I'm facing an issue in giving my chart a gradient background color because I cannot access the canvas context since my chart is rendered within a wrapper component that I developed.
Here is the desired outcome: https://i.sstatic.net/RdXEu.png
The current structure of my wrapper component looks like this:
<script>
import { Line, mixins } from "vue-chartjs";
const { reactiveProp } = mixins;
export default {
extends: Line,
mixins: [reactiveProp],
props: ["options"],
components: {},
mounted() {
// The chartData is generated within the mixin
this.renderChart(this.chartData, this.options);
}
};
</script>
I am using this wrapper for various line charts and allowing the parent component to pass down relevant data - at times utilizing the wrapper multiple times on a single page.
All configurations (options, labels, etc.) are managed in the parent component which utilizes the wrapper.
My dilemma lies in finding a way to transfer the canvas context from the wrapper to the parent component utilizing it.
In order to create the gradient effect, you typically need to do something along the lines of:
this.gradient = this.$refs.canvas
.getContext("2d")
.createLinearGradient(0, 0, 0, 450);
this.gradient.addColorStop(0, "rgba(255, 0,0, 0.5)");
this.gradient.addColorStop(0.5, "rgba(255, 0, 0, 0.25)");
this.gradient.addColorStop(1, "rgba(255, 0, 0, 0)");
However, I am encountering an issue where this.$refs.canvas is undefined in the parent component, thus hindering me from accessing the context needed to create a gradient effect.