initial commit towards HistoryManager implementation

Timeline/src/org/sleuthkit/autopsy/timeline/HistoryManager.java

@@ -0,0 +1,94 @@
+/*
+ * Autopsy Forensic Browser
+ *
+ * Copyright 2014 Basis Technology Corp.
+ * Contact: carrier <at> sleuthkit <dot> org
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.sleuthkit.autopsy.timeline;
+
+import javafx.beans.property.ReadOnlyObjectWrapper;
+import javax.annotation.concurrent.GuardedBy;
+import org.sleuthkit.autopsy.coreutils.ObservableStack;
+
+/**
+ *
+ */
+public class HistoryManager<T> {
+
+    /** list based stack to hold history, 'top' is at index 0; */
+    @GuardedBy("this")
+    private final ObservableStack<T> historyStack = new ObservableStack<>();
+
+    @GuardedBy("this")
+    private final ObservableStack<T> forwardStack = new ObservableStack<>();
+
+    private final ReadOnlyObjectWrapper<T> currentState = new ReadOnlyObjectWrapper<>();
+
+    public ReadOnlyObjectWrapper<T> getCurrentState() {
+        return currentState;
+    }
+
+    public T currentState() {
+        return currentState.get();
+    }
+
+    synchronized public ObservableStack<T> getHistoryStack() {
+        return historyStack;
+    }
+
+    synchronized public ObservableStack<T> getForwardStack() {
+        return forwardStack;
+    }
+
+    synchronized public T advance() {
+
+        final T peek = forwardStack.peek();
+
+        if (peek != null && peek.equals(currentState.get()) == false) {
+            historyStack.push(currentState.get());
+            currentState.set(peek);
+            forwardStack.pop();
+        }
+        return peek;
+    }
+
+    synchronized public T retreat() {
+
+        final T peek = historyStack.peek();
+
+        if (peek != null && peek.equals(currentState.get()) == false) {
+            forwardStack.push(currentState.get());
+            currentState.set(peek);
+        } else if (peek != null && peek.equals(currentState)) {
+            historyStack.pop();
+            return retreat();
+        }
+        return peek;
+    }
+
+    synchronized private void advance(T newState) {
+
+        if (currentState.equals(newState) == false) {
+            historyStack.push(currentState.get());
+            currentState.set(newState);
+            if (newState.equals(forwardStack.peek())) {
+                forwardStack.pop();
+            } else {
+                forwardStack.clear();
+            }
+        }
+    }
+
+}

Timeline/src/org/sleuthkit/autopsy/timeline/TimeLineController.java

@@ -529,22 +529,14 @@ public class TimeLineController {
         return peek;
     }
 
-    @Deprecated
-    synchronized public void popZoomUpTo(ZoomParams zCrumb) {
-        ZoomParams popped = historyStack.peek();
  
-        while (popped.equals(zCrumb) == false) {
-            popped = historyStack.pop();
-        }
-        pushZoom(zCrumb);
-    }
 
-    synchronized private void pushZoom(ZoomParams zCrumb, boolean force) {
+    synchronized private void pushZoom(ZoomParams zCrumb) {
         final ZoomParams currentZoom = filteredEvents.getRequestedZoomParamters().get();
 
-        if (force || currentZoom.equals(zCrumb) == false) {
+        if ( currentZoom.equals(zCrumb) == false) {
             historyStack.push(currentZoom);
-            filteredEvents.requestZoomState(zCrumb, force);
+            filteredEvents.requestZoomState(zCrumb, false);
             if (zCrumb.equals(forwardStack.peek())) {
                 forwardStack.pop();
             } else {
@@ -553,9 +545,7 @@ public class TimeLineController {
         }
     }
 
-    synchronized private void pushZoom(ZoomParams zCrumb) {
-        pushZoom(zCrumb, false);
-    }
+  
 
     public void selectTimeAndType(Interval interval, EventType type) {
         final Interval timeRange = filteredEvents.getSpanningInterval().overlap(interval);