300 lines
15 KiB
VB.net
300 lines
15 KiB
VB.net
Public NotInheritable Class SystemDropShadowChrome
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Inherits Decorator
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'源码来源于：https://referencesource.microsoft.com/#PresentationFramework.Aero/parent/Shared/Microsoft/Windows/Themes/SystemDropShadowChrome.cs,6d9c27d92a8128c1
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Public Shared ReadOnly ColorProperty As DependencyProperty = DependencyProperty.Register("Color", GetType(Color), GetType(SystemDropShadowChrome), New FrameworkPropertyMetadata(Color.FromArgb(&H71, &H0, &H0, &H0), FrameworkPropertyMetadataOptions.AffectsRender, New PropertyChangedCallback(AddressOf ClearBrushes)))
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Public Property Color As Color
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Get
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Return CType(GetValue(ColorProperty), Color)
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End Get
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Set(value As Color)
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SetValue(ColorProperty, value)
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End Set
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End Property
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Public Shared ReadOnly CornerRadiusProperty As DependencyProperty = DependencyProperty.Register("CornerRadius", GetType(CornerRadius), GetType(SystemDropShadowChrome), New FrameworkPropertyMetadata(New CornerRadius(), FrameworkPropertyMetadataOptions.AffectsRender, New PropertyChangedCallback(AddressOf ClearBrushes)), New ValidateValueCallback(AddressOf IsCornerRadiusValid))
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Public Property CornerRadius As CornerRadius
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Get
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Return CType(GetValue(CornerRadiusProperty), CornerRadius)
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End Get
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Set(value As CornerRadius)
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SetValue(CornerRadiusProperty, value)
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End Set
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End Property
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Private Shared Function IsCornerRadiusValid(value As Object) As Boolean
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Dim cr As CornerRadius = CType(value, CornerRadius)
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Return Not (cr.TopLeft < 0.0 OrElse cr.TopRight < 0.0 OrElse cr.BottomLeft < 0.0 OrElse cr.BottomRight < 0.0 OrElse Double.IsNaN(cr.TopLeft) OrElse Double.IsNaN(cr.TopRight) OrElse Double.IsNaN(cr.BottomLeft) OrElse Double.IsNaN(cr.BottomRight) OrElse Double.IsInfinity(cr.TopLeft) OrElse Double.IsInfinity(cr.TopRight) OrElse Double.IsInfinity(cr.BottomLeft) OrElse Double.IsInfinity(cr.BottomRight))
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End Function
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Private Const ShadowDepth As Double = 5
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Protected Overrides Sub OnRender(drawingContext As DrawingContext)
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Dim cornerRadius As CornerRadius = Me.CornerRadius
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Dim shadowBounds As New Rect(New Point(ShadowDepth, ShadowDepth), New Size(RenderSize.Width, RenderSize.Height))
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Dim color As Color = Me.Color
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If shadowBounds.Width > 0 AndAlso shadowBounds.Height > 0 AndAlso color.A > 0 Then
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Dim centerWidth As Double = shadowBounds.Right - shadowBounds.Left - 2 * ShadowDepth
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Dim centerHeight As Double = shadowBounds.Bottom - shadowBounds.Top - 2 * ShadowDepth
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Dim maxRadius As Double = Math.Min(centerWidth * 0.5, centerHeight * 0.5)
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cornerRadius.TopLeft = Math.Min(cornerRadius.TopLeft, maxRadius)
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cornerRadius.TopRight = Math.Min(cornerRadius.TopRight, maxRadius)
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cornerRadius.BottomLeft = Math.Min(cornerRadius.BottomLeft, maxRadius)
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cornerRadius.BottomRight = Math.Min(cornerRadius.BottomRight, maxRadius)
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Dim brushes As Brush() = GetBrushes(color, cornerRadius)
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Dim centerTop As Double = shadowBounds.Top + ShadowDepth
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Dim centerLeft As Double = shadowBounds.Left + ShadowDepth
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Dim centerRight As Double = shadowBounds.Right - ShadowDepth
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Dim centerBottom As Double = shadowBounds.Bottom - ShadowDepth
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Dim guidelineSetX As Double() = New Double() {centerLeft, centerLeft + cornerRadius.TopLeft, centerRight - cornerRadius.TopRight, centerLeft + cornerRadius.BottomLeft, centerRight - cornerRadius.BottomRight, centerRight}
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Dim guidelineSetY As Double() = New Double() {centerTop, centerTop + cornerRadius.TopLeft, centerTop + cornerRadius.TopRight, centerBottom - cornerRadius.BottomLeft, centerBottom - cornerRadius.BottomRight, centerBottom}
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drawingContext.PushGuidelineSet(New GuidelineSet(guidelineSetX, guidelineSetY))
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cornerRadius.TopLeft += ShadowDepth
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cornerRadius.TopRight += ShadowDepth
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cornerRadius.BottomLeft += ShadowDepth
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cornerRadius.BottomRight += ShadowDepth
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Dim topLeft As New Rect(shadowBounds.Left, shadowBounds.Top, cornerRadius.TopLeft, cornerRadius.TopLeft)
