Question

我发现a fun program允许您overlay snowflakes over your desktop and windows。作为编程挑战，我有兴趣试图弄清楚如何自己做这件事。更不用说这个程序有点内存耗费（如果它没有内存泄漏）。以下是我的开始。我试图通过一个图像得到基础，然后将展开。

我真正想要帮助的是让图像更加流畅自然地移动。

编辑：

我在答案部分下面发布了一个解决方案，但它比我想要的CPU密集程度更高，还有什么想法？

WPF XAML代码：

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    AllowsTransparency="True"
        WindowStyle="None"
    Title="MainWindow" Height="350" Width="525" Background="Transparent" Topmost="True" WindowState="Maximized" ResizeMode="NoResize">
    <Grid Name="grid1">
        <Image Height="26" HorizontalAlignment="Left" Margin="{Binding flakeMargin}" Name="Image1" Stretch="Fill" VerticalAlignment="Top" Width="28" Source="/snowTest;component/Images/blue-pin-md.png" />
    </Grid>
</Window>

VB代码：

Imports System.ComponentModel

    Class MainWindow
        Dim bw As BackgroundWorker = New BackgroundWorker
        Dim flake0 As New flake

        Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
            grid1.DataContext = flake0
            AddHandler bw.DoWork, AddressOf backgroundMover
            bw.RunWorkerAsync()
        End Sub

        Private Sub backgroundMover(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs)
            While (True)
                flake0.move()
                System.Threading.Thread.Sleep(100)
            End While
        End Sub
    End Class

鳞片类：

Imports System.ComponentModel

Public Class flake
    Implements INotifyPropertyChanged

    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

    Private Sub NotifyPropertyChanged(ByVal info As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(info))
    End Sub

    Private Property startLeft As Integer = 300
    Private Property left As Integer = left
    Private Property top As Integer = 100
    Private Property speed As Integer = 1

    Public ReadOnly Property flakeMargin As Thickness
        Get
            Return New Thickness(left, top, 0, 0)
        End Get
    End Property

    Public Sub move()
        top += speed
        left = (Math.Cos(top - 100)) * 6 + startLeft
        NotifyPropertyChanged("flakeMargin")
    End Sub
End Class

Answer 1

这是我目前提出的解决方案：最终的最大修正因素是我使用画布，它允许我以非整数增量移动，我也更有效地使用cos函数。它比我想要的CPU密集度更高（25-30％）。有没有人想减少对CPU的影响？

WPF / XAML：

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    AllowsTransparency="True"
        WindowStyle="None"
    Title="MainWindow" Height="350" Width="525" Background="Transparent" Topmost="True" WindowState="Maximized" ResizeMode="NoResize">
    <Canvas Name="canvas1">

    </Canvas>
</Window>

VB.NET主窗口：

Imports System.ComponentModel

Class MainWindow

    Dim bw As New BackgroundWorker
    Dim flakes(17) As flake

    Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
        For i = 0 To flakes.Count - 1
            flakes(i) = New flake
            flakes(i).image.DataContext = flakes(i)
            flakes(i).image.SetBinding(Canvas.LeftProperty, "left")
            flakes(i).image.SetBinding(Canvas.TopProperty, "top")
            canvas1.Children.Add(flakes(i).image)
        Next

        AddHandler bw.DoWork, AddressOf backgroundMover
        bw.RunWorkerAsync()
    End Sub


    Private Sub backgroundMover()
        While (True)
            For Each f In flakes
                f.move()
            Next
            System.Threading.Thread.Sleep(50)
        End While
    End Sub
End Class

VB.Net flake class：

Imports System.ComponentModel

Public Class flake
    Implements INotifyPropertyChanged

    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

    Private Sub NotifyPropertyChanged(ByVal info As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(info))
    End Sub

    Private Property startLeft As Double
    Private Property _left As Double
    Private Property _top As Double
    Private Property speed As Double
    Private Property amplitude As Double
    Private Property period As Double
    Public Property image As New Image
    Private Shared Property r As New Random

    Public Sub New()
        _image.Width = 28
        _image.Height = 26
        _image.Source = New System.Windows.Media.Imaging.BitmapImage(New Uri("/snowTest;component/Images/blue-pin-md.png", UriKind.Relative))
        startFresh()
    End Sub

    Public ReadOnly Property left As Double
        Get
            Return _left
        End Get
    End Property

    Public ReadOnly Property top As Double
        Get
            Return _top
        End Get
    End Property

    Public Sub startFresh()
        _top = -30
        amplitude = r.Next(5, 35)
        period = 1 / r.Next(20, 60)
        speed = r.Next(15, 25) / 10
        startLeft = r.Next(0, System.Windows.SystemParameters.PrimaryScreenWidth)
    End Sub

    Public Sub move()
        If _top > System.Windows.SystemParameters.PrimaryScreenHeight Then
            startFresh()
        Else
            _top += speed
            _left = amplitude * Math.Cos(period * _top) + startLeft
        End If

        NotifyPropertyChanged("top")
        NotifyPropertyChanged("left")
    End Sub
End Class

Answer 2

为什么你自己移动它而不是使用动画？

如果您使用WPF的动画（在Expression Blend中很容易做到），我认为您将获得所需的平滑度，并且可以获得一些动作变化，使其更加真实。< / p>

WPF Expression Blend Videos

Basic Animation

像飘落的雪花一样移动元素

2 个答案: