MPSImageScale(3)       MetalPerformanceShaders.framework      MPSImageScale(3)

NAME

       MPSImageScale

SYNOPSIS

       #import <MPSImageResampling.h>

       Inherits MPSUnaryImageKernel.

       Inherited by MPSImageBilinearScale, and MPSImageLanczosScale.

   Instance Methods
       (nonnull instancetype) - initWithDevice:
       (nullable instancetype) - initWithCoder:device:

   Properties
       const MPSScaleTransform * scaleTransform

   Additional Inherited Members

Detailed Description

       MPSImageResampling.h  MetalPerformanceShaders

       Copyright:
           Copyright (c) 2015 Apple Inc. All rights reserved.  Resampling
           filters for MetalPerformanceShaders

       Resize an image and / or change its aspect ratio  The MPSImageScale
       filter can be used to resample an existing image using a different
       sampling frequency in each dimension. This can be used to enlarge or
       reduce the size of an image, or change the aspect ratio of an image.

       The resample methods supported are: Bilinear Bicubcic Lanczos

Method Documentation

   - (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 MPSUnaryImageKernel.

       Reimplemented in MPSImageLanczosScale, and MPSImageBilinearScale.

   - (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 MPSUnaryImageKernel.

       Reimplemented in MPSImageLanczosScale, and MPSImageBilinearScale.

Property Documentation

   - scaleTransform [read],  [write],  [nonatomic],  [assign]
       An optional transform that describes how to scale and translate the
       source image  If the scaleTransform is NULL, then the
       MPSImageLanczosScale filter will rescale the image so that the source
       image fits exactly into the destination texture. If the transform is
       not NULL, then the transform is used for determining how to map the
       source image to the destination. Default: NULL

       When the scaleTransform is set to non-NULL, the values pointed to by
       the new scaleTransform are copied to object storage, and the pointer is
       updated to point to internal storage. Do not attempt to free it. You
       may free your copy of the MPSScaleTransform as soon as the property set
       operation is complete.

       When calculating a scaleTransform, use the limits of the bounding box
       for the intended source region of interest and the destination
       clipRect. Adjustments for pixel center coordinates are handled
       internally to the function. For example, the scale transform to convert
       the entire source image to the entire destination image size (clipRect
       = MPSRectNoClip) would be:


       scaleTransform.scaleX = (double) dest.width / source.width;
       scaleTransform.scaleY = (double) dest.height / source.height;
       scaleTransform.translateX = scaleTransform.translateY = 0.0;


       The translation parameters allow you to adjust the region of the source
       image used to create the destination image. They are in destination
       coordinates. To place the top left corner of the destination clipRect
       to represent the position {x,y} in source coordinates, we solve for the
       translation based on the standard scale matrix operation for each axis:


       dest_position = source_position * scale + translation;
       translation = dest_position - source_position * scale;


       For the top left corner of the clipRect, the dest_position is
       considered to be {0,0}. This gives us a translation of:


       scaleTransform.translateX = -source_origin.x * scaleTransform.scaleX;
       scaleTransform.translateY = -source_origin.y * scaleTransform.scaleY;


       One would typically use non-zero translations to do tiling, or provide
       a resized view into a internal segment of an image.

       Changing the Lanczos scale factor may trigger recalculation of
       signficant state internal to the object when the filter is encoded to
       the command buffer. The scale factor is scaleTransform->scaleX,Y, or
       the ratio of source and destination image sizes if scaleTransform is
       NULL. Reuse a MPSImageLanczosScale object for frequently used scalings
       to avoid redundantly recreating expensive resampling state.

Author

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





Version MetalPerformanceShaders-Thu2Jul 13 2017               MPSImageScale(3)


Mac OS X 10.12.6 - Generated Mon Oct 30 18:14:24 CDT 2017