我在VB.NET中的http://blogs.msdn.com/dwayneneed/archive/2007/10/05/blurry-bitmaps.aspx使用以下示例。代码如下所示。
当我的应用程序加载CPU时，我遇到问题是50-70％。我已确定问题出在Bitmap类。 OnLayoutUpdated()方法不断调用InvalidateVisual()。这是因为有些点没有返回相等，而是Point(0.0,-0.5)
任何人都可以在此代码中看到任何错误，或者知道像素捕捉Bitmap图像的更好的实现，因此它不是模糊的吗？
P.S。示例代码在C＃中，但我相信它已正确转换。
Imports System
Imports System.Collections.Generic
Imports System.Windows
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Class Bitmap Inherits FrameworkElement
' Use FrameworkElement instead of UIElement so Data Binding works as expected
Private _sourceDownloaded As EventHandler
Private _sourceFailed As EventHandler(Of ExceptionEventArgs)
Private _pixelOffset As Windows.Point
Public Sub New()
_sourceDownloaded = New EventHandler(AddressOf OnSourceDownloaded)
_sourceFailed = New EventHandler(Of ExceptionEventArgs)(AddressOf OnSourceFailed)
AddHandler LayoutUpdated, AddressOf OnLayoutUpdated
End Sub
Public Shared ReadOnly SourceProperty As DependencyProperty = DependencyProperty.Register("Source", GetType(BitmapSource), GetType(Bitmap), New FrameworkPropertyMetadata(Nothing, FrameworkPropertyMetadataOptions.AffectsRender Or FrameworkPropertyMetadataOptions.AffectsMeasure, New PropertyChangedCallback(AddressOf Bitmap.OnSourceChanged)))
Public Property Source() As BitmapSource
Get
Return DirectCast(GetValue(SourceProperty), BitmapSource)
End Get
Set(ByVal value As BitmapSource)
SetValue(SourceProperty, value)
End Set
End Property
Public Shared Function FindParentWindow(ByVal child As DependencyObject) As Window
Dim parent As DependencyObject = VisualTreeHelper.GetParent(child)
'Check if this is the end of the tree
If parent Is Nothing Then
Return Nothing
End If
Dim parentWindow As Window = TryCast(parent, Window)
If parentWindow IsNot Nothing Then
Return parentWindow
Else
' Use recursion until it reaches a Window
Return FindParentWindow(parent)
End If
End Function
Public Event BitmapFailed As EventHandler(Of ExceptionEventArgs)
' Return our measure size to be the size needed to display the bitmap pixels.
'
' Use MeasureOverride instead of MeasureCore so Data Binding works as expected.
' Protected Overloads Overrides Function MeasureCore(ByVal availableSize As Size) As Size
Protected Overloads Overrides Function MeasureOverride(ByVal availableSize As Size) As Size
Dim measureSize As New Size()
Dim bitmapSource As BitmapSource = Source
If bitmapSource IsNot Nothing Then
Dim ps As PresentationSource = PresentationSource.FromVisual(Me)
If Me.VisualParent IsNot Nothing Then
Dim window As Window = window.GetWindow(Me.VisualParent)
If window IsNot Nothing Then
ps = PresentationSource.FromVisual(window.GetWindow(Me.VisualParent))
ElseIf FindParentWindow(Me) IsNot Nothing Then
ps = PresentationSource.FromVisual(FindParentWindow(Me))
End If
End If
'
If ps IsNot Nothing Then
Dim fromDevice As Matrix = ps.CompositionTarget.TransformFromDevice
Dim pixelSize As New Vector(bitmapSource.PixelWidth, bitmapSource.PixelHeight)
Dim measureSizeV As Vector = fromDevice.Transform(pixelSize)
measureSize = New Size(measureSizeV.X, measureSizeV.Y)
Else
measureSize = New Size(bitmapSource.PixelWidth, bitmapSource.PixelHeight)
End If
End If
Return measureSize
End Function
Protected Overloads Overrides Sub OnRender(ByVal dc As DrawingContext)
Dim bitmapSource As BitmapSource = Me.Source
If bitmapSource IsNot Nothing Then
_pixelOffset = GetPixelOffset()
' Render the bitmap offset by the needed amount to align to pixels.
dc.DrawImage(bitmapSource, New Rect(_pixelOffset, DesiredSize))
End If
End Sub
Private Shared Sub OnSourceChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
Dim bitmap As Bitmap = DirectCast(d, Bitmap)
Dim oldValue As BitmapSource = DirectCast(e.OldValue, BitmapSource)
Dim newValue As BitmapSource = DirectCast(e.NewValue, BitmapSource)
If ((oldValue IsNot Nothing) AndAlso (bitmap._sourceDownloaded IsNot Nothing)) AndAlso (Not oldValue.IsFrozen AndAlso (TypeOf oldValue Is BitmapSource)) Then
RemoveHandler DirectCast(oldValue, BitmapSource).DownloadCompleted, bitmap._sourceDownloaded
RemoveHandler DirectCast(oldValue, BitmapSource).DownloadFailed, bitmap._sourceFailed
' ((BitmapSource)newValue).DecodeFailed -= bitmap._sourceFailed; // 3.5
End If
If ((newValue IsNot Nothing) AndAlso (TypeOf newValue Is BitmapSource)) AndAlso Not newValue.IsFrozen Then
AddHandler DirectCast(newValue, BitmapSource).DownloadCompleted, bitmap._sourceDownloaded
AddHandler DirectCast(newValue, BitmapSource).DownloadFailed, bitmap._sourceFailed
' ((BitmapSource)newValue).DecodeFailed += bitmap._sourceFailed; // 3.5
End If
End Sub
Private Sub OnSourceDownloaded(ByVal sender As Object, ByVal e As EventArgs)
InvalidateMeasure()
InvalidateVisual()
End Sub
Private Sub OnSourceFailed(ByVal sender As Object, ByVal e As ExceptionEventArgs)
Source = Nothing
' setting a local value seems scetchy...
