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MPSUnaryImageKernel(3)




NAME

       MPSUnaryImageKernel


SYNOPSIS

       #import <MPSImageKernel.h>

       Inherits MPSKernel.

       Inherited by MPSImageAreaMax, MPSImageBox, MPSImageConversion,
       MPSImageConvolution, MPSImageDilate, MPSImageGaussianBlur,
       MPSImageHistogramEqualization, MPSImageHistogramSpecification,
       MPSImageIntegral, MPSImageIntegralOfSquares, MPSImageLaplacian,
       MPSImageMedian, MPSImagePyramid, MPSImageScale, MPSImageSobel,
       MPSImageStatisticsMean, MPSImageStatisticsMeanAndVariance,
       MPSImageStatisticsMinAndMax, MPSImageThresholdBinary,
       MPSImageThresholdBinaryInverse, MPSImageThresholdToZero,
       MPSImageThresholdToZeroInverse, MPSImageThresholdTruncate, and
       MPSImageTranspose.

   Instance Methods
       (nonnull instancetype) - initWithDevice:
       (nullable instancetype) - initWithCoder:device:
       (BOOL) - encodeToCommandBuffer:inPlaceTexture:fallbackCopyAllocator:
       (void) - encodeToCommandBuffer:sourceTexture:destinationTexture:
       (void) - encodeToCommandBuffer:sourceImage:destinationImage:
       (MPSRegion) - sourceRegionForDestinationSize:

   Properties
       MPSOffset offset
       MTLRegion clipRect
       MPSImageEdgeMode edgeMode

   Additional Inherited Members

Detailed Description

       This depends on Metal.framework  A MPSUnaryImageKernel consumes one
       MTLTexture and produces one MTLTexture.


Method Documentation

   - (BOOL) encodeToCommandBuffer: (nonnull id< MTLCommandBuffer >)
       commandBuffer(__nonnull id< MTLTexture > __strong *__nonnull)
       texture(nullable MPSCopyAllocator) copyAllocator
       This method attempts to apply the MPSKernel in place on a texture.

           In-place operation means that the same texture is used both to hold the input
           image and the results. Operating in-place can be an excellent way to reduce
           resource utilization, and save time and energy. While simple Metal kernels can
           not operate in place because textures can not be readable and writable at the
           same time, some MPSKernels can operate in place because they use
           multi-pass algorithms. Whether a MPSKernel can operate in-place can
           depend on current hardware, operating system revision and the parameters
           and properties passed to it. You should never assume that a MPSKernel will
           continue to work in place, even if you have observed it doing so before.



       If the operation succeeds in-place, YES is returned. If the in-place
       operation fails and no copyAllocator is provided, then NO is returned.
       Without a fallback MPSCopyAllocator, in neither case is the pointer
       held at *texture modified.

       Failure during in-place operation is very common and will occur
       inconsistently across different hardware platforms and OS releases.
       Without a fallback MPSCopyAllocator, operating in place may require
       significant error handling code to accompany each call to
       -encodeToCommandBuffer:..., complicating your code.

       You may find it simplifies your code to provide a fallback
       MPSCopyAllocator so that the operation can proceed reliably even when
       it can not proceed in-place. When an in-place filter fails, the
       MPSCopyAllocator (if any) will be invoked to create a new texture in
       which to write the results, allowing the filter to proceed reliably
       out-of-place. The original texture will be released, replaced with a
       pointer to the new texture and YES will be returned. If the allocator
       returns an invalid texture, it is released, *texture remains unmodified
       and NO is returned. Please see the MPSCopyAllocator definition for a
       sample allocator implementation.

       Sample usage with a copy allocator:

       id <MTLTexture> inPlaceTex = ...;
       MPSImageSobel *sobelFiler = [[MPSImageSobel alloc] initWithDevice: my_device];

       // With a fallback MPSCopyAllocator, failure should only occur in exceptional
       // conditions such as MTLTexture allocation failure or programmer error.
       // That is, the operation is roughly as robust as the MPSCopyAllocator.
       // Depending on the quality of that, we might decide we are justified here
       // in not checking the return value.
       [sobelFilter encodeToCommandBuffer: my_command_buffer
                           inPlaceTexture: &inPlaceTex  // may be replaced!
                    fallbackCopyAllocator: myAllocator];

