Introduce basic dithering tool

src/css/tools.css

@@ -114,6 +114,12 @@
   background-size: 30px;
 }
 
+.tool-icon.tool-dithering {
+  background-image: url(../img/tools/dithering.png);
+  background-position: 8px 9px;
+  background-size: 30px;
+}
+
 /*
  * Tool cursors:
  */
@@ -128,7 +134,8 @@
 }
 
 .tool-pen .drawing-canvas-container:hover,
-.tool-lighten .drawing-canvas-container:hover {
+.tool-lighten .drawing-canvas-container:hover,
+.tool-dithering .drawing-canvas-container:hover {
   cursor: url(../img/icons/pen.png) 0 15, pointer;
 }
 

src/js/app.js

@@ -38,6 +38,9 @@
       this.paletteService = new pskl.service.palette.PaletteService();
       this.paletteService.addDynamicPalette(new pskl.service.palette.CurrentColorsPalette());
 
+      this.selectedColorsService = new pskl.service.SelectedColorsService();
+      this.selectedColorsService.init();
+
       this.paletteController = new pskl.controller.PaletteController();
       this.paletteController.init();
 

src/js/controller/PaletteController.js

@@ -2,6 +2,7 @@
   var ns = $.namespace('pskl.controller');
 
   ns.PaletteController = function () {
+    // TODO(grosbouddha): Reuse default colors from SelectedColorsService.
     this.primaryColor =  Constants.DEFAULT_PEN_COLOR;
     this.secondaryColor =  Constants.TRANSPARENT_COLOR;
   };

src/js/controller/ToolController.js

@@ -19,6 +19,7 @@
       toDescriptor('rectangleSelect', 'S', new pskl.tools.drawing.RectangleSelect()),
       toDescriptor('shapeSelect', 'Z', new pskl.tools.drawing.ShapeSelect()),
       toDescriptor('lighten', 'U', new pskl.tools.drawing.Lighten()),
+      toDescriptor('dithering', 'T', new pskl.tools.drawing.DitheringTool()),
       toDescriptor('colorPicker', 'O', new pskl.tools.drawing.ColorPicker())
     ];
 

src/js/service/SelectedColorsService.js

@@ -0,0 +1,28 @@
+(function () {
+  var ns = $.namespace('pskl.service');
+
+  ns.SelectedColorsService = function () {
+    this.primaryColor_ = Constants.DEFAULT_PEN_COLOR;
+    this.secondaryColor_ = Constants.TRANSPARENT_COLOR;
+  };
+
+  ns.SelectedColorsService.prototype.init = function () {
+    $.subscribe(Events.PRIMARY_COLOR_SELECTED, this.onPrimaryColorUpdate_.bind(this));
+    $.subscribe(Events.SECONDARY_COLOR_SELECTED, this.onSecondaryColorUpdate_.bind(this));
+  };
+
+  ns.SelectedColorsService.prototype.getColors = function () {
+    if (this.primaryColor_ == null || this.secondaryColor_ == null) {
+      throw "SelectedColorsService not properly intialized.";
+    }
+    return [this.primaryColor_, this.secondaryColor_];
+  };
+
+  ns.SelectedColorsService.prototype.onPrimaryColorUpdate_ = function (evt, color) {
+    this.primaryColor_ = color;
+  };
+
+  ns.SelectedColorsService.prototype.onSecondaryColorUpdate_ = function (evt, color) {
+    this.secondaryColor_ = color;
+  };
+})();

src/js/tools/drawing/DitheringTool.js

@@ -0,0 +1,30 @@
+/**
+ * @provide pskl.tools.drawing.DitheringTool
+ *
+ * @require pskl.utils
+ */
+(function() {
+  var ns = $.namespace('pskl.tools.drawing');
+
+  ns.DitheringTool = function() {
+    ns.SimplePen.call(this);
+    this.toolId = 'tool-dithering';
+    this.helpText = 'Dithering tool';
+  };
+  pskl.utils.inherit(ns.DitheringTool, ns.SimplePen);
+
+  /**
+   * @override
+   */
+  ns.DitheringTool.prototype.applyToolAt = function(col, row, color, frame, overlay, event) {
+    var ditheringColor;
+    var currentColors = pskl.app.selectedColorsService.getColors();
+    // XOR on either row or col parity.
+    if (((col % 2 == 0) && !(row % 2 == 0)) || (!(col % 2 == 0) && (row % 2 == 0))) {
+      ditheringColor = currentColors[0];
+    } else {
+      ditheringColor = currentColors[1];
+    }
+    this.superclass.applyToolAt.call(this, col, row, ditheringColor, frame, overlay, event);
+  };
+})();

src/piskel-script-list.js

@@ -160,6 +160,7 @@
   "js/service/ImageUploadService.js",
   "js/service/CurrentColorsService.js",
   "js/service/FileDropperService.js",
+  "js/service/SelectedColorsService.js",
 
   // Tools
   "js/tools/ToolsHelper.js",
@@ -181,6 +182,7 @@
   "js/tools/drawing/selection/ShapeSelect.js",
   "js/tools/drawing/ColorPicker.js",
   "js/tools/drawing/ColorSwap.js",
+  "js/tools/drawing/DitheringTool.js",
   "js/tools/transform/Transform.js",
   "js/tools/transform/Clone.js",
   "js/tools/transform/Flip.js",