找不到 Xamarin.Forms.Platform.Android.LabelRenderer(xamarin 表单)的构造函数 [英] No constructor found for Xamarin.Forms.Platform.Android.LabelRenderer (xamarin forms)
本文介绍了找不到 Xamarin.Forms.Platform.Android.LabelRenderer(xamarin 表单)的构造函数的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我在 pcl 项目上的 xaml 中有一个图像列表当我在我的三星 Galaxy s5 设备上测试我的应用程序时我这样做:我进入列表的页面，然后我按下操作栏上的后退按钮......我做了很多次......然后，它发生了:
I have a list of image in my xaml on pcl project when I test my app in my samsumg galaxy s5 device I do this: I enter in the page of the list, then I press the back button on the action bar...I do it many times...then, it happens:
System.NotSupportedException:无法从本机句柄 0x20e0001d (key_handle 0x42433c30) 激活 Xamarin.Forms.Platform.Android.Platform+DefaultRenderer 类型的实例.
System.NotSupportedException: Unable to activate instance of type Xamarin.Forms.Platform.Android.Platform+DefaultRenderer from native handle 0x20e0001d (key_handle 0x42433c30).
或
无法从本机激活 Xamarin.Forms.Platform.Android.LabelRenderer 类型的实例
Unable to activate instance of type Xamarin.Forms.Platform.Android.LabelRenderer from native
<小时>
更新
我添加了这个脚本:
using System;
using Android.Runtime;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
[assembly: ExportRenderer(typeof(Xamarin.Forms.Label), typeof(LabelRenderer))]
namespace neoFly_Montana.Droid
{
/// <summary>
/// This renderer was added to resolve a bug that crashed the application in known case
/// Bug 36285 - Android App (Always) Crashes After Navigating Away From Page With A ScrollView In HeaderTemplate of ListView
/// <seealso cref="https://bugzilla.xamarin.com/show_bug.cgi?id=36285"/>
/// and
/// Bug 32462 - Crash after a page disappeared if a ScrollView is in the HeaderTemplate property of a ListView
/// <seealso cref="https://bugzilla.xamarin.com/show_bug.cgi?id=32462"/>
/// </summary>
public class LabelRenderer : Xamarin.Forms.Platform.Android.LabelRenderer
{
public LabelRenderer()
{ }
public LabelRenderer(IntPtr javaReference, JniHandleOwnership transfer): base()
{ }
}
}
错误仍然存在
-------------------------------------- 更新
-------------------------------------- update
然后，我改变了，现在我的代码是:
Then, I changed and Now my code is:
using System;
using Android.Runtime;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using neoFly_Montana.Droid;
using Android.Content;
[assembly: ExportRenderer(typeof(Xamarin.Forms.Label),
typeof(NeoFly_MontanaLabelRenderer))]
namespace neoFly_Montana.Droid
{
public class NeoFly_MontanaLabelRenderer : Xamarin.Forms.Platform.Android.LabelRenderer
{
public NeoFly_MontanaLabelRenderer(Context context) : base(context)
{
}
}
}
然后，我可以经常看到这个错误.
then, I can see this error frequently.
