用ViewGroup实现左右滚动_viewgroup 左右滑动-优快云博客

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Scroller;
public class scollgroup extends ViewGroup implements OnGestureListener{
public static final String tag = "CScrollView";
public static final int TOUCH_STATUS_NORMAL = 0;
public static final int TOUCH_STATUS_FLING = 1;
public static final int TOUCH_STATUS_SCROLLING = 2;
public static final int TOUCH_STATUS_MOVING = 3;
/** 滚动一屏所花的时间*/
private static final int SCROLL_ANIMATION_TIME = 1000;
/** 首屏和尾屏的超屏数值*/
private static final int SCREEN_OFFSET = 100;
public int mStatus = TOUCH_STATUS_NORMAL;
protected GestureDetector mGestureDetector;
protected Scroller mScroller;
private int mCurrentPosX = 0;
private int mLastPosX;
private int mCurrentScreen = 0;
private int mDownPosX = 0;
private IndicatorControl mIndicatorControl;
public scollgroup(Context context, AttributeSet attrs) {
super(context, attrs);
mGestureDetector = new GestureDetector(this);
mScroller = new Scroller(context);
}
public scollgroup(Context context) {
super(context);
mGestureDetector = new GestureDetector(this);
mScroller = new Scroller(context);
}
/**
* 设置指示控制器
* @param indicatorControl 指示控制器
*/
public void setIndicatorControl(IndicatorControl indicatorControl) {
this.mIndicatorControl = indicatorControl;
if(mIndicatorControl != null) {
indicatorControl.setCount(this.getChildCount());
}
}
/**
* 计算每个子控件的位置
*/
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
final int childCount = getChildCount();
int left = 0;
View child = null;
for(int i = 0; i < childCount; i++) {
child = getChildAt(i);
if(child.getVisibility() == View.GONE)
continue;
final int width = child.getMeasuredWidth();
child.layout(left, 0, left + width, child.getMeasuredHeight());
left += width;
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final int childCount = getChildCount();
View child = null;
for(int i = 0; i < childCount; i++) {
child = getChildAt(i);
child.measure(widthMeasureSpec, heightMeasureSpec);
// Log.d(tag, "width = " + MeasureSpec.getSize(widthMeasureSpec) + "; height = " + MeasureSpec.getSize(heightMeasureSpec));
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
switch(event.getAction()) {
case MotionEvent.ACTION_DOWN:
Log.d(tag, "onInterceptTouchEvent => ACTION_DOWN");
return false;
//触屏移动时，则传递事件到OnTouch事件
case MotionEvent.ACTION_MOVE:
Log.d(tag, "onInterceptTouchEvent => ACTION_MOVE");
return true;
}
Log.d(tag, "onInterceptTouchEvent => " + event.getAction());
return true;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
final int x = (int)event.getX();
mGestureDetector.onTouchEvent(event);
switch(event.getAction()) {
case MotionEvent.ACTION_DOWN:
Log.d(tag, "onTouchEvent => ACTION_DOWN");
if(!mScroller.isFinished()) {
mScroller.abortAnimation();
}
mStatus = TOUCH_STATUS_MOVING;
mLastPosX = mCurrentPosX;
mDownPosX = x;
case MotionEvent.ACTION_MOVE:
Log.d(tag, "onTouchEvent => ACTION_MOVE");
//计算当前滚动到的坐标
mCurrentPosX = mLastPosX + mDownPosX - x;
//屏幕第一屏和最后一屏越界不能超过10
mCurrentPosX = Math.max(
Math.min(mCurrentPosX, (getChildCount() - 1)
* getMeasuredWidth() + SCREEN_OFFSET), -SCREEN_OFFSET);
// Log.d(tag, "mCurrentX = " + mCurrentPosX + "; mDownPosX = " + mDownPosX + "; x = " + x);
scrollTo(mCurrentPosX, 0);
break;
case MotionEvent.ACTION_UP:
Log.d(tag, "onTouchEvent => ACTION_UP");
//计算当前滚动到的屏幕,如果已触发FLING事件，则不用计算当前屏幕，因为已在onFling事件中计算出来了
if(mStatus != TOUCH_STATUS_FLING)
mCurrentScreen = calculateScreen(mCurrentPosX);
// Log.d(tag, "mCurrentScreen = " + mCurrentScreen);
scrollTo(mCurrentScreen);
break;
}
return true;
}
/**
* 将控件滚动到指定Subview
* @param screenIndex
*/
public void scrollTo(int screenIndex) {
int targetX = screenIndex * getMeasuredWidth();
// Log.d(tag, "getMeasuredWidth = " + getMeasuredWidth());
//计算执行滚动事件所花的时间
int time = Math.abs(mCurrentPosX - screenIndex * getMeasuredWidth())
* SCROLL_ANIMATION_TIME / getMeasuredWidth();
mStatus = TOUCH_STATUS_SCROLLING;
// Log.d(tag, "mCurrentPosX = " + mCurrentPosX + "; targetX -mCurrentPosX = " + (targetX -mCurrentPosX));
mScroller.startScroll(mCurrentPosX, 0, targetX - mCurrentPosX , 0, time);
computeScroll();
}
@Override
public void computeScroll() {
if(mStatus == TOUCH_STATUS_SCROLLING && mScroller.computeScrollOffset()) {
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
mCurrentPosX = mScroller.getCurrX();
postInvalidate();
} else if(mStatus == TOUCH_STATUS_SCROLLING) {
mStatus = TOUCH_STATUS_NORMAL;
mCurrentPosX = mScroller.getCurrX();
if(mIndicatorControl != null) {
mIndicatorControl.setSelected(calculateScreen(mCurrentPosX));
}
}
}
/**
* 通过当前所在坐标计算出屏幕属于哪一屏
* @param curPos 当前坐标
*/
private int calculateScreen(int curPos) {
int curScreen = curPos / getMeasuredWidth();
if((curPos - curScreen * getMeasuredWidth()) > getMeasuredWidth() / 2) {
curScreen ++;
}
return Math.min(Math.max(0, curScreen), getChildCount() - 1);
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
// Log.i(tag, "Fling >> velocityX : " + velocityX + "; velocityY : " + velocityY);
// Log.i(tag, "Fling >> event1 : " + e1.getX() + ", " + e1.getY() + "; event2 : " + e2.getX() + ", " + e2.getY());
mStatus = TOUCH_STATUS_FLING;
if(velocityX > 0) {
mCurrentScreen = Math.max(mCurrentScreen - 1, 0);
} else {
mCurrentScreen = Math.min(mCurrentScreen + 1, getChildCount() - 1);
}
return false;
}
public void requestInvalidate(int width) {
mCurrentPosX = width * mCurrentScreen;
scrollTo(mCurrentPosX, 0);
}
@Override
public boolean onDown(MotionEvent e) {
// TODO Auto-generated method stub
return false;
}
@Override
public void onShowPress(MotionEvent e) {
// TODO Auto-generated method stub
}
@Override
public boolean onSingleTapUp(MotionEvent e) {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
float distanceY) {
// TODO Auto-generated method stub
return false;
}
@Override
public void onLongPress(MotionEvent e) {
// TODO Auto-generated method stub
}
/**
* 指示器控制接口
* @author 郑澍璋
*/
public static interface IndicatorControl {
/**
* 设置指示索引的数量
*/
public void setCount(int count);
/**
* 获取当前所指示的索引值
*/
public int getCount();
/**
* 设置当前选中哪一项
*/
public void setSelected(int index);
}
}