【发布时间】：2018-11-17 07:28:49
【问题描述】：
我有一个 masterdetailpage 并用我使用列表视图的文本和图标填充菜单，我可以显示标题和图标，我想要当一个人点击列表视图中的特定单元格并且选择单元格时我想要图标要更改，我该怎么做？
我已经尝试使用两张图片，一张用于选择图标，另一张用于取消选择图标，但我不知道何时取消选择单元格，列表视图没有该事件。
谢谢。
MasterDetailPage：
<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:viewModels="clr-namespace:Cantina2.ViewModels;assembly=Cantina2"
xmlns:controls="clr-namespace:ImageCircle.Forms.Plugin.Abstractions;assembly=ImageCircle.Forms.Plugin.Abstractions"
x:Class="test2.ViewModels.Views.Menu" Title="Menu1" >
<MasterDetailPage.Master>
<ContentPage Icon="hamburger.png" Title="Menu" BackgroundColor="White">
<ContentPage.BindingContext>
<viewModels:MenuViewModel></viewModels:MenuViewModel>
</ContentPage.BindingContext>
<StackLayout Orientation="Vertical">
<!--left, top, right, bottom-->
<StackLayout BackgroundColor="#01426A" HeightRequest="130">
<controls:CircleImage x:Name="CircleImage" Source="{Binding fotoProf}" Aspect="AspectFill" HorizontalOptions="StartAndExpand" FillColor="Transparent" Margin="15,10,0,0">
<controls:CircleImage.WidthRequest>
<OnPlatform x:TypeArguments="x:Double">
<On Platform="Android, iOS">55</On>
</OnPlatform>
</controls:CircleImage.WidthRequest>
<controls:CircleImage.HeightRequest>
<OnPlatform x:TypeArguments="x:Double">
<On Platform="Android, iOS">55</On>
</OnPlatform>
</controls:CircleImage.HeightRequest>
<!--<controls:CircleImage.GestureRecognizers>
<TapGestureRecognizer
Tapped="OnTapGestureRecognizerTapped"
NumberOfTapsRequired="1" />
</controls:CircleImage.GestureRecognizers>-->
</controls:CircleImage>
<Label Text="{Binding NomeColaborador}" Margin="15,10,0,0" TextColor="White">
<Label.FontSize>
<OnPlatform x:TypeArguments="x:Double">
<On Platform="iOS">12</On>
</OnPlatform>
</Label.FontSize>
<Label.FontFamily>
<OnPlatform x:TypeArguments="x:String">
<On Platform="iOS" Value="OpenSans-Semibold"/>
<On Platform="Android" Value="Calibri.ttf#Calibri"/>
<On Platform="UWP" Value="Assets\Fonts\OpenSans-Semibold.ttf#Open Sans"/>
</OnPlatform>
</Label.FontFamily>
</Label>
<Label Text="{Binding UsernameFormated}" Margin="15,-5,0,0" FontAttributes="Bold" TextColor="#597CBE" IsVisible="True" Opacity="0.50">
<Label.FontSize>
<OnPlatform x:TypeArguments="x:Double">
<On Platform="iOS">12</On>
</OnPlatform>
</Label.FontSize>
<Label.FontFamily>
<OnPlatform x:TypeArguments="x:String">
<On Platform="iOS" Value="OpenSans-Semibold"/>
<On Platform="Android" Value="Calibri.ttf#Calibri"/>
<On Platform="UWP" Value="Assets\Fonts\OpenSans-Semibold.ttf#Open Sans"/>
</OnPlatform>
</Label.FontFamily>
</Label>
</StackLayout>
<ListView x:Name="NavigationDrawerList" RowHeight="60"
SeparatorVisibility="None" BackgroundColor="White"
ItemSelected="OnMenuItemSelected" ItemsSource="{Binding menuLista}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout VerticalOptions="FillAndExpand"
Orientation="Horizontal"
Padding="20,10,0,10" Spacing="20">
<Image x:Name="ListviewMenuIcon" Source="{Binding IconSource}"
WidthRequest="30" HeightRequest="30"
VerticalOptions="Center" />
