這篇效果和上一篇:http://blog.csdn.net/qq_18148011/article/details/53761576的效果是一樣的,但是不再在OnTouchEvent中寫代碼,而是使用系統自帶的類GestureDetector來監聽手勢以及滑動事件等等,它內置了滑動,點擊,長按等事件,而且有快速滑動,比較方便,比自己寫的細節處理要好。
代碼:
package com.example.libingyuan.horizontallistview.ScrollViewGroup;
import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Scroller;
/**
* 自定義ViewGroup(橫向滾動)
*/
public class ScrollViewGroup extends ViewGroup {
//滾動計算輔助類
private Scroller mScroller;
//屏幕寬度
private int screenWidth;
//可以移動的最大距離
private int mMaxDistance;
//自定義手勢監聽類
private ScrollTouchLisener mTouchLisener;
//手勢監聽
private GestureDetector mDetector;
/**
* 使用new關鍵字創建對象的時候調用
*/
public ScrollViewGroup(Context context) {
this(context, null);
}
/**
* 在XML文件中使用的時候調用
*/
public ScrollViewGroup(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
/**
* 在xml文件中調用,並且使用了自定義屬性的時候調用
*/
public ScrollViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
/**
* 初始化方法
* 初始化滾動輔助類Scroller以及計算出屏幕寬度
*/
private void init(Context context) {
//初始化輔助類
mScroller = new Scroller(context);
//獲取屏幕寬度
WindowManager manager = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
manager.getDefaultDisplay().getMetrics(outMetrics);
screenWidth = outMetrics.widthPixels;
//手勢指示器初始化
mTouchLisener = new ScrollTouchLisener();
mDetector = new GestureDetector(context, mTouchLisener);
}
/**
* 滾動時需要重寫的方法,用於控制滾動
*/
@Override
public void computeScroll() {
//判斷滾動時候停止
if (mScroller.computeScrollOffset()) {
//滾動到指定的位置
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
//這句話必須寫,否則不能實時刷新
postInvalidate();
}
}
/**
* 手指觸屏事件監聽
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
mDetector.onTouchEvent(event);
if (event.getAction() == MotionEvent.ACTION_UP) {
this.onUp(event);
}
return true;
}
/*
*測量方法,測量父佈局的寬度和高度
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//重新設置寬高
this.setMeasuredDimension(measureWidth(widthMeasureSpec, heightMeasureSpec), measureHeight(widthMeasureSpec, heightMeasureSpec));
}
/**
* 測量寬度
*/
private int measureWidth(int widthMeasureSpec, int heightMeasureSpec) {
// 寬度
int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
//父控件的寬(wrap_content)
int width = 0;
int childCount = getChildCount();
//重新測量子view的寬度,以及最大高度
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
measureChild(child, widthMeasureSpec, heightMeasureSpec);
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
width += childWidth;
}
return modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width;
}
/**
* 測量高度
*/
private int measureHeight(int widthMeasureSpec, int heightMeasureSpec) {
//高度
int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
//父控件的高(wrap_content)
int height = 0;
int childCount = getChildCount();
//重新測量子view的寬度,以及最大高度
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
measureChild(child, widthMeasureSpec, heightMeasureSpec);
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
height += childHeight;
}
height = height / childCount;
return modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height;
}
/**
* 給子佈局設定位置
*/
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int childLeft = 0;//子View左邊的間距
int childWidth;//子View的寬度
int height = getHeight();//屏幕的寬度
int childCount = getChildCount();//子View的數量
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
child.layout(childLeft, 0, childLeft + childWidth, height);
childLeft += childWidth;
}
}
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new MarginLayoutParams(getContext(), attrs);
}
/*
*按下事件 ACTION_DOWN
*/
public boolean onDown(MotionEvent e) {
//如果停止滾動則取消動畫(即手指按下就停止滾動)
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
return false;
}
/*
*擡起事件 ACTION_UP
*/
public boolean onUp(MotionEvent e) {
//得到最後一個子View
View lastChild = getChildAt(getChildCount() - 1);
//獲取滑動的最大滑動距離(最後一個Child的右邊框的座標減去屏幕的寬度)
int finalyChild = (int) (lastChild.getX() + lastChild.getWidth() - screenWidth);
mMaxDistance = finalyChild;
//如果滑動的距離小於第一個控件的最左邊(0)則回彈至(0,0)點
if (getScrollX() < 0) {
scrollTo(0, 0);
}
//如果滑動的距離大於最大可滑動距離則滑動到最後一個子View
if (getScrollX() >= finalyChild)
scrollTo(finalyChild, 0);
//刷新界面
invalidate();
return false;
}
/*
*ACTION_DOWN 、短按不移動
*/
public void onShowPress(MotionEvent e) {
}
/*
*短按ACTION_DOWN、ACTION_UP
*/
public boolean onSingleTapUp(MotionEvent e) {
return false;
}
/*
*ACTION_DOWN 、慢滑動
*/
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
//滾動
scrollBy((int) distanceX, 0);
return false;
}
// ACTION_DOWN 、長按不滑動
public void onLongPress(MotionEvent e) {
}
/*
*ACTION_DOWN 、快滑動、 ACTION_UP
*/
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
mScroller.fling(getScrollX(), 0, (int) -velocityX, 0, 0, mMaxDistance, 0, 0);
return false;
}
/**
* 自定義手勢監聽類
*/
private class ScrollTouchLisener implements GestureDetector.OnGestureListener {
//按下事件
@Override
public boolean onDown(MotionEvent e) {
return ScrollViewGroup.this.onDown(e);
}
//單擊事件
@Override
public void onShowPress(MotionEvent e) {
ScrollViewGroup.this.onShowPress(e);
}
//手指擡起事件
@Override
public boolean onSingleTapUp(MotionEvent e) {
return ScrollViewGroup.this.onSingleTapUp(e);
}
//滾動事件
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
return ScrollViewGroup.this.onScroll(e1, e2, distanceX, distanceY);
}
//長按事件
@Override
public void onLongPress(MotionEvent e) {
ScrollViewGroup.this.onLongPress(e);
}
//滑動事件
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
return ScrollViewGroup.this.onFling(e1, e2, velocityX, velocityY);
}
}
}