public override bool OnDependentViewChanged(CoordinatorLayout parent, Java.Lang.Object child, View dependency)
{
var view = child.JavaCast <TextView> ();
int offset = dependency.Top - view.Top;
ViewCompat.OffsetTopAndBottom(view, offset);
return(true);
}
public override bool OnLayoutChild(CoordinatorLayout parent, Java.Lang.Object cChild, int layoutDirection)
{
// return base.OnLayoutChild(parent, child, layoutDirection);
var child = cChild.JavaCast <View>();
// First let the parent lay it out
if (_state != StateDragging && _state != StateSettling)
{
if (parent.FitsSystemWindows && !child.FitsSystemWindows)
{
child.SetFitsSystemWindows(true);
}
parent.OnLayoutChild(child, layoutDirection);
}
// Offset the bottom sheet
_parentHeight = parent.Height;
_minOffset = System.Math.Max(0, _parentHeight - child.Height);
_maxOffset = System.Math.Max(_parentHeight - _peekHeight, _minOffset);
/**
* New behavior
*/
switch (_state)
{
case StateAnchorPoint:
ViewCompat.OffsetTopAndBottom(child, AnchorPoint);
break;
case StateExpanded:
ViewCompat.OffsetTopAndBottom(child, _minOffset);
break;
case StateHidden:
if (Hideable)
{
ViewCompat.OffsetTopAndBottom(child, _parentHeight);
}
break;
case StateCollapsed:
ViewCompat.OffsetTopAndBottom(child, _maxOffset);
break;
}
;
if (_viewDragHelper == null)
{
_viewDragHelper = ViewDragHelper.Create(parent, _dragCallback);
}
_viewRef = new WeakReference <View>(child);
_nestedScrollingChildRef = new WeakReference <View>(FindScrollingChild(child));
return(true);
}
public override bool OnLayoutChild(
CoordinatorLayout parent, Java.Lang.Object childObject, int layoutDirection)
{
Debug.WriteLineIf(DebugTrace, $"OnLayoutChild");
View child = Android.Runtime.Extensions.JavaCast <View>(childObject);
if (ViewCompat.GetFitsSystemWindows(parent) && !ViewCompat.GetFitsSystemWindows(child))
{
ViewCompat.SetFitsSystemWindows(child, true);
}
int savedTop = child.Top;
// First let the parent lay it out
parent.OnLayoutChild(child, layoutDirection);
// Offset the bottom sheet
mParentHeight = parent.Height;
mMinOffset = Math.Max(0, mParentHeight - child.Height);
mMaxOffset = Math.Max(mParentHeight - mPeekHeight, mMinOffset);
mAnchorOffset = (int)Math.Max(mParentHeight * mAnchorThreshold, mMinOffset);
Debug.WriteLineIf(DebugTrace, $"offset computed => savedTop:{savedTop} mMinOffset:{mMinOffset} mMaxOffset:{mMaxOffset} mAnchorOffset:{mAnchorOffset} ");
if (mState == STATE_EXPANDED)
{
ViewCompat.OffsetTopAndBottom(child, mMinOffset);
}
else if (mState == STATE_ANCHOR)
{
ViewCompat.OffsetTopAndBottom(child, mAnchorOffset);
}
else if (mHideable && mState == STATE_HIDDEN)
{
ViewCompat.OffsetTopAndBottom(child, mParentHeight);
}
else if (mState == STATE_COLLAPSED)
{
ViewCompat.OffsetTopAndBottom(child, mMaxOffset);
}
else if (mState == STATE_DRAGGING || mState == STATE_SETTLING)
{
ViewCompat.OffsetTopAndBottom(child, savedTop - child.Top);
}
if (mViewDragHelper == null || mViewDragHelper.Handle == IntPtr.Zero)
{
mViewDragHelper = ViewDragHelper.Create(parent, mDragCallback);
}
mViewRef = new WeakReference <View>(child);
mNestedScrollingChildRef = new WeakReference <View>(findScrollingChild(child));
return(true);
}
public override bool OnLayoutChild(CoordinatorLayout parent, Java.Lang.Object child, int layoutDirection)
{
if (!(child is NestedScrollView view))
{
return(base.OnLayoutChild(parent, child, layoutDirection));
}
// First layout the child as normal.
parent.OnLayoutChild(view, layoutDirection);
// Center the FAB vertically along the top edge of the card.
int fabHalfHeight = view.FindViewById(Resource.Id.fab).Height / 2;
SetTopMargin(view.FindViewById(Resource.Id.cardview), fabHalfHeight);
// Give the RecyclerView a maximum height to ensure the card will never
// overlap the toolbar as it scrolls.
int rvMaxHeight =
view.Height
- fabHalfHeight
- view.FindViewById(Resource.Id.card_title).Height
- view.FindViewById(Resource.Id.card_subtitle).Height;
MaxHeightRecyclerView rv = view.FindViewById <MaxHeightRecyclerView>(Resource.Id.card_recyclerview);
rv.SetMaxHeight(rvMaxHeight);
// Give the card container top padding so that only the top edge of the card
// initially appears at the bottom of the screen. The total padding will
// be the distance from the top of the screen to the FAB's top edge.
View cardContainer = view.FindViewById(Resource.Id.card_container);
int toolbarContainerHeight = parent.GetDependencies(view)[0].Height;
SetPaddingTop(cardContainer, rvMaxHeight - toolbarContainerHeight);
// Offset the child's height so that its bounds don't overlap the
// toolbar container.
