[platform-ui-dev] ImageRegistry

["Steve Ketcham" <sketcham@xxxxxxxxxx>]

I have a question and posible improvement to ImageRegistry.java. Is this the
right group/mailing list?

Synopsis:
When using the jface class MessageDialog, I am encountering an unusual
problem which I think might be a bug. I was interested in seeing if anyone
else had similar troubles. If I create a message dialog once it is
fine. If I then dispose of the current display and later create another
display I can no longer create MessageDialogs without a null pointer
exception. The error is ultimate because of code found in ImageRegistry.

ImageRegistry has a number of places where
Entry entry = (Entry)table.get(key);
and
table.put(key, entry);
are called. In an application where you have a long lived central Display
this works fine. In other cases the table field member can be set to null
from private void hookDisplayDispose(Display display). This throws errors at
inappropriate times. We would like to change all direct references to table
to a method call.

//old method example:
   public Image get(String key) {
      Entry entry = (Entry)table.get(key);
      if (entry == null) {
         return null;
      }
      if (entry.image == null && entry.descriptor != null) {
         entry.image = entry.descriptor.createImage();
      }
      return entry.image;
   }

//new method example
   public Image get(String key)   {
      Entry entry = getEntry(key);
      if(entry == null){
         return null;
      }
      if(entry.image == null && entry.descriptor != null){
         entry.image = entry.descriptor.createImage();
      }
      return entry.image;
   }


//new propsed methods
   private Entry getEntry(String key){
     return (Entry)getTable().get(key);
  }

   private void setEntry(String key, Entry entry){
      getTable().put(key, entry);
   }

   private Map getTable(){
      if (table == null){
         table = new HashMap(10);
      }
      return table
   }

   private Map table = null;

Aaron Coble, software development
Steven Ketcham, software development

Digital Solutions Inc.
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