System.NotSupportedException:无法从本机句柄激活 neoFly_Montana.Droid.NeoFly_MontanaLabelRenderer 类型的实例
System.NotSupportedException: Unable to activate instance of type neoFly_Montana.Droid.NeoFly_MontanaLabelRenderer from native handle
当我按下顶部栏上的后退按钮时正在运行的页面并且出现错误XAML(PCL):
the page that is running when I press the back button on the top bar and the error occurs XAML (PCL):
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="neoFly_Montana.Views.ProdutosView"
xmlns:local="clr-namespace:neoFly_Montana.LayoutScripts"
xmlns:interface="clr-namespace:neoFly_Montana.Interface"
xmlns:effect="clr-namespace:neoFly_Montana.Effects"
xmlns:ffimageloading="clr-namespace:FFImageLoading.Forms;assembly=FFImageLoading.Forms"
BackgroundImage="prodBackground.jpg"
x:Name="ParentHost">
<ContentPage.Content>
<Grid HorizontalOptions="FillAndExpand" RowSpacing="0" VerticalOptions="StartAndExpand">
<Grid.RowDefinitions>
<RowDefinition Height="9.5*"/>
<RowDefinition Height="0.5*"/>
</Grid.RowDefinitions>
<!-- Lista de produtos -->
<ListView Grid.Row="0" Grid.Column="0" ItemSelected="ListView_ItemSelected" CachingStrategy="RecycleElement" BackgroundColor="Transparent" x:Name="listview_produtos" Margin="10,0,10,0" SeparatorVisibility="None" HasUnevenRows="True" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
<ListView.Header>
<!-- Observação -->
<StackLayout>
<StackLayout x:Name="prod_stack_obser" IsVisible="False" Orientation="Horizontal" Spacing="0" HorizontalOptions="FillAndExpand">
<Label x:Name="label_observ" HorizontalTextAlignment="Start" VerticalOptions="Center" FontSize="Small" TextColor="White" Style="{StaticResource labelsfont}" Margin="20,10,0,10" />
<ffimageloading:CachedImage x:Name="lapis" Source="lapis.png" IsVisible="False" HorizontalOptions="EndAndExpand"/>
</StackLayout>
<BoxView HeightRequest="20"/>
</StackLayout>
</ListView.Header>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid Margin="20,0,20,20">
<ffimageloading:CachedImage Source="texturaCateg.png" BackgroundColor="{Binding FundoColor, Source={x:Reference ParentHost}}" Grid.Row="0" Grid.Column="0" Aspect="Fill" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand"/>
<StackLayout Grid.Row="0" Grid.Column="0" VerticalOptions="FillAndExpand" x:Name="produtos_stack_color" Spacing="10">
<StackLayout Spacing="0" Grid.Row="0" Grid.Column="0" HorizontalOptions="FillAndExpand" VerticalOptions="CenterAndExpand">
<StackLayout Orientation="Horizontal" Padding="10,10,10,0" VerticalOptions="Center" HorizontalOptions="FillAndExpand">
<ffimageloading:CachedImage FadeAnimationForCachedImages="True" DownsampleUseDipUnits="True" DownsampleHeight="60" HeightRequest="83" WidthRequest="130" Source="{Binding imagem}" Aspect="Fill" VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" >
<!--<ffimageloading:CachedImage.CacheKeyFactory>
<interface:CustomCacheKeyFactory/>
</ffimageloading:CachedImage.CacheKeyFactory>-->
</ffimageloading:CachedImage>
<!--HeightRequest="83" WidthRequest="100"-->
<!--DownsampleHeight="83"-->
<!--<StackLayout Orientation="Horizontal" VerticalOptions="Center" HorizontalOptions="EndAndExpand">
<Label Style="{StaticResource labelsfont}" Text="R$" VerticalOptions="CenterAndExpand" TextColor="{Binding TextColor, Source={x:Reference ParentHost}}" FontSize="Medium"/>