       // If myAllocator was not called:
       //
       //      inPlaceTex holds the original texture with the result pixels in it
       //
       // else,
       //
       //      1) myAllocator creates a new texture.
       //      2) The new texture pixel data is overwritten by MPSUnaryImageKernel.
       //      3) The old texture passed in *inPlaceTex is released once.
       //      4) *inPlaceTex = the new texture
       //
       // In either case, the caller should now hold one reference to the texture now held in
       // inPlaceTex, whether it was replaced or not. Most of the time that means that nothing
       // further needs to be done here, and you can proceed to the next image encoding operation.
       // However, if other agents held references to the original texture, they still hold them
       // and may need to be alerted that the texture has been replaced so that they can retain
       // the new texture and release the old one.

       [sobelFilter release];  // if not ARC, clean up the MPSImageSobel object



       Note: Image filters that look at neighboring pixel values may actually
       consume more memory when operating in place than out of place. Many
       such operations are tiled internally to save intermediate texture
       storage, but can not tile when operating in place. The memory savings
       for tiling is however very short term, typically the lifetime of the
       MTLCommandBuffer.

       Attempt to apply a MPSKernel to a texture in place.

       Parameters:
           commandBuffer A valid MTLCommandBuffer to receive the encoded
           filter
           texture A pointer to a valid MTLTexture containing source image. On
           success, the image contents and possibly texture itself will be
           replaced with the result image.
           copyAllocator An optional block to allocate a new texture to hold
           the results, in case in-place operation is not possible. The
           allocator may use a different MTLPixelFormat or size than the
           original texture. You may enqueue operations on the provided
           MTLCommandBuffer using the provided MTLComputeCommandEncoder to
           initialize the texture contents.

       Returns:
           On success, YES is returned. The texture may have been replaced
           with a new texture if a copyAllocator was provided. On failure, NO
           is returned. The texture is unmodified.



   - (void) encodeToCommandBuffer: (nonnull id< MTLCommandBuffer >)
       commandBuffer(nonnull MPSImage *) sourceImage(nonnull MPSImage *)
       destinationImage
       Encode a MPSKernel into a command Buffer. The operation shall proceed
       out-of-place.

       Parameters:
           commandBuffer A valid MTLCommandBuffer to receive the encoded
           filter
           sourceImage A valid MPSImage containing the source image.
           destinationImage A valid MPSImage to be overwritten by result
           image. DestinationImage may not alias sourceImage.



   - (void) encodeToCommandBuffer: (nonnull id< MTLCommandBuffer >)
       commandBuffer(nonnull id< MTLTexture >) sourceTexture(nonnull id<
       MTLTexture >) destinationTexture
       Encode a MPSKernel into a command Buffer. The operation shall proceed
       out-of-place.

       Parameters:
           commandBuffer A valid MTLCommandBuffer to receive the encoded
           filter
           sourceTexture A valid MTLTexture containing the source image.
           destinationTexture A valid MTLTexture to be overwritten by result
           image. DestinationTexture may not alias sourceTexture.



   - (nullable instancetype) initWithCoder: (NSCoder *__nonnull)
       aDecoder(nonnull id< MTLDevice >) device
       NSSecureCoding compatability  While the standard
       NSSecureCoding/NSCoding method -initWithCoder: should work, since the
       file can't know which device your data is allocated on, we have to
       guess and may guess incorrectly. To avoid that problem, use
       initWithCoder:device instead.

       Parameters:
           aDecoder The NSCoder subclass with your serialized MPSKernel
           device The MTLDevice on which to make the MPSKernel

       Returns:
           A new MPSKernel object, or nil if failure.



       Reimplemented from MPSKernel.

       Reimplemented in MPSImagePyramid, MPSImageSobel,
       MPSImageHistogramSpecification, MPSImageThresholdToZeroInverse,
       MPSImageThresholdToZero, MPSImageHistogramEqualization, MPSImageBox,
       MPSImageGaussianBlur, MPSImageStatisticsMean, MPSImageThresholdBinary,
       MPSImageThresholdTruncate, MPSImageDilate, MPSImageScale,
       MPSImageLanczosScale, MPSImageBilinearScale,
       MPSImageStatisticsMeanAndVariance, MPSImageConvolution,
       MPSImageThresholdBinaryInverse, MPSImageStatisticsMinAndMax,
       MPSImageMedian, and MPSImageAreaMax.

