protected override void OnMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
if (_child?.Element == null)
{
SetMeasuredDimension(0, 0);
return;
}
VisualElement element = _child.Element;
Context ctx = Context;
var width = (int)ctx.FromPixels(MeasureSpecFactory.GetSize(widthMeasureSpec));
SizeRequest request = element.Measure(width, double.PositiveInfinity, MeasureFlags.IncludeMargins);
Microsoft.Maui.Controls.Compatibility.Layout.LayoutChildIntoBoundingRegion(element, new Rectangle(0, 0, width, request.Request.Height));
int widthSpec = MeasureSpecFactory.MakeMeasureSpec((int)ctx.ToPixels(width), MeasureSpecMode.Exactly);
int heightSpec = MeasureSpecFactory.MakeMeasureSpec((int)ctx.ToPixels(request.Request.Height), MeasureSpecMode.Exactly);
_child.View.Measure(widthMeasureSpec, heightMeasureSpec);
SetMeasuredDimension(widthSpec, heightSpec);
}
public void UpdateLayout()
{
Performance.Start(out string reference);
VisualElement view = _renderer.Element;
AView aview = _renderer.View;
var headlessOffset = CompressedLayout.GetHeadlessOffset(view);
var x = (int)_context.ToPixels(view.X + headlessOffset.X);
var y = (int)_context.ToPixels(view.Y + headlessOffset.Y);
var width = Math.Max(0, (int)_context.ToPixels(view.Width));
var height = Math.Max(0, (int)_context.ToPixels(view.Height));
var formsViewGroup = aview as Controls.Android.FormsViewGroup;
if (formsViewGroup == null)
{
Performance.Start(reference, "Measure");
aview.Measure(MeasureSpecFactory.MakeMeasureSpec(width, MeasureSpecMode.Exactly), MeasureSpecFactory.MakeMeasureSpec(height, MeasureSpecMode.Exactly));
Performance.Stop(reference, "Measure");
Performance.Start(reference, "Layout");
aview.Layout(x, y, x + width, y + height);
Performance.Stop(reference, "Layout");
}
else
{
Performance.Start(reference, "MeasureAndLayout");
formsViewGroup.MeasureAndLayout(MeasureSpecFactory.MakeMeasureSpec(width, MeasureSpecMode.Exactly), MeasureSpecFactory.MakeMeasureSpec(height, MeasureSpecMode.Exactly), x, y, x + width, y + height);
Performance.Stop(reference, "MeasureAndLayout");
}
// If we're running sufficiently new Android, we have to make sure to update the ClipBounds to
// match the new size of the ViewGroup
if ((int)Forms.SdkInt >= 18)
{
UpdateClipToBounds();
}
UpdateClip();
Performance.Stop(reference);
//On Width or Height changes, the anchors needs to be updated
UpdateAnchorX();
UpdateAnchorY();
}
void OnScrollToRequested(object sender, ScrollToRequestedEventArgs e)
{
if (!_isAttached)
{
_pendingScrollTo = e;
return;
}
Cell cell;
int scrollPosition;
var scrollArgs = (ITemplatedItemsListScrollToRequestedEventArgs)e;
var templatedItems = TemplatedItemsView.TemplatedItems;
if (Element.IsGroupingEnabled)
{
var results = templatedItems.GetGroupAndIndexOfItem(scrollArgs.Group, scrollArgs.Item);
int indexOfGroup = results.Item1;
int indexOfItem = results.Item2;
if (indexOfGroup == -1)
{
return;
}
int itemIndex = indexOfItem == -1 ? 0 : indexOfItem;
var group = templatedItems.GetGroup(indexOfGroup);
if (group.Count == 0)
{
cell = group.HeaderContent;
}
else
{
cell = group[itemIndex];
}
//Increment Scroll Position by 1 when Grouping is enabled. Android offsets position of cells when using header.