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drawingContext.DrawRectangle(brushes(Placement.TopLeft), Nothing, topLeft)
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Dim topWidth As Double = guidelineSetX(2) - guidelineSetX(1)
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If topWidth > 0 Then
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Dim top As New Rect(guidelineSetX(1), shadowBounds.Top, topWidth, ShadowDepth)
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drawingContext.DrawRectangle(brushes(Placement.Top), Nothing, top)
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End If
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Dim topRight As New Rect(guidelineSetX(2), shadowBounds.Top, cornerRadius.TopRight, cornerRadius.TopRight)
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drawingContext.DrawRectangle(brushes(Placement.TopRight), Nothing, topRight)
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Dim leftHeight As Double = guidelineSetY(3) - guidelineSetY(1)
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If leftHeight > 0 Then
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Dim left As New Rect(shadowBounds.Left, guidelineSetY(1), ShadowDepth, leftHeight)
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drawingContext.DrawRectangle(brushes(Placement.Left), Nothing, left)
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End If
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Dim rightHeight As Double = guidelineSetY(4) - guidelineSetY(2)
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If rightHeight > 0 Then
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Dim right As New Rect(guidelineSetX(5), guidelineSetY(2), ShadowDepth, rightHeight)
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drawingContext.DrawRectangle(brushes(Placement.Right), Nothing, right)
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End If
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Dim bottomLeft As New Rect(shadowBounds.Left, guidelineSetY(3), cornerRadius.BottomLeft, cornerRadius.BottomLeft)
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drawingContext.DrawRectangle(brushes(Placement.BottomLeft), Nothing, bottomLeft)
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Dim bottomWidth As Double = guidelineSetX(4) - guidelineSetX(3)
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If bottomWidth > 0 Then
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Dim bottom As New Rect(guidelineSetX(3), guidelineSetY(5), bottomWidth, ShadowDepth)
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drawingContext.DrawRectangle(brushes(Placement.Bottom), Nothing, bottom)
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End If
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Dim bottomRight As New Rect(guidelineSetX(4), guidelineSetY(4), cornerRadius.BottomRight, cornerRadius.BottomRight)
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drawingContext.DrawRectangle(brushes(Placement.BottomRight), Nothing, bottomRight)
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If cornerRadius.TopLeft = ShadowDepth AndAlso cornerRadius.TopLeft = cornerRadius.TopRight AndAlso cornerRadius.TopLeft = cornerRadius.BottomLeft AndAlso cornerRadius.TopLeft = cornerRadius.BottomRight Then
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Dim center As New Rect(guidelineSetX(0), guidelineSetY(0), centerWidth, centerHeight)
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drawingContext.DrawRectangle(brushes(Placement.Center), Nothing, center)
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Else
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Dim figure As New PathFigure()
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If cornerRadius.TopLeft > ShadowDepth Then
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figure.StartPoint = New Point(guidelineSetX(1), guidelineSetY(0))
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(1), guidelineSetY(1)), True))
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(0), guidelineSetY(1)), True))
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Else
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figure.StartPoint = New Point(guidelineSetX(0), guidelineSetY(0))
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End If
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If cornerRadius.BottomLeft > ShadowDepth Then
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(0), guidelineSetY(3)), True))
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(3), guidelineSetY(3)), True))
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(3), guidelineSetY(5)), True))
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Else
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(0), guidelineSetY(5)), True))
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End If
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If cornerRadius.BottomRight > ShadowDepth Then
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(4), guidelineSetY(5)), True))
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(4), guidelineSetY(4)), True))
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(5), guidelineSetY(4)), True))
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Else
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(5), guidelineSetY(5)), True))
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End If
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If cornerRadius.TopRight > ShadowDepth Then
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(5), guidelineSetY(2)), True))
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(2), guidelineSetY(2)), True))
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(2), guidelineSetY(0)), True))
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Else
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figure.Segments.Add(New LineSegment(New Point(guidelineSetX(5), guidelineSetY(0)), True))
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End If
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figure.IsClosed = True
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figure.Freeze()
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Dim geometry As New PathGeometry()
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geometry.Figures.Add(figure)
