make the legend movable

The legend ("key" in Gnuplot speak) is no longer part of the image.
Instead it is a floating&movable overlay.

In the gallery we still use the legend/key in the image.

pdb-js/src/app/plot-view/plot-view.component.html

@@ -1,3 +1,14 @@
+
+<!---->
+<div cdkDrag 
+    [ngClass]="{'hidden': !imageUrl || showStats}" 
+    class="plot-view--legend" 
+    [cdkDragFreeDragPosition]="legendInitialPosition">
+  <div cdkDragHandle></div>
+  <ol>
+    <li *ngFor="let stat of dataSeries()"><div class="{{ pointTypeClass(stat.dashTypeAndColor) }}" title="{{ stat.name }}"></div>{{ stat.name }}</li>
+  </ol>
+</div>
 <div
   *ngIf="imageUrl">
   <div 

pdb-js/src/app/plot-view/plot-view.component.scss

@@ -20,4 +20,50 @@ img {
   background-color: white;
   box-shadow: 5px 5px 10px 0px #e0e0e0;
   overflow: auto;
+}
+
+.plot-view--legend {
+  padding-bottom: 0.5em;
+  border: solid 1px #ccc;
+  display: flex;
+  flex-direction: column;
+  background: #fff;
+  border-radius: 4px;
+  position: fixed;
+  z-index: 1;
+  transition: box-shadow 200ms cubic-bezier(0, 0, 0.2, 1);
+  box-shadow: 0 3px 1px -2px rgba(0, 0, 0, 0.2),
+              0 2px 2px 0 rgba(0, 0, 0, 0.14),
+              0 1px 5px 0 rgba(0, 0, 0, 0.12);
+  background-color: white;
+}
+
+.plot-view--legend:active {
+  box-shadow: 0 5px 5px -3px rgba(0, 0, 0, 0.2),
+              0 8px 10px 1px rgba(0, 0, 0, 0.14),
+              0 3px 14px 2px rgba(0, 0, 0, 0.12);
+}
+.plot-view--legend div[cdkDragHandle] {
+  visibility: hidden;
+  height: 1.2rem;
+}
+
+.plot-view--legend:hover div[cdkDragHandle] {
+  cursor: move;
+  visibility: visible;
+  background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAQAAAAECAIAAAAmkwkpAAAAF0lEQVQI12P4//8/AwMDhGSEUFCAUwYAJl4R8Z1D4wIAAAAASUVORK5CYII=);
+}
+
+.plot-view--legend ol {
+  padding-inline-start: 0.7em;
+}
+
+.plot-view--legend ol li {
+  list-style-type: none;
+  display: flex;
+  flex-direction: row;
+  align-items: center
+}
+.plot-view--legend ol li .plot-details-plotType{
+  margin-right: 0.3em; 
 }

pdb-js/src/app/plot-view/plot-view.component.ts

@@ -1,15 +1,16 @@
-import { Component, OnInit, Output, EventEmitter } from '@angular/core';
-import { DataType, AxesTypes, PlotResponseStats, PlotConfig, PlotService, PlotResponse, PlotRequest, RenderOptions  } from '../plot.service';
+import { Component, Output, EventEmitter } from '@angular/core';
+import { DataType, AxesTypes, PlotResponseStats, PlotConfig, PlotService, PlotResponse, PlotRequest, RenderOptions, DataSeriesStats, DashTypeAndColor  } from '../plot.service';
 import { MatSnackBar } from '@angular/material/snack-bar';
 import * as moment from 'moment';
 import { WidgetDimensions } from '../dashboard.service';
+import { Overlay } from "@angular/cdk/overlay";
 
 @Component({
   selector: 'pdb-plot-view',
   templateUrl: './plot-view.component.html',
   styleUrls: ['./plot-view.component.scss']
 })
-export class PlotViewComponent implements OnInit {
+export class PlotViewComponent {
 
   readonly DATE_PATTERN = "YYYY-MM-DD HH:mm:ss"; // for moment-JS
 
@@ -18,6 +19,7 @@ export class PlotViewComponent implements OnInit {
   readonly gnuplotTMargin = 57; // The top margin configured for gnuplot
   readonly gnuplotBMargin = 76; // The bottom margin configured for gnuplot
 
+  isOpen = false;
 
   imageUrl! : string;
   stats: PlotResponseStats | null = null;
@@ -47,10 +49,9 @@ export class PlotViewComponent implements OnInit {
 
   config? : PlotConfig;
 
-  constructor(private service : PlotService, private snackBar: MatSnackBar) { }
+  legendInitialPosition = {x:115,y:60};
 
-  ngOnInit() {
-  }
+  constructor(private service : PlotService, private snackBar: MatSnackBar, private overlay: Overlay) { }
 
 
   showError(message:string) {
@@ -283,7 +284,7 @@ export class PlotViewComponent implements OnInit {
         'main': new RenderOptions(actualDimension.height, actualDimension.width, false, true)
       });
     return request;
- }
+  }
 
  /**
    * Zoom in/out by zoomFaktor, so that the anchorInPercentOfDateRange keeps the same position.
@@ -335,6 +336,18 @@ export class PlotViewComponent implements OnInit {
      duration: moment.duration(endDate.diff(startDate))
    };
   }
+
+
+
+  dataSeries(): Array<DataSeriesStats> {
+    return this.stats ? this.stats.dataSeriesStats : [];
+  }
+
+  pointTypeClass(typeAndColor: DashTypeAndColor): string {
+    return "plot-details-plotType"
+      +" plot-details-plotType_"+typeAndColor.pointType
+      +" plot-details-plotType_"+typeAndColor.color.toLocaleLowerCase();
+  } 
 }
 
 export class SelectionRange {