MATLAB®

Annotation Objects

Introduction

Users typically create annotation objects from the Plot Edit toolbar or the Insert menu (select Plot Edit in the View menu to display the Plot Edit toolbar). However, you can also create annotation objects using the annotation function.

Annotation objects are created in a hidden axes that extends the full width and height of the figure. This enables you to specify the locations of annotation objects anywhere in the figure using normalized coordinates (the lower left corner is the point 0,0, the upper right corner is the point 1,1).

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Annotation Object Properties

Note   You should not change any of the properties of the annotation axes or parent any graphics objects to this axes. Use the annotation function or the graphics tools to create annotation objects.

The following links access descriptions of the properties you can set on the respective annotation objects.

• Annotation arrow properties

• Annotation doublearrow properties

• Annotation ellipse properties

• Annotation line properties

• Annotation rectangle properties

• Annotation textarrow properties

• Annotation textbox properties

To modify the appearance of annotation objects created with the plotting tools, use The Property Editor.

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Example — Enclosing Subplots with an Annotation Rectangle

The following example shows how to create a rectangle annotation object and use it to highlight two subplots in a figure. This example uses the axes properties Position and TightInset to determine the location and size of the annotation rectangle.

1. First create an array of subplots.

   x = -2*pi:pi/12:2*pi;
   y = x.^2;
   subplot(2,2,1:2)
   plot(x,y)
   h1=subplot(223);
   y = x.^4;
   plot(x,y)
   h2=subplot(224);
   y = x.^5;
   plot(x,y)
   

2. Determine the location and size of the annotation rectangle required to enclose axes, tick mark labels, and title using the axes Position and TightInset properties.

   p1 = get(h1,'Position'); 
   t1 = get(h1,'TightInset');
   p2 = get(h2,'Position');
   t2 = get(h2,'TightInset');
   x1 = p1(1)-t1(1); y1 = p1(2)-t1(2); 
   x2 = p2(1)-t2(1); y2 = p2(2)-t2(2); 
   w = x2-x1+t1(1)+p2(3)+t2(3); h = p2(4)+t2(2)+t2(4);
   

3. Create the annotation rectangle to enclose the lower two subplots. Make the rectangle a translucent red with a solid border.

   annotation('rectangle',[x1,y1,w,h],...
    'FaceAlpha',.2,'FaceColor','red','EdgeColor','red');
   

   

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Linking Graphs to Variables — Data Source Properties

Group Objects