【WPF】如何使用wpf实现屏幕最前端的绘图？

[b]引言[/b]

在知乎上面看到如何使用wpf实现屏幕最前端的绘图? 这么一个问题,觉得全屏弹幕很有趣,所以把它实现了.

[b]实现[/b]

界面设置很简单,Window界面无边框+最大化+允许不规则+背景色透明+置顶,如下

<Window x:Class="FullScreen.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" WindowState="Maximized"  Topmost="True" AllowsTransparency="True" Background="Transparent" WindowStyle="None" >
<Canvas Name="canvas">

</Canvas>
</Window>

弹幕信息出现的位置和速度都随机产生,还要保证永远最大化和置顶,如下

public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.Loaded += MainWindow_Loaded;
this.Deactivated += MainWindow_Deactivated;
this.StateChanged += MainWindow_StateChanged;
}
/// <summary>
/// 确保永远最大化
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void MainWindow_StateChanged(object sender, EventArgs e)
{
this.WindowState = WindowState.Maximized;
}
/// <summary>
/// 确保永远置顶
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void MainWindow_Deactivated(object sender, EventArgs e)
{
this.Topmost = true;
}
void MainWindow_Loaded(object sender, RoutedEventArgs e)
{
List<string> list = new List<string>();
list.Add("你们的");
list.Add("生活");
list.Add("真丰富");
list.Add("不像我");
list.Add("一个");
list.Add("帅");
list.Add("字");
list.Add("竟贯穿了");
list.Add("一生");
Barrage(list);
}

/// <summary>
/// 在Window界面上显示弹幕信息,速度和位置随机产生
/// </summary>
/// <param name="contentlist"></param>
public void Barrage(IEnumerable<string> contentlist)
{
Random random = new Random();
foreach (var item in contentlist)
{   //获取位置随机数
double randomtop = random.NextDouble();
double inittop = canvas.ActualHeight * randomtop;
//获取速度随机数
double randomspeed = random.NextDouble();
double initspeed = 50 * randomspeed;
//实例化TextBlock和设置基本属性,并添加到Canvas中
TextBlock textblock = new TextBlock();
textblock.Text = item;
textblock.FontSize = 50;
Canvas.SetTop(textblock, inittop);
canvas.Children.Add(textblock);
//实例化动画
DoubleAnimation animation = new DoubleAnimation();
Timeline.SetDesiredFrameRate(animation,60);  //如果有性能问题,这里可以设置帧数
animation.From = 0;
animation.To = canvas.ActualWidth;
animation.Duration = TimeSpan.FromSeconds(initspeed);
animation.AutoReverse = true;
animation.RepeatBehavior = RepeatBehavior.Forever;
animation.Completed += (object sender, EventArgs e) =>
{
canvas.Children.Remove(textblock);
};
//启动动画
textblock.BeginAnimation(Canvas.LeftProperty, animation);
}

}

}

效果图



[b]小结[/b]

本文主要利用了WPF的动画和窗体的不规则化属性,这些WPF特性使实现起来的界面效果可以千变万化.