<Label Text="{Binding Title}"
FontSize="Small"
VerticalOptions="Center"
TextColor="#01426A">
<Label.FontFamily>
<OnPlatform x:TypeArguments="x:String">
<On Platform="iOS" Value="OpenSans-Semibold"/>
<On Platform="Android" Value="Calibri.ttf#Calibri"/>
<On Platform="UWP" Value="Assets\Fonts\OpenSans-Semibold.ttf#Open Sans"/>
</OnPlatform>
</Label.FontFamily>
</Label>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ContentPage>
</MasterDetailPage.Master>
<MasterDetailPage.Detail>
<ContentPage></ContentPage>
</MasterDetailPage.Detail>
Menu.xaml.cs
public partial class Menu : MasterDetailPage
{
public ObservableCollection<MenuViewModel> _menuLista;
public Menu()
{
InitializeComponent();
Settings.Page = "Menu";
NavigationPage.SetHasNavigationBar(this, false);
_menuLista = ItemService.GetMenuItems();
NavigationDrawerList.ItemsSource = _menuLista;
Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(Inicio_Menu)));
if (Settings.InicioNavi < 2)
{
Navigation.PopPopupAsync();
}
var seconds = TimeSpan.FromSeconds(0.7);
Xamarin.Forms.Device.StartTimer(seconds,
() =>
{
CheckConnection();
return true;
});
}
public async void CheckConnection()
{
try
{
if (!CrossConnectivity.Current.IsConnected)
{
Settings.InternetCon += 1;
if (Settings.InternetCon < 2)
{
await Navigation.PushPopupAsync(new ConnectionActivityIndicator());
}
}
else
{
if (Settings.InternetCon > 0)
{
Settings.InternetCon = 0;
await Navigation.PopPopupAsync();
return;
}
}
}
catch (Exception)
{
}
}
private async void OnMenuItemSelected(object sender, SelectedItemChangedEventArgs e)
{
if (CrossConnectivity.Current.IsConnected)
{
try
{
var item = (MenuViewModel)e.SelectedItem;
//Obtem o tipo do objeto
Type pagina = item.TargetType;
Settings.Semana = "Current";
Settings.day = "";
string itemResult = item.IconSource;
if (itemResult == "Logout.png")
{
Settings.InicioNavi = 0;
Settings.Username = "";
CrossSecureStorage.Current.DeleteKey("LOGIN");
CrossSecureStorage.Current.DeleteKey("パスワード");
var vHomePage = new LoginUI();
Navigation.InsertPageBefore(vHomePage, this);
await Navigation.PopAsync();
IsPresented = false;
}
else
{
Detail = new NavigationPage((Page)Activator.CreateInstance(pagina));
IsPresented = false;
}
}
catch (Exception)
{
await Navigation.PopPopupAsync();
if (Device.RuntimePlatform == Device.Android)
{
XFToast.ShortMessage("Error");
}
if (Device.RuntimePlatform == Device.iOS)
{
ToastIOS.ShortIOSMessage("Error");
}
}
}
else
{
if (Device.RuntimePlatform == Device.Android)
{
XFToast.ShortMessage("No Connection");
}
if (Device.RuntimePlatform == Device.iOS)
{
ToastIOS.ShortIOSMessage("No Connection");
}
}
}
谢谢
【问题讨论】：
-
你在使用 Mvvm 吗？或背后的代码
-
在这种情况下，.cs MenuViewModel 包含模型。
-
为@Mina Fawzy 的问题添加了更多代码。
-
'Unselecting' 只不过是在列表中选择其他东西......所以通常你会在列表视图的 Selected item 事件中做两件事。 1. 恢复上一个选中的项目（所以把图标改回原来的） 2. 改变新选中的图标 > 所以你需要跟踪上一个选中的项目。
-
这是一个很好的例子...如果您查看 SelectedItem 的设置器，而不是执行 _selectedItem.Selected = false;把你的代码改成 _selectedItem.IconImageSource = oldImageSource;
标签： c# xamarin xamarin.forms