Cyb*_*Dog 5 .net c# silverlight xaml windows-phone-7
我是XAML和C#的新手,但在我玩过它的几周内一直很喜欢使用它.我已经开始在一个应用程序上工作,并在XAML中组合了一个简单的"设置"页面; 现在我正在尝试将事件连接到控件以(a)在用户与它们交互时更新应用程序状态,以及(b)在访问页面时具有当前状态.
我打了两个(相关的)路障但是:
工具包:当我在XAML中定义"ListPickerItem"时,ListPicker控件似乎不能正常工作,所以在SettingsPage构造函数中,我手动设置了内容:
lpColour.ItemsSource = new List<string>()
{
"Red","Blue","Green","Custom…"
};
lpColour.SelectedIndex = 1; // set the currently selected item to "Blue"
但是,因为控件(在此示例中为lpColour)在SelectionChanged上有一个事件,所以会触发两个事件(一个选中"红色"作为框填充,然后另一个选择"蓝色").我现在不想处理"SelectionChanged"; 只有当用户自己与控件交互时(例如,如果他们选择"自定义..."),我可以显示一个单独的文本框并给出焦点;但我不想在我设置时这样做页面,他们之前选择了"自定义...",否则用户在打开"设置"页面时会立即显示键盘...)
我想也许有一些方法可以从"SelectionChangedEventArgs"或"RoutedEventArgs"获得事件的"起源"(例如"代码"或"用户输入")......但也许不是？
我还尝试设置一个"初始化"bool值(默认情况下为"false",运行构造函数后设置为"true",并将事件处理代码包装为"if(initialized){...}";但是在构造函数完成"lpColour.ItemSource = ..."和"lpColour.SelectedIndex = 1"代码完成时,"初始化"为"假"时,事件似乎仍然被触发.非常奇怪.:P
我希望我能清楚地解释一下 - 我以前从未在这里发布过!
我很感激您提供的任何帮助.谢谢!
更新 - 感谢@ MyKuLLSKI的回答,这给了我一个很棒的工作场所.
作为旁注,在这个想法的基础上,我尝试将它们保持为'List',并将"IgnoreSelectionChanged"作为一个"倒计时"的int(所以在设置ListPicker的ItemSource之前,我设置"IgnoreSelectionChanged + = 2" (考虑将被解雇的两个事件);类似地,我在手动设置SelectedIndex之前设置"IgnoreSelectionChanged ++"......这似乎也有效.
但是,使用绑定到ListPicker的"ObservableCollection"并依赖它来表示更改似乎比使用ListPicker自己的"SelectionChanged"事件更好,所以我将修改我的代码以使用它.
再次感谢!
我会尽力回答你所有的问题
你在XAML中设置ItemSource的原因是因为我几乎可以肯定你有一些Binding问题.要使Bindings工作,您需要在UIElement上使用DataContext和Binding.
购买属性的东西必须是DependencyProperty或INotifyPropertyChanged
List也不是一个很好的Collection类型来绑定ListPicker.相反,您可能希望使用ObservableCollextion()代替.如果此集合绑定到ListPicker并且项目更改,则ListPicker将自动更新.
SelectionChanged事件被触发2次的原因是因为你将它更改了两次.首次创建ListPicker时,Selected项为null或-1,因为其中没有项.然后,当您设置ItemSource时,它会自动将SelectedIndex更改为0,然后将其更改为1.
一种方法是每当您知道更改代码变量的用户时添加标记
Silverlight缺少IsLoaded属性,所以你想在页面加载为true时添加一个bool.
当Binding不更改UIElement中的属性时.而是更改其绑定的属性.
以下是我的解决方案,应解决您的所有问题(WP7.1):
<phone:PhoneApplicationPage
x:Class="WP7Sandbox.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:toolkit="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="768"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait" Orientation="Portrait"
shell:SystemTray.IsVisible="True"
Loaded="PhoneApplicationPageLoaded">
<Grid>
<StackPanel>
<toolkit:ListPicker ItemsSource="{Binding ListPickerCollection, Mode=TwoWay}" SelectionChanged="ListPickerSelectionChanged" SelectedIndex="{Binding ListPickerSelectedIndex, Mode=TwoWay}"/>
<Button Click="ButtonClick" Content="Selection Change and Ignore Event"/>
<Button Click="Button2Click" Content="Selection Change and Trigger Event"/>
<toolkit:ToggleSwitch IsChecked="{Binding ToggleSwitchValue, Mode=TwoWay}"/>
</StackPanel>
</Grid>
</phone:PhoneApplicationPage>
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using Microsoft.Phone.Controls;
namespace WP7Sandbox
{
public partial class MainPage : PhoneApplicationPage, INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
private bool IsLoaded;
private bool IgnoreSelectionChanged;
public ObservableCollection<string> ListPickerCollection { get; private set; }
private bool _ToggleSwitchValue;
public bool ToggleSwitchValue
{
get
{
return _ToggleSwitchValue;
}
set
{
_ToggleSwitchValue = value;
OnPropertyChanged("ToggleSwitchValue");
}
}
private int _ListPickerSelectedIndex;
public int ListPickerSelectedIndex
{
get
{
return _ListPickerSelectedIndex;
}
set
{
_ListPickerSelectedIndex = value;
OnPropertyChanged("ListPickerSelectedIndex");
}
}
public MainPage()
{
InitializeComponent();
ListPickerCollection = new ObservableCollection<string>()
{
"Red",
"Blue",
"Green",
"Custom…"
};
}
private void PhoneApplicationPageLoaded(object sender, RoutedEventArgs e)
{
IsLoaded = true;
}
private void ListPickerSelectionChanged(object sender, SelectionChangedEventArgs e)
{
if (IsLoaded && !IgnoreSelectionChanged)
{
}
IgnoreSelectionChanged = false;
}
private void ButtonClick(object sender, RoutedEventArgs e)
{
// I want to ignore this SelectionChanged Event
IgnoreSelectionChanged = true;
ChangeListPickerSelectedIndex();
}
private void Button2Click(object sender, RoutedEventArgs e)
{
// I want to trigger this SelectionChanged Event
IgnoreSelectionChanged = false; // Not needed just showing you
ChangeListPickerSelectedIndex();
}
private void ChangeListPickerSelectedIndex()
{
if (ListPickerSelectedIndex - 1 < 0)
ListPickerSelectedIndex = ListPickerCollection.Count - 1;
else
ListPickerSelectedIndex--;
}
}
}
有很多,但它应该有所帮助
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