preferredAlignmentAndRowBytes(width:height:bitsPerPixel:)

Declaration

static func preferredAlignmentAndRowBytes(width: Int, height: Int, bitsPerPixel: UInt32) throws -> (alignment: Int, rowBytes: Int)

Parameters

• width:

  The width of the image, in pixels.

• height:

  The height of the image, in pixels.

• bitsPerPixel:

  The number of bits in a single pixel.

Return Value

A tuple that contains the alignment and row bytes.

Discussion

If you provide your own buffer storage, call preferredAlignmentAndRowBytes(width:height:bitsPerPixel:) to get the row stride that ensures your buffer achieves the best performance.

let width = 10
let height = 5

let alignmentAndRowBytes = try vImage_Buffer.preferredAlignmentAndRowBytes(
    width: width,
    height: height,
    bitsPerPixel: 8)

// Prints "16".
print(alignmentAndRowBytes.rowBytes)

let data = UnsafeMutableRawPointer.allocate(
    byteCount: alignmentAndRowBytes.rowBytes * height,
    alignment: alignmentAndRowBytes.alignment)

let buffer = vImage_Buffer(data: data,
                           height: vImagePixelCount(height),
                           width: vImagePixelCount(width),
                           rowBytes: alignmentAndRowBytes.rowBytes)

See Also

Creating a buffer that references existing data

• init(data:height:width:rowBytes:)