<Label Style="{StaticResource labelsfont}" Text="{Binding valor}" TextColor="{Binding TextColor, Source={x:Reference ParentHost}}" FontAttributes="Bold" VerticalOptions="Start" FontSize="30"/>
</StackLayout>-->
</StackLayout>
<!--nome-->
<Label Text="{Binding nome}" Margin="0,10,0,10" Style="{StaticResource labelsfont}" TextColor="{Binding TextColor, Source={x:Reference ParentHost}}" HorizontalTextAlignment="Center" FontAttributes="Bold" FontSize="Medium" HorizontalOptions="CenterAndExpand"/>
</StackLayout>
<Grid VerticalOptions="FillAndExpand">
<BoxView Grid.Row="0" Grid.Column="0" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" BackgroundColor="WhiteSmoke" Opacity="0.2"/>
<Label Grid.Row="0" Grid.Column="0" Margin="10,10,10,10" HorizontalTextAlignment="Center" Text="{Binding observacao}" Opacity="1" FontSize="Small" Style="{StaticResource labelsfont}" TextColor="{Binding TextColor, Source={x:Reference ParentHost}}" HorizontalOptions="Center" />
</Grid>
</StackLayout>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.Footer>
<StackLayout>
<Grid x:Name="prod_rl_fundo" >
<Grid.Margin>
<OnPlatform x:TypeArguments="Thickness"
iOS="20,0,20,0"
Android="20,10,20,10"/>
</Grid.Margin>
<ffimageloading:CachedImage x:Name="prod_acomp_img" Source="texturaCateg.png" Grid.Row="0" Grid.Column="0" HorizontalOptions="FillAndExpand" Aspect="Fill" VerticalOptions="FillAndExpand"></ffimageloading:CachedImage>
<!--Acompanhamentos-->
<StackLayout x:Name="stack_acompanhamentos" Spacing="0" Grid.Row="0" Grid.Column="0">
<Grid x:Name="prod_acompanhamentos_title" HorizontalOptions="FillAndExpand">
<BoxView Grid.Row="0" Grid.Column="0" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" BackgroundColor="WhiteSmoke" Opacity="0.2"/>
<Label x:Name="produtos_acomp_title" Text="+ Dois Acompanhamentos" Grid.Row="0" Grid.Column="0" Style="{StaticResource labelsfont}" Margin="20,20,20,20" FontAttributes="Bold" VerticalOptions="CenterAndExpand" HorizontalOptions="Center" />
</Grid>
</StackLayout>
</Grid>
<BoxView HeightRequest="50"></BoxView>
</StackLayout>
</ListView.Footer>
</ListView>
<!--Rodapé Grid-->
<Grid Grid.Row="1" Grid.Column="0" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand">
<ffimageloading:CachedImage Source="rodape.png"
HorizontalOptions="FillAndExpand"
Aspect="AspectFill"
VerticalOptions="FillAndExpand"
Grid.Row="0"/>
<!--Escrito Rodapé-->
<StackLayout StyleId="rodapemenu" Orientation="Horizontal"
Margin ="5,5,5,5" VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" Grid.Row="0">
<Label
FontSize="Micro"
Text="Você está em:"
Style="{StaticResource labelsfont}"
VerticalOptions="CenterAndExpand"
TextColor="White"/>
<StackLayout.Effects>
<effect:SafeAreaPaddingEffect />
</StackLayout.Effects>
<Label FontSize="Micro"
Text="loja"
x:Name="prod_lbl_lojaprox"
Style="{StaticResource labelsfont}"
VerticalOptions="CenterAndExpand"
TextColor="{StaticResource laranjacolor}"
LineBreakMode="TailTruncation"
FontAttributes="Bold" />
</StackLayout>
</Grid>
</Grid>
</ContentPage.Content>
C# 的那个
using FFImageLoading;
using FFImageLoading.Forms;
using neoFly_Montana.Api;
using neoFly_Montana.Model;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace neoFly_Montana.Views
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ProdutosView : ContentPage
{
List<Produtos> lstProdutos = new List<Produtos>();
Categorias categEscolhida;
public Color FundoColor { get { return fundoColor; } }
