v5

Custom Widgets

OpenC3 5 allows you to build custom widgets which can be deployed with your plugin and used in Telemetry Viewer. Building custom widgets can utilitize any javascript frameworks but since OpenC3 is written with Vue.js, we will use that framework in this tutorial.

Custom Widgets

We’re basically going to follow the OpenC3 Demo and explain how that custom widget was created.

If you look at the bottom of the Demo’s plugin.txt file you’ll see we declare the widgets:

WIDGET BIG
WIDGET HELLOWORLD

When the plugin is deployed this causes OpenC3 to look for the as-built widgets. For the BIG widget it will look for the widget at tools/widgets/BigWidget/BigWidget.umd.min.js. Similarly it looks for HELLOWORLD at tools/widgets/HelloworldWidget/HelloworldWidget.umd.min.js. These directories and file names may seem mysterious but it’s all about how the widgets get built.

Helloworld Widget

The Helloworld Widget source code is found in the plugin’s src directory and is called HelloworldWidget.vue. The basic structure is as follows:

<template>
  <!-- Implement widget here -->
</template>

<script>
import Widget from "@openc3/tool-common/src/components/widgets/Widget";
export default {
  mixins: [Widget],
  data() {
    return {
      // Reactive data items
    };
  },
};
</script>
<style scoped>
/* widget specific style */
</style>
Vue & Vuetify

For more information about how the OpenC3 frontend is built (including all the Widgets) please check out Vue.js and Vuetify.

To build this custom widget we changed the Demo Rakefile to call yarn run build when the plugin is built. yarn run XXX looks for ‘scripts’ to run in the package.json file. If we open package.json we find the following:

  "scripts": {
    "build": "vue-cli-service build --target lib --dest tools/widgets/HelloworldWidget --formats umd-min src/HelloworldWidget.vue --name HelloworldWidget && vue-cli-service build --target lib --dest tools/widgets/BigWidget --formats umd-min src/BigWidget.vue --name BigWidget"
  },

This uses the vue-cli-service to build the code found at src/HelloworldWidget.vue and formats as umd-min and puts it in the tools/widgets/HelloworldWidget directory. So this is why the plugin looks for the plugin at tools/widgets/HelloworldWidget/HelloworldWidget.umd.min.js. Click here for the vue-cli-service build documentation.

If you look at the Demo plugin’s simple.txt screen you’ll see we’re using the widgets:

SCREEN AUTO AUTO 0.5
LABELVALUE <%= target_name %> HEALTH_STATUS CCSDSSEQCNT
HELLOWORLD
BIG <%= target_name %> HEALTH_STATUS TEMP1

Opening this screen in Telemetry Viewer results in the following:

Simple Screen

While this is a simple example the possibilities with custom widgets are limitless!