Doesn't work with chart.js 2.7.x

[nullpointer77]

Samples do not work with chart.js 2.7.x

[nullpointer77]

This seems to ultimately be a problem with the annotations plugin.
chartjs/chartjs-plugin-annotation#88

Please see my post on that issue to understand what I believe the root cause is. I was able to get around this problem by doing the following. .

static getChartById(chartId: string): any {
        var foundChart = null;
        Chart.helpers.each(Chart.instances,(instance) => {
            if (chartId == instance.canvas.id) {
                foundChart = instance;
                return;
            }
        });

        return foundChart;
    }

 var unFilteredCharJsInstance = ChartJsHelper.getChartById("UnfilteredChartFirst");
        
        unFilteredCharJsInstance.options.annotation.annotations.pop();
        unFilteredCharJsInstance.options.annotation.annotations.push({
            type: 'line',
            mode: 'vertical',
            scaleID: 'x-axis-0',
            value: point,
            draggable: true,
            borderColor: ConstantsService.constants['CprEditingLine'],
            borderWidth: 3,
            onDragEnd: function (event) {
                let xaxis = unFilteredCharJsInstance.scales['x-axis-0'];
                let x = event.x;
                let epoch = xaxis.getValueForPixel(x);

                //Below is a fix for chartjs-annotation and chartjs-dragable.  Chart.js 2.7.x breaks these frameworks.  This is a hack that may cause problems in the future.
                
                this.value = epoch._i;

//THIS IS THE IMPORTANT BIT HERE
                unFilteredCharJsInstance.options.annotation.annotations.pop();
                unFilteredCharJsInstance.options.annotation.annotations.push(this);
                unFilteredCharJsInstance.update(0);
            }
        });
        

The above seems to give the draggable plugin a working chart instance and dragging starts to work.

Please note that this shouldn't be considered a permanent fix, only a work around until the author of this plug is able to get a fix in place.

[nullpointer77]

Quick update for those that care. I have likely tracked this bug to ChartJS. I have filed a bug/question to the chartjs team to see what direction they want to go. Please refer to this thread. chartjs/Chart.js#5111

[juxtar]

Hi,

I got it working with Chart.js 2.9.3, you just have to add an id to the annotation, like so:

annotation: {
    drawTime: "afterDraw",
    events: ["click"],
    annotations: [
        {
            id: "line1",
            type: "line",
            mode: "vertical",
            scaleID: "x-axis-0",
            value: 3,
            borderColor: "red",
            borderWidth: 2,
            draggable: true,
            onDragEnd: function() {
                console.log(this.value);
            }
        }
    ]
}

Here's a working pen: https://codepen.io/juxtar/pen/jOEpWRB

[lukasschueler]

Hey @juxtar,
does this pen still work for you? For me the annotation is not draggable.
Can you maybe tell me which browser you use?

Best,
Lukas

[juxtar]

Yep, still works for me with Chrome 89.

[lukasschueler]

Alright, thanks @juxtar!