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Image Explorer XBlock

This package provides the Image Explorer XBlock that allows you to use an image with hotspots in a course. When the student clicks a hotspot icon, tooltip containing custom content is displayed.

Screenshot below shows the Image Explorer XBlock rendered inside the edX LMS with an activated tooltip containing and embedded YouTube video.

Student view


Install the requirements into the python virtual environment of your edx-platform installation.

$ pip install -r requirements.txt

Enabling in Studio

You can enable the Image Explorer XBlock in studio through the advanced settings.

  1. From the main page of a specific course, navigate to Settings -> Advanced Settings from the top menu.
  2. Check for the advanced_modules policy key, and add "image-explorer" to the policy value list.
  3. Click the "Save changes" button.


Make sure you have a python virtual environment with xblock-sdk version 0.1.5 or higher:

pip install -e git://
cd $VIRTUAL_ENV/src/xblock-sdk/ && make install && cd -
pip install -r requirements.txt

To run the unit tests, run:

python tests/unit

To run the integration tests, you'll need geckodriver and xvfb installed.

export DISPLAY=:99
xvfb-run python tests/integration


When you add the Image Explorer component to a course in the studio, the block is field with default content, shown in the screenshot below.

Edit view

The basic structure of the image_explorer XBlock looks like this:

<image_explorer schema_version="1">
  <background src="http://link/to/image.jpg" />
  <description>...custom HTML content...</description>
    <hotspot x="370" y="20">
      <feedback width="300" height="300">
        <header>...custom HTML content...</header>
        <body>...custom HTML content...</body>
        <youtube video_id="dmoZXcuozFQ" width="400" height="300" />

The schema_version attribute of the <image_explorer> wrapper element should be set to 1. It currently isn't used but will provide help for easier schema migrations if the XML schema changes in future versions.

The <image_explorer> element should contain the following child elements:

  • <background> (required)
  • <description> (optional)
  • <hotspots> (required)

The background element

The src attribute of the <background> element defines the image over which the hotspots are placed.

The description element

The optional <description> element can contain arbitrary HTML content that is rendered above the image.

The hotspots element

The <hotspots> element wraps an arbitrary number of child <hotspot> elements. These define the position of the hotspots on the background image and the content of the tooltips.

The supported attributes of <hotspot> elements are x and y (both required) that specify the position of the hotspot on the background image, item-id which can be set to a unique string used to identify the hotspot in the emitted events and optional side attribute that allows to override hotspot's popup position. If side attribute is missing or set to anything except left and right automatic positioning is used.

Each <hotspot> element must contain the <feedback> child element. The <feedback> element supports width, height and max-height attributes (all optional) that specify the dimensions of the tooltip element. The default width is 300px and if no height is specified, the max-height is set to 500px. So the content will be sized dynamically with a vertical scrollbar for the overflow.

The <feedback> element can contain the following child elements:

  • <header>
  • <body>
  • <youtube>

The header element

If present, the <header> specifies the tooltip header. It may contain arbitrary HTML content.

The body element

The <body> element can contain arbitrary HTML content that is rendered in the tooltip.

The youtube element

The <youtube> element offers a convenient way of placing an embedded YouTube video into a tooltip. The required attributes are video_id, width, and height.

The Ooyala element

The <ooyala> element offers a convenient way of placing an embedded Ooyala video into a tooltip. The required attributes are video_id, width, and height.

API for native mobile frontends

Retrieve fixed data for all Image Explorer XBlocks in a course:

GET https://<lms_server_url>/api/courses/v1/blocks/?course_id=<course_id>&username=<username>&depth=all&requested_fields=student_view_data

Example image explorer return value:

"student_view_data": {
    "hotspots": [
            "item_id": "hotspotA",
            "x": "370",
            "feedback": {
                "body": "<ul><li>Once there was a police car up here</li><li>Also there was a Fire Truck put up there</li></ul>",
                "width": "300",
                "youtube": null,
                "max_height": null,
                "height": "240",
                "header": "<p>This is where many pranks take place. Below are some of the highlights:</p>",
                "type": "text",
                "side": "auto"
            "y": "20"
            "item_id": "hotspotB",
            "x": "250",
            "feedback": {
                "body": null,
                "width": "440",
                "youtube": {
                    "width": "400",
                    "video_id": "dmoZXcuozFQ",
                    "id": "youtube-f6c7d27d30834097bb1b17af1074e98c",
                    "height": "300"
                "max_height": null,
                "height": "400",
                "header": "<p>Watch the Red Line subway go around the dome</p>",
                "type": "youtube",
                "side": "auto"
            "y": "70"
    "description": "<p>Enjoy using the Image Explorer. Click around the MIT Dome and see what you find!</p>",
    "background": {
        "src": "//",
        "height": null,
        "width": null

Downloading translations from Transifex

If you want to download translations from Transifex install Transifex client and run this command while inside project root directory

tx pull -f --mode=reviewed -l en,ar,es_419,fr,he,hi,ko_KR,pt_BR,ru,zh_CN


The Image Explorer XBlock is available under the GNU Affero General Public License (AGPLv3).