直播带货app开发利用ScrollView实现下拉内容刷新的效果
直播带货app开发利用ScrollView实现下拉内容刷新的效果
<com.lucas.yanfriends.myview.smoothscroll.StretchContainer
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/white"
app:ratio="0.6">
<com.lucas.yanfriends.myview.smoothscroll.StretchScrollView
android:id="@+id/notify9999"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/white"
android:fillViewport="true">
</com.lucas.yanfriends.myview.smoothscroll.StretchScrollView>
</com.lucas.yanfriends.myview.smoothscroll.StretchContainer>
StretchContainer.class
package com.lucas.yanfriends.myview.smoothscroll;
import android.content.Context;
import android.content.res.TypedArray;
import android.support.annotation.AttrRes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ViewConfiguration;
import android.view.animation.DecelerateInterpolator;
import android.widget.FrameLayout;
import android.widget.Scroller;
import com.lucas.yanfriends.R;
/**
* @author Gimpo create on 2017/9/1 10:54
* @email : jimbo922@163.com
*/
public class StretchContainer extends FrameLayout {
/**
* 弹性系数 越小说明这个view越难被拉动
*/
private float ratio;
/**
* view作出反应最小滑动距离
*/
private int mTouchSlop;
/**
* 这个scroller可以让滑动更加的顺滑 不是很突兀的那种 写法固定
*/
private Scroller mScroller;
/**
* 允许最大的下拉距离
*/
private float maxY = 600;
/**
* 包裹的滚动view 可以是所有的view 这个view最好能滚动
*/
private StretchScrollView mScrollView;
/**
* 最大滑动距离
*/
private float mLastY;
/**
* 当前view被拖拽
*/
private boolean mIsDraging;
/**
* 回弹时间
*/
private int duration = 500;
public StretchContainer(@NonNull Context context) {
super(context);
initView(context, null);
}
public StretchContainer(@NonNull Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
initView(context, attrs);
}
public StretchContainer(@NonNull Context context, @Nullable AttributeSet attrs, @AttrRes int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context, attrs);
}
public void initView(Context context, AttributeSet attrs) {
if (attrs != null) {
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.StretchContainer);
ratio = a.getFloat(R.styleable.StretchContainer_ratio, 1.0f);
}
ViewConfiguration config = ViewConfiguration.get(context);
mTouchSlop = config.getScaledTouchSlop();
DecelerateInterpolator interpolator = new DecelerateInterpolator();
mScroller = new Scroller(context, interpolator);
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
mScrollView = (StretchScrollView) getChildAt(0);
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
float currentY = ev.getY();
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mLastY = currentY;
break;
case MotionEvent.ACTION_MOVE:
float distanceY = currentY - mLastY;
if (mIsDraging) {
if (distanceY <= 0) {
if(mScrollView.isScrolledToTop()) {
scrollTo(0, 0);
mIsDraging = false;
return super.dispatchTouchEvent(ev);
}
}else{
if(mScrollView.isScrolledToBottom()){
scrollTo(0, 0);
mIsDraging = false;
return super.dispatchTouchEvent(ev);
}
}
scrollTo(0, (int) (-distanceY * ratio));
return true;
} else {
if (Math.abs(distanceY) > mTouchSlop) {
if (distanceY > 0) { // 向下
if (mScrollView.isScrolledToTop()) {
mLastY = currentY;
mIsDraging = true;
}
}else{
if(mScrollView.isScrolledToBottom()){
mLastY = currentY;
mIsDraging = true;
}
}
}
}
break;
case MotionEvent.ACTION_UP:
if (mIsDraging) {
int scrollY = getScrollY();
mScroller.startScroll(0, scrollY, 0, -scrollY, duration);
mIsDraging = false;
invalidate();
return true;
}
break;
}
return super.dispatchTouchEvent(ev);
}
@Override
public void computeScroll() {
//判断是否还在滚动，还在滚动为true
if (mScroller.computeScrollOffset()) {
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
//更新界面
postInvalidate();
}
super.computeScroll();
}
}
StretchScrollView.class
package com.lucas.yanfriends.myview.smoothscroll;
import android.content.Context;
import android.util.AttributeSet;
import android.widget.ScrollView;
/**
* @author Gimpo create on 2017/9/1 12:06
* @email : jimbo922@163.com
*/
public class StretchScrollView extends ScrollView {
private boolean isScrolledToTop = true;
private boolean isScrolledToBottom;
public StretchScrollView(Context context) {
super(context);
}
public StretchScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public StretchScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (getScrollY() == 0) { // 小心踩坑1: 这里不能是getScrollY() <= 0
setScrolledToTop(true);
setScrolledToBottom(false);
} else if (getScrollY() + getHeight() - getPaddingTop()-getPaddingBottom() == getChildAt(0).getHeight()) {
// 小心踩坑2: 这里不能是 >=
// 小心踩坑3（可能忽视的细节2）：这里最容易忽视的就是ScrollView上下的padding
setScrolledToTop(false);
setScrolledToBottom(true);
} else {
setScrolledToTop(false);
setScrolledToBottom(false);
}
}
public boolean isScrolledToTop() {
return isScrolledToTop;
}
public void setScrolledToTop(boolean scrolledToTop) {
isScrolledToTop = scrolledToTop;
}
public boolean isScrolledToBottom() {
return isScrolledToBottom;
}
public void setScrolledToBottom(boolean scrolledToBottom) {
isScrolledToBottom = scrolledToBottom;
}
}
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