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geometry.Freeze()
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drawingContext.DrawGeometry(brushes(Placement.Center), Nothing, geometry)
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End If
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drawingContext.Pop()
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End If
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End Sub
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Private Enum Placement
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TopLeft = 0
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Top = 1
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TopRight = 2
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Left = 3
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Center = 4
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Right = 5
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BottomLeft = 6
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Bottom = 7
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BottomRight = 8
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End Enum
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Private Shared _commonBrushes As Brush()
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Private Shared _commonCornerRadius As CornerRadius
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Private Shared ReadOnly _resourceAccess As New Object()
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Private _brushes As Brush()
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Private Shared Sub ClearBrushes(o As DependencyObject, e As DependencyPropertyChangedEventArgs)
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CType(o, SystemDropShadowChrome)._brushes = Nothing
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End Sub
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Private Shared Function CreateStops(c As Color, cornerRadius As Double) As GradientStopCollection
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Dim gradientScale As Double = 1 / (cornerRadius + ShadowDepth)
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Dim gsc As New GradientStopCollection From {
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New GradientStop(c, (0.5 + cornerRadius) * gradientScale)
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}
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Dim stopColor As Color = c
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stopColor.A = CByte(0.74336 * c.A)
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gsc.Add(New GradientStop(stopColor, (1.5 + cornerRadius) * gradientScale))
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stopColor.A = CByte(0.38053 * c.A)
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gsc.Add(New GradientStop(stopColor, (2.5 + cornerRadius) * gradientScale))
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stopColor.A = CByte(0.12389 * c.A)
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gsc.Add(New GradientStop(stopColor, (3.5 + cornerRadius) * gradientScale))
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stopColor.A = CByte(0.02654 * c.A)
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gsc.Add(New GradientStop(stopColor, (4.5 + cornerRadius) * gradientScale))
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stopColor.A = 0
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gsc.Add(New GradientStop(stopColor, (5 + cornerRadius) * gradientScale))
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gsc.Freeze()
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Return gsc
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End Function
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Private Shared Function CreateBrushes(c As Color, cornerRadius As CornerRadius) As Brush()
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Dim brushes As Brush() = New Brush(8) {}
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brushes(Placement.Center) = New SolidColorBrush(c)
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brushes(Placement.Center).Freeze()
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Dim sideStops As GradientStopCollection = CreateStops(c, 0)
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Dim top As New LinearGradientBrush(sideStops, New Point(0, 1), New Point(0, 0))
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top.Freeze()
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brushes(Placement.Top) = top
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Dim left As New LinearGradientBrush(sideStops, New Point(1, 0), New Point(0, 0))
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left.Freeze()
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brushes(Placement.Left) = left
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Dim right As New LinearGradientBrush(sideStops, New Point(0, 0), New Point(1, 0))
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right.Freeze()
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brushes(Placement.Right) = right
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Dim bottom As New LinearGradientBrush(sideStops, New Point(0, 0), New Point(0, 1))
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bottom.Freeze()
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brushes(Placement.Bottom) = bottom
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Dim topLeftStops As GradientStopCollection
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If cornerRadius.TopLeft = 0 Then
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topLeftStops = sideStops
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Else
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topLeftStops = CreateStops(c, cornerRadius.TopLeft)
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End If
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Dim topLeft As New RadialGradientBrush(topLeftStops) With {
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.RadiusX = 1,
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.RadiusY = 1,
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.Center = New Point(1, 1),
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.GradientOrigin = New Point(1, 1)
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}