   - (nonnull instancetype) initWithDevice: (nonnull id< MTLDevice >) device
       Standard init with default properties per filter type

       Parameters:
           device The device that the filter will be used on. May not be NULL.

       Returns:
           a pointer to the newly initialized object. This will fail,
           returning nil if the device is not supported. Devices must be
           MTLFeatureSet_iOS_GPUFamily2_v1 or later.



       Reimplemented from MPSKernel.

       Reimplemented in MPSImagePyramid, MPSImageSobel,
       MPSImageThresholdToZeroInverse, MPSImageThresholdToZero, MPSImageBox,
       MPSImageGaussianBlur, MPSImageStatisticsMean, MPSImageThresholdBinary,
       MPSImageThresholdTruncate, MPSImageDilate, MPSImageScale,
       MPSImageLanczosScale, MPSImageBilinearScale,
       MPSImageStatisticsMeanAndVariance, MPSImageThresholdBinaryInverse,
       MPSImageStatisticsMinAndMax, MPSImageMedian, and MPSImageAreaMax.

   - (MPSRegion) sourceRegionForDestinationSize: (MTLSize) destinationSize
       sourceRegionForDestinationSize: is used to determine which region of
       the sourceTexture will be read by
       encodeToCommandBuffer:sourceTexture:destinationTexture (and similar)
       when the filter runs. This information may be needed if the source
       image is broken into multiple textures. The size of the full (untiled)
       destination image is provided. The region of the full (untiled) source
       image that will be read is returned. You can then piece together an
       appropriate texture containing that information for use in your tiled
       context.

       The function will consult the MPSUnaryImageKernel offset and clipRect
       parameters, to determine the full region read by the function. Other
       parameters such as sourceClipRect, kernelHeight and kernelWidth will be
       consulted as necessary. All properties should be set to intended values
       prior to calling sourceRegionForDestinationSize:.

       Caution: This function operates using global image coordinates, but
       -encodeToCommandBuffer:... uses coordinates local to the source and
       destination image textures. Consequently, the offset and clipRect
       attached to this object will need to be updated using a global to
       local coordinate transform before -encodeToCommandBuffer:... is
       called.



       Determine the region of the source texture that will be read for a
       encode operation

       Parameters:
           destinationSize The size of the full virtual destination image.

       Returns:
           The area in the virtual source image that will be read.




Property Documentation

   - clipRect [read],  [write],  [nonatomic],  [assign]
       An optional clip rectangle to use when writing data. Only the pixels in
       the rectangle will be overwritten.  A MTLRegion that indicates which
       part of the destination to overwrite. If the clipRect does not lie
       completely within the destination image, the intersection between clip
       rectangle and destination bounds is used. Default: MPSRectNoClip
       (MPSKernel::MPSRectNoClip) indicating the entire image.

       See Also: MetalPerformanceShaders.h subsubsection_clipRect

   - edgeMode [read],  [write],  [nonatomic],  [assign]
       The MPSImageEdgeMode to use when texture reads stray off the edge of an
       image  Most MPSKernel objects can read off the edge of the source
       image. This can happen because of a negative offset property, because
       the offset + clipRect.size is larger than the source image or because
       the filter looks at neighboring pixels, such as a Convolution or
       morphology filter. Default: usually MPSImageEdgeModeZero. (Some
       MPSKernel types default to MPSImageEdgeModeClamp, because
       MPSImageEdgeModeZero is either not supported or would produce
       unexpected results.)

       See Also: MetalPerformanceShaders.h subsubsection_edgemode

   - offset [read],  [write],  [nonatomic],  [assign]
       The position of the destination clip rectangle origin relative to the
       source buffer.  The offset is defined to be the position of
       clipRect.origin in source coordinates. Default: {0,0,0}, indicating
       that the top left corners of the clipRect and source image align.

       See Also: MetalPerformanceShaders.h subsubsection_mpsoffset



Author

       Generated automatically by Doxygen for
       MetalPerformanceShaders.framework from the source code.





Version MetalPerformanceShaders-Thu2Jul 13 2017         MPSUnaryImageKernel(3)


Mac OS X 10.13.1 - Generated Tue Nov 7 19:12:36 CST 2017
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