Xamarin.Froms帧BackgroudColor更改未显示
Xamarin.Froms帧BackgroudColor更改未显示
提问于 2020-02-18 10:14:17
我有这样的场景:一个ListView和每个单元格都是一个框架。当显示列表时，所有帧的背景颜色都是白色的，当我单击框架时，我希望在blie中更改颜色。我改变颜色，但不提神。这是我的代码:在xaml页面中
<pages:PopupPage.Resources>
<local1:ChangeFrameBackgroudColor x:Key="ChangeFrameBackgroudColor" />
</ResourceDictionary>-->
</pages:PopupPage.Resources>
<ListView x:Name="IzberiFirmaListView" HasUnevenRows="True" ItemsSource="{Binding KorisnikFirmi}" SelectedItem="{Binding IzbranaFirmaId } " Header="{Binding}" ItemTapped="IzberiFirmaListView_ItemTapped">
<ListView.ItemTemplate >
<DataTemplate>
<local:ExtendedViewCell SelectedBackgroundColor="#2188ff" >
<StackLayout Padding="20, 10" >
<Frame x:Name="frameLabel" BorderColor="#2188ff" BackgroundColor="{Binding IsActive, Converter={StaticResource ChangeFrameBackgroudColor}}">
<Label FontAttributes="Bold" FontSize="18" TextColor="Black" Text="{Binding Naziv}" ></Label>
</Frame>
</StackLayout>
</local:ExtendedViewCell>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.HeaderTemplate>
<DataTemplate>
<ContentView BackgroundColor="#006BE6" >
<Label Margin="10" HorizontalOptions="CenterAndExpand" Text="ОДБЕРЕТЕ ФИРМА" TextColor="White" FontSize="20" FontAttributes="Bold"/>
</ContentView>
</DataTemplate>
</ListView.HeaderTemplate>
</ListView>在xaml.cs页面中：
private void IzberiFirmaListView_ItemTapped(object sender, ItemTappedEventArgs e)
{
var vm = BindingContext as OdberiFirmaPopupViewModel;
var firm = e.Item as SysDashFirma;
vm.ChangeColorOnItemSelected(firm);
}在viewModel中
public List<SysDashFirma> KorisnikFirmi
{
get { return korisnikFirmi; }
set
{
if (korisnikFirmi != value)
{
korisnikFirmi = value;
SetProperty(ref korisnikFirmi, value);
OnPropertyChanged("KorisnikFirmi");
}
}
}
public void ChangeColorOnItemSelected(SysDashFirma firm)
{
if (_oldFirmSelected == firm)
{
//firm.BackColor = "#2188ff";
firm.IsActive = true;
UpdateSelectedFirmItemColor(firm);
}
else
{
if(_oldFirmSelected != null)
{
//_oldFirmSelected.BackColor = "#f5f5f5";
_oldFirmSelected.IsActive = false;
UpdateSelectedFirmItemColor(_oldFirmSelected);
}
// firm.BackColor = "#2188ff";
firm.IsActive = true;
UpdateSelectedFirmItemColor(firm);
}
_oldFirmSelected = firm;
}
private void UpdateSelectedFirmItemColor(SysDashFirma firm)
{
var index = KorisnikFirmi.IndexOf(firm);
KorisnikFirmi.Remove(firm);
KorisnikFirmi.Insert(index,firm);
}在列表中进行更改，更改标志，可能无法刷新从一开始就读取的转换上下文。
回答 1
Stack Overflow用户
回答已采纳
发布于 2020-02-18 11:45:57
使用OnPropertyChanged对IsActive属性通知UI其更改。
public class Firm : INotifyPropertyChanged
{
private string name = "Unknown";
public string Name
{
get
{
return name;
}
set
{
name = value;
OnPropertyChanged();
}
}
private bool isActive;
public bool IsActive
{
get
{
return isActive;
}
set
{
isActive = value;
OnPropertyChanged();
}
}
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public event PropertyChangedEventHandler PropertyChanged;
}我建议仅更改IsActive属性，因为没有必要删除和添加该项。
<ListView
ItemTapped="ListView_ItemTapped"
ItemsSource="{Binding FirmCollection}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame
Padding="2"
BackgroundColor="{Binding IsActive, Converter={StaticResource converterTest}}">
<Label Text="{Binding Name}"/>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>ViewModel
public class ViewModel : INotifyPropertyChanged
{
....
....
private Firm oldSelectedFirm;
public Firm OldSelectedFirm
{
get
{
return oldSelectedFirm;
}
set
{
oldSelectedFirm = value;
OnPropertyChanged();
}
}
...
...
}Xaml.cs
void ListView_ItemTapped(System.Object sender, Xamarin.Forms.ItemTappedEventArgs e)
{
var tappedFirm = (e.Item as Firm);
var vm = (BindingContext as ViewModel);
if (vm.OldSelectedFirm != null)
vm.OldSelectedFirm.IsActive = false;
tappedFirm.IsActive = true;
vm.OldSelectedFirm = tappedFirm;
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/60278467
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