From 0cc15e9b4f67d0641ee9f29dfae36f9e97f4302a Mon Sep 17 00:00:00 2001
From: Unknown <marty.oehme@gmail.com>
Date: Wed, 14 Feb 2018 18:00:13 +0100
Subject: [PATCH] Add per Pixel Quantize Methods

---
 lib/Dither.dart | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/lib/Dither.dart b/lib/Dither.dart
index b51e2ea..1201655 100644
--- a/lib/Dither.dart
+++ b/lib/Dither.dart
@@ -21,16 +21,23 @@ class Pixed {
     PixelArray pxArr = new PixelArray.fromPixelArray(image);
     for (var y = 0; y < pxArr.getHeight(); y++) {
       for (var x = 0; x < pxArr.getWidth(); x++) {
-        var px = pxArr.getPixel(x, y);
-        px.r = (steps * px.r / 255).round() * (255 ~/ steps);
-        px.g = (steps * px.g / 255).round() * (255 ~/ steps);
-        px.b = (steps * px.b / 255).round() * (255 ~/ steps);
+        pxArr.setPixel( _quantizePixel(pxArr.getPixel(x, y)) );
       }
     }
     return pxArr;
   }
 
-  static PixelArray calcQuantizeError(PixelArray original, PixelArray quantized) {
+  static Pixel _quantizePixel(Pixel pixel, [int steps=1]) {
+    return new Pixel(
+        pixel.x,
+        pixel.y,
+        (steps * pixel.r / 255).round() * (255 ~/ steps),
+        (steps * pixel.g / 255).round() * (255 ~/ steps),
+        (steps * pixel.b / 255).round() * (255 ~/ steps),
+        pixel.a);
+  }
+
+  static PixelArray quantizeError(PixelArray original, PixelArray quantized) {
     PixelArray pxArr = new PixelArray.fromPixelArray(original);
     for (var y = 0; y < pxArr.getHeight(); y++) {
       for (var x = 0; x < pxArr.getWidth(); x++) {
@@ -43,6 +50,14 @@ class Pixed {
     }
     return pxArr;
   }
+
+  static Pixel _quantizeErrorPixel(Pixel original, Pixel quantized) {
+    return new Pixel(original.x, original.y,
+        original.r - quantized.r,
+        original.g - quantized.g,
+        original.b - quantized.b,
+        original.a);
+  }
 }
 
 class Pixel {
@@ -92,7 +107,6 @@ class PixelArray {
     int y = 0;
     int x = 0;
     pixels[y] = new List(imageWidth);
-    print(pixels[0].length.toString() + ","+ pixels.length.toString());
     for (var pos = 0; pos < array.length; pos = pos + 4) {
       if (x >= imageWidth) {
         x = 0;
@@ -107,7 +121,7 @@ class PixelArray {
   PixelArray.fromImageData(ImageData imagedata, int imageWidth): this.fromByteArray(imagedata.data, imageWidth);
 
   PixelArray.fromPixelArray(PixelArray pixelArray) {
-    pixels = new List<List<Pixel>>.from(pixelArray.pixels);
+    pixels = pixelArray.clone().pixels;
   }
 
   Uint8ClampedList toByteArray() {