“What happens if we replace a
specific resource? Would that be reflected in all objects using the resource? And if not, can we
bind to the resource dynamically?”
接上篇博文，如果我们需要在C#代码中动态替换某个logical resource，我们该如何做呢？
如，Window的Resources属性赋值如下：
<Window x:Class="DynamicallyBindingToALogicalResource.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <Window.Resources> <LinearGradientBrush x:Key="brush1"> <GradientStop Offset="0.3" Color="Yellow"/> <GradientStop Offset="0.7" Color="Brown"/> </LinearGradientBrush> </Window.Resources> <StackPanel> <Rectangle Height="100" Stroke="Pink" StrokeThickness="20" Fill="{StaticResource brush1}"/> <Button x:Name="button1" Content="Replace Brush" Height="100" Click="OnReplaceBrush"/> </StackPanel> </Window>
Button Click事件中Replace Window的key为"brush1"的Resources
private void OnReplaceBrush(object sender, RoutedEventArgs e) { var brush = new LinearGradientBrush(); brush.GradientStops.Add(new GradientStop(Colors.Pink, 0.2)); brush.GradientStops.Add(new GradientStop(Colors.Blue, 0.5)); brush.GradientStops.Add(new GradientStop(Colors.Violet, 0.8)); this.Resources["brush1"] = brush; }
点击按钮，程序没有任何反应，可以通过DynamicResource这个markup extension实现。
“Run the application and click on the button. You'll notice nothing happens. Now
change the StaticResource markup extension to DynamicResource on the
Rectangle:”
<Rectangle Height="100" Stroke="Violet" StrokeThickness="20" Fill="{DynamicResource brush1}" />
程序运行如下：
点击Button后：
附XAML和C#代码：
<Window x:Class="DynamicallyBindingToALogicalResource.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <Window.Resources> <LinearGradientBrush x:Key="brush1"> <GradientStop Offset="0.3" Color="Yellow"/> <GradientStop Offset="0.7" Color="Brown"/> </LinearGradientBrush> </Window.Resources> <StackPanel> <Rectangle Height="100" Stroke="Pink" StrokeThickness="20" Fill="{StaticResource brush1}"/> <Rectangle Height="100" Stroke="Violet" StrokeThickness="20" Fill="{DynamicResource brush1}" /> <Button x:Name="button1" Content="Replace Brush" Height="100" Click="OnReplaceBrush"/> </StackPanel> </Window>
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; namespace DynamicallyBindingToALogicalResource { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void OnReplaceBrush(object sender, RoutedEventArgs e) { var brush = new LinearGradientBrush(); brush.GradientStops.Add(new GradientStop(Colors.Pink, 0.2)); brush.GradientStops.Add(new GradientStop(Colors.Blue, 0.5)); brush.GradientStops.Add(new GradientStop(Colors.Violet, 0.8)); this.Resources["brush1"] = brush; } } }