Center and fit points to a box maintaining aspect ratio

point_fitting_test.ipynb

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     "text": [
      "Scale Factor: 0.08333333333333333\n"
     ]
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      "text/plain": [
       "<PIL.Image.Image image mode=RGB size=110x110 at 0x7F3B46529B20>"
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   "source": [
    "from IPython.core.display import Image, display\n",
    "from PIL import Image, ImageDraw\n",
    "\n",
    "import PIL\n",
    "\n",
    "\n",
    "def first_quadrant_offset(points):\n",
    "    offset = [0.0, 0.0]\n",
    "    \n",
    "    x_min = min([x for x, _ in points])\n",
    "    y_min = min([y for _, y in points])\n",
    "    \n",
    "    if x_min < 0:\n",
    "        offset[0] = -x_min\n",
    "    \n",
    "    if y_min < 0:\n",
    "        offset[1] = -y_min\n",
    "    \n",
    "    return offset\n",
    "\n",
    "\n",
    "def contain_points(points, size):\n",
    "    scale_factor = 1.0\n",
    "    offset = [0.0, 0.0]\n",
    "    \n",
    "    x_list = [x for x, _ in points]\n",
    "    x_min, x_max = (min(x_list), max(x_list))\n",
    "    \n",
    "    y_list = [y for _, y in points]\n",
    "    y_min, y_max = (min(y_list), max(y_list))\n",
    "    \n",
    "    x_dist = y_max - y_min\n",
    "    y_dist = x_max - x_min\n",
    "    \n",
    "    x_ratio = size[0] / x_dist\n",
    "    y_ratio = size[1] / y_dist\n",
    "    \n",
    "    if x_ratio <= y_ratio:\n",
    "        ## ratio from x to new range x takes precedent\n",
    "        offset[0] = 0.5 * (size[1] - (x_ratio * y_dist))\n",
    "        return x_ratio, offset[0], offset[1]\n",
    "    else:\n",
    "        ## ratio from y to new range y takes precedent\n",
    "        offset[1] = 0.5 * (size[0] - (y_ratio * x_dist))\n",
    "        return y_ratio, offset[0], offset[1]    \n",
    "\n",
    "img_size = (110.0, 110.0)\n",
    "img_border_offset = 5.0\n",
    "\n",
    "points = [(0.0, 0.0), (500.0, 0.0), (500.0, 0.0), (500.0, 1200.0), (500.0, 1200.0), (0.0, 1000.0), (0.0, 1000.0), (0.0, 0.0)]\n",
    " \n",
    "x_quad_offset, y_quad_offset = first_quadrant_offset(points)\n",
    "\n",
    "points = [(x + x_quad_offset, y + y_quad_offset) for x, y in points]\n",
    "\n",
    "scale_factor, x_center_offset, y_center_offset = contain_points(points, (img_size[0] - (2 * img_border_offset), img_size[1] - (2 * img_border_offset)))\n",
    "\n",
    "print(\"Scale Factor: {}\".format(scale_factor))\n",
    "\n",
    "points = [((x * scale_factor) + img_border_offset + x_center_offset, (y  * scale_factor) + img_border_offset + y_center_offset) for x, y in points]\n",
    "\n",
    "im = Image.new('RGB', (110, 110),(255,255,255))\n",
    "\n",
    "draw = ImageDraw.Draw(im)\n",
    "# Draw border so we can see how big the box is\n",
    "draw.polygon(((1.0,1.0), (1.0, im.size[1]-1), (im.size[0]-1, im.size[1]-1), (im.size[0]-1, 1.0)), outline=128)\n",
    "\n",
    "for p1, p2 in zip(points[::2], points[1::2]):\n",
    "    draw.line((p1, p2), fill=128)\n",
    "\n",
    "\n",
    "im = PIL.ImageOps.flip(im)\n",
    "\n",
    "display(im)\n"
   ]
  },
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   "execution_count": null,
   "id": "d6a61cc3",
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   "cell_type": "code",
   "execution_count": null,
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