Windows Phone Applications: Timing using DispatcherTimer
Applications may want to performs actions with certain timing, or tick intervals. One example is a turn-based game like a card game where each computer player takes some time to play a turn. An example which will be shown below is a slideshow application where photos are changed at 2 seconds intervals. These are the controls used:
1. CheckBox - to toggle slideshow on/off
2. TextBox - to display the file name
3. Image - to display the image
4. ProgressBar - to display progress
For this sample slideshow application, drag and drop some images from your Sample Pictures folder to your project. I used Koala.jpg, Jellyfish.jpg and Penguins.jpg.
This is the xaml:
<Grid x:Name="LayoutRoot" Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<CheckBox Content="Slideshow Mode" Checked="CheckBox_Checked" Unchecked="CheckBox_Unchecked" IsChecked="True" />
<Grid x:Name="TitlePanel" Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<TextBlock VerticalAlignment="Center" Text="File name: " />
<TextBox Grid.Column="1" x:Name="textBox1" />
</Grid>
<Grid x:Name="ContentGrid" Grid.Row="2">
<Image x:Name="Image1" />
</Grid>
<ProgressBar x:Name="ProgressBar1" Grid.Row="3" />
</Grid>
And this is the code:
public partial class MainPage : PhoneApplicationPage
{
DispatcherTimer timer = new DispatcherTimer();
List<string> files = new List<string>() { "Koala.jpg", "Jellyfish.jpg", "Penguins.jpg" };
List<BitmapImage> images = new List<BitmapImage>();
int current = 0;
// Constructor
public MainPage()
{
InitializeComponent();
ProgressBar1.Maximum = files.Count;
foreach (string file in files)
{
BitmapImage image = new BitmapImage(new Uri(file, UriKind.Relative));
images.Add(image);
}
timer = new DispatcherTimer();
timer.Interval = TimeSpan.FromSeconds(2);
timer.Tick += new EventHandler(timer_Tick);
timer.Start();
}
void timer_Tick(object sender, EventArgs e)
{
Image1.Source = images[current];
textBox1.Text = files[current];
ProgressBar1.Value = current;
current++;
if (current >= files.Count)
current = 0;
}
private void CheckBox_Checked(object sender, RoutedEventArgs e)
{
timer.Start();
}
private void CheckBox_Unchecked(object sender, RoutedEventArgs e)
{
timer.Stop();
}
}