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* tests: add tests checking if floodFill funtions throw when location is outside * refactor: reduce code duplication by adding `checkLocation` to `FloodFill` * refactor: add and use `isInside` Co-authored-by: appgurueu <34514239+appgurueu@users.noreply.github.com> * Deduplicate further --------- Co-authored-by: appgurueu <34514239+appgurueu@users.noreply.github.com>
130 lines
3.6 KiB
JavaScript
130 lines
3.6 KiB
JavaScript
/**
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* Flood fill.
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*
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* Flood fill, also called seed fill, is an algorithm that determines and alters the area connected to a given node in a
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* multi-dimensional array with some matching attribute. It is used in the "bucket" fill tool of paint programs to fill
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* connected, similarly-colored areas with a different color.
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*
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* (description adapted from https://en.wikipedia.org/wiki/Flood_fill)
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* @see https://www.techiedelight.com/flood-fill-algorithm/
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*/
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const neighborOffsets = [
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[-1, -1],
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[-1, 0],
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[-1, 1],
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[0, -1],
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[0, 1],
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[1, -1],
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[1, 0],
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[1, 1]
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]
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function isInside(rgbData, location) {
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const x = location[0]
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const y = location[1]
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return x >= 0 && x < rgbData.length && y >= 0 && y < rgbData[0].length
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}
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function checkLocation(rgbData, location) {
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if (!isInside(rgbData, location)) {
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throw new Error('location should point to a pixel within the rgbData')
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}
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}
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function* neighbors(rgbData, location) {
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for (const offset of neighborOffsets) {
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const neighborLocation = [location[0] + offset[0], location[1] + offset[1]]
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if (isInside(rgbData, neighborLocation)) {
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yield neighborLocation
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}
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}
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}
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/**
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* Implements the flood fill algorithm through a breadth-first approach using a queue.
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*
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* @param rgbData The image to which the algorithm is applied.
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* @param location The start location on the image.
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* @param targetColor The old color to be replaced.
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* @param replacementColor The new color to replace the old one.
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*/
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export function breadthFirstSearch(
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rgbData,
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location,
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targetColor,
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replacementColor
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) {
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checkLocation(rgbData, location)
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const queue = []
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queue.push(location)
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while (queue.length > 0) {
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breadthFirstFill(rgbData, location, targetColor, replacementColor, queue)
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}
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}
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/**
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* Implements the flood fill algorithm through a depth-first approach using recursion.
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*
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* @param rgbData The image to which the algorithm is applied.
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* @param location The start location on the image.
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* @param targetColor The old color to be replaced.
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* @param replacementColor The new color to replace the old one.
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*/
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export function depthFirstSearch(
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rgbData,
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location,
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targetColor,
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replacementColor
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) {
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checkLocation(rgbData, location)
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depthFirstFill(rgbData, location, targetColor, replacementColor)
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}
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/**
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* Utility-function to implement the breadth-first loop.
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*
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* @param rgbData The image to which the algorithm is applied.
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* @param location The start location on the image.
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* @param targetColor The old color to be replaced.
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* @param replacementColor The new color to replace the old one.
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* @param queue The locations that still need to be visited.
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*/
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function breadthFirstFill(
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rgbData,
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location,
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targetColor,
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replacementColor,
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queue
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) {
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const currentLocation = queue[0]
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queue.shift()
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if (rgbData[currentLocation[0]][currentLocation[1]] === targetColor) {
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rgbData[currentLocation[0]][currentLocation[1]] = replacementColor
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for (const neighborLocation of neighbors(rgbData, currentLocation)) {
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queue.push(neighborLocation)
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}
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}
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}
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/**
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* Utility-function to implement the depth-first loop.
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*
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* @param rgbData The image to which the algorithm is applied.
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* @param location The start location on the image.
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* @param targetColor The old color to be replaced.
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* @param replacementColor The new color to replace the old one.
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*/
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function depthFirstFill(rgbData, location, targetColor, replacementColor) {
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if (rgbData[location[0]][location[1]] === targetColor) {
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rgbData[location[0]][location[1]] = replacementColor
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for (const neighborLocation of neighbors(rgbData, location)) {
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depthFirstFill(rgbData, neighborLocation, targetColor, replacementColor)
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}
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}
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}
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