package com.roboo.like.netease.view;
import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
import android.widget.ScrollView;
import com.roboo.like.netease.utils.PixelUtils;
/**
* 自定义ScrollView
*
* @author MarkMjw
* @date 2013-09-13
*/
public class PullScrollView extends ScrollView {
/** 阻尼系数,越小阻力就越大. */
private static final float SCROLL_RATIO = 0.35f;
/** 滑动至翻转的距离. */
private static final int TURN_DISTANCE = 50;
/** 头部图片. */
private ImageView mHeadImage;
/** 头部图片显示高度. */
private int mHeadImageH;
/** 孩子View. */
private View mChildView;
/** ScrollView的孩子View矩形. */
private Rect mRect = new Rect();
/** 首次点击的Y坐标. */
private float mTouchDownY;
/** 是否关闭ScrollView的滑动. */
private boolean mEnableTouch = false;
/** 是否开始移动. */
private boolean isMoving = false;
/** 头部图片初始顶部和底部. */
private int mInitTop, mInitBottom;
/** 头部图片拖动时顶部和底部. */
private int mCurrentTop, mCurrentBottom;
/** 状态变化时的监听器. */
private OnTurnListener mOnTurnListener;
/** 状态：上部，下部，默认. */
private enum State {
UP, DOWN, NORMAL
}
/** 状态. */
private State state = State.NORMAL;
public PullScrollView(Context context) {
super(context);
}
public PullScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PullScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
/**
* 初始化
*
* @param imageView 头部图片
*/
public void init(ImageView imageView) {
mHeadImage = imageView;
mHeadImageH = PixelUtils.dp2px(94);
}
/**
* 设置状态改变时的监听器
*
* @param turnListener
*/
public void setOnTurnListener(OnTurnListener turnListener) {
mOnTurnListener = turnListener;
}
/**
* 根据 XML 生成视图工作完成.该函数在生成视图的最后调用，在所有子视图添加完之后.
* 即使子类覆盖了 onFinishInflate 方法，也应该调用父类的方法，使该方法得以执行.
*/
@Override
protected void onFinishInflate() {
if (getChildCount() > 0) {
mChildView = getChildAt(0);
}
}
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
// 当滚动到顶部时，将状态设置为正常，避免先向上拖动再向下拖动到顶端后首次触摸不响应的问题
if (getScrollY() == 0) {
state = State.NORMAL;
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (mChildView != null) {
doTouchEvent(ev);
}
// 禁止控件本身的滑动.
if (mEnableTouch) {
return true;
} else {
return super.onTouchEvent(ev);
}
}
/**
* 触摸事件处理
*
* @param event
*/
private void doTouchEvent(MotionEvent event) {
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
mTouchDownY = event.getY();
mCurrentTop = mInitTop = mHeadImage.getTop();
mCurrentBottom = mInitBottom = mHeadImage.getBottom();
break;
case MotionEvent.ACTION_MOVE:
float deltaY = event.getY() - mTouchDownY;
doActionMove(deltaY);
break;
case MotionEvent.ACTION_UP:
// 回滚动画
if (isNeedAnimation()) {
rollBackAnimation();
}
if (getScrollY() == 0) {
state = State.NORMAL;
}
isMoving = false;
mEnableTouch = false;
break;
default:
break;
}
}
/**
* 执行移动动画
*
* @param deltaY
*/
private void doActionMove(float deltaY) {
// 对于首次Touch操作要判断方位：UP OR DOWN
if (deltaY < 0 && state == State.NORMAL) {
state = State.UP;
} else if (deltaY > 0 && state == State.NORMAL) {
state = State.DOWN;
}
if (state == State.UP) {
deltaY = deltaY < 0 ? deltaY : 0;
isMoving = false;
mEnableTouch = false;
} else if (state == State.DOWN) {
if (getScrollY() <= deltaY) {
mEnableTouch = true;
isMoving = true;
}
deltaY = deltaY < 0 ? 0 : deltaY;
}
if (isMoving) {
// 初始化头部矩形
if (mRect.isEmpty()) {
// 保存正常的布局位置
mRect.set(mChildView.getLeft(), mChildView.getTop(), mChildView.getRight(),
mChildView.getBottom());
}
// 移动背景图(手势移动的距离*阻尼系数*0.5)
float bgMoveH = deltaY * 0.5f * SCROLL_RATIO;
mCurrentTop = (int) (mInitTop + bgMoveH);
mCurrentBottom = (int) (mInitBottom + bgMoveH);
mHeadImage.layout(mHeadImage.getLeft(), mCurrentTop, mHeadImage.getRight(),
mCurrentBottom);
// 移动布局(手势移动的距离*阻尼系数)
float childMoveH = deltaY * SCROLL_RATIO;
// 修正移动的距离，避免超过图片的底边缘
int top = mCurrentBottom - mHeadImageH;
if (mRect.top + childMoveH > top) {
childMoveH -= mRect.top + childMoveH - top;
}
mChildView.layout(mRect.left, (int) (mRect.top + childMoveH),
mRect.right, (int) (mRect.bottom + childMoveH));
}
}
/**
* 回滚动画
*/
private void rollBackAnimation() {
TranslateAnimation image_Anim = new TranslateAnimation(0, 0,
Math.abs(mInitTop - mCurrentTop), 0);
image_Anim.setDuration(200);
mHeadImage.startAnimation(image_Anim);
mHeadImage.layout(mHeadImage.getLeft(), mInitTop, mHeadImage.getRight(), mInitBottom);
// 开启移动动画
TranslateAnimation inner_Anim = new TranslateAnimation(0, 0, mChildView.getTop(), mRect.top);
inner_Anim.setDuration(200);
mChildView.startAnimation(inner_Anim);
mChildView.layout(mRect.left, mRect.top, mRect.right, mRect.bottom);
mRect.setEmpty();
// 回调监听器
if (mCurrentTop > mInitTop + TURN_DISTANCE && mOnTurnListener != null){
mOnTurnListener.onTurn();
}
}
/**
* 是否需要开启动画
*/
private boolean isNeedAnimation() {
return !mRect.isEmpty() && isMoving;
}
/**
* 执行翻转
*
* @author MarkMjw
*/
public interface OnTurnListener {
/**
* 翻转回调方法
*/
public void onTurn();
}
}