diff --git a/Recursive/FloodFill.js b/Recursive/FloodFill.js new file mode 100644 index 000000000..c1389f07e --- /dev/null +++ b/Recursive/FloodFill.js @@ -0,0 +1,180 @@ +/** + * Flood fill, also called seed fill, is an algorithm that determines and alters the area connected + * to a given node in a multi-dimensional array with some matching attribute. It is used in the + * "bucket" fill tool of paint programs to fill connected, similarly-colored areas with a different + * color. (description adapted from https://en.wikipedia.org/wiki/Flood_fill) (see also: + * https://www.techiedelight.com/flood-fill-algorithm/). + */ + +const neighbors = [[-1, -1], [-1, 0], [-1, 1], [0, -1], [0, 1], [1, -1], [1, 0], [1, 1]] + +const black = [0, 0, 0] +const green = [0, 255, 0] +const violet = [255, 0, 255] +const white = [255, 255, 255] +const orange = [255, 128, 0] // eslint-disable-line + +/* +Doctests +> testBreadthFirst([1, 1], green, orange, [1, 1]); +orange +> testBreadthFirst([1, 1], green, orange, [0, 1]); +violet +> testBreadthFirst([1, 1], green, orange, [6, 4]); +white +> testDepthFirst([1, 1], green, orange, [1, 1]); +orange +> testDepthFirst([1, 1], green, orange, [0, 1]); +violet +> testDepthFirst([1, 1], green, orange, [6, 4]); +white +*/ + +/** +* Implements the flood fill algorithm through a breadth-first approach using a queue. +* +* @param rgbData The image to which the algorithm is applied. +* @param location The start location on the image. +* @param targetColor The old color to be replaced. +* @param replacementColor The new color to replace the old one. +*/ +function breadthFirstSearch (rgbData, location, targetColor, replacementColor) { + if (location[0] < 0 || + location[0] >= rgbData.length || + location[1] < 0 || + location[1] >= rgbData[0].length) { + throw new Error('location should point to a pixel within the rgbData') + } + + const queue = [] + queue.push(location) + + while (queue.length > 0) { + breadthFirstFill(rgbData, location, targetColor, replacementColor, queue) + } +} + +/** +* Implements the flood fill algorithm through a depth-first approach using recursion. +* +* @param rgbData The image to which the algorithm is applied. +* @param location The start location on the image. +* @param targetColor The old color to be replaced. +* @param replacementColor The new color to replace the old one. +*/ +function depthFirstSearch (rgbData, location, targetColor, replacementColor) { + if (location[0] < 0 || + location[0] >= rgbData.length || + location[1] < 0 || + location[1] >= rgbData[0].length) { + throw new Error('location should point to a pixel within the rgbData') + } + + depthFirstFill(rgbData, location, targetColor, replacementColor) +} + +/** +* Utility-function to implement the breadth-first loop +* +* @param rgbData The image to which the algorithm is applied. +* @param location The start location on the image. +* @param targetColor The old color to be replaced. +* @param replacementColor The new color to replace the old one. +* @param queue The locations that still need to be visited. +*/ +function breadthFirstFill (rgbData, location, targetColor, replacementColor, queue) { + const currentLocation = queue[0] + queue.shift() + + if (rgbData[currentLocation[0]][currentLocation[1]] === targetColor) { + rgbData[currentLocation[0]][currentLocation[1]] = replacementColor + + for (let i = 0; i < neighbors.length; i++) { + const x = currentLocation[0] + neighbors[i][0] + const y = currentLocation[1] + neighbors[i][1] + if (x >= 0 && x < rgbData.length && y >= 0 && y < rgbData[0].length) { + queue.push([x, y]) + } + } + } +} + +/** +* Utility-function to implement the depth-first loop +* +* @param rgbData The image to which the algorithm is applied. +* @param location The start location on the image. +* @param targetColor The old color to be replaced. +* @param replacementColor The new color to replace the old one. +*/ +function depthFirstFill (rgbData, location, targetColor, replacementColor) { + if (rgbData[location[0]][location[1]] === targetColor) { + rgbData[location[0]][location[1]] = replacementColor + + for (let i = 0; i < neighbors.length; i++) { + const x = location[0] + neighbors[i][0] + const y = location[1] + neighbors[i][1] + if (x >= 0 && x < rgbData.length && y >= 0 && y < rgbData[0].length) { + depthFirstFill(rgbData, [x, y], targetColor, replacementColor) + } + } + } +} + +/** +* Generates the rgbData-matrix for the tests +* +* @return example rgbData-matrix +*/ +function generateTestRgbData () { + const layout = [ + [violet, violet, green, green, black, green, green], + [violet, green, green, black, green, green, green], + [green, green, green, black, green, green, green], + [black, black, green, black, white, white, green], + [violet, violet, black, violet, violet, white, white], + [green, green, green, violet, violet, violet, violet], + [violet, violet, violet, violet, violet, violet, violet] + ] + + // transpose layout-matrix so the x-index comes before the y-index + const transposed = [] + for (let x = 0; x < layout[0].length; x++) { + transposed[x] = [] + for (let y = 0; y < layout.length; y++) { + transposed[x][y] = layout[y][x] + } + } + + return transposed +} + +/** +* Utility-function to test the function "breadthFirstSearch" +* +* @param fillLocation The start location on the image where the flood fill is applied. +* @param targetColor The old color to be replaced. +* @param replacementColor The new color to replace the old one. +* @param testLocation The location of the color to be checked. +* @return The color at testLocation +*/ +function testBreadthFirst (fillLocation, targetColor, replacementColor, testLocation) {// eslint-disable-line + const rgbData = generateTestRgbData() + breadthFirstSearch(rgbData, fillLocation, targetColor, replacementColor) + return rgbData[testLocation[0]][testLocation[1]] +} + +/** +* Utility-function to test the function "depthFirstSearch" +* +* @param fillLocation The start location on the image where the flood fill is applied. +* @param targetColor The old color to be replaced. +* @param replacementColor The new color to replace the old one. +* @param testLocation The location of the color to be checked. +* @return The color at testLocation +*/ +function testDepthFirst (fillLocation, targetColor, replacementColor, testLocation) {// eslint-disable-line + const rgbData = generateTestRgbData() + depthFirstSearch(rgbData, fillLocation, targetColor, replacementColor) + return rgbData[testLocation[0]][testLocation[1]] +}