A WPF based irregular pop up window demo
This article describes how to create a fade in and fade out irregular pop up window using WPF
Introduction
That a small pop up window displaying some information appears at the right lower corner of the screen just like what Live Messenger does is more friendly to the user, isn't it? In .NET 2.0, we can use Form.Opacity property to create a fade in & fade out window with serveral rows of codes, but it is much difficult to create a irregular window. Now we have WPF in .NET 3.5 and with it you can create a irregular window by only changing some window's properties and we can also have more smooth fade in & fade out animation experience.
Background
This is my first WPF program, just for fun. I wish all of you will be interested in it.
How to create a fade in & fade out window using XAML
First, we need to create a window :) , and add what you want on it, text boxes, combo boxes and etc. Then we need to create a Storyboard which is a container timeline and a DoubleAnimation, which animates the value of a Double property between two target values using linear interpolation over a specified Duration, for this window like this:
<BeginStoryboard>
<Storyboard Name="FormFade">
<DoubleAnimation Name="FormFadeAnimation"
Storyboard.TargetName="winMain"
Storyboard.TargetProperty="(Window.Opacity)"
From="0.0" To="1.0" Duration="0:0:2"
AutoReverse="False" RepeatBehavior="1x"
/>
</Storyboard>
</BeginStoryboard>
Here comes some explainations about the above XAML, you can get more detailed information about each key word by searching MSDN.
Finally we need to attach this animation to the window.Loaded event, we need to add an event trigger, so the final XAML likes this:
<Window.Triggers>
<EventTrigger RoutedEvent="Window.Loaded">
<BeginStoryboard>
<Storyboard Name="FormFade">
<DoubleAnimation Name="FormFadeAnimation"
Storyboard.TargetName="winMain"
Storyboard.TargetProperty="(Window.Opacity)"
From="0.0" To="1.0" Duration="0:0:2"
AutoReverse="False" RepeatBehavior="1x"
/>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Window.Triggers>
Now we have a main window with fade in animation by only writing XAML, no C# codes at all.
How to create a fade in & fade out irregular window using codes
For the above fade in & fade out window (above window only have fade in animation, you can change AutoReverse to True in order to get the fade out animation), we can also use C# codes to implement it. This is our major point in this section.
We want to create a window fade in in 1.5 seconds, display some text on it and then fade out in another 1.5 secondes. Of course, this window is irregular and displayed on the right lower corner of the screen.
First, we need to create a instance of Window object.
//Create a Window
Window popUp = new Window();
popUp.Name = "PopUp";
//The following properties are used to create a irregular window
popUp.AllowsTransparency = true;
popUp.Background = Brushes.Transparent;
popUp.WindowStyle = WindowStyle.None;
popUp.ShowInTaskbar = false;
popUp.Topmost = true;
popUp.Height = winHeight;
popUp.Width = winWidth;
//Set postion to right lower corner of the screen
popUp.Left = Screen.PrimaryScreen.Bounds.Width - winWidth;
popUp.Top = Screen.PrimaryScreen.Bounds.Height - winHeight - 30;
In order to create a irregular window, we need to set three properties:
Then we create a Grid as a container, a Image to show a irregular backgroud image as the border of the window and a TextBlock for message displaying:
//Create a inner Grid
Grid g = new Grid();
//Create a Image for irregular background display
Image img = new Image();
img.Stretch = Stretch.Fill;
img.Source = bgImg;
img.BitmapEffect = new System.Windows.Media.Effects.DropShadowBitmapEffect();
g.Children.Add(img);
//Create a TextBlock for message display
TextBlock msg = new TextBlock();
msg.Padding = msgPadding;
msg.VerticalAlignment = VerticalAlignment.Center;
msg.HorizontalAlignment = System.Windows.HorizontalAlignment.Center;
msg.TextWrapping = TextWrapping.Wrap;
msg.Text = msgText;
g.Children.Add(msg);
popUp.Content = g;
Now we have our window, the next step is to add the fade in & fade out animation to this window.
For the animation, we have to create a NameScope before creating the Storyboard which is a container timeline mentioned above. We creates a DoubleAnimation just like the above XAML. One point to mention is that, in order to close the window when it fades out, a delegate function is attached to the DoubleAnimation.Complete event to call Window.Close() method.
Then we add this animation to the Storyboard and add another delegate function to the Window.Loaded event to start playing this animation when the Window is loaded. Finally, we call Window.Show() method to display the form and we can see the animation starts playing automatically.
//Register the window's name, this is necessary for creating Storyboard using codes instead of XAML
NameScope.SetNameScope(popUp, new NameScope());
popUp.RegisterName(popUp.Name, popUp);
//Create the fade in & fade out animation
DoubleAnimation winFadeAni = new DoubleAnimation();
winFadeAni.From = 0;
winFadeAni.To = 1;
winFadeAni.Duration = new Duration(TimeSpan.FromSeconds(1.5)); //Duration for 1.5 seconds
winFadeAni.AutoReverse = true;
winFadeAni.Completed += delegate(object sender, EventArgs e) //Close the window when this animation is completed
{
popUp.Close();
};
// Configure the animation to target the window's opacity property
Storyboard.SetTargetName(winFadeAni, popUp.Name);
Storyboard.SetTargetProperty(winFadeAni, new PropertyPath(Window.OpacityProperty));
// Add the fade in & fade out animation to the Storyboard
Storyboard winFadeStoryBoard = new Storyboard();
winFadeStoryBoard.Children.Add(winFadeAni);
// Set event trigger, make this animation played on window.Loaded
popUp.Loaded += delegate(object sender, RoutedEventArgs e)
{
winFadeStoryBoard.Begin(popUp);
};
//Finally show the window
popUp.Show();
This is final pop up window, have fun.
Points of Interest
With WPF, we can create a beautiful UI with less codes, we can play animation in our window and we can have our animation more smooth. WPF brings many new features and a greate UI experience, these are the real ppoints of interest. Have any new idea in using WPF?
History
2008.6.17, Version 1.0.0