public Color TextColor { get { return textColor; } }
Color fundoColor;
Color textColor;
string lojaProx;
string codLoja;
public ProdutosView(string codLoja, Object categEscolhida, object produtos, string lojaProx)
{
this.codLoja = codLoja;
this.categEscolhida = new Categorias();
this.categEscolhida = (Categorias)categEscolhida;
lstProdutos = (List<Produtos>)produtos;
fundoColor = Color.FromHex(this.categEscolhida.corFundo);
textColor = Color.FromHex(this.categEscolhida.corTexto);
this.Title = this.categEscolhida.nome;
//TrataImagens();
InitializeComponent();
if (lojaProx != null)
{
this.lojaProx = lojaProx;
prod_lbl_lojaprox.Text = lojaProx;
}
PopulaListView();
//if (Device.OS == TargetPlatform.iOS)
//{
// this.Padding = new Thickness(0, Device.OnPlatform(20, 0, 0), 0, 0);
//}
}
void TrataImagens()
{
foreach (var item in lstProdutos)
{
if (item.imagem != null && item.imagem.Trim() != "")
{
int initIndex = item.imagem.IndexOf(',');
string u = item.imagem.Substring(initIndex+1);
try
{
var bytes= Convert.FromBase64String(item.imagem);
item.imagem = System.Text.Encoding.Unicode.GetString(bytes, 0, bytes.Length);
// item.imagem = Encoding.UTF8.GetString(bytes);
}
catch (Exception e)
{
var ss = e.Message;
}
}
}
}
private void ListView_ItemSelected(object sender, SelectedItemChangedEventArgs e)
{
var list = (ListView)sender;
list.SelectedItem = null;
}
void PopulaListView()
{
int row = 0;
int column = 0;
Grid grid_acompanhamentos = new Grid
{
// BackgroundColor = Color.Red,
RowSpacing = 0,
Padding = new Thickness(0, 0, 0, 0),
HorizontalOptions = LayoutOptions.CenterAndExpand,
Margin = new Thickness(10, 10, 10, 10),
ColumnSpacing = 0,
};
//CachedImage prod_acomp_img = new CachedImage
//{
// Source = "texturaCateg.png",
// Aspect = Aspect.Fill,
// BackgroundColor = Color.FromHex(this.categEscolhida.corFundo)
//};
//produtos
listview_produtos.ItemsSource = lstProdutos;
//observação
if (categEscolhida.observacao != null && categEscolhida.observacao.Trim() != "") {
label_observ.Text = categEscolhida.observacao;
prod_stack_obser.IsVisible = true;
lapis.IsVisible = true;
}
//acompanhamentos
if (categEscolhida.acompanhamentos == null || categEscolhida.acompanhamentos.Count() == 0)
{
stack_acompanhamentos.IsVisible = false;
}
else
{
//prod_acompanhamentos_title.BackgroundColor = fundoColor;
prod_acomp_img.BackgroundColor = fundoColor;
produtos_acomp_title.TextColor = textColor;
foreach (var item in categEscolhida.acompanhamentos)
{
StackLayout stack = new StackLayout();
stack.Margin = new Thickness (0,10,0,10);
stack.HorizontalOptions = LayoutOptions.StartAndExpand;
//stack.BackgroundColor = Color.Orange;
stack.Spacing = 0;
stack.Children.Add(new Label { Text = item.nome, HorizontalTextAlignment = TextAlignment.Start, TextColor = textColor, HorizontalOptions=LayoutOptions.Start, FontAttributes = FontAttributes.Bold, FontSize = Device.GetNamedSize(NamedSize.Micro, typeof(Label)) });
if (item.observacao != null)
stack.Children.Add(new Label { Text = item.observacao, HorizontalTextAlignment = TextAlignment.Start, HorizontalOptions = LayoutOptions.Start, TextColor = textColor, FontSize = Device.GetNamedSize(NamedSize.Micro, typeof(Label)) });
else
stack.Children.Add(new Label { Text = " ", TextColor = textColor, HorizontalTextAlignment = TextAlignment.Start, HorizontalOptions = LayoutOptions.Start, FontSize = Device.GetNamedSize(NamedSize.Micro, typeof(Label)) });
