1 files changed, 138 insertions, 0 deletions
diff --git a/src/com/android/gallery3d/photoeditor/ActionBar.java b/src/com/android/gallery3d/photoeditor/ActionBar.java
new file mode 100644
index 000000000..52dfb0bd7
--- /dev/null
+++ b/src/com/android/gallery3d/photoeditor/ActionBar.java
@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2010 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.photoeditor;
+
+import android.content.Context;
+import android.os.Handler;
+import android.os.Message;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.RelativeLayout;
+
+import com.android.gallery3d.R;
+
+/**
+ * Action bar that contains buttons such as undo, redo, save, etc. and listens to stack changes for
+ * enabling/disabling buttons.
+ */
+public class ActionBar extends RelativeLayout implements FilterStack.StackListener {
+
+    /**
+     * Listener of action button clicked.
+     */
+    public interface ActionBarListener {
+
+        void onUndo();
+
+        void onRedo();
+
+        void onSave();
+    }
+
+    private static final int ENABLE_BUTTON = 1;
+    private static final float ENABLED_ALPHA = 1;
+    private static final float DISABLED_ALPHA = 0.47f;
+
+    private final Handler handler;
+    private View undo;
+    private View redo;
+    private View save;
+
+    public ActionBar(Context context, AttributeSet attrs) {
+        super(context, attrs);
+
+        handler = new Handler() {
+
+            @Override
+            public void handleMessage(Message msg) {
+                switch (msg.what) {
+                    case ENABLE_BUTTON:
+                        boolean canUndo = (msg.arg1 > 0);
+                        boolean canRedo = (msg.arg2 > 0);
+                        enableButton(undo, canUndo);
+                        enableButton(redo, canRedo);
+                        enableButton(save, canUndo);
+                        break;
+                }
+            }
+        };
+    }
+
+    /**
+     * Initializes with a non-null ActionBarListener.
+     */
+    public void initialize(final ActionBarListener listener) {
+        undo = findViewById(R.id.undo_button);
+        undo.setOnClickListener(new OnClickListener() {
+
+            @Override
+            public void onClick(View v) {
+                if (isEnabled()) {
+                    listener.onUndo();
+                }
+            }
+        });
+
+        redo = findViewById(R.id.redo_button);
+        redo.setOnClickListener(new OnClickListener() {
+
+            @Override
+            public void onClick(View v) {
+                if (isEnabled()) {
+                    listener.onRedo();
+                }
+            }
+        });
+
+        save = findViewById(R.id.save_button);
+        save.setOnClickListener(new OnClickListener() {
+
+            @Override
+            public void onClick(View v) {
+                if (isEnabled()) {
+                    listener.onSave();
+                }
+            }
+        });
+
+        resetButtons();
+    }
+
+    public void resetButtons() {
+        // Disable buttons immediately instead of waiting for ENABLE_BUTTON messages which may
+        // happen some time later after stack changes.
+        enableButton(undo, false);
+        enableButton(redo, false);
+        enableButton(save, false);
+    }
+
+    public void disableSave() {
+        enableButton(save, false);
+    }
+
+    private void enableButton(View button, boolean enabled) {
+        button.setEnabled(enabled);
+        button.setAlpha(enabled ? ENABLED_ALPHA : DISABLED_ALPHA);
+    }
+
+    @Override
+    public void onStackChanged(boolean canUndo, boolean canRedo) {
+        // Listens to stack changes that may come from the worker thread; send messages to enable
+        // buttons only in the UI thread.
+        handler.sendMessage(handler.obtainMessage(ENABLE_BUTTON, canUndo ? 1 : 0, canRedo ? 1 : 0));
+    }
+}