我有一个环绕整个布局的ScrollView，这样整个屏幕都可以滚动。我在这个ScrollView中的第一个元素是一个HorizontalScrollView块，它具有可以水平滚动的功能。我已经添加了一个ontouchlistener到horizontalscrollview来处理触摸事件，并强制视图“捕捉”到ACTION_UP事件上最近的图像。
所以我想要的效果就像普通的android主屏幕，你可以从一个屏幕滚动到另一个屏幕，当你抬起手指时，它就会切换到一个屏幕。
这一切都很好，除了一个问题:我需要几乎完美地水平地从左向右滑动ACTION_UP才能注册。如果我至少垂直滑动(我认为许多人倾向于在手机上左右滑动时这样做)，我将收到ACTION_CANCEL而不是ACTION_UP。我的理论是，这是因为horizontalscrollview在一个scrollview中，而scrollview劫持了垂直触摸来允许垂直滚动。
我如何才能禁用触摸事件为滚动视图从我的水平滚动视图，但仍然允许正常的垂直滚动在滚动视图的其他地方?
下面是我的代码示例:
public class HomeFeatureLayout extends HorizontalScrollView {
private ArrayList<ListItem> items = null;
private GestureDetector gestureDetector;
View.OnTouchListener gestureListener;
private static final int SWIPE_MIN_DISTANCE = 5;
private static final int SWIPE_THRESHOLD_VELOCITY = 300;
private int activeFeature = 0;
public HomeFeatureLayout(Context context, ArrayList<ListItem> items){
super(context);
setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
setFadingEdgeLength(0);
this.setHorizontalScrollBarEnabled(false);
this.setVerticalScrollBarEnabled(false);
LinearLayout internalWrapper = new LinearLayout(context);
internalWrapper.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
internalWrapper.setOrientation(LinearLayout.HORIZONTAL);
addView(internalWrapper);
this.items = items;
for(int i = 0; i< items.size();i++){
LinearLayout featureLayout = (LinearLayout) View.inflate(this.getContext(),R.layout.homefeature,null);
TextView header = (TextView) featureLayout.findViewById(R.id.featureheader);
ImageView image = (ImageView) featureLayout.findViewById(R.id.featureimage);
TextView title = (TextView) featureLayout.findViewById(R.id.featuretitle);
title.setTag(items.get(i).GetLinkURL());
TextView date = (TextView) featureLayout.findViewById(R.id.featuredate);
header.setText("FEATURED");
Image cachedImage = new Image(this.getContext(), items.get(i).GetImageURL());
image.setImageDrawable(cachedImage.getImage());
title.setText(items.get(i).GetTitle());
date.setText(items.get(i).GetDate());
internalWrapper.addView(featureLayout);
}
gestureDetector = new GestureDetector(new MyGestureDetector());
setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if (gestureDetector.onTouchEvent(event)) {
return true;
}
else if(event.getAction() == MotionEvent.ACTION_UP || event.getAction() == MotionEvent.ACTION_CANCEL ){
int scrollX = getScrollX();
int featureWidth = getMeasuredWidth();
activeFeature = ((scrollX + (featureWidth/2))/featureWidth);
int scrollTo = activeFeature*featureWidth;
smoothScrollTo(scrollTo, 0);
return true;
}
else{
return false;
}
}
});
}
class MyGestureDetector extends SimpleOnGestureListener {
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
try {
//right to left
if(e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
activeFeature = (activeFeature < (items.size() - 1))? activeFeature + 1:items.size() -1;
smoothScrollTo(activeFeature*getMeasuredWidth(), 0);
return true;
}
//left to right
else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
activeFeature = (activeFeature > 0)? activeFeature - 1:0;
smoothScrollTo(activeFeature*getMeasuredWidth(), 0);
return true;
}
} catch (Exception e) {
// nothing
}
return false;
}
}
}
这对我来说并不是很有效。我换了，现在工作很顺利。如果有人感兴趣的话。
public class ScrollViewForNesting extends ScrollView {
private final int DIRECTION_VERTICAL = 0;
private final int DIRECTION_HORIZONTAL = 1;
private final int DIRECTION_NO_VALUE = -1;
private final int mTouchSlop;
private int mGestureDirection;
private float mDistanceX;
private float mDistanceY;
private float mLastX;
private float mLastY;
public ScrollViewForNesting(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
final ViewConfiguration configuration = ViewConfiguration.get(context);
mTouchSlop = configuration.getScaledTouchSlop();
}
public ScrollViewForNesting(Context context, AttributeSet attrs) {
this(context, attrs,0);
}
public ScrollViewForNesting(Context context) {
this(context,null);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mDistanceY = mDistanceX = 0f;
mLastX = ev.getX();
mLastY = ev.getY();
mGestureDirection = DIRECTION_NO_VALUE;
break;
case MotionEvent.ACTION_MOVE:
final float curX = ev.getX();
final float curY = ev.getY();
mDistanceX += Math.abs(curX - mLastX);
mDistanceY += Math.abs(curY - mLastY);
mLastX = curX;
mLastY = curY;
break;
}
return super.onInterceptTouchEvent(ev) && shouldIntercept();
}
private boolean shouldIntercept(){
if((mDistanceY > mTouchSlop || mDistanceX > mTouchSlop) && mGestureDirection == DIRECTION_NO_VALUE){
if(Math.abs(mDistanceY) > Math.abs(mDistanceX)){
mGestureDirection = DIRECTION_VERTICAL;
}
else{
mGestureDirection = DIRECTION_HORIZONTAL;
}
}
if(mGestureDirection == DIRECTION_VERTICAL){
return true;
}