grid_acompanhamentos.Children.Add(stack, column, row);
if (column == 0)
{
column = 1;
}
else
{
column = 0;
row++;
}
}
stack_acompanhamentos.Children.Add(grid_acompanhamentos);
//produtos_rl_acompanhamentos.Children.Add(grid_acompanhamentos,
// Constraint.RelativeToParent((parent) =>
// {
// return (parent.Width / 2) - (grid_acompanhamentos.Width / 2);
// }),
// Constraint.RelativeToParent((parent) =>
// {
// return (parent.Height / 2) - (grid_acompanhamentos.Height / 2);
// })
//);
//produtos_rl_acompanhamentos.Children.Add(prod_acomp_img, Constraint.RelativeToParent((parent) => {
// return parent.X;
//}), Constraint.RelativeToParent((parent) => {
// return parent.Y;
//}), Constraint.RelativeToParent((parent) => {
// return parent.Width;
//}), Constraint.RelativeToView(grid_acompanhamentos, (parent, sibling) => {
// var teste = sibling.Height;
// return teste;
//}));
//UpdateConstraintsBasedOnWidth(produtos_rl_acompanhamentos, grid_acompanhamentos);
// produtos_rl_acompanhamentos.RaiseChild(grid_acompanhamentos);
}
}
public static void UpdateConstraintsBasedOnWidth(Xamarin.Forms.RelativeLayout layout, Xamarin.Forms.View view)
{
view.PropertyChanged += (object sender, System.ComponentModel.PropertyChangedEventArgs e) =>
{
if (e.PropertyName == "Width") { layout.ForceLayout(); }
};
view.PropertyChanged += (object sender, System.ComponentModel.PropertyChangedEventArgs e) =>
{
if (e.PropertyName == "Height") { layout.ForceLayout(); }
};
}
}
}
上一页 发生错误时应返回的上一页XAML (PCL)
The Previous page That the page above should back to when the error occurs XAML (PCL)
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="neoFly_Montana.Views.CategoriasView"
xmlns:effect="clr-namespace:neoFly_Montana.Effects"
xmlns:ffimageloading="clr-namespace:FFImageLoading.Forms;assembly=FFImageLoading.Forms"
Title="Cardápio">
<ContentPage.Content>
<Grid HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
<ffimageloading:CachedImage Source="familiaBackground.jpg" Grid.Row="0" Grid.Column="0" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" Aspect="Fill"/>
<!--Categ grid-->
<Grid Grid.Row="0" Grid.Column="0">
<Grid.RowDefinitions>
<RowDefinition Height="9.5*"/>
<RowDefinition Height="0.5*"/>
</Grid.RowDefinitions>
<Grid x:Name="gridtextura" RowSpacing="20" BindingContext="{Binding nome}" Padding="10, 10, 10, 10" Margin="10,10,10,10"/>
<!--Rodapé Grid-->
<Grid Grid.Row="1" Grid.Column="0" VerticalOptions="FillAndExpand">
<Image Source="rodape.png"
Aspect="Fill"
Grid.Row="0"
VerticalOptions="FillAndExpand"/>
<!--Escrito Rodapé-->
<StackLayout StyleId="rodapemenu" Orientation="Horizontal" VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" Grid.Row="0" Grid.Column="0">
<StackLayout.Effects>
<effect:SafeAreaPaddingEffect />
</StackLayout.Effects>
<Label
FontSize="Micro"
Text="Você está em:"
Style="{StaticResource labelsfont}"
VerticalOptions="CenterAndExpand"
TextColor="White"/>
<Label FontSize="Micro"
Text="loja"
x:Name="categorias_lbl_ljproxima"
Style="{StaticResource labelsfont}"
VerticalOptions="CenterAndExpand"
TextColor="{StaticResource laranjacolor}"
LineBreakMode="TailTruncation"
FontAttributes="Bold" />
</StackLayout>
</Grid>
</Grid>
</Grid>
</ContentPage.Content>
背后的代码
using FFImageLoading.Forms;
using neoFly_Montana.Api;
using neoFly_Montana.Model;
