public void captureChildView(View childView, int activePointerId) {
        if (childView.getParent() != mParentView) {
            throw new IllegalArgumentException("captureChildView: parameter must be a descendant " +
                    "of the ViewDragHelper's tracked parent view (" + mParentView + ")");
        }

        mCapturedView = childView;
        mActivePointerId = activePointerId;
        mCallback.onViewCaptured(childView, activePointerId);
        setDragState(STATE_DRAGGING);
    }
Capture a specific child view for dragging within the parent. The callback will be notified
but {@link Callback#tryCaptureView(View, int)} will not be asked permission to
capture this view.

@param childView Child view to capture
@param activePointerId ID of the pointer that is dragging the captured child view
app/src/main/java/home/smart/fly/animations/widget/slidepanel/ViewDragHelper.java