1 files changed, 172 insertions, 0 deletions
diff --git a/src/com/android/gallery3d/filtershow/history/HistoryManager.java b/src/com/android/gallery3d/filtershow/history/HistoryManager.java
new file mode 100644
index 000000000..755e2ea58
--- /dev/null
+++ b/src/com/android/gallery3d/filtershow/history/HistoryManager.java
@@ -0,0 +1,172 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * 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 com.android.gallery3d.filtershow.history;
+
+import android.graphics.drawable.Drawable;
+import android.view.MenuItem;
+
+import java.util.Vector;
+
+public class HistoryManager {
+    private static final String LOGTAG = "HistoryManager";
+
+    private Vector<HistoryItem> mHistoryItems = new Vector<HistoryItem>();
+    private int mCurrentPresetPosition = 0;
+    private MenuItem mUndoMenuItem = null;
+    private MenuItem mRedoMenuItem = null;
+    private MenuItem mResetMenuItem = null;
+
+    public void setMenuItems(MenuItem undoItem, MenuItem redoItem, MenuItem resetItem) {
+        mUndoMenuItem = undoItem;
+        mRedoMenuItem = redoItem;
+        mResetMenuItem = resetItem;
+        updateMenuItems();
+    }
+
+    private int getCount() {
+        return mHistoryItems.size();
+    }
+
+    public HistoryItem getItem(int position) {
+        return mHistoryItems.elementAt(position);
+    }
+
+    private void clear() {
+        mHistoryItems.clear();
+    }
+
+    private void add(HistoryItem item) {
+        mHistoryItems.add(item);
+    }
+
+    private void notifyDataSetChanged() {
+        // TODO
+    }
+
+    public boolean canReset() {
+        if (getCount() <= 1) {
+            return false;
+        }
+        return true;
+    }
+
+    public boolean canUndo() {
+        if (mCurrentPresetPosition == getCount() - 1) {
+            return false;
+        }
+        return true;
+    }
+
+    public boolean canRedo() {
+        if (mCurrentPresetPosition == 0) {
+            return false;
+        }
+        return true;
+    }
+
+    public void updateMenuItems() {
+        if (mUndoMenuItem != null) {
+            setEnabled(mUndoMenuItem, canUndo());
+        }
+        if (mRedoMenuItem != null) {
+            setEnabled(mRedoMenuItem, canRedo());
+        }
+        if (mResetMenuItem != null) {
+            setEnabled(mResetMenuItem, canReset());
+        }
+    }
+
+    private void setEnabled(MenuItem item, boolean enabled) {
+        item.setEnabled(enabled);
+        Drawable drawable = item.getIcon();
+        if (drawable != null) {
+            drawable.setAlpha(enabled ? 255 : 80);
+        }
+    }
+
+    public void setCurrentPreset(int n) {
+        mCurrentPresetPosition = n;
+        updateMenuItems();
+        notifyDataSetChanged();
+    }
+
+    public void reset() {
+        if (getCount() == 0) {
+            return;
+        }
+        HistoryItem first = getItem(getCount() - 1);
+        clear();
+        addHistoryItem(first);
+        updateMenuItems();
+    }
+
+    public HistoryItem getLast() {
+        if (getCount() == 0) {
+            return null;
+        }
+        return getItem(0);
+    }
+
+    public HistoryItem getCurrent() {
+        return getItem(mCurrentPresetPosition);
+    }
+
+    public void addHistoryItem(HistoryItem preset) {
+        insert(preset, 0);
+        updateMenuItems();
+    }
+
+    private void insert(HistoryItem preset, int position) {
+        if (mCurrentPresetPosition != 0) {
+            // in this case, let's discount the presets before the current one
+            Vector<HistoryItem> oldItems = new Vector<HistoryItem>();
+            for (int i = mCurrentPresetPosition; i < getCount(); i++) {
+                oldItems.add(getItem(i));
+            }
+            clear();
+            for (int i = 0; i < oldItems.size(); i++) {
+                add(oldItems.elementAt(i));
+            }
+            mCurrentPresetPosition = position;
+            notifyDataSetChanged();
+        }
+        mHistoryItems.insertElementAt(preset, position);
+        mCurrentPresetPosition = position;
+        notifyDataSetChanged();
+    }
+
+    public int redo() {
+        mCurrentPresetPosition--;
+        if (mCurrentPresetPosition < 0) {
+            mCurrentPresetPosition = 0;
+        }
+        notifyDataSetChanged();
+        updateMenuItems();
+        return mCurrentPresetPosition;
+    }
+
+    public int undo() {
+        mCurrentPresetPosition++;
+        if (mCurrentPresetPosition >= getCount()) {
+            mCurrentPresetPosition = getCount() - 1;
+        }
+        notifyDataSetChanged();
+        updateMenuItems();
+        return mCurrentPresetPosition;
+    }
+
+}