scrollPosition = templatedItems.GetGlobalIndexForGroup(group) + itemIndex + 1;
}
else
{
scrollPosition = templatedItems.GetGlobalIndexOfItem(scrollArgs.Item);
if (scrollPosition == -1)
{
return;
}
cell = templatedItems[scrollPosition];
}
//Android offsets position of cells when using header
int realPositionWithHeader = scrollPosition + 1;
if (e.Position == ScrollToPosition.MakeVisible)
{
if (e.ShouldAnimate)
{
Control.SmoothScrollToPosition(realPositionWithHeader);
}
else
{
Control.SetSelection(realPositionWithHeader);
}
return;
}
int height = Control.Height;
var cellHeight = (int)cell.RenderHeight;
if (cellHeight == -1)
{
int first = Control.FirstVisiblePosition;
if (first <= scrollPosition && scrollPosition <= Control.LastVisiblePosition)
{
cellHeight = Control.GetChildAt(scrollPosition - first).Height;
}
else
{
AView view = _adapter.GetView(scrollPosition, null, null);
view.Measure(MeasureSpecFactory.MakeMeasureSpec(Control.Width, MeasureSpecMode.AtMost), MeasureSpecFactory.MakeMeasureSpec(0, MeasureSpecMode.Unspecified));
cellHeight = view.MeasuredHeight;
}
}
var y = 0;
if (e.Position == ScrollToPosition.Center)
{
y = height / 2 - cellHeight / 2;
}
else if (e.Position == ScrollToPosition.End)
{
y = height - cellHeight;
}
if (e.ShouldAnimate)
{
Control.SmoothScrollToPositionFromTop(realPositionWithHeader, y);
}
else
{
Control.SetSelectionFromTop(realPositionWithHeader, y);
}
}
public void LayoutView(double x, double y, double width, double height, double?maxWidth = null, double?maxHeight = null)
{
if (width == -1)
{
width = double.PositiveInfinity;
}
if (height == -1)
{
height = double.PositiveInfinity;
}
Width = width;
Height = height;
MaxWidth = maxWidth;
MaxHeight = maxHeight;
X = x;
Y = y;
Context context;
if (Renderer == null || !(_context.TryGetTarget(out context)) || !Renderer.View.IsAlive())
{
return;
}
if (View == null)
{
var empty = MeasureSpecFactory.GetSize(0);
Renderer.View.Measure(empty, empty);
return;
}
var request = View.Measure(width, height, MeasureFlags.None);
var layoutParams = NativeView.LayoutParameters;
if (double.IsInfinity(height))
{
height = request.Request.Height;
}
if (double.IsInfinity(width))
{
width = request.Request.Width;
}
if (height > maxHeight)
{
height = maxHeight.Value;
}
if (width > maxWidth)
{
width = maxWidth.Value;
}
if (layoutParams.Width != LP.MatchParent)
{
layoutParams.Width = (int)context.ToPixels(width);
}
if (layoutParams.Height != LP.MatchParent)
{
layoutParams.Height = (int)context.ToPixels(height);
}
NativeView.LayoutParameters = layoutParams;
View.Layout(new Rectangle(x, y, width, height));
Renderer.UpdateLayout();
}
void IPlatformLayout.OnLayout(bool changed, int l, int t, int r, int b)
{
if (Page == null)
{
return;
}
if (changed)
{
LayoutRootPage(Page, r - l, b - t);
}
GetRenderer(Page)?.UpdateLayout();
for (var i = 0; i < _renderer.ChildCount; i++)
{
AView child = _renderer.GetChildAt(i);
if (child is ModalContainer)
{
child.Measure(MeasureSpecFactory.MakeMeasureSpec(r - l, MeasureSpecMode.Exactly), MeasureSpecFactory.MakeMeasureSpec(t - b, MeasureSpecMode.Exactly));
child.Layout(l, t, r, b);
}
}
}
public void UpdateLayout()
{
Performance.Start(out string reference);
VisualElement view = _renderer.Element;
AView aview = _renderer.View;
var headlessOffset = CompressedLayout.GetHeadlessOffset(view);
var x = (int)_context.ToPixels(view.X + headlessOffset.X);
var y = (int)_context.ToPixels(view.Y + headlessOffset.Y);
var width = Math.Max(0, (int)_context.ToPixels(view.Width));
var height = Math.Max(0, (int)_context.ToPixels(view.Height));
if (aview is FormsViewGroup formsViewGroup)
{
Performance.Start(reference, "MeasureAndLayout");
formsViewGroup.MeasureAndLayout(MeasureSpecFactory.MakeMeasureSpec(width, MeasureSpecMode.Exactly), MeasureSpecFactory.MakeMeasureSpec(height, MeasureSpecMode.Exactly), x, y, x + width, y + height);
Performance.Stop(reference, "MeasureAndLayout");
}
else if ((aview is LayoutViewGroup || aview is ContentViewGroup || aview is CoordinatorLayout || aview is FragmentContainerView) && width == 0 && height == 0)
{
// Nothing to do here; just chill.
}
else
{
Performance.Start(reference, "Measure");
aview.Measure(MeasureSpecFactory.MakeMeasureSpec(width, MeasureSpecMode.Exactly), MeasureSpecFactory.MakeMeasureSpec(height, MeasureSpecMode.Exactly));
Performance.Stop(reference, "Measure");
Performance.Start(reference, "Layout");
aview.Layout(x, y, x + width, y + height);
Performance.Stop(reference, "Layout");
}
// We have to make sure to update the ClipBounds to match the new size of the ViewGroup
UpdateClipToBounds();
UpdateClip();
Performance.Stop(reference);
//On Width or Height changes, the anchors needs to be updated
UpdateAnchorX();
UpdateAnchorY();
}