protected override void OnElementChanged(ElementChangedEventArgs <TabbedPage> e)
{
base.OnElementChanged(e);
var activity = Context.GetActivity();
var isDesigner = Context.IsDesignerContext();
var themeContext = isDesigner ? Context : activity;
if (e.OldElement != null)
{
((IPageController)e.OldElement).InternalChildren.CollectionChanged -= OnChildrenCollectionChanged;
}
if (e.NewElement != null)
{
if (IsBottomTabPlacement)
{
if (_relativeLayout == null)
{
_relativeLayout = new AWidget.RelativeLayout(Context)
{
LayoutParameters = new LayoutParams(LayoutParams.MatchParent, LayoutParams.MatchParent),
};
if (_bottomNavigationView != null)
{
_relativeLayout.RemoveView(_bottomNavigationView);
_bottomNavigationView.SetOnNavigationItemSelectedListener(null);
}
var bottomNavigationViewLayoutParams = new AWidget.RelativeLayout.LayoutParams(
LayoutParams.MatchParent,
LayoutParams.WrapContent);
bottomNavigationViewLayoutParams.AddRule(AWidget.LayoutRules.AlignParentBottom);
_bottomNavigationView = new BottomNavigationView(Context)
{
LayoutParameters = bottomNavigationViewLayoutParams,
Id = Platform.GenerateViewId()
};
var viewPagerParams = new AWidget.RelativeLayout.LayoutParams(LayoutParams.MatchParent, LayoutParams.MatchParent);
viewPagerParams.AddRule(AWidget.LayoutRules.Above, _bottomNavigationView.Id);
FormsViewPager pager = _viewPager = CreateFormsViewPager(themeContext, e.NewElement);
pager.Id = Platform.GenerateViewId();
pager.AddOnPageChangeListener(this);
_relativeLayout.AddView(pager, viewPagerParams);
_relativeLayout.AddView(_bottomNavigationView, bottomNavigationViewLayoutParams);
AddView(_relativeLayout);
}
}
else
{
if (_tabLayout == null)
{
TabLayout tabs;
if (FormsAppCompatActivity.TabLayoutResource > 0 && !isDesigner)
{
tabs = _tabLayout = activity.LayoutInflater.Inflate(FormsAppCompatActivity.TabLayoutResource, null).JavaCast <TabLayout>();
}
else
{
tabs = _tabLayout = new TabLayout(themeContext)
{
TabMode = TabLayout.ModeFixed, TabGravity = TabLayout.GravityFill
}
};
FormsViewPager pager = _viewPager = CreateFormsViewPager(themeContext, e.NewElement);
pager.Id = Platform.GenerateViewId();
pager.AddOnPageChangeListener(this);
AddView(pager);
AddView(tabs);
}
}
OnChildrenCollectionChanged(null, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
TabbedPage tabbedPage = e.NewElement;
if (tabbedPage.CurrentPage != null)
{
ScrollToCurrentPage();
}
_previousPage = tabbedPage.CurrentPage;
((IPageController)tabbedPage).InternalChildren.CollectionChanged += OnChildrenCollectionChanged;
UpdateBarBackgroundColor();
UpdateBarTextColor();
UpdateItemIconColor();
if (!isDesigner)
{
UpdateSwipePaging();
UpdateOffscreenPageLimit();
}
}
}
protected override void OnLayout(bool changed, int l, int t, int r, int b)
{
FormsViewPager pager = _viewPager;
Context context = Context;
var width = r - l;
var height = b - t;
if (IsBottomTabPlacement)
{
if (width <= 0 || height <= 0)
{
return;
}
_relativeLayout.Measure(
MeasureSpec.MakeMeasureSpec(width, MeasureSpecMode.Exactly),
MeasureSpec.MakeMeasureSpec(height, MeasureSpecMode.Exactly));
