Initial data commit

Task/Color-wheel/Delphi/color-wheel.delphi

@@ -0,0 +1,95 @@
+program Color_wheel;
+
+{$APPTYPE CONSOLE}
+
+uses
+  Winapi.Windows,
+  System.SysUtils,
+  Vcl.Graphics,
+  System.Math,
+  Vcl.Imaging.pngimage;
+
+const
+  TAU = 2 * PI;
+
+function HSBtoColor(hue, sat, bri: Double): TColor;
+var
+  f, h: Double;
+  u, p, q, t: Byte;
+begin
+  u := Trunc(bri * 255 + 0.5);
+  if sat = 0 then
+    Exit(rgb(u, u, u));
+
+  h := (hue - Floor(hue)) * 6;
+  f := h - Floor(h);
+  p := Trunc(bri * (1 - sat) * 255 + 0.5);
+  q := Trunc(bri * (1 - sat * f) * 255 + 0.5);
+  t := Trunc(bri * (1 - sat * (1 - f)) * 255 + 0.5);
+
+  case Trunc(h) of
+    0:
+      result := rgb(u, t, p);
+    1:
+      result := rgb(q, u, p);
+    2:
+      result := rgb(p, u, t);
+    3:
+      result := rgb(p, q, u);
+    4:
+      result := rgb(t, p, u);
+    5:
+      result := rgb(u, p, q);
+  else
+    result := clwhite;
+  end;
+
+end;
+
+function ColorWheel(Width, Height: Integer): TPngImage;
+var
+  Center: TPoint;
+  Radius: Integer;
+  x, y: Integer;
+  Hue, dy, dx, dist, theta: Double;
+  Bmp: TBitmap;
+begin
+  Bmp := TBitmap.Create;
+  Bmp.SetSize(Width, Height);
+  with Bmp.Canvas do
+  begin
+    Brush.Color := clWhite;
+    FillRect(ClipRect);
+    Center := ClipRect.CenterPoint;
+    Radius := Center.X;
+    if Center.Y < Radius then
+      Radius := Center.Y;
+    for y := 0 to Height - 1 do
+    begin
+      dy := y - Center.y;
+      for x := 0 to Width - 1 do
+      begin
+        dx := x - Center.x;
+        dist := Sqrt(Sqr(dx) + Sqr(dy));
+        if dist <= Radius then
+        begin
+          theta := ArcTan2(dy, dx);
+          Hue := (theta + PI) / TAU;
+          Pixels[x, y] := HSBtoColor(Hue, 1, 1);
+        end;
+      end;
+    end;
+  end;
+
+  Result := TPngImage.Create;
+  Result.Assign(Bmp);
+  Bmp.Free;
+end;
+
+begin
+  with ColorWheel(500, 500) do
+  begin
+    SaveToFile('ColorWheel.png');
+    Free;
+  end;
+end.