package com.chen.weixin.test;
import android.R.bool;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.View.MeasureSpec;
import android.widget.Scroller;
public class MyScrollLayout extends ViewGroup{
private static final String TAG = "ScrollLayout";
private VelocityTracker mVelocityTracker; // ç¨äºå¤æç©å¨æå¿
private static final int SNAP_VELOCITY = 600;
private Scroller mScroller; // æ»å¨æ§å¶å?
private int mCurScreen;
private int mDefaultScreen = 0;
private float mLastMotionX;
// private int mTouchSlop;
// private static final int TOUCH_STATE_REST = 0;
// private static final int TOUCH_STATE_SCROLLING = 1;
// private int mTouchState = TOUCH_STATE_REST;
private OnViewChangeListener mOnViewChangeListener;
public MyScrollLayout(Context context) {
super(context);
// TODO Auto-generated constructor stub
init(context);
}
public MyScrollLayout(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
init(context);
}
public MyScrollLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
init(context);
}
private void init(Context context)
{
mCurScreen = mDefaultScreen;
// mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
mScroller = new Scroller(context);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// TODO Auto-generated method stub
if (changed) {
int childLeft = 0;
final int childCount = getChildCount();
for (int i=0; i<childCount; i++) {
final View childView = getChildAt(i);
if (childView.getVisibility() != View.GONE) {
final int childWidth = childView.getMeasuredWidth();
childView.layout(childLeft, 0,
childLeft+childWidth, childView.getMeasuredHeight());
childLeft += childWidth;
}
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final int width = MeasureSpec.getSize(widthMeasureSpec);
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
final int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
scrollTo(mCurScreen * width, 0);
}
public void snapToDestination() {
final int screenWidth = getWidth();
final int destScreen = (getScrollX()+ screenWidth/2)/screenWidth;
snapToScreen(destScreen);
}
public void snapToScreen(int whichScreen) {
// get the valid layout page
whichScreen = Math.max(0, Math.min(whichScreen, getChildCount()-1));
if (getScrollX() != (whichScreen*getWidth())) {
final int delta = whichScreen*getWidth()-getScrollX();
mScroller.startScroll(getScrollX(), 0,
delta, 0, Math.abs(delta)*2);
mCurScreen = whichScreen;
invalidate(); // Redraw the layout
if (mOnViewChangeListener != null)
{
mOnViewChangeListener.OnViewChange(mCurScreen);
}
}
}
@Override
public void computeScroll() {
// TODO Auto-generated method stub
if (mScroller.computeScrollOffset()) {
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
final int action = event.getAction();
final float x = event.getX();
final float y = event.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.i("", "onTouchEvent ACTION_DOWN");
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
mVelocityTracker.addMovement(event);
}
if (!mScroller.isFinished()){
mScroller.abortAnimation();
}
mLastMotionX = x;
break;
case MotionEvent.ACTION_MOVE:
int deltaX = (int)(mLastMotionX - x);
if (IsCanMove(deltaX))
{
if (mVelocityTracker != null)
{
mVelocityTracker.addMovement(event);
}
mLastMotionX = x;
scrollBy(deltaX, 0);
}
break;
case MotionEvent.ACTION_UP:
int velocityX = 0;
if (mVelocityTracker != null)
{
mVelocityTracker.addMovement(event);
mVelocityTracker.computeCurrentVelocity(1000);
velocityX = (int) mVelocityTracker.getXVelocity();
}
if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
// Fling enough to move left
Log.e(TAG, "snap left");
snapToScreen(mCurScreen - 1);
} else if (velocityX < -SNAP_VELOCITY
&& mCurScreen < getChildCount() - 1) {
// Fling enough to move right
Log.e(TAG, "snap right");
snapToScreen(mCurScreen + 1);
} else {
snapToDestination();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
// mTouchState = TOUCH_STATE_REST;
break;
}
return true;
}
//
// public boolean onInterceptTouchEvent(MotionEvent ev) {
// // TODO Auto-generated method stub
// final int action = ev.getAction();
// if ((action == MotionEvent.ACTION_MOVE)
// && (mTouchState != TOUCH_STATE_REST)) {
// Log.i("", "onInterceptTouchEvent return true");
// return true;
// }
// final float x = ev.getX();
// final float y = ev.getY();
// switch (action) {
// case MotionEvent.ACTION_MOVE:
// final int xDiff = (int) Math.abs(mLastMotionX - x);
// if (xDiff > mTouchSlop) {
// mTouchState = TOUCH_STATE_SCROLLING;
// }
// break;
//
// case MotionEvent.ACTION_DOWN:
// mLastMotionX = x;
//