ViewCompat.OffsetTopAndBottom(view, toolbarContainerHeight);
// Add the same amount of bottom padding to the RecyclerView so it doesn't
// display its content underneath the navigation bar.
SetPaddingBottom(rv, toolbarContainerHeight);
// Return true so that the parent doesn't waste time laying out the
// child again (any modifications made above will have triggered a second
// layout pass anyway).
return(true);
}
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Create your application here
SetContentView(Resource.Layout.activity_coordinatorbehavior);
;
var depentent = (TextView)FindViewById(Resource.Id.depentent);
depentent.Click += (object sender, EventArgs e) => {
ViewCompat.OffsetTopAndBottom(depentent, 5);
};
//使用代码关联Behavior
// var child = (TextView)FindViewById (Resource.Id.child);
// CoordinatorLayout.LayoutParams _params =
// (CoordinatorLayout.LayoutParams)child.LayoutParameters;
// _params.Behavior = new CustomBehavior ();
}
public override void OnNestedPreScroll(
CoordinatorLayout coordinatorLayout,
Java.Lang.Object childObject,
View target,
int dx,
int dy,
int[] consumed)
{
Debug.WriteLineIf(DebugTrace, $"OnNestedPreScroll");
View child = Android.Runtime.Extensions.JavaCast <View>(childObject);
View scrollingChild;
mNestedScrollingChildRef.TryGetTarget(out scrollingChild);
if (target != scrollingChild)
{
return;
}
int currentTop = child.Top;
int newTop = currentTop - dy;
Debug.WriteLineIf(DebugTrace, $"currentTop:{currentTop} newTop:{newTop}");
if (dy > 0)
{ // Upward
Debug.WriteLineIf(DebugTrace, $"dy > 0: Upward");
if (newTop < mMinOffset)
{
Debug.WriteLineIf(DebugTrace, $"newTop < mMinOffset: STATE_EXPANDED");
consumed[1] = currentTop - mMinOffset;
ViewCompat.OffsetTopAndBottom(child, -consumed[1]);
setStateInternal(STATE_EXPANDED);
}
else
{
Debug.WriteLineIf(DebugTrace, $"else: STATE_DRAGGING");
consumed[1] = dy;
ViewCompat.OffsetTopAndBottom(child, -dy);
setStateInternal(STATE_DRAGGING);
}
}
else if (dy < 0)
{
// Downward
Debug.WriteLineIf(DebugTrace, $"dy < 0: Downward");
if (!ViewCompat.CanScrollVertically(target, -1))
{
if (newTop <= mMaxOffset || mHideable)
{
Debug.WriteLineIf(DebugTrace, $"newTop <= mMaxOffset || mHideable: STATE_DRAGGING");
consumed[1] = dy;
ViewCompat.OffsetTopAndBottom(child, -dy);
setStateInternal(STATE_DRAGGING);
}
else
{
Debug.WriteLineIf(DebugTrace, $"else: STATE_COLLAPSED");
consumed[1] = currentTop - mMaxOffset;
ViewCompat.OffsetTopAndBottom(child, -consumed[1]);
setStateInternal(STATE_COLLAPSED);
}
}
}
dispatchOnSlide(child.Top);
mLastNestedScrollDy = dy;
mNestedScrolled = true;
}
public override void OnNestedPreScroll(CoordinatorLayout coordinatorLayout, Java.Lang.Object cChild, View target, int dx, int dy, int[] consumed, int type)
{
var child = cChild.JavaCast <View>();
_nestedScrollingChildRef.TryGetTarget(out View scrollingChild);
if (target != scrollingChild)
{
return;
}
_scrollVelocityTracker.RecordScroll(dy);
int currentTop = child.Top;
int newTop = currentTop - dy;
// Force stop at the anchor - do not go from collapsed to expanded in one scroll
if ((_lastStableState == StateCollapsed && newTop < AnchorPoint) ||
(_lastStableState == StateExpanded && newTop > AnchorPoint))
{
consumed[1] = dy;
ViewCompat.OffsetTopAndBottom(child, AnchorPoint - currentTop);
DispatchOnSlide(child.Top);
_nestedScrolled = true;
return;
}
if (dy > 0)
{ // Upward
if (newTop < _minOffset)
{
consumed[1] = currentTop - _minOffset;
ViewCompat.OffsetTopAndBottom(child, -consumed[1]);
SetStateInternal(StateExpanded);
}
else
{
consumed[1] = dy;
ViewCompat.OffsetTopAndBottom(child, -dy);
SetStateInternal(StateDragging);
}
}
else if (dy < 0)
{ // Downward
if (!ViewCompat.CanScrollVertically(target, -1))
{
if (newTop <= _maxOffset || Hideable)
{
// Restrict STATE_COLLAPSED if restrictedState is set
if (Collapsible == true || (Collapsible == false && (AnchorPoint - newTop) >= 0))
{
consumed[1] = dy;
ViewCompat.OffsetTopAndBottom(child, -dy);
SetStateInternal(StateDragging);
}
}
else
{
consumed[1] = currentTop - _maxOffset;
ViewCompat.OffsetTopAndBottom(child, -consumed[1]);
SetStateInternal(StateCollapsed);
}
}
}
DispatchOnSlide(child.Top);
_nestedScrolled = true;
}
