问题
I'm trying to make a swipeable layout so you can swipe it to dismiss like in Google now. I managed to getting it worked on a view such as button using this codes:
SwipeDismissTouchListener:
public class SwipeDismissTouchListener implements View.OnTouchListener {
// Cached ViewConfiguration and system-wide constant values
private int mSlop;
private int mMinFlingVelocity;
private int mMaxFlingVelocity;
private long mAnimationTime;
// Fixed properties
private View mView;
private DismissCallbacks mCallbacks;
private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero
// Transient properties
private float mDownX;
private float mDownY;
private boolean mSwiping;
private int mSwipingSlop;
private Object mToken;
private VelocityTracker mVelocityTracker;
private float mTranslationX;
/**
* The callback interface used by {@link SwipeDismissTouchListener} to inform its client
* about a successful dismissal of the view for which it was created.
*/
public interface DismissCallbacks {
/**
* Called to determine whether the view can be dismissed.
*/
boolean canDismiss(Object token);
/**
* Called when the user has indicated they she would like to dismiss the view.
*
* @param view The originating {@link android.view.View} to be dismissed.
* @param token The optional token passed to this object's constructor.
*/
void onDismiss(View view, Object token);
}
/**
* Constructs a new swipe-to-dismiss touch listener for the given view.
*
* @param view The view to make dismissable.
* @param token An optional token/cookie object to be passed through to the callback.
* @param callbacks The callback to trigger when the user has indicated that she would like to
* dismiss this view.
*/
public SwipeDismissTouchListener(View view, Object token, DismissCallbacks callbacks) {
ViewConfiguration vc = ViewConfiguration.get(view.getContext());
mSlop = vc.getScaledTouchSlop();
mMinFlingVelocity = vc.getScaledMinimumFlingVelocity() * 16;
mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
mAnimationTime = view.getContext().getResources().getInteger(
android.R.integer.config_shortAnimTime);
mView = view;
mToken = token;
mCallbacks = callbacks;
}
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
// offset because the view is translated during swipe
motionEvent.offsetLocation(mTranslationX, 0);
if (mViewWidth < 2) {
mViewWidth = mView.getWidth();
}
switch (motionEvent.getActionMasked()) {
case MotionEvent.ACTION_DOWN: {
// TODO: ensure this is a finger, and set a flag
mDownX = motionEvent.getRawX();
mDownY = motionEvent.getRawY();
if (mCallbacks.canDismiss(mToken)) {
mVelocityTracker = VelocityTracker.obtain();
mVelocityTracker.addMovement(motionEvent);
}
return false;
}
case MotionEvent.ACTION_UP: {
if (mVelocityTracker == null) {
break;
}
float deltaX = motionEvent.getRawX() - mDownX;
mVelocityTracker.addMovement(motionEvent);
mVelocityTracker.computeCurrentVelocity(1000);
float velocityX = mVelocityTracker.getXVelocity();
float absVelocityX = Math.abs(velocityX);
float absVelocityY = Math.abs(mVelocityTracker.getYVelocity());
boolean dismiss = false;
boolean dismissRight = false;
if (Math.abs(deltaX) > mViewWidth / 2 && mSwiping) {
dismiss = true;
dismissRight = deltaX > 0;
} else if (mMinFlingVelocity <= absVelocityX && absVelocityX <= mMaxFlingVelocity
&& absVelocityY < absVelocityX
&& absVelocityY < absVelocityX && mSwiping) {
// dismiss only if flinging in the same direction as dragging
dismiss = (velocityX < 0) == (deltaX < 0);
dismissRight = mVelocityTracker.getXVelocity() > 0;
}
if (dismiss) {
// dismiss
mView.animate()
.translationX(dismissRight ? mViewWidth : -mViewWidth)
.alpha(0)
.setDuration(mAnimationTime)
.setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
performDismiss();
}
});
} else if (mSwiping) {
// cancel
mView.animate()
.translationX(0)
.alpha(1)
.setDuration(mAnimationTime)
.setListener(null);
}
mVelocityTracker.recycle();
mVelocityTracker = null;
mTranslationX = 0;
mDownX = 0;