RaiseEvent BitmapFailed(Me, e)
End Sub
Private Sub OnLayoutUpdated(ByVal sender As Object, ByVal e As EventArgs)
' This event just means that layout happened somewhere. However, this is
' what we need since layout anywhere could affect our pixel positioning.
Dim pixelOffset As Windows.Point = GetPixelOffset()
If Not AreClose(pixelOffset, _pixelOffset) Then
InvalidateVisual()
End If
End Sub
' Gets the matrix that will convert a Windows.Point from "above" the
' coordinate space of a visual into the the coordinate space
' "below" the visual.
Private Function GetVisualTransform(ByVal v As Visual) As Matrix
If v IsNot Nothing Then
Dim m As Matrix = Matrix.Identity
Dim transform As Transform = VisualTreeHelper.GetTransform(v)
If transform IsNot Nothing Then
Dim cm As Matrix = transform.Value
m = Matrix.Multiply(m, cm)
End If
Dim offset As Vector = VisualTreeHelper.GetOffset(v)
m.Translate(offset.X, offset.Y)
Return m
End If
Return Matrix.Identity
End Function
Private Function TryApplyVisualTransform(ByVal Point As Windows.Point, ByVal v As Visual, ByVal inverse As Boolean, ByVal throwOnError As Boolean, ByRef success As Boolean) As Windows.Point
success = True
If v IsNot Nothing Then
Dim visualTransform As Matrix = GetVisualTransform(v)
If inverse Then
If Not throwOnError AndAlso Not visualTransform.HasInverse Then
success = False
Return New Windows.Point(0, 0)
End If
visualTransform.Invert()
End If
Point = visualTransform.Transform(Point)
End If
Return Point
End Function
Private Function ApplyVisualTransform(ByVal Point As Windows.Point, ByVal v As Visual, ByVal inverse As Boolean) As Windows.Point
Dim success As Boolean = True
Return TryApplyVisualTransform(Point, v, inverse, True, success)
End Function
Private Function GetPixelOffset() As Windows.Point
Dim pixelOffset As New Windows.Point()
Dim ps As PresentationSource = PresentationSource.FromVisual(Me)
If ps IsNot Nothing Then
Dim rootVisual As Visual = ps.RootVisual
' Transform (0,0) from this element up to pixels.
pixelOffset = Me.TransformToAncestor(rootVisual).Transform(pixelOffset)
pixelOffset = ApplyVisualTransform(pixelOffset, rootVisual, False)
pixelOffset = ps.CompositionTarget.TransformToDevice.Transform(pixelOffset)
' Round the origin to the nearest whole pixel.
pixelOffset.X = Math.Round(pixelOffset.X)
pixelOffset.Y = Math.Round(pixelOffset.Y)
' Transform the whole-pixel back to this element.
pixelOffset = ps.CompositionTarget.TransformFromDevice.Transform(pixelOffset)
pixelOffset = ApplyVisualTransform(pixelOffset, rootVisual, True)
pixelOffset = rootVisual.TransformToDescendant(Me).Transform(pixelOffset)
End If
Return pixelOffset
End Function
Private Function AreClose(ByVal Point1 As Windows.Point, ByVal Point2 As Windows.Point) As Boolean
Return AreClose(Point1.X, Point2.X) AndAlso AreClose(Point1.Y, Point2.Y)
End Function
Private Function AreClose(ByVal value1 As Double, ByVal value2 As Double) As Boolean
If value1 = value2 Then
Return True
End If
Dim delta As Double = value1 - value2
Return ((delta < 0.00000153) AndAlso (delta > -0.00000153))
End Function
End Class
答案 0 :(得分：2)
首先，永远不要挂钩OnLayoutUpdated，这是一个记忆困难。
这就是我在Xaml中防止模糊位图的方法，它确实有效：D，确保你的位图在图像编辑程序中以96 dpi保存。
<Image Source="{StaticResource img}"
VerticalAlignment="Center"
HorizontalAlignment="Center"
SnapsToDevicePixels="True"
RenderOptions.BitmapScalingMode="NearestNeighbor"
RenderOptions.EdgeMode="Aliased"
Width="16"
Height="16"
gi:ImageGreyer.IsGreyable="True"/>
答案 1 :(得分：1)
您可能需要考虑尝试在 WPF4 中使用新属性。将RenderOptions.BitmapScalingMode保留为 HighQuality ，或者不要声明它。
NearestNeighbor 为我工作，除了它在放大应用程序时导致锯齿状位图。它似乎也没有解决任何图标以奇怪的方式进行大小调整的故障。
在您的根元素（即您的主窗口）上添加以下属性：UseLayoutRounding="True"。
以前只在Silverlight中可用的属性现在修复了所有Bitmap大小调整问题。 ：）
您可能想要检查的旧代码修复程序位于下方。
来自 Nbd-Tech 的Nir不久前在这篇文章中贴了这个帖子：http://www.nbdtech.com/Blog/archive/2008/11/20/blurred-images-in-wpf.aspx
使用以下代码替换Bitmap类中的MeasureCore方法：
protected override Size MeasureCore(Size availableSize)
{
Size measureSize = new Size();
BitmapSource bitmapSource = Source;
if(bitmapSource != null)
{
measureSize = new Size(bitmapSource.PixelWidth, bitmapSource.PixelHeight);
}
return measureSize;
}