How to swipe to dismiss a DialogFragment in android

Question

I set this View.OnTouchListener on my DialogFragment's layout:

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;

    private boolean mWasMoved;

    /**
     * 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 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);
                }
                break;
            }

            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();
                                }
                            });
                    return true;
                } 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();
    }
}

And I've used it before on EditTexts and it's worked, but I'm not getting the expected behavior with DialogFragments. What's happening with the DialogFragments is that when I swipe it, the layout begins to animate as expected, but not the underlying window that my layout is placed in. Here is what it looks like:

As you can see, my layout is dismissing, but only in the context of the underlying layout that it is in. I thought that when a layout was created, my layout's root was the root of the view, but in this case it seems to be something different; something that I can't get access to to set an View.OnTouchListener on. Any idea on what I need to do in order to get the expected behavior?

Answer 1

this works for me!

    WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams();
    layoutParams.copyFrom(mDialog.getWindow().getAttributes());
    layoutParams.width = WindowManager.LayoutParams.MATCH_PARENT;
    layoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
    layoutParams.gravity = Gravity.CENTER;
    mDialog.getWindow().setAttributes(layoutParams);
    root.setOnTouchListener(new SwipeDismissTouchListener(mDialog.getWindow().getDecorView(),
            null, new SwipeDismissTouchListener.DismissCallbacks() {
        @Override
        public boolean canDismiss(Object token) {
            return true;
        }

        @Override
        public void onDismiss(View view, Object token) {
            dismiss();
        }
    }));

Answer 2

The key was to set the SwipeDimissTouchListener on the view returned by the DialoFragment's Dialog's Window's getDecorView() in the DialogFragment's onResume method, like so:

    @Override
    public void onResume() {
        super.onResume();
        Window window = getDialog().getWindow();
        window.getDecorView().setOnTouchListener(new SwipeDismissTouchListener(window.getDecorView(), null, new SwipeDismissTouchListener.DismissCallbacks() {
            @Override
            public boolean canDismiss(Object token) {
                return true;
            }

            @Override
            public void onDismiss(View view, Object token) {
                dismiss();
            }
        }));
    }