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ShaderEffect Class

Provides a custom bitmap effect by using a PixelShader.

Namespace:  System.Windows.Media.Effects
Assembly:  PresentationCore (in PresentationCore.dll)

public abstract class ShaderEffect : Effect

The ShaderEffect type exposes the following members.

  NameDescription
Protected methodShaderEffectInitializes a new instance of the ShaderEffect class.
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  NameDescription
Public propertyCanFreezeGets a value that indicates whether the object can be made unmodifiable. (Inherited from Freezable.)
Protected propertyDdxUvDdyUvRegisterIndexGets or sets a value that indicates the shader register to use for the partial derivatives of the texture coordinates with respect to screen space.
Public propertyDependencyObjectTypeGets the DependencyObjectType that wraps the CLR type of this instance.  (Inherited from DependencyObject.)
Public propertyDispatcherGets the Dispatcher this DispatcherObject is associated with. (Inherited from DispatcherObject.)
Protected propertyEffectMappingWhen overridden in a derived class, transforms mouse input and coordinate systems through the effect. (Inherited from Effect.)
Public propertyHasAnimatedPropertiesGets a value that indicates whether one or more AnimationClock objects is associated with any of this object's dependency properties. (Inherited from Animatable.)
Public propertyIsFrozenGets a value that indicates whether the object is currently modifiable. (Inherited from Freezable.)
Public propertyIsSealedGets a value that indicates whether this instance is currently sealed (read-only). (Inherited from DependencyObject.)
Protected propertyPaddingBottomGets or sets a value indicating that the effect's output texture is larger than its input texture along the bottom edge.
Protected propertyPaddingLeftGets or sets a value indicating that the effect's output texture is larger than its input texture along the left edge.
Protected propertyPaddingRightGets or sets a value indicating that the effect's output texture is larger than its input texture along the right edge.
Protected propertyPaddingTopGets or sets a value indicating that the effect's output texture is larger than its input texture along the top edge.
Protected propertyPixelShaderGets or sets the PixelShader to use for the effect.
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  NameDescription
Public methodApplyAnimationClock(DependencyProperty, AnimationClock)Applies an AnimationClock to the specified DependencyProperty. If the property is already animated, the SnapshotAndReplace handoff behavior is used. (Inherited from Animatable.)
Public methodApplyAnimationClock(DependencyProperty, AnimationClock, HandoffBehavior)Applies an AnimationClock to the specified DependencyProperty. If the property is already animated, the specified HandoffBehavior is used. (Inherited from Animatable.)
Public methodBeginAnimation(DependencyProperty, AnimationTimeline)Applies an animation to the specified DependencyProperty. The animation is started when the next frame is rendered. If the specified property is already animated, the SnapshotAndReplace handoff behavior is used. (Inherited from Animatable.)
Public methodBeginAnimation(DependencyProperty, AnimationTimeline, HandoffBehavior)Applies an animation to the specified DependencyProperty. The animation is started when the next frame is rendered. If the specified property is already animated, the specified HandoffBehavior is used. (Inherited from Animatable.)
Public methodCheckAccessDetermines whether the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)
Public methodClearValue(DependencyProperty)Clears the local value of a property. The property to be cleared is specified by a DependencyProperty identifier. (Inherited from DependencyObject.)
Public methodClearValue(DependencyPropertyKey)Clears the local value of a read-only property. The property to be cleared is specified by a DependencyPropertyKey. (Inherited from DependencyObject.)
Public methodCloneCreates a modifiable clone of this ShaderEffect object, making deep copies of this object's values. When copying this object's dependency properties, this method copies resource references and data bindings (which may no longer resolve), but not animations or their current values.
Protected methodCloneCoreMakes the instance a clone (deep copy) of the specified Freezable using base (non-animated) property values. (Overrides Freezable.CloneCore(Freezable).)
Public methodCloneCurrentValueCreates a modifiable clone of this ShaderEffect object, making deep copies of this object's current values. Resource references, data bindings, and animations are not copied, but their current values are copied.
Protected methodCloneCurrentValueCoreMakes the instance a modifiable clone (deep copy) of the specified Freezable using current property values. (Overrides Freezable.CloneCurrentValueCore(Freezable).)
Public methodCoerceValueCoerces the value of the specified dependency property. This is accomplished by invoking any CoerceValueCallback function specified in property metadata for the dependency property as it exists on the calling DependencyObject. (Inherited from DependencyObject.)
Protected methodCreateInstanceInitializes a new instance of the Freezable class. (Inherited from Freezable.)
Protected methodCreateInstanceCoreWhen implemented in a derived class, creates a new instance of the Freezable derived class. (Overrides Freezable.CreateInstanceCore().)
Public methodEqualsDetermines whether a provided DependencyObject is equivalent to the current DependencyObject. (Inherited from DependencyObject.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodFreeze()Makes the current object unmodifiable and sets its IsFrozen property to true. (Inherited from Freezable.)
