From 91197049c458f07092b31501d2ed512180b13d58 Mon Sep 17 00:00:00 2001
From: Chiao Cheng <chiaocheng@google.com>
Date: Fri, 24 Aug 2012 14:19:37 -0700
Subject: Moving more classes from contacts into dialer.

- These classes are only used by dialer code.
- Fixed import order.

Bug: 6993891
Change-Id: I7941a029989c4793b766fdc77a4666f9f99b750a
---
 src/com/android/dialer/BackScrollManager.java | 89 +++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 src/com/android/dialer/BackScrollManager.java

(limited to 'src/com/android/dialer/BackScrollManager.java')

diff --git a/src/com/android/dialer/BackScrollManager.java b/src/com/android/dialer/BackScrollManager.java
new file mode 100644
index 000000000..57287022a
--- /dev/null
+++ b/src/com/android/dialer/BackScrollManager.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2011 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.dialer;
+
+import android.view.View;
+import android.widget.AbsListView;
+import android.widget.ListView;
+
+/**
+ * Handles scrolling back of a list tied to a header.
+ * <p>
+ * This is used to implement a header that scrolls up with the content of a list to be partially
+ * obscured.
+ */
+public class BackScrollManager {
+    /** Defines the header to be scrolled. */
+    public interface ScrollableHeader {
+        /** Sets the offset by which to scroll. */
+        public void setOffset(int offset);
+        /** Gets the maximum offset that should be applied to the header. */
+        public int getMaximumScrollableHeaderOffset();
+    }
+
+    private final ScrollableHeader mHeader;
+    private final ListView mListView;
+
+    private final AbsListView.OnScrollListener mScrollListener =
+            new AbsListView.OnScrollListener() {
+                @Override
+                public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
+                        int totalItemCount) {
+                    if (firstVisibleItem != 0) {
+                        // The first item is not shown, the header should be pinned at the top.
+                        mHeader.setOffset(mHeader.getMaximumScrollableHeaderOffset());
+                        return;
+                    }
+
+                    View firstVisibleItemView = view.getChildAt(firstVisibleItem);
+                    if (firstVisibleItemView == null) {
+                        return;
+                    }
+                    // We scroll the header up, but at most pin it to the top of the screen.
+                    int offset = Math.min(
+                            (int) -view.getChildAt(firstVisibleItem).getY(),
+                            mHeader.getMaximumScrollableHeaderOffset());
+                    mHeader.setOffset(offset);
+                }
+
+                @Override
+                public void onScrollStateChanged(AbsListView view, int scrollState) {
+                    // Nothing to do here.
+                }
+            };
+
+    /**
+     * Creates a new instance of a {@link BackScrollManager} that connected the header and the list
+     * view.
+     */
+    public static void bind(ScrollableHeader header, ListView listView) {
+        BackScrollManager backScrollManager = new BackScrollManager(header, listView);
+        backScrollManager.bind();
+    }
+
+    private BackScrollManager(ScrollableHeader header, ListView listView) {
+        mHeader = header;
+        mListView = listView;
+    }
+
+    private void bind() {
+        mListView.setOnScrollListener(mScrollListener);
+        // We disable the scroll bar because it would otherwise be incorrect because of the hidden
+        // header.
+        mListView.setVerticalScrollBarEnabled(false);
+    }
+}
-- 
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