else{
return false;
}
}
}
这对我来说并不是很有效。我换了，现在工作很顺利。如果有人感兴趣的话。
public class ScrollViewForNesting extends ScrollView {
private final int DIRECTION_VERTICAL = 0;
private final int DIRECTION_HORIZONTAL = 1;
private final int DIRECTION_NO_VALUE = -1;
private final int mTouchSlop;
private int mGestureDirection;
private float mDistanceX;
private float mDistanceY;
private float mLastX;
private float mLastY;
public ScrollViewForNesting(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
final ViewConfiguration configuration = ViewConfiguration.get(context);
mTouchSlop = configuration.getScaledTouchSlop();
}
public ScrollViewForNesting(Context context, AttributeSet attrs) {
this(context, attrs,0);
}
public ScrollViewForNesting(Context context) {
this(context,null);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mDistanceY = mDistanceX = 0f;
mLastX = ev.getX();
mLastY = ev.getY();
mGestureDirection = DIRECTION_NO_VALUE;
break;
case MotionEvent.ACTION_MOVE:
final float curX = ev.getX();
final float curY = ev.getY();
mDistanceX += Math.abs(curX - mLastX);
mDistanceY += Math.abs(curY - mLastY);
mLastX = curX;
mLastY = curY;
break;
}
return super.onInterceptTouchEvent(ev) && shouldIntercept();
}
private boolean shouldIntercept(){
if((mDistanceY > mTouchSlop || mDistanceX > mTouchSlop) && mGestureDirection == DIRECTION_NO_VALUE){
if(Math.abs(mDistanceY) > Math.abs(mDistanceX)){
mGestureDirection = DIRECTION_VERTICAL;
}
else{
mGestureDirection = DIRECTION_HORIZONTAL;
}
}
if(mGestureDirection == DIRECTION_VERTICAL){
return true;
}
else{
return false;
}
}
}
日期:2021年5月12日
看起来很无聊，但相信我，如果你想在垂直滚动视图中水平滚动任何视图，这是值得的!!
在jetpack中也可以通过创建一个自定义视图并扩展你想要水平滚动的视图;在垂直滚动视图中，并在AndroidView组合中使用该自定义视图(现在，“Jetpack Compose is in 1.0.0-beta06”)
这是最优的解决方案，如果你想要水平自由滚动和垂直自由滚动，而不让垂直滚动条拦截你的触摸，当你在水平滚动视图中垂直滚动时，只允许垂直滚动条拦截触摸:
private class HorizontallyScrollingView @JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null
) : ViewThatYouWannaScrollHorizontally(context, attrs){
override fun onTouchEvent(event: MotionEvent?): Boolean {
// When the user's finger touches the webview and starts moving
if(event?.action == MotionEvent.ACTION_MOVE){
// get the velocity tracker object
val mVelocityTracker = VelocityTracker.obtain();
// connect the velocity tracker object with the event that we are emitting while we are touching the webview
mVelocityTracker.addMovement(event)
// compute the velocity in terms of pixels per 1000 millisecond(i.e 1 second)
mVelocityTracker.computeCurrentVelocity(1000);
// compute the Absolute Velocity in X axis
val xVelocityABS = abs(mVelocityTracker.getXVelocity(event?.getPointerId((event?.actionIndex))));
// compute the Absolute Velocity in Y axis
val yVelocityABS = abs(mVelocityTracker.getYVelocity(event?.getPointerId((event?.actionIndex))));
// If the velocity of x axis is greater than y axis then we'll consider that it's a horizontal scroll and tell the parent layout
// "Hey parent bro! im scrolling horizontally, this has nothing to do with ur scrollview so stop capturing my event and stay the f*** where u are "
if(xVelocityABS > yVelocityABS){
// So, we'll disallow the parent to listen to any touch events until i have moved my fingers off the screen
parent.requestDisallowInterceptTouchEvent(true)
}
} else if (event?.action == MotionEvent.ACTION_CANCEL || event?.action == MotionEvent.ACTION_UP){
// If the touch event has been cancelled or the finger is off the screen then reset it (i.e let the parent capture the touch events on webview as well)
parent.requestDisallowInterceptTouchEvent(false)
}
return super.onTouchEvent(event)
}
}
这里，viewthatyouwannascrollhorizontal是你想要水平滚动的视图，当你水平滚动时，你不希望垂直滚动条捕捉到触摸并认为“哦!用户在垂直滚动所以parent。requestdisallowintercepttouchevent (true)基本上会说垂直滚动条"hey you!不要捕捉任何触摸，因为用户是水平滚动的”
当用户完成水平滚动并试图垂直滚动置于垂直滚动条内的水平滚动条时，它会看到Y轴的触摸速度大于X轴，这表明用户没有水平滚动而水平滚动的东西会说“嘿，你!家长，你听到了吗?用户正在垂直滚动通过我，现在你可以拦截触摸，并在垂直滚动中显示我下面的东西。”
更新:我知道了。在我的ScrollView上，我需要重写onInterceptTouchEvent方法，以仅在Y运动是X运动时拦截触摸事件。ScrollView的默认行为似乎是每当有任何Y运动时截取触摸事件。因此，通过修正，ScrollView只会在用户故意在Y方向上滚动时拦截事件，并在这种情况下将ACTION_CANCEL传递给子代。
下面是我的滚动视图类的代码，它包含了HorizontalScrollView:
public class CustomScrollView extends ScrollView {
private GestureDetector mGestureDetector;
public CustomScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
mGestureDetector = new GestureDetector(context, new YScrollDetector());
setFadingEdgeLength(0);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return super.onInterceptTouchEvent(ev) && mGestureDetector.onTouchEvent(ev);
}
// Return false if we're scrolling in the x direction
class YScrollDetector extends SimpleOnGestureListener {
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
return Math.abs(distanceY) > Math.abs(distanceX);
}
}
}
