Adding images (or any other resources) to Eclipse cheat sheets

Sometimes it's useful to use images inside cheat sheets. There is one problem, the editor does not allow including images, or any other resources. This tutor describes how to do such things.

This is an excerpt of my little ebook Steps 2 Eclipse Plug-in. This book describes, how my  plug-in for Eclipse: XML Parsing in Java Kit, was written.

If you are interested in this ebook, and/or you want to help the author, please think to buy it.

Adding images or other resources is done using an ItemExtension, this will use a class that handles drawing the images, for instance. The class must implements : org.eclipse.ui.cheatsheets.AbstractItemExtensionElement. This class is associated with an attribute that can be used with an item in your cheat sheet

Adding an extension
Extension tab -> Click on Add button

Select org.eclipse.ui.cheatsheets.cheatSheetItemExtension from the list.
Finish

This will add an extension-point



Right click on the newly created extension-point -> New -> ItemExtension

1. Give a name of your choice to the attribute ItemAttribut (this attribute will be used within  an Item tag, in a cheat sheet later)

2. Give a name (preferably full qualified name) to the class that will handle this attribute

3. Click on class link will open a New Java Class dialog for creating the class




The New Java Class dialog is opened
The class's name and its super class are entered automatically by Eclipse
Click on Finish

This class in one of its method createControl(Composite) we add a control  (for instance a label with an image, to its Composite argument, like the following:

    //create a Label
    Label msg=new Label(composite, SWT.BORDER);
    msg.setText("This is a label");

ItemExtensionHandler
Must have a constructor with a String (done automatically by eclipse)

public class ItemExtensionHandler extends AbstractItemExtensionElement {
private String attributeValue;
    public ItemExtensionHandler(String attributeName) {
        
        super(attributeName);
       
    }

    @Override
    public void handleAttribute(String attributeValue) {
     
        this.attributeValue=attributeValue;

    }

    @Override
    public void createControl(Composite composite) {

        //get the image from ImageRegistry    
        AbstractUIPlugin plugin=Activator.getDefault();
        ImageRegistry reg=plugin.getImageRegistry();
        Image logo=reg.get(Activator.LOGO_ID);
    
          //add a label to composite
          Label label=new Label(composite,SWT.BORDER);
         //Use the label to display the image
         label.setImage(logo);

    }

    @Override
    public void dispose() {
        // TODO Auto-generated method stub

    }

}
plugin.xml
When the extension was added in the plug-in editor, information about this extension was written in this file, with the attribute name and its handler class.

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
   <extension
         point="org.eclipse.ui.editors.templates">
      <include
            file="xml_templates_en_1.5.xml">
      </include>
   </extension>
   <extension
         point="org.eclipse.ui.cheatsheets.cheatSheetContent">
      <category
            id="com.java_javafx.eclipse_plugin.category1"
            name="com.java_javafx.eclipse_plugin.kaesar_cheatsheets">
      </category>
   </extension>
   <extension
         point="org.eclipse.ui.cheatsheets.cheatSheetItemExtension">
      <itemExtension
            class="ItemExtensionHandler"
            itemAttribute="myAtt">
      </itemExtension>
   </extension>

</plugin>



Add the attribute to a cheat sheet
The ItemExtension handler class defined above, is associated with an attribute. Its name was entered in ItemAttribute. We are going to use this item's attribute in a cheat sheet. This attribute will be replaced, by whatever we want to display in createControl(Composite) method of the handler class



Let's create a new cheat sheet to hold the image (you can use the image in any other cheat sheet, alongside a text, using this attribute)

Create a new cheat sheet to hold an image

In composite cheat sheet editor -> click on Add Task
Give the task any Name. Click on Path link to open new simple cheat sheet dialog



Give the new file a name in File name, with .xml extension.
Finish
This will open the simple cheat sheet editor




Give a name to this cheat sheet
Click on item to change its name in Title



Click on Source tab. This will open an editor with the source of the cheat sheet .xml file

Using the item's attribut

Use after any item's title the ItemAttribute's name entered when defining ItemExtension. You can give this attribute any value. This value can be obtained in the handler class

cheatsheet_with_logo.xml

<?xml version="1.0" encoding="UTF-8"?>
<cheatsheet
      title="Cheat sheet with logo">
   <intro>
      <description>
         <b>Body</b>
      </description>
   </intro>
   <item
         title="logo" myAtt="value_of_my_attribute">
      <description>
         
      </description>
   </item>
</cheatsheet>


Give it a try

In MANIFEST.MF editor (click on META-INF/MANIFEST.MF in Package Explorer)
Select Overview tab
Under Testing
Click on Launch an Eclipse application link

A new instance of Eclipse is launched. Click on Workbench

Click on Help menu -> Cheat Sheets

  Enjoy !