Show an image

New in v13.7.0

ImageView and ImageAndDataView as replacement for the specific image views.

Currently, the following image types are supported:

• PNG
• JPG
• SVG
• GIF (>= v13.7.0)

Implementation

The easiest way to show an image in the ImageView is by using a static file:

1. Add an image to your app repository.

   my-app
   ├── app.py
   ├── image.png
   └── ...

2. Create a view method on the controller decorated with ImageView which returns an ImageResult:

   from pathlib import Path
   from viktor.views import ImageView, ImageResult
   
   class Controller(ViktorController):
       ...
   
       @ImageView("Image", duration_guess=1)
       def create_img_result(self, params, **kwargs):
           image_path = Path(__file__).parent / 'image.png'
           return ImageResult.from_path(image_path)

The image can also be dynamically created, for example using Matplitlib, svgwrite, drawSvg, etc. An example of Matplotlib is shown below:

import matplotlib.pyplot as plt
import numpy as np
from io import StringIO
from viktor.views import ImageView, ImageResult

class Controller(ViktorController):
   ...

    @ImageView("Plot", duration_guess=1)
    def create_result(self, params, **kwargs):
        # initialize figure
        fig = plt.figure()

        # create plot data
        x = np.random.randn(10)
        plt.plot(x)

        # save figure
        svg_data = StringIO()
        fig.savefig(svg_data, format='svg')
        plt.close()

        return ImageResult(svg_data)

The ImageView is only suitable for static visualizations. See WebView if interactivity is desired.

An image view can be combined with data using an ImageAndDataView.

Testing

New in v13.3.0

mock_View decorator for easier testing of view methods

Methods decorated with @ImageView, @ImageAndDataView, @PNGView, @PNGAndDataView, @JPGView, @JPGAndDataView, @SVGView, or @SVGAndDataView need to be mocked within the context of (automated) testing.

import unittest

from viktor.testing import mock_View

from app.my_entity_type.controller import MyEntityTypeController

class TestMyEntityTypeController(unittest.TestCase):

    @mock_View(MyEntityTypeController)
    def test_img_view(self):
        params = ...
        result = MyEntityTypeController().img_view(params=params)
        self.assertEqual(result.image.getvalue(), ...)