns the handle of the current object in the current image 
Hnd1_gco=gco
% Find the attribute that contains the specified attribute , Object with specified value . You can specify multiple properties / value ,findobj  Returns only the object handle that matches it .
H_fig = findobj('Type', 'figure') 

result ：

>> Hnd

Hnd1 = 

  Line -  attribute :

              Color: [0 0.4470 0.7410]
          LineStyle: '-'
          LineWidth: 2
             Marker: 'none'
         MarkerSize: 6
    MarkerFaceColor: 'none'
              XData: [1×63 double]
              YData: [1×63 double]
              ZData: [1×0 double]
Hnd1_gcf = 

  Figure (1) -  attribute :

      Number: 1
        Name: ''
       Color: [0.9400 0.9400 0.9400]
    Position: [680 678 560 420]
       Units: 'pixels'

   Show   All attributes 


Hnd1_gca = 

  Axes -  attribute :

             XLim: [-4 4]
             YLim: [-1 1]
           XScale: 'linear'
           YScale: 'linear'
    GridLineStyle: '-'
         Position: [0.1300 0.1100 0.7750 0.8150]
            Units: 'normalized'

   Show   All attributes 


Hnd1_gco = 

  Line -  attribute :

              Color: [0 0.4470 0.7410]
          LineStyle: '--'
          LineWidth: 4
             Marker: 'none'
         MarkerSize: 6
    MarkerFaceColor: 'none'
              XData: [1×63 double]
              YData: [1×63 double]
              ZData: [1×0 double]

   Show   All attributes 


H_fig = 

  Figure (1) -  attribute :

      Number: 1
        Name: ''
       Color: [0.9400 0.9400 0.9400]
    Position: [680 678 560 420]
       Units: 'pixels'

   Show   All attributes 

3 Location and unit

All objects contain locations ”Position“ attribute , Used to specify the location and size of objects on the computer screen .

Position return vector [left bottom width height]

% Get location and units 
position=get(gcf,'Position')
units=get(gcf,'Units')

result ：

position =

   680   678   560   420


units =

    'pixels'

explain ：

The distance between the lower left corner of the current image window and the right side of the screen is 680pixel, The distance from the bottom of the screen is 678pixel. The width of the image is 560pixel, The upper and lower height is 420pixel. Note that this is the diagrammable area of the image , Include boundary , Scroll bar , menu , And the title area of the image .

Company ("units") The default value of the property is pixels (pixels); Its attribute value can also be feet (inches), A centimeter (centimeters), spot (points), Or normalized coordinates (normalixed coordinates); The minimum resolution of a typical computer screen is 640×480; The normalized coordinates are 0 To 1 Within the scope of . In normalized coordinates , The bottom left corner of the screen is [0,0] The upper right corner is [1.0, 1.0];

Normalized is usually used normalized coordinate , Regardless of the size of the monitor ：

H = figure(1)
set(H,'units', 'normalized','position',[0.2 ,0.2 ,0.2, 0.1]) 

Example ：

% Data preparation 
x=-pi:0.1:pi;
y=sin(x);
% Create a curve 
Hnd1=plot(x,y, 'LineWidth', 2)

H = figure(1)
set(H,'units', 'normalized','position',[0.2 ,0.2 ,0.2, 0.1]) 

%get Detect the properties of any object 
get(Hnd1)
%set Function to modify properties 
set(Hnd1,'LineWidth',4,'LineStyle','--');
% Open Attribute Editor  
propedit(Hnd1);
% adopt set Function lists possible attribute values 
set(Hnd1,'LineStyle')
%  result ：
%     {'-'   }
%     {'--'  }
%     {':'   }
%     {'-.'  }
%     {'none'}

% All possible values of all properties of the object 
set(Hnd1)
 
 % Custom data ,DataValue Data values can be numbers , It could be a string 
setappdata(Hnd1,'plot_name','plot(sinex)')
 % Call custom data , return 'plot(sinex)'
value_set=getappdata(Hnd1,'plot_name')
struct=getappdata(Hnd1)

% For some reason , The handle to the object is missing , You can find by function 
% Gets the handle of the current image . If this image does not exist ,gcf  Will create a 
Hnd1_gcf=gcf
% Returns the handle of the current coordinate system in the current image , If the image does not exist , Or there is no coordinate system in the current image ,
% So the function  gca  A coordinate system is created , And return its handle 
Hnd1_gca=gca
% Returns the handle of the current object in the current image 
Hnd1_gco=gco
% Find the attribute that contains the specified attribute , Object with specified value . You can specify multiple properties / value ,findobj  Returns only the object handle that matches it .
H_fig = findobj('Type', 'figure')  


% Get location and units 
position=get(gcf,'Position')
units=get(gcf,'Units')