C＃WPF）动态添加控件时有时会缺少DropShadowEffect [英] C# WPF) DropShadowEffect is sometimes missing when dynamically adding a control
问题描述
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);
}
我使用上面的简单代码动态添加了一个矩形，如图所示。
I dynamically add a Rectangle with above simple code as shown image.
但是，有时候，随机会有一些没有DropShadowEffect的矩形，例如最低的黄色矩形和1个蓝色的矩形。
However, sometimes, randomly, there're rectangles without DropShadowEffect like yellow rectangles and 1 blue rectangle at the lowest.
如您所见，如果添加了矩形，则必须使用DropShadowEffect的代码。
As you see the code, if a rectangle is added, the code for DropShadowEffect should have to be worked.
我想知道为什么会这样。
I'm wondering why this is happening.
谢谢！
已添加XAML代码-
<Grid x:Name="Grid_Timeline" ScrollViewer.VerticalScrollBarVisibility="Auto" UseLayoutRounding="True" Width="1159" HorizontalAlignment="Left" VerticalAlignment="Top" SnapsToDevicePixels="True">
</Grid>
添加了要重新生成的最小代码-
Minimal code to re-produce is added-
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 Window的XAML代码
XAML code of WPF Window
<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）
Raw data of dt (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
/ a>
Result of above minimal code
另一个随机创建矩形的最小代码-
Another minimal code to create rectangles randomly-
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);
}
推荐答案
您是否尝试过使用画布放置矩形？
Have you tried to use Canvas to place your rectangles?
具有Canvas来放置形状（例如矩形，圆形或什至具有随机位置的图形路径）的效果比放在固定布局容器（例如）上更好网格或 StackPanel 。
Having Canvas to place your shapes such as rectangles, circles, or even graphical paths with random locations is better than placing on fixed layout container such as Grid or StackPanel.
众所周知，如果只是将具有诸如DropShadow之类效果的形状放置在固定布局（具有任意X，Y位置）上，例如 Grid 和 StackPanel ，您的形状可能会被剪切。因为将始终在渲染时检查形状边缘的像素边界，并且这通常是由于在尝试重新计算固定布局控件的边缘时渲染计算重叠造成的。
It is quite known that if you just placed shapes with effects such as DropShadow on fixed layout (with arbitrary X,Y locations) such as Grid and StackPanel, your shapes may be clipped. Because the shapes edges will always be checked for pixel boundaries at render time, and often this is caused by overlapped rendering calculations when it tries to recalculate edges of fixed layout controls.
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