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-rw-r--r--src/com/android/gallery3d/ui/ScrollerHelper.java97
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diff --git a/src/com/android/gallery3d/ui/ScrollerHelper.java b/src/com/android/gallery3d/ui/ScrollerHelper.java
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+/*
+ * 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.ui;
+
+import android.content.Context;
+import android.view.ViewConfiguration;
+
+import com.android.gallery3d.common.OverScroller;
+import com.android.gallery3d.common.Utils;
+
+public class ScrollerHelper {
+ private OverScroller mScroller;
+ private int mOverflingDistance;
+ private boolean mOverflingEnabled;
+
+ public ScrollerHelper(Context context) {
+ mScroller = new OverScroller(context);
+ ViewConfiguration configuration = ViewConfiguration.get(context);
+ mOverflingDistance = configuration.getScaledOverflingDistance();
+ }
+
+ public void setOverfling(boolean enabled) {
+ mOverflingEnabled = enabled;
+ }
+
+ /**
+ * Call this when you want to know the new location. The position will be
+ * updated and can be obtained by getPosition(). Returns true if the
+ * animation is not yet finished.
+ */
+ public boolean advanceAnimation(long currentTimeMillis) {
+ return mScroller.computeScrollOffset();
+ }
+
+ public boolean isFinished() {
+ return mScroller.isFinished();
+ }
+
+ public void forceFinished() {
+ mScroller.forceFinished(true);
+ }
+
+ public int getPosition() {
+ return mScroller.getCurrX();
+ }
+
+ public float getCurrVelocity() {
+ return mScroller.getCurrVelocity();
+ }
+
+ public void setPosition(int position) {
+ mScroller.startScroll(
+ position, 0, // startX, startY
+ 0, 0, 0); // dx, dy, duration
+
+ // This forces the scroller to reach the final position.
+ mScroller.abortAnimation();
+ }
+
+ public void fling(int velocity, int min, int max) {
+ int currX = getPosition();
+ mScroller.fling(
+ currX, 0, // startX, startY
+ velocity, 0, // velocityX, velocityY
+ min, max, // minX, maxX
+ 0, 0, // minY, maxY
+ mOverflingEnabled ? mOverflingDistance : 0, 0);
+ }
+
+ // Returns the distance that over the scroll limit.
+ public int startScroll(int distance, int min, int max) {
+ int currPosition = mScroller.getCurrX();
+ int finalPosition = mScroller.isFinished() ? currPosition :
+ mScroller.getFinalX();
+ int newPosition = Utils.clamp(finalPosition + distance, min, max);
+ if (newPosition != currPosition) {
+ mScroller.startScroll(
+ currPosition, 0, // startX, startY
+ newPosition - currPosition, 0, 0); // dx, dy, duration
+ }
+ return finalPosition + distance - newPosition;
+ }
+}