From d40c7d9f09d9b012837d6060a4c598b23b19646f Mon Sep 17 00:00:00 2001
From: Martin Ashby <martin@martin-laptop.lan>
Date: Thu, 17 May 2018 18:18:11 +0100
Subject: Palette, tools, load & save working

---
 src/Utils.js | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 src/Utils.js

(limited to 'src/Utils.js')

diff --git a/src/Utils.js b/src/Utils.js
new file mode 100644
index 0000000..f7bba5c
--- /dev/null
+++ b/src/Utils.js
@@ -0,0 +1,103 @@
+/**
+ * Converts RGB array to named object
+ * @param {[]} item, a length 3 array containing 8 bit RGB value
+ */
+function rgb(item) {
+    return {
+        r: item[0],
+        g: item[1],
+        b: item[2]
+    }
+}
+
+/**
+ * Converts XY array to named object
+ * @param {[]} item, a 2 length array containing x and y values
+ */
+function xy(item) {
+    return {
+        x: item[0],
+        y: item[1]
+    }
+}
+
+function colorEqual(item1, item2) {
+    if (!item1 || !item2) {
+        return false
+    }
+    if (Array.isArray(item1)) {
+        item1 = rgb(item1)
+    }
+    if (Array.isArray(item2)) {
+        item2 = rgb(item2)
+    }
+    return item1.r === item2.r
+        && item1.g === item2.g
+        && item1.b === item2.b
+}
+
+function coordsEqual(item1, item2) {
+    if (!item1 || !item2) {
+        return false
+    }
+
+    if (Array.isArray(item1)) {
+        item1 = xy(item1)
+    }
+    if (Array.isArray(item2)) {
+        item2 = xy(item2)
+    }
+    return item1.x === item2.x 
+        && item1.y === item2.y
+}
+
+function getPixel(x, y, pixels) {
+    let row = pixels[y]
+    if (!row) {
+        return
+    }
+    return row[x]
+}
+
+function findContiguousPixels(x, y, pixels, targetColor = getPixel(x, y, pixels), contiguousPixels=[[x, y]]) {
+    let adjescent = [
+      [x-1, y],
+      [x+1, y],
+      [x, y-1],
+      [x, y+1]
+    ]
+  
+    adjescent.forEach((coord) => {
+      let px = xy(coord)
+      let pxCol = getPixel(px.x, px.y, pixels)
+      if (!pxCol) {
+          return
+      }
+
+      // add adjescents uniquely if they are the target color
+      let ix = contiguousPixels.findIndex((existingCoord) => coordsEqual(coord, existingCoord))
+      if (ix !== -1) {
+          return 
+      }
+
+      if (!colorEqual(pxCol, targetColor)) {
+          return
+      }
+      contiguousPixels.push(coord)
+      let morePixels = findContiguousPixels(px.x, px.y, pixels, targetColor, contiguousPixels)
+      contiguousPixels.concat(morePixels)
+    })
+  
+    return contiguousPixels
+}
+  
+
+export {
+    xy,
+    rgb,
+    colorEqual,
+    coordsEqual,
+    findContiguousPixels,
+    getPixel
+}
+
-- 
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