Create app.js

apps/colorwheel/app.js

@@ -0,0 +1,80 @@
+//----------------------------------------------------------------------------//
+//--          ColorWheel - draws a "wheel" of good looking colors           --//
+//----------------------------------------------------------------------------//
+
+  let ColorList = [
+    '#0000FF', '#8000FF', '#FF00FF', '#FF0080', '#FF0000', '#FF8000',
+    '#FFFF00', '#80FF00', '#00FF00', '#00FF80', '#00FFFF', '#0080FF'
+  ];
+
+  let ScreenWidth  = g.getWidth(),  CenterX = ScreenWidth/2;
+  let ScreenHeight = g.getHeight(), CenterY = ScreenHeight/2;
+
+  let outerRadius = Math.min(CenterX,CenterY) * 0.9;
+  let innerRadius = outerRadius*0.5;
+
+  let sin = Math.sin, cos = Math.cos;
+  let twoPi = 2*Math.PI, halfPi = Math.PI/2;
+
+  let DeltaPhi = twoPi/72;
+  let Epsilon  = 0.001;
+
+  g.clear();
+
+  g.setColor(0,0,0);
+  g.fillRect(0,0, ScreenWidth,ScreenHeight);
+
+  for (let i = 0; i < 12; i++) {
+    let Phi0 = i * twoPi/12, Phi1 = (i+1) * twoPi/12;
+
+    let Polygon = [];
+      for (let Phi = Phi0; Phi <= Phi1+Epsilon; Phi += DeltaPhi) {
+        Polygon.push(CenterX + outerRadius * sin(Phi));
+        Polygon.push(CenterY - outerRadius * cos(Phi));
+      }
+
+      for (let Phi = Phi1; Phi >= Phi0-Epsilon; Phi -= DeltaPhi) {
+        Polygon.push(CenterX + innerRadius * sin(Phi));
+        Polygon.push(CenterY - innerRadius * cos(Phi));
+      }
+    g.setColor(ColorList[i]);
+    g.fillPoly(Polygon);
+  }
+
+  g.setColor(1,1,1);
+  g.fillCircle(CenterX,CenterY, innerRadius);
+
+  g.setFont12x20();
+  g.setFontAlign(0,0);
+  g.setColor(0,0,0);
+
+  g.drawString('Tap',   CenterX,CenterY-20);
+  g.drawString('on',    CenterX,CenterY);
+  g.drawString('Color', CenterX,CenterY+20);
+
+  Bangle.on('touch', function (Button,Position) {
+    Bangle.buzz();
+
+    let dx = Position.x - CenterX;
+    let dy = Position.y - CenterY;
+
+    let Radius = Math.sqrt(dx*dx + dy*dy);
+
+    let Color;
+      switch (true) {
+        case (Radius > outerRadius): Color = '#000000'; break;
+        case (Radius < innerRadius): Color = '#FFFFFF'; break;
+        default:
+          let Phi = Math.atan2(dy,dx) + halfPi;
+          if (Phi < 0)     { Phi += twoPi; }
+          if (Phi > twoPi) { Phi -= twoPi; }
+
+          let Index = Math.floor(12*Phi/twoPi);
+          Color = ColorList[Index];
+      }
+    g.setColor(1,1,1);
+    g.fillCircle(CenterX,CenterY, innerRadius);
+
+    g.setColor(0,0,0);
+    g.drawString(Color, CenterX,CenterY);
+  });