using neoFly_Montana.PopUp;
using Rg.Plugins.Popup.Services;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace neoFly_Montana.Views
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class CategoriasView : ContentPage
{
ActivityIndicator indicator;
string codigoLoja;
List<Categorias> lstCategorias;
List<Produtos> lstProdutos = new List<Produtos>();
List<Acompanhamento> lstAcompanhamentos;
Categorias categoriaEscolhida;
string observacao;
string codCategoria;
string lojaProx;
LoadingPopUp loading;
public CategoriasView(string codigoLoja, string lojaProx, object lstCategorias)
{
this.codigoLoja = codigoLoja;
this.lojaProx = lojaProx;
//this.codigoLoja = "162";
this.lstCategorias = (List<Categorias>)lstCategorias;
InitializeComponent();
categorias_lbl_ljproxima.Text = lojaProx;
CriaTela();
}
void CriaLoading()
{
LoadingPopUp loading = new LoadingPopUp("Carregando...", Color.Brown);
PopupNavigation.PushAsync(loading, false);
}
private void CriaTela()
{
int row = 0;
int column = 0;
gridtextura.RowSpacing = 5;
gridtextura.ColumnSpacing = 15;
lstCategorias = lstCategorias.OrderBy(o => o.nome).ToList();
foreach (var item in lstCategorias)
{
Grid GridContent = new Grid
{
RowSpacing = 0,
Margin = new Thickness(0, 5, 0, 0),
VerticalOptions = LayoutOptions.FillAndExpand,
RowDefinitions =
{
new RowDefinition { Height = new GridLength(8, GridUnitType.Star) },
new RowDefinition { Height = new GridLength(2, GridUnitType.Star) }
}
};
var textura = new CachedImage();
textura.Source = "texturaCateg";
textura.HorizontalOptions = LayoutOptions.FillAndExpand;
textura.VerticalOptions = LayoutOptions.FillAndExpand;
textura.Aspect = Aspect.Fill;
GridContent.BindingContext = item;
Grid boxColorView = new Grid
{
RowSpacing = 0,
//InputTransparent = true,
VerticalOptions = LayoutOptions.FillAndExpand,
RowDefinitions =
{
new RowDefinition { Height = new GridLength(2, GridUnitType.Star) },
new RowDefinition { Height = new GridLength(8, GridUnitType.Star) }
}
};
boxColorView.Children.Add(new StackLayout { BackgroundColor = Color.FromHex(item.corFundo), VerticalOptions = LayoutOptions.FillAndExpand }, 0, 1);
boxColorView.Children.Add(textura, 0, 1);
// boxColorView.Children.Add(new BoxView { VerticalOptions = LayoutOptions.FillAndExpand }, 0, 0);
gridtextura.Children.Add(boxColorView, column, row);
gridtextura.Children.Add(GridContent, column, row);
//Qual categoria foi escolhida?
var CliqueCategoria = new TapGestureRecognizer();
CliqueCategoria.NumberOfTapsRequired = 1;
CliqueCategoria.Tapped += (s, e) =>
{
CriaLoading();
var stacklayout = s as Grid;
categoriaEscolhida = (Categorias)stacklayout.BindingContext;
ChamaProdutos();
};
GridContent.GestureRecognizers.Add(CliqueCategoria);
if (item.imagem != null && item.imagem != "")
{
int initIndex = item.imagem.IndexOf(',');
string image = "";
image = item.imagem.Substring(initIndex + 1);
try
{
GridContent.Children.Add(new CachedImage { Source = ImageSource.FromStream(() => new MemoryStream(Convert.FromBase64String(image))), VerticalOptions = LayoutOptions.FillAndExpand, DownsampleHeight = 60 }, 0, 0);
}
catch (Exception e)
{
GridContent.Children.Add(new CachedImage { Source = "error.png", VerticalOptions = LayoutOptions.FillAndExpand, DownsampleHeight = 50, HorizontalOptions = LayoutOptions.Fill, HeightRequest = 50, WidthRequest = 50 }, 0, 0);
}
}
