ScrollerProxy.java

/*******************************************************************************
 * Copyright 2011, 2012 Chris Banes.
 *
 * 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 uk.co.senab.photoview;

import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build.VERSION;
import android.os.Build.VERSION_CODES;
import android.widget.OverScroller;
import android.widget.Scroller;

public abstract class ScrollerProxy {

	public static ScrollerProxy getScroller(Context context) {
		if (VERSION.SDK_INT < VERSION_CODES.GINGERBREAD) {
			return new PreGingerScroller(context);
		} else {
			return new GingerScroller(context);
		}
	}

	public abstract boolean computeScrollOffset();

	public abstract void fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY,
			int maxY, int overX, int overY);

	public abstract void forceFinished(boolean finished);

	public abstract int getCurrX();

	public abstract int getCurrY();

	@TargetApi(9)
	private static class GingerScroller extends ScrollerProxy {

		private OverScroller mScroller;

		public GingerScroller(Context context) {
			mScroller = new OverScroller(context);
		}

		@Override
		public boolean computeScrollOffset() {
			return mScroller.computeScrollOffset();
		}

		@Override
		public void fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY,
				int overX, int overY) {
			mScroller.fling(startX, startY, velocityX, velocityY, minX, maxX, minY, maxY, overX, overY);
		}

		@Override
		public void forceFinished(boolean finished) {
			mScroller.forceFinished(finished);
		}

		@Override
		public int getCurrX() {
			return mScroller.getCurrX();
		}

		@Override
		public int getCurrY() {
			return mScroller.getCurrY();
		}
	}

	private static class PreGingerScroller extends ScrollerProxy {

		private Scroller mScroller;

		public PreGingerScroller(Context context) {
			mScroller = new Scroller(context);
		}

		@Override
		public boolean computeScrollOffset() {
			return mScroller.computeScrollOffset();
		}

		@Override
		public void fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY,
				int overX, int overY) {
			mScroller.fling(startX, startY, velocityX, velocityY, minX, maxX, minY, maxY);
		}

		@Override
		public void forceFinished(boolean finished) {
			mScroller.forceFinished(finished);
		}

		@Override
		public int getCurrX() {
			return mScroller.getCurrX();
		}

		@Override
		public int getCurrY() {
			return mScroller.getCurrY();
		}
	}
}