From ccc48a3c8d8624250c14a117cd3039cc298de9f6 Mon Sep 17 00:00:00 2001
From: Tissevert <tissevert+devel@marvid.fr>
Date: Mon, 25 Jul 2022 15:40:19 +0200
Subject: [PATCH] Implement surface painting

---
 js/Grid.js | 45 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/js/Grid.js b/js/Grid.js
index c4bc787..a98bd23 100644
--- a/js/Grid.js
+++ b/js/Grid.js
@@ -3,7 +3,7 @@ import {color, tool} from Toolbox;
 
 var grid = {
 	element: null,
-	data: {}
+	data: null
 };
 var down = false;
 
@@ -17,13 +17,21 @@ function init(size, elementId) {
 		grid.element.appendChild(
 			makeRow({tag: 'td', attributes: bodyAttributes, row: row, size: size})
 		);
-		grid.data[row] = {};
 	}
+	grid.data = emptyGrid(size);
 	grid.element.addEventListener('mouseleave', function() {
 		down = false;
 	});
 }
 
+function emptyGrid(size) {
+	var result = {};
+	for(var i = 0; i < size; i++) {
+		result[i] = {};
+	}
+	return result;
+}
+
 function makeRow(config) {
 	var cells = [];
 	for(var column = 0; column < config.size; column++) {
@@ -37,21 +45,46 @@ function bodyAttributes(i, j) {
 		onMousedown: function(e) {
 			down = true;
 			if(tool() == 'draw') {
-				colorize(i, j, e);
+				colorize(i, j, e.target);
 			}
 		},
 		onMouseup: function(e) {
 			down = false;
+			if(tool() == 'paint') {
+				paint(i, j);
+			}
 		},
 		onMouseenter: function(e) {
 			if(down && tool() == 'draw') {
-				colorize(i, j, e);
+				colorize(i, j, e.target);
 			}
 		}
 	};
 }
 
-function colorize(i, j, e) {
+function colorize(i, j, element) {
 	grid.data[i][j] = color();
-	e.target.className = grid.data[i][j];
+	element.className = grid.data[i][j];
+}
+
+function paint(i0, j0) {
+	var originColor = grid.data[i0][j0];
+	var size = grid.element.children.length;
+	var done = emptyGrid(size);
+	var queue = [{i: i0, j: j0}];
+	while(queue.length > 0) {
+		var p0 = queue[0];
+		colorize(p0.i, p0.j, grid.element.children[p0.i].children[p0.j]);
+		done[p0.i][p0.j] = true;
+		for(var d = -1; d < 2; d += 2) {
+			[{i: p0.i + d, j: p0.j}, {i: p0.i, j: p0.j + d}].forEach(function(p1) {
+				if(p1.i >= 0 && p1.i < size && p1.j >= 0 && p1.j < size
+					&& !done[p1.i][p1.j]
+					&& grid.data[p1.i][p1.j] == originColor) {
+					queue.push(p1);
+				}
+			});
+		}
+		queue.shift();
+	}
 }