Protected methodFreezeCoreMakes this Animatable object unmodifiable or determines whether it can be made unmodifiable. (Inherited from Animatable.)
Public methodGetAnimationBaseValueReturns the non-animated value of the specified DependencyProperty. (Inherited from Animatable.)
Public methodGetAsFrozenCreates a frozen copy of the Freezable, using base (non-animated) property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (Inherited from Freezable.)
Protected methodGetAsFrozenCoreMakes the instance a frozen clone of the specified Freezable using base (non-animated) property values. (Overrides Freezable.GetAsFrozenCore(Freezable).)
Public methodGetCurrentValueAsFrozenCreates a frozen copy of the Freezable using current property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (Inherited from Freezable.)
Protected methodGetCurrentValueAsFrozenCoreMakes the current instance a frozen clone of the specified Freezable. If the object has animated dependency properties, their current animated values are copied. (Overrides Freezable.GetCurrentValueAsFrozenCore(Freezable).)
Public methodGetHashCodeGets a hash code for this DependencyObject. (Inherited from DependencyObject.)
Public methodGetLocalValueEnumeratorCreates a specialized enumerator for determining which dependency properties have locally set values on this DependencyObject. (Inherited from DependencyObject.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodGetValueReturns the current effective value of a dependency property on this instance of a DependencyObject. (Inherited from DependencyObject.)
Public methodInvalidatePropertyRe-evaluates the effective value for the specified dependency property (Inherited from DependencyObject.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodOnChangedCalled when the current Freezable object is modified. (Inherited from Freezable.)
Protected methodOnFreezablePropertyChanged(DependencyObject, DependencyObject)Ensures that appropriate context pointers are established for a DependencyObjectType data member that has just been set. (Inherited from Freezable.)
Protected methodOnFreezablePropertyChanged(DependencyObject, DependencyObject, DependencyProperty)This member supports the Windows Presentation Foundation (WPF) infrastructure and is not intended to be used directly from your code. (Inherited from Freezable.)
Protected methodOnPropertyChangedOverrides the DependencyObject implementation of OnPropertyChanged to also invoke any Changed handlers in response to a changing dependency property of type Freezable. (Inherited from Freezable.)
Protected methodStatic memberPixelShaderConstantCallbackAssociates a dependency property value with a pixel shader's float constant register.
Protected methodStatic memberPixelShaderSamplerCallback(Int32)Associates a dependency property value with a pixel shader's sampler register.
Protected methodStatic memberPixelShaderSamplerCallback(Int32, SamplingMode)Associates a dependency property value with a pixel shader's sampler register and a SamplingMode.
Public methodReadLocalValueReturns the local value of a dependency property, if it exists. (Inherited from DependencyObject.)
Protected methodReadPreambleEnsures that the Freezable is being accessed from a valid thread. Inheritors of Freezable must call this method at the beginning of any API that reads data members that are not dependency properties. (Inherited from Freezable.)
Protected methodStatic memberRegisterPixelShaderSamplerProperty(String, Type, Int32)Associates a dependency property with a shader sampler register.
Protected methodStatic memberRegisterPixelShaderSamplerProperty(String, Type, Int32, SamplingMode)Associates a dependency property with a shader sampler register and a SamplingMode.
Public methodSetCurrentValueSets the value of a dependency property without changing its value source. (Inherited from DependencyObject.)
Public methodSetValue(DependencyProperty, Object)Sets the local value of a dependency property, specified by its dependency property identifier. (Inherited from DependencyObject.)
Public methodSetValue(DependencyPropertyKey, Object)Sets the local value of a read-only dependency property, specified by the DependencyPropertyKey identifier of the dependency property. (Inherited from DependencyObject.)
Protected methodShouldSerializePropertyReturns a value that indicates whether serialization processes should serialize the value for the provided dependency property. (Inherited from DependencyObject.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Protected methodUpdateShaderValueNotifies the effect that the shader constant or sampler corresponding to the specified dependency property should be updated.
Public methodVerifyAccessEnforces that the calling thread has access to this DispatcherObject. (Inherited from DispatcherObject.)
Protected methodWritePostscriptRaises the Changed event for the Freezable and invokes its OnChanged method. Classes that derive from Freezable should call this method at the end of any API that modifies class members that are not stored as dependency properties. (Inherited from Freezable.)
Protected methodWritePreambleVerifies that the Freezable is not frozen and that it is being accessed from a valid threading context. Freezable inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties. (Inherited from Freezable.)
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  NameDescription
Public eventChangedOccurs when the Freezable or an object it contains is modified. (Inherited from Freezable.)
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  NameDescription
Protected fieldStatic memberPixelShaderPropertyIdentifies the PixelShader dependency property.
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Derive from the ShaderEffect class to implement a custom effect based on a single pixel shader.

