Add ability to delay messages in Filter based on constraint. Use this to delay 500ms for delete keys in the search dialog.

Holding down delete is nice and zippy in the browser now :)

core/java/android/app/SuggestionsAdapter.java

@@ -40,6 +40,7 @@ import android.view.ViewGroup;
 import android.widget.ImageView;
 import android.widget.ResourceCursorAdapter;
 import android.widget.TextView;
+import android.widget.Filter;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
@@ -90,6 +91,12 @@ class SuggestionsAdapter extends ResourceCursorAdapter {
     private final Runnable mStartSpinnerRunnable;
     private final Runnable mStopSpinnerRunnable;
 
+    /**
+     * The amount of time we delay in the filter when the user presses the delete key.
+     * @see Filter#setDelayer(android.widget.Filter.Delayer).
+     */
+    private static final long DELETE_KEY_POST_DELAY = 500L;
+
     public SuggestionsAdapter(Context context, SearchDialog searchDialog, SearchableInfo searchable,
             WeakHashMap<String, Drawable> outsideDrawablesCache, boolean globalSearchMode) {
         super(context,
@@ -119,6 +126,18 @@ class SuggestionsAdapter extends ResourceCursorAdapter {
                 mSearchDialog.setWorking(false);
             }
         };
+
+        // delay 500ms when deleting
+        getFilter().setDelayer(new Filter.Delayer() {
+
+            private int mPreviousLength = 0;
+
+            public long getPostingDelay(CharSequence constraint) {
+                long delay = constraint.length() < mPreviousLength ? DELETE_KEY_POST_DELAY : 0;
+                mPreviousLength = constraint.length();
+                return delay;
+            }
+        });
     }
 
     /**

core/java/android/widget/Filter.java

@@ -46,6 +46,8 @@ public abstract class Filter {
     private Handler mThreadHandler;
     private Handler mResultHandler;
 
+    private Delayer mDelayer;
+
     private final Object mLock = new Object();
 
     /**
@@ -55,6 +57,20 @@ public abstract class Filter {
         mResultHandler = new ResultsHandler();
     }
 
+    /**
+     * Provide an interface that decides how long to delay the message for a given query.  Useful
+     * for heuristics such as posting a delay for the delete key to avoid doing any work while the
+     * user holds down the delete key.
+     *
+     * @param delayer The delayer.
+     * @hide
+     */
+    public void setDelayer(Delayer delayer) {
+        synchronized (mLock) {
+            mDelayer = delayer;
+        }
+    }
+
     /**
      * <p>Starts an asynchronous filtering operation. Calling this method
      * cancels all previous non-executed filtering requests and posts a new
@@ -90,6 +106,8 @@ public abstract class Filter {
                 thread.start();
                 mThreadHandler = new RequestHandler(thread.getLooper());
             }
+
+            final long delay = (mDelayer == null) ? 0 : mDelayer.getPostingDelay(constraint);
             
             Message message = mThreadHandler.obtainMessage(FILTER_TOKEN);
     
@@ -102,7 +120,7 @@ public abstract class Filter {
     
             mThreadHandler.removeMessages(FILTER_TOKEN);
             mThreadHandler.removeMessages(FINISH_TOKEN);
-            mThreadHandler.sendMessage(message);
+            mThreadHandler.sendMessageDelayed(message, delay);
         }
     }
 
@@ -289,4 +307,17 @@ public abstract class Filter {
          */
         FilterResults results;
     }
+
+    /**
+     * @hide
+     */
+    public interface Delayer {
+
+        /**
+         * @param constraint The constraint passed to {@link Filter#filter(CharSequence)}
+         * @return The delay that should be used for
+         *         {@link Handler#sendMessageDelayed(android.os.Message, long)}
+         */
+        long getPostingDelay(CharSequence constraint);
+    }
 }