Contents

vImageFloodFill_ARGB8888(_:_:_:_:_:_:_:)

Applies a flood-fill operation to an 8-bit-per-channel, four-channel interleaved image.

Declaration

func vImageFloodFill_ARGB8888(_ srcDest: UnsafePointer<vImage_Buffer>, _ tempBuffer: UnsafeMutableRawPointer!, _ seedX: vImagePixelCount, _ seedY: vImagePixelCount, _ newValue: UnsafeMutablePointer<UInt8>!, _ connectivity: Int32, _ flags: vImage_Flags) -> vImage_Error

Parameters

  • srcDest:

    A pointer to a vImage buffer structure that contains the source image and receives the destination image. This function always works in place, that is, the input and the output point to the same memory.

  • tempBuffer:

    A pointer to workspace memory the function uses as it operates on an image. Pass nil to instruct the function to allocate, use, and then free its own temporary buffer.

  • seedX:

    The x-coordinate that defines the position of the seed pixel inside the connected component.

  • seedY:

    The y-coordinate that defines the position of the seed pixel inside the connected component.

  • newValue:

    The new pixel value that overwrites the pixels in the connected component.

  • connectivity:

    An integer that specifies which pixels the operation includes as neighbors. Pass either 4 or 8. The four-connected neighborhood of a pixel are the pixels to the left and right, and those above and below. The eight-connected neighborhood also includes the pixels on the four diagonals.

  • flags:

    The options to use when performing the operation. If your code implements its own tiling or its own multithreading, pass Kvimagedonottile; otherwise, pass Kvimagenoflags.

    To instruct the function to return the minimum size of the workspace memory, set the Kvimagegettempbuffersize flag.

Mentioned in

Return Value

kvImageNoError; otherwise, a negative value indicates one of the error codes that Data Types and Constants describes, and a positive value indicates the required size for the temporary buffer.

Discussion

The flood-fill function sets all pixels that are neighboring and identical to the seed pixel to a new color. The operation continues until it reaches the image boundary or until it sets all pixels within the connected component to the new value.

Optimize performance with temporary buffers

This function uses a multiple-pass algorithm that saves intermediate pixel values between passes. In some cases, the destination buffer may not be large enough to store that intermediate data, so the operation requires additional storage.

Pass nil to the tempBuffer parameter to have vImage create and manage this temporary storage for you.

In cases where your code calls the function frequently (for example, when processing video), create and manage this temporary buffer yourself and reuse it across function calls. Reusing a buffer avoids vImage allocating the temporary storage with each call.

To use your own temporary buffer, first call the function with the same values for all other parameters that you intend to use for subsequent calls. In addition, pass the kvImageGetTempBufferSize flag. The kvImageGetTempBufferSize instructs the function not to perform any processing, and to return a positive value that represents the minimum size, in bytes, of the temporary buffer. A negative return value represents an error.

After you allocate the memory for the temporary buffer, pass that to the tempBuffer parameter for subsequent calls to the function, and don’t pass the kvImageGetTempBufferSize flag.

You can use the same workspace memory for a group of images that are different sizes. To do this, create a vImage buffer structure with a size that shares the maximum width and maximum height of the images that you’re working with. For example, to create a workspace memory that’s suitable for 4x4, 5x4, and 4x5 images, pass a buffer with the size 5x5.

See Also

Flood-filling buffers