The following steps show how to create a custom effect.

  1. Load a PixelShader from precompiled High Level Shading Language (HLSL) bytecode.

  2. Define dependency properties that represent the parameters of the effect and the Brush-based surface inputs. Use one of the RegisterPixelShaderSamplerProperty overloads to associate these inputs with register numbers that are referenced in the HLSL bytecode.

The number of samplers is limited to 4.

The following restrictions apply when using a PS 3.0 shader.

  • When a PS 3.0 shader is assigned, the number of samplers increases to 8. Assign the PS 3.0 shader before other shaders to enable registering 8 samplers.

  • The full shader constant register limit of 224 for floats is used. For more information, see ps_3_0.

  • The following data types are supported in PS 3.0 shaders only. An exception is thrown if these are used in lower shader versions.

    • int and types convertible to int: uint, byte, sbyte, long, ulong, short, ushort, char

    • bool

  • If a valid PS 3.0 shader is loaded on a computer that does not have hardware support for PS 3.0, the shader is ignored. If the shader is invalid, no exception is thrown.

  • If a computer has more than one video card, the behavior is defined by the least capable video card. For example, if the computer has two video cards, one of which supports PS 3.0 and one of which does not, the behavior is the same as if the computer does not support PS 3.0.

  • If a computer supports rendering PS 3.0 in hardware, but an invalid PS 3.0 shader is assigned, the InvalidPixelShaderEncountered event is raised. An example of an invalid PS 3.0 shader is one compiled with the ps_3_sw flag. The ShaderEffect class accepts only PS 3.0 shaders that are compiled with the ps_3_0 flag passed to fxc.exe. For more information, see Effect-Compiler Tool.

NoteNote

PS 2.0 shaders run when rendering in software. However, even if PS 3.0 is supported by the system's hardware, PS 3.0 shaders do not run during software rendering.

The following code example shows how to derive from the ShaderEffect class.

using System;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Effects;
using System.Reflection;

namespace ShaderEffectDemo
{

    public class ThresholdEffect : ShaderEffect
    {
        private static PixelShader _pixelShader =
            new PixelShader() { UriSource = MakePackUri("ThresholdEffect.fx.ps") };

        public ThresholdEffect()
        {
            PixelShader = _pixelShader;

            UpdateShaderValue(InputProperty);
            UpdateShaderValue(ThresholdProperty);
            UpdateShaderValue(BlankColorProperty);
        }

        // MakePackUri is a utility method for computing a pack uri 
        // for the given resource.  
        public static Uri MakePackUri(string relativeFile)
        {
            Assembly a = typeof(ThresholdEffect).Assembly;

            // Extract the short name. 
            string assemblyShortName = a.ToString().Split(',')[0];

            string uriString = "pack://application:,,,/" +
                assemblyShortName +
                ";component/" +
                relativeFile;

            return new Uri(uriString);
        }

        ///////////////////////////////////////////////////////////////////////
        #region Input dependency property

        public Brush Input
        {
            get { return (Brush)GetValue(InputProperty); }
            set { SetValue(InputProperty, value); }
        }

        public static readonly DependencyProperty InputProperty =
            ShaderEffect.RegisterPixelShaderSamplerProperty("Input", typeof(ThresholdEffect), 0);

        #endregion

        ///////////////////////////////////////////////////////////////////////
        #region Threshold dependency property

        public double Threshold
        {
            get { return (double)GetValue(ThresholdProperty); }
            set { SetValue(ThresholdProperty, value); }
        }

        public static readonly DependencyProperty ThresholdProperty =
            DependencyProperty.Register("Threshold", typeof(double), typeof(ThresholdEffect),
                    new UIPropertyMetadata(0.5, PixelShaderConstantCallback(0)));

        #endregion

        ///////////////////////////////////////////////////////////////////////
        #region BlankColor dependency property

        public Color BlankColor
        {
            get { return (Color)GetValue(BlankColorProperty); }
            set { SetValue(BlankColorProperty, value); }
        }

        public static readonly DependencyProperty BlankColorProperty =
            DependencyProperty.Register("BlankColor", typeof(Color), typeof(ThresholdEffect),
                    new UIPropertyMetadata(Colors.Transparent, PixelShaderConstantCallback(1)));

        #endregion
    }
}

The following code example shows a shader that corresponds to the previous ShaderEffect class.

// Threshold shader 

// Object Declarations

sampler2D implicitInput : register(s0);
float threshold : register(c0);
float4 blankColor : register(c1);

//--------------------------------------------------------------------------------------
// Pixel Shader
//--------------------------------------------------------------------------------------
float4 main(float2 uv : TEXCOORD) : COLOR
{
    float4 color = tex2D(implicitInput, uv);
    float intensity = (color.r + color.g + color.b) / 3;

    float4 result;
    if (intensity > threshold)
    {
        result = color;
    }
    else
    {
        result = blankColor;
    }

    return result;
}

The following XAML shows how to use the custom shader effect.

<Window x:Class="ShaderEffectDemo.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:ShaderEffectDemo"
    Title="Window1" Height="300" Width="300">
    <Window.Resources>
        <local:ThresholdEffect x:Key="thresholdEffect" Threshold="0.25" BlankColor="Orange" />
    </Window.Resources>

    <Grid Effect="{StaticResource thresholdEffect}">

    </Grid>
</Window>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5 SP1, 3.0 SP2

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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