Wpf Staticresource Vs Dynamicresource Complete Guide

Overview

• StaticResource: Resolves a resource at compile time. This means that if the resource changes at runtime, the change won't be reflected in UI elements that use StaticResource.
• DynamicResource: Resolves a resource at runtime. If the resource changes, the change is automatically reflected in all UI elements that use DynamicResource.

Step-by-Step Example

Let's create a simple application to demonstrate the differences between StaticResource and DynamicResource. We'll define a simple SolidColorBrush resource and use it in two different ways.

Step 1: Create a New WPF Project

Open Visual Studio and create a new WPF App (.NET Core) or WPF App (.NET Framework). Name it StaticDynamicResourceDemo.

Step 2: Define Resources in XAML

Open the MainWindow.xaml file and modify the Window.Resources section to include a SolidColorBrush resource.

<Window x:Class="StaticDynamicResourceDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Static vs Dynamic Resource Demo" Height="350" Width="525">
    <Window.Resources>
        <!-- Define a SolidColorBrush resource -->
        <SolidColorBrush x:Key="myBrush" Color="Red"/>
    </Window.Resources>
    <Grid>
        <!-- Buttons using StaticResource and DynamicResource -->
        <Button x:Name="StaticButton" Content="Static Button" HorizontalAlignment="Left" VerticalAlignment="Top"
                Width="150" Height="50" Margin="10" Background="{StaticResource myBrush}"/>
        <Button x:Name="DynamicButton" Content="Dynamic Button" HorizontalAlignment="Left" VerticalAlignment="Top"
                Width="150" Height="50" Margin="170,10,0,0" Background="{DynamicResource myBrush}"/>

        <!-- Button to change the resource -->
        <Button Content="Change Color" HorizontalAlignment="Left" 
                VerticalAlignment="Top" Margin="330,10,0,0" Width="150" Click="ChangeColor_Click"/>

        <!-- TextBlock to explain the differences -->
        <TextBlock VerticalAlignment="Top" HorizontalAlignment="Center" TextAlignment="Center" 
                   FontSize="18" Text="StaticResource uses the color defined at compile time. 
                                       DynamicResource can refresh the color at runtime." Margin="0,70,0,0"/>
    </Grid>
</Window>

Step 3: Handle Resource Change in Code-Behind

Next, open MainWindow.xaml.cs and add the event handler for the ChangeColor button. In this method, we will change the color of the SolidColorBrush resource.

using System.Windows;
using System.Windows.Media;

namespace StaticDynamicResourceDemo
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void ChangeColor_Click(object sender, RoutedEventArgs e)
        {
            // Access the resource dictionary
            var dict = Application.Current.Resources;

            // Check if the resource exists and change its value dynamically.
            if (dict.Contains("myBrush"))
            {
                dict["myBrush"] = new SolidColorBrush(Colors.Green);
            }
            else
            {
                // For demonstration purposes only, we should not reach here.
                MessageBox.Show("myBrush key not found");
            }
        }
    }
}

Explanation

1. StaticResource:

   • The StaticButton uses a SolidColorBrush defined with StaticResource. This means the color of the button is set to "Red" when the application starts and will remain "Red" even if we change the resource later.

2. DynamicResource:

   • The DynamicButton uses the same SolidColorBrush, but defined with DynamicResource. When we click the "Change Color" button, the SolidColorBrush's color is changed to "Green", and the DynamicButton automatically reflects this change in its background color.

Running the Application

1. Build and run the application.
2. Observe the initial colors of both buttons.
3. Click the "Change Color" button.
4. Notice how the DynamicButton changes its color to green, while the StaticButton remains red.

Conclusion

• Use StaticResource when you know the resource value will not change during the life of the application, and need the best performance.
• Use DynamicResource when the resource value might change during the application execution and you want the changes to reflect immediately across all controls that use the resource.