GridContent.Children.Add(new Label { Text = item.nome, TextColor = Color.FromHex(item.corTexto), FontSize = Device.GetNamedSize(NamedSize.Micro, typeof(Label)), FontAttributes = FontAttributes.Bold, HorizontalTextAlignment = TextAlignment.Center, VerticalOptions = LayoutOptions.Start, HorizontalOptions = LayoutOptions.CenterAndExpand, LineBreakMode = LineBreakMode.TailTruncation }, 0, 1);
if (column == 0)
{
column = 1;
}
else
{
column = 0;
row++;
}
}
}
async Task ChamaProdutos()
{
await CallingProdutosAsync();
await CallingAcompanhamentosAsync();
await Navigation.PushAsync(new Views.ProdutosView(codigoLoja, categoriaEscolhida, lstProdutos, lojaProx), true);
PopupNavigation.PopAsync();
if (lstProdutos == null)
DisplayAlert("Ops", "Verifique sua conexão com a internet e tente novamente.", "Ok");
}
//carregamento de dados para a tela de produtos
async Task CallingProdutosAsync()
{
lstProdutos = await Webservice.GetProdutosAsync(codigoLoja, categoriaEscolhida.idCategoria);
}
//este pode estar zerado
async Task CallingAcompanhamentosAsync()
{
categoriaEscolhida.acompanhamentos = new List<Acompanhamento>();
categoriaEscolhida.acompanhamentos = await Webservice.GetAcompanhamentoAsync(codigoLoja, categoriaEscolhida.idCategoria);
}
}
}
---------更新------------现在，标签渲染器错误似乎不再发生……但默认+渲染器错误仍然存在……还有一个空引用异常(我认为它与我的标签渲染器代码中的构造函数有关)
-----------------update------------ Now, it seems that the label renderer error doesn't occur anymore...but the default+renderer error still here...and a null reference exception as well (I think it's related with the constructor in my label renderer code)
推荐答案
您已将您的类命名为 LabelRenderer，该类已存在于 Xamarin.Forms.Platform.Android 命名空间.
You've named your class LabelRenderer, which already exists in the Xamarin.Forms.Platform.Android namespace.
在程序集属性中，typeof(LabelRenderer)等价于typeof(Xamarin.Forms.Platform.Android.LabelRenderer)，但我们需要它是typeof(neoFly_Montana.Droid.LabelRenderer).
In the assembly attribute, typeof(LabelRenderer) is equivalent to typeof(Xamarin.Forms.Platform.Android.LabelRenderer), but we need it to be typeof(neoFly_Montana.Droid.LabelRenderer).
避免这些命名空间冲突的一种简单方法是使用唯一的类名，例如 NeoFly_MontanaLabelRenderer.
An easy way to avoid these namespace conflicts going forward is to use a unique class name, like NeoFly_MontanaLabelRenderer.
当使用 Xamarin.Forms v2.5+ 时，我们需要使用我在下面添加的重载构造函数.
And when using Xamarin.Forms v2.5+, we need to use an overloaded Constructor, which I've added below.
using System;
using Android.Runtime;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using neoFly_Montana.Droid;
[assembly: ExportRenderer(typeof(Xamarin.Forms.Label), typeof(NeoFly_MontanaLabelRenderer))]
namespace neoFly_Montana.Droid
{
public class NeoFly_MontanaLabelRenderer : Xamarin.Forms.Platform.Android.LabelRenderer
{
}
}
对于 Xamarin.Forms v2.5+
using System;
using Android.Runtime;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using neoFly_Montana.Droid;
[assembly: ExportRenderer(typeof(Xamarin.Forms.Label), typeof(NeoFly_MontanaLabelRenderer))]
namespace neoFly_Montana.Droid
{
public class NeoFly_MontanaLabelRenderer : Xamarin.Forms.Platform.Android.LabelRenderer
{
public NeoFly_MontanaLabelRenderer(Context context) : base(context)
{
}
}
}
这篇关于找不到 Xamarin.Forms.Platform.Android.LabelRenderer(xamarin 表单)的构造函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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