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topLeft.Freeze()
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brushes(Placement.TopLeft) = topLeft
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Dim topRightStops As GradientStopCollection
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If cornerRadius.TopRight = 0 Then
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topRightStops = sideStops
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ElseIf cornerRadius.TopRight = cornerRadius.TopLeft Then
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topRightStops = topLeftStops
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Else
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topRightStops = CreateStops(c, cornerRadius.TopRight)
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End If
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Dim topRight As New RadialGradientBrush(topRightStops) With {
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.RadiusX = 1,
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.RadiusY = 1,
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.Center = New Point(0, 1),
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.GradientOrigin = New Point(0, 1)
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}
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topRight.Freeze()
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brushes(Placement.TopRight) = topRight
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Dim bottomLeftStops As GradientStopCollection
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If cornerRadius.BottomLeft = 0 Then
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bottomLeftStops = sideStops
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ElseIf cornerRadius.BottomLeft = cornerRadius.TopLeft Then
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bottomLeftStops = topLeftStops
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ElseIf cornerRadius.BottomLeft = cornerRadius.TopRight Then
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bottomLeftStops = topRightStops
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Else
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bottomLeftStops = CreateStops(c, cornerRadius.BottomLeft)
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End If
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Dim bottomLeft As New RadialGradientBrush(bottomLeftStops) With {
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.RadiusX = 1,
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.RadiusY = 1,
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.Center = New Point(1, 0),
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.GradientOrigin = New Point(1, 0)
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}
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bottomLeft.Freeze()
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brushes(Placement.BottomLeft) = bottomLeft
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Dim bottomRightStops As GradientStopCollection
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If cornerRadius.BottomRight = 0 Then
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bottomRightStops = sideStops
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ElseIf cornerRadius.BottomRight = cornerRadius.TopLeft Then
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bottomRightStops = topLeftStops
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ElseIf cornerRadius.BottomRight = cornerRadius.TopRight Then
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bottomRightStops = topRightStops
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ElseIf cornerRadius.BottomRight = cornerRadius.BottomLeft Then
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bottomRightStops = bottomLeftStops
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Else
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bottomRightStops = CreateStops(c, cornerRadius.BottomRight)
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End If
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Dim bottomRight As New RadialGradientBrush(bottomRightStops) With {
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.RadiusX = 1,
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.RadiusY = 1,
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.Center = New Point(0, 0),
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.GradientOrigin = New Point(0, 0)
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}
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bottomRight.Freeze()
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brushes(Placement.BottomRight) = bottomRight
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Return brushes
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End Function
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Private Function GetBrushes(c As Color, cornerRadius As CornerRadius) As Brush()
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If _commonBrushes Is Nothing Then
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SyncLock _resourceAccess
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If _commonBrushes Is Nothing Then
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_commonBrushes = CreateBrushes(c, cornerRadius)
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_commonCornerRadius = cornerRadius
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End If
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End SyncLock
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End If
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If c = CType(_commonBrushes(Placement.Center), SolidColorBrush).Color AndAlso cornerRadius = _commonCornerRadius Then
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_brushes = Nothing
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Return _commonBrushes
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ElseIf _brushes Is Nothing Then
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_brushes = CreateBrushes(c, cornerRadius)
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End If
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Return _brushes
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End Function
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End Class
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