examples/screenshot_generator.ipynb

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   "cell_type": "markdown",
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   "source": [
    "# Making screenshots programmatically\n",
    "\n",
    "Making screenshots on the frontent triggered by `plot.fetch_screenshot()` requires special care.\n",
    "1. One needs to wait for data before it is synchronized. \n",
    "2. Before calling `plot.fetch_screenshot()` the plot object must be displayed.\n",
    "\n",
    "To change dpi of the image one can use for example: `plot.screenshot_scale = 4.0`.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import k3d\n",
    "import numpy as np\n",
    "from IPython.display import Image\n",
    "\n",
    "points_number = 15\n",
    "spread_range = 30\n",
    "positions = spread_range * np.random.random_sample((points_number, 3)) - spread_range / 2\n",
    "colors = np.random.randint(0, 0xFFFFFF, points_number)\n",
    "\n",
    "plot = k3d.plot(height=240)\n",
    "points = k3d.points(positions.astype(np.float32), colors.astype(np.uint32), point_size=3.0, shader='mesh')\n",
    "plot += points\n",
    "\n",
    "plot.display()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Single screenshot\n",
    "\n",
    "First, let's generate a single screenshot:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "plot.fetch_screenshot()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Note**: this operation is asynchronous.\n",
    "\n",
    "We need to wait for the widgets to synchronize behind the scenes, before calling the next cell."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "with open('screenshot.png', 'wb') as f:\n",
    "    try:\n",
    "        out = plot.screenshot.decode('base64')\n",
    "    except: # Python 3\n",
    "        from base64 import b64decode\n",
    "        out = b64decode(plot.screenshot)    \n",
    "    f.write(out)\n",
    "    \n",
    "Image(url='screenshot.png')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Multiple screenshots \n",
    "\n",
    "\n",
    "If we want to generate many screenshots within a single cell, it is possible to do it in a following way:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import ipywidgets\n",
    "\n",
    "plot.camera_auto_fit = False\n",
    "plot.grid_auto_fit = False\n",
    "\n",
    "speeds = -0.5 * np.sign(positions)\n",
    "out = ipywidgets.Output()\n",
    "\n",
    "@plot.yield_screenshots\n",
    "def coroutine():\n",
    "    global positions\n",
    "    for i in range(12):\n",
    "        positions += speeds\n",
    "        points.positions = positions.astype(np.float32)\n",
    "        plot.fetch_screenshot()\n",
    "        screenshot = yield\n",
    "        with open('screenshot_%03d.png'%i, 'wb') as f:\n",
    "            f.write(screenshot)\n",
    "        with out:\n",
    "            print('screenshot_%03d.png saved.'%i)\n",
    "    with out:\n",
    "        print('done.')\n",
    "\n",
    "coroutine()\n",
    "print('loop is running in background...')\n",
    "out"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "!convert screenshot_*.png screenshot.gif && rm screenshot_*.png"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "Image('screenshot.gif')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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