withUnsafeBufferPointer(_:)

Declaration

func withUnsafeBufferPointer<R>(_ body: (UnsafeBufferPointer<Format.ComponentType>) throws -> R) rethrows -> R

Parameters

• body:

  A closure with an Unsafebufferpointer parameter that points to the contiguous storage for the pixel buffer.

Return Value

The return value, if any, of the body closure parameter.

Discussion

You can use this function to simplify interoperation with other libraries and frameworks. For example, the following code uses Accelerate’s vForce library to raise each pixel value to the power of 1 / 2.2:

let srcBuffer = vImage.PixelBuffer(pixelValues: [0.1, 0.2, 0.3, 0.4],
                                   size: vImage.Size(width: 4, height: 1),
                                   pixelFormat: vImage.PlanarF.self)

let destBuffer =  vImage.PixelBuffer(size: srcBuffer.size,
                                     pixelFormat: vImage.PlanarF.self)

var exponent = Float(1 / 2.2)
var count = Int32(4)

srcBuffer.withUnsafeBufferPointer { src in
    destBuffer.withUnsafeMutableBufferPointer { dest in
        
        vvpowsf(dest.baseAddress!,
                &exponent,
                src.baseAddress!,
                &count)
    }
}