mDownY = 0;
mSwiping = false;
break;
}
case MotionEvent.ACTION_CANCEL: {
if (mVelocityTracker == null) {
break;
}
mView.animate()
.translationX(0)
.alpha(1)
.setDuration(mAnimationTime)
.setListener(null);
mVelocityTracker.recycle();
mVelocityTracker = null;
mTranslationX = 0;
mDownX = 0;
mDownY = 0;
mSwiping = false;
break;
}
case MotionEvent.ACTION_MOVE: {
if (mVelocityTracker == null) {
break;
}
mVelocityTracker.addMovement(motionEvent);
float deltaX = motionEvent.getRawX() - mDownX;
float deltaY = motionEvent.getRawY() - mDownY;
if (Math.abs(deltaX) > mSlop && Math.abs(deltaY) < Math.abs(deltaX) / 2) {
mSwiping = true;
mSwipingSlop = (deltaX > 0 ? mSlop : -mSlop);
mView.getParent().requestDisallowInterceptTouchEvent(true);
// Cancel listview's touch
MotionEvent cancelEvent = MotionEvent.obtain(motionEvent);
cancelEvent.setAction(MotionEvent.ACTION_CANCEL |
(motionEvent.getActionIndex() <<
MotionEvent.ACTION_POINTER_INDEX_SHIFT));
mView.onTouchEvent(cancelEvent);
cancelEvent.recycle();
}
if (mSwiping) {
mTranslationX = deltaX;
mView.setTranslationX(deltaX - mSwipingSlop);
// TODO: use an ease-out interpolator or such
mView.setAlpha(Math.max(0f, Math.min(1f,
1f - 2f * Math.abs(deltaX) / mViewWidth)));
return true;
}
break;
}
}
return false;
}
private void performDismiss() {
// Animate the dismissed view to zero-height and then fire the dismiss callback.
// This triggers layout on each animation frame; in the future we may want to do something
// smarter and more performant.
final ViewGroup.LayoutParams lp = mView.getLayoutParams();
final int originalHeight = mView.getHeight();
ValueAnimator animator = ValueAnimator.ofInt(originalHeight, 1).setDuration(mAnimationTime);
animator.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
mCallbacks.onDismiss(mView, mToken);
// Reset view presentation
mView.setAlpha(1f);
mView.setTranslationX(0);
lp.height = originalHeight;
mView.setLayoutParams(lp);
}
});
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
lp.height = (Integer) valueAnimator.getAnimatedValue();
mView.setLayoutParams(lp);
}
});
animator.start();
}
}
Calling it:
dismissableButton.setOnTouchListener(new SwipeDismissTouchListener(
dismissableButton,
null,
new SwipeDismissTouchListener.DismissCallbacks() {
@Override
public boolean canDismiss(Object token) {
return true;
}
@Override
public void onDismiss(View view, Object token) {
group.removeView(dismissableButton);
}
}));
I want to make this code work on a layout so i could swipe the layout to dismiss, for example so i could place a RelativeLayout inside a ViewGroup and make the RelativeLayout swipeable to dismiss.
回答1:
I just used the same SwipeDismissTouchListener class to implement a swipe gesture on a RelativeLayout, and at first had the problem of ACTION_MOVE never getting passed through, or any action other than ACTION_DOWN.
Found out that the problem is in ACTION_DOWN returning false. So just change your case ACTION_DOWN to return true, and it will work properly, as that will make other actions also get passed through.
回答2:
you should know that if you return false for action_down , you will not get any further actions regarding this touch event
https://developer.android.com/training/gestures/detector#capture-touch-events-for-an-activity-or-view
"Beware of creating a listener that returns false for the ACTION_DOWN event. If you do this, the listener will not be called for the subsequent ACTION_MOVE and ACTION_UP string of events. This is because ACTION_DOWN is the starting point for all touch events."
回答3:
This code worked for me. I was able to Swipe-dismiss Relative and Linear Layouts. Just make sure you call the removeView() method from the correct immediate parent layout.
@Override
public void onDismiss(View view, Object token) {
ViewGroup parent=(ViewGroup)dissmissableLayout.getParent();
parent.removeView(dismissableLayout);
}
来源：https://stackoverflow.com/questions/24641966/android-swipe-layout-to-dismiss