C#WPF)动态添加控件时,有时会丢失DropShadowEffect

Question

foreach (DataRow dr in dt.Rows)
{
    Rectangle rectangle_timeline = new Rectangle();
    rectangle_timeline.Height = 19;
    rectangle_timeline.Cursor = Cursors.Hand;

    rectangle_timeline.Effect = new DropShadowEffect
    {
        Color = new Color { A = 255, R = 0, G = 0, B = 0 },
        Direction = 315,
        ShadowDepth = 5,
        Opacity = 1
    };

    Grid_Timeline.Children.Add(rectangle_timeline);
}

我动态添加一个带有上面简单代码的Rectangle,如图所示.

然而,有时,随机地,没有DropShadowEffect的矩形像黄色矩形和最低的1个蓝色矩形.

在您看到代码时,如果添加了一个矩形,则必须使用DropShadowEffect的代码.

我想知道为什么会这样.

谢谢 !

XAML代码添加了 -

<Grid x:Name="Grid_Timeline" ScrollViewer.VerticalScrollBarVisibility="Auto" UseLayoutRounding="True" Width="1159" HorizontalAlignment="Left" VerticalAlignment="Top" SnapsToDevicePixels="True">
</Grid>

增加了重新制作的最小代码 -

private void Window_Loaded(object sender, RoutedEventArgs e)
{
        int count_each_category = 0;
        string current_therapeutic_category = String.Empty;

        foreach (DataRow dr_test in dt.Rows)
        {
            if (dr_test != null)
            {
                if (current_category == String.Empty)
                {
                    count_each_category++;

                    current_category = dr_test["category"].ToString();
                }
                else
                {
                    if (current_category == dr_test["category"].ToString())
                    {
                        // empty
                    }
                    else
                    {
                        count_each_category++;

                        current_category = dr_test["category"].ToString();
                    }
                }

                Rectangle rectangle_test = new Rectangle();

                rectangle_test.HorizontalAlignment = HorizontalAlignment.Left;
                rectangle_test.VerticalAlignment = VerticalAlignment.Top;

                rectangle_test.Margin = new Thickness(119 + (((Convert.ToDateTime(dr_test["date"]) - DateTime.Today.AddYears(-10)).TotalDays) * 0.27), count_each_category * 50, 0, 0);

                rectangle_test.Width = 0.27 * Convert.ToInt32(dr_test["howlong"]);
                rectangle_test.Height = 19;

                rectangle_test.Effect = new DropShadowEffect
                {
                    Color = new Color { A = 255, R = 0, G = 0, B = 0 },
                    Direction = 315,
                    ShadowDepth = 5,
                    Opacity = 1
                };

                rectangle_test.Fill = Brushes.LightGreen;

                Grid_Timeline.Children.Add(rectangle_test);
            }
        }
}

WPF窗口的XAML代码

<Window x:Class="OperationSWdummy.Green_Timeline"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:OperationSWdummy"
    mc:Ignorable="d"
    Title="Green_Timeline" Width="1165" Background="White" ResizeMode="CanMinimize" ScrollViewer.VerticalScrollBarVisibility="Auto" UseLayoutRounding="True" SnapsToDevicePixels="True" Loaded="Window_Loaded">
<Grid x:Name="Grid_Timeline" ScrollViewer.VerticalScrollBarVisibility="Auto" UseLayoutRounding="True" Width="1159" HorizontalAlignment="Left" VerticalAlignment="Top" SnapsToDevicePixels="True">
</Grid>
</Window>

dt的原始数据(DataTable)

date        datetime

category    NVARCHAR

howlong     int

   date     category howlong 
2015-01-25    HHH      60 
2014-04-03    AAA      60 
2015-01-25    DDD      60 
2014-04-03    UUU      60 
2015-01-25    CCC      60 
2015-11-07    PPP      30 
2015-01-25    TTT      60 
2015-11-07    MMM      30 
2015-02-22    MMM      30 
2015-11-07    VVV       8 

以上最小代码的结果

另一个随机创建矩形的最小代码 -

for (int k = 0; k < 191; k++)
        {
            Rectangle rec_test = new Rectangle();
            rec_test.Margin = new Thickness(random_margin.Next(100, 1000), 29 * (k % 10), 0, 0);
            rec_test.Width = random_width.Next(10, 40);
            rec_test.HorizontalAlignment = HorizontalAlignment.Left;
            rec_test.VerticalAlignment = VerticalAlignment.Top;
            rec_test.Height = 14;
            rec_test.Cursor = Cursors.Hand;
            rec_test.Effect = new DropShadowEffect
            {
                Color = new Color { A = 255, R = 0, G = 0, B = 0 },
                Direction = 315,
                ShadowDepth = 5,
                Opacity = 1
            };

            rec_test.Fill = Brushes.Green;

            Grid_Timeline.Children.Add(rec_test);
        }

Answer 1

你有没有试过用来Canvas放置你的矩形？

使用 Canvas 放置形状（例如矩形、圆形或什至具有随机位置的图形路径）比放置在固定布局容器（例如Grid或 ）上要好StackPanel。

这是很了解，如果你只是放在形状与效果，如在固定版面阴影效果（任意X，Y位置），如Grid和StackPanel，你的形状可能会被裁剪。因为在渲染时总是会检查形状边缘的像素边界，这通常是由尝试重新计算固定布局控件的边缘时重叠渲染计算引起的。

Answer 2

可能是您的图形硬件的驱动程序问题。尝试禁用硬件加速，看看是否有帮助。

public partial class App : Application
{
    protected override void OnStartup(StartupEventArgs e)
    {
         RenderOptions.ProcessRenderMode = RenderMode.SoftwareOnly;
    }
}

一般来说，我建议不要使用它，DropShadowEffect因为它会对渲染性能产生显着的负面影响。