pager.Measure(MeasureSpecFactory.MakeMeasureSpec(width, MeasureSpecMode.AtMost), MeasureSpecFactory.MakeMeasureSpec(height, MeasureSpecMode.AtMost));
if (width > 0 && height > 0)
{
PageController.ContainerArea = new Rectangle(0, 0, context.FromPixels(width), context.FromPixels(height - _bottomNavigationView.MeasuredHeight));
SetNavigationRendererPadding(0, _bottomNavigationView.MeasuredHeight);
pager.Layout(0, 0, width, b);
// We need to measure again to ensure that the tabs show up
_relativeLayout.Measure(
MeasureSpec.MakeMeasureSpec(width, MeasureSpecMode.Exactly),
MeasureSpec.MakeMeasureSpec(height, MeasureSpecMode.Exactly));
_relativeLayout.Layout(0, 0, _relativeLayout.MeasuredWidth, _relativeLayout.MeasuredHeight);
}
}
else
{
TabLayout tabs = _tabLayout;
tabs.Measure(MeasureSpecFactory.MakeMeasureSpec(width, MeasureSpecMode.Exactly), MeasureSpecFactory.MakeMeasureSpec(height, MeasureSpecMode.AtMost));
var tabsHeight = 0;
if (tabs.Visibility != ViewStates.Gone)
{
//MinimumHeight is only available on API 16+
if ((int)System.Maui.Maui.SdkInt >= 16)
{
tabsHeight = Math.Min(height, Math.Max(tabs.MeasuredHeight, tabs.MinimumHeight));
}
else
{
tabsHeight = Math.Min(height, tabs.MeasuredHeight);
}
}
pager.Measure(MeasureSpecFactory.MakeMeasureSpec(width, MeasureSpecMode.AtMost), MeasureSpecFactory.MakeMeasureSpec(height, MeasureSpecMode.AtMost));
if (width > 0 && height > 0)
{
PageController.ContainerArea = new Rectangle(0, context.FromPixels(tabsHeight), context.FromPixels(width), context.FromPixels(height - tabsHeight));
SetNavigationRendererPadding(tabsHeight, 0);
pager.Layout(0, 0, width, b);
// We need to measure again to ensure that the tabs show up
tabs.Measure(MeasureSpecFactory.MakeMeasureSpec(width, MeasureSpecMode.Exactly), MeasureSpecFactory.MakeMeasureSpec(tabsHeight, MeasureSpecMode.Exactly));
tabs.Layout(0, 0, width, tabsHeight);
UpdateTabBarTranslation(pager.CurrentItem, 0);
}
}
base.OnLayout(changed, l, t, r, b);
}
protected override void Dispose(bool disposing)
{
if (disposing && !_disposed)
{
_disposed = true;
if (Element != null)
{
PageController.InternalChildren.CollectionChanged -= OnChildrenCollectionChanged;
foreach (Page pageToRemove in Element.Children)
{
TeardownPage(pageToRemove);
}
}
RemoveAllViews();
if (_viewPager != null)
{
_viewPager.ClearOnPageChangeListeners();
_viewPager.Adapter.Dispose();
_viewPager.Dispose();
_viewPager = null;
}
if (_tabLayout != null)
{
_tabLayout.ClearOnTabSelectedListeners();
_tabLayout.Dispose();
_tabLayout = null;
}
if (_bottomNavigationView != null)
{
_bottomNavigationView.SetOnNavigationItemSelectedListener(null);
_bottomNavigationView.Dispose();
_bottomNavigationView = null;
}
if (_relativeLayout != null)
{
_relativeLayout.Dispose();
_relativeLayout = null;
}
if (Element != null)
{
foreach (Page pageToRemove in Element.Children)
{
IVisualElementRenderer pageRenderer = Platform.GetRenderer(pageToRemove);
pageRenderer?.Dispose();
pageToRemove.ClearValue(Platform.RendererProperty);
}
}
_previousPage = null;
}
base.Dispose(disposing);
}