Dim RenderTargetBitmap As New RenderTargetBitmap(1920, 1080, 144, 144,PixelFormats.Pbgra32)

RenderTargetBitmap.Render(drawingVisual)

• 例子

现在假设系统DPI为默认100%设置,在DrawingVisual画一条一个像素宽的清晰横线

Public Class Window1

    Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)

        Dim drawingVisual As New DrawingVisual()

        Dim drawingContext As DrawingContext = drawingVisual.RenderOpen()

        Dim Thickness As Double = 1 '线宽1个单位,此处等同于1个像素

        Dim HalfThickness As Double = Thickness * 0.5

        drawingContext.DrawLine(New Pen(Brushes.Black, Thickness),

                                New Point(0, 100 - HalfThickness),

                                New Point(1920, 100 - HalfThickness)

        )

        drawingContext.Close()

        Dim RenderTargetBitmap As New RenderTargetBitmap(1920, 1080, 96, 96, PixelFormats.Pbgra32) '注意这里创建的是96DPI的图像对象

        RenderTargetBitmap.Render(drawingVisual)

        Dim image As New Image

        image.Source = RenderTargetBitmap

        Canvas1.Children.Add(image)

    End Sub

End Class

<Window

    x:Class="Window1"

    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:local="clr-namespace:WpfApp3"

    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

    Title="Window1"

    Width="300"

    Height="300"

    mc:Ignorable="d" Loaded="Window_Loaded">

    <Canvas x:Name="Canvas1">

    </Canvas>

</Window>

Public Class Window1

    Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)

        Dim drawingVisual As New DrawingVisual()

        Dim drawingContext As DrawingContext = drawingVisual.RenderOpen()

        Dim Thickness As Double = 1 / 1.5 '在144(150%)DPI的情况下,线宽1个像素

        Dim HalfThickness As Double = Thickness * 0.5

        drawingContext.DrawLine(New Pen(Brushes.Black, Thickness),

                                New Point(0, 100 / 1.5 - HalfThickness),

                                New Point(1920, 100 / 1.5 - HalfThickness)

        )

        drawingContext.Close()

        Dim RenderTargetBitmap As New RenderTargetBitmap(1920, 1080, 144, 144, PixelFormats.Pbgra32) '注意这里创建的是144DPI的图像对象

        RenderTargetBitmap.Render(drawingVisual)

        Dim image As New Image

        image.Source = RenderTargetBitmap

        Canvas1.Children.Add(image)

    End Sub

End Class

• 其它

 

在写此笔记之前在网上查阅过很多文章,基本上都是以使用参考线(GuidelineSet)进行像素对齐的方式避免模糊,但参考线也不是完美的解决方案,因为当要求在两个显示器像素之间进行绘制时WPF到底会将其对齐到哪个像素呢?其结果并不一定是我们想要的,

以MSDN的此文为例https://msdn.microsoft.com/zh-cn/library/aa348553(v=vs.110).aspx

左侧是使用了参考线得到的清晰图形,右侧是没有使用参考线得到的模糊图形(注意原文中写反了).