graph: zooming and dragging, changed default repulsion force

frontend/src/Editor.svelte

@@ -8,10 +8,16 @@
 
   let selectedTask: string | null = null;
   let clickedTask: string | null = null;
-
+  let repulsionForce: number = -600;
   let clicked: string[] = [];
 
   function clickTask(e: CustomEvent<TaskDescriptor>) {
+    // sanity check
+    if (selectedTask == null) {
+      alert("tohle je divny event");
+      return;
+    }
+
     // ukladani seznamu poslednich kliknuti
     clicked.push(selectedTask);
     if (clicked.length > 3)
@@ -41,6 +47,9 @@
         }
       });
       tasks = tasks;
+
+      // run simulation
+      toggleDivnaPromena();
     } else {
       alert("Nope, prvni musis nekam klikat...");
     }
@@ -48,7 +57,7 @@
 
   let hovnoDivnaPromenaKteraJeFaktFuj = true;
   function toggleDivnaPromena() {
-      hovnoDivnaPromenaKteraJeFaktFuj = ! hovnoDivnaPromenaKteraJeFaktFuj;
+    hovnoDivnaPromenaKteraJeFaktFuj = !hovnoDivnaPromenaKteraJeFaktFuj;
   }
 </script>
 
@@ -62,7 +71,7 @@
     display: flex;
     flex-direction: row;
     margin: 0;
-    height: 100vh;
+    height: 99vh;
     width: 100%;
   }
 
@@ -106,7 +115,12 @@
   <div class="left">
     <div class="lastClicked">Last clicked: <b>{clicked.join(' | ')}</b></div>
     <div class="graph">
-      <Graph {tasks} bind:selectedTask on:selectTask={clickTask} runSimulationWeirdHack={hovnoDivnaPromenaKteraJeFaktFuj} />
+      <Graph
+        {tasks}
+        {repulsionForce}
+        bind:selectedTask
+        on:selectTask={clickTask}
+        runSimulationWeirdHack={hovnoDivnaPromenaKteraJeFaktFuj} />
     </div>
   </div>
   <div class="right">
@@ -115,12 +129,14 @@
       <div>
         <button on:click={addEdge}>Pridat hranu - posledni vyzaduje predposledni</button>
       </div>
+      <div><button on:click={toggleDivnaPromena}>Spustit simulaci</button></div>
       <div>
-        <button on:click={toggleDivnaPromena}>Spustit simulaci</button>
+        Repulsion force: <input type="number" bind:value={repulsionForce} name="repulsionForceInput" max="1000" min="-10000" />
       </div>
     </div>
     <div class="taskDetails">
       {#if currentTask != null}
+        start
         <h3>{currentTask}</h3>
         <span>{taskMap.get(currentTask).comment}</span>
         <ul>

frontend/src/Graph.svelte

@@ -10,6 +10,7 @@
 
   export let tasks: TasksFile;
   export let selectedTask: null | string = null;
+  export let repulsionForce: number = -600;
 
   $: nodes = tasks.tasks;
   $: edges = createLinksFromTaskMap(tasks);
@@ -45,7 +46,7 @@
           }) // This provide  the id of a node
           .links(edges) // and this the list of links
       )
-      .force("charge", d3.forceManyBody().strength(-400)) // This adds repulsion between nodes. Play with the -400 for the repulsion strength
+      .force("charge", d3.forceManyBody().strength(repulsionForce)) // This adds repulsion between nodes. Play with the -400 for the repulsion strength
       .force("x", d3.forceX()) // attracts elements to the zero X coord
       .force("y", d3.forceY()) // attracts elements to the zero Y coord
       .on("tick", ticked)
@@ -61,19 +62,29 @@
   // run on create
   onMount(() => {
     // set the dimensions and margins of the graph
-    var margin = { top: 10, right: 30, bottom: 30, left: 40 },
-      width = container.clientWidth - margin.left - margin.right,
-      height = container.clientHeight - margin.top - margin.bottom;
+      const width = container.clientWidth;
+      const height = container.clientHeight;
 
     // resize the svg object
     var svg = d3
       .select(container)
       .select("svg")
-      .attr("width", width + margin.left + margin.right)
-      .attr("height", height + margin.top + margin.bottom)
+      .attr("width", width)
+      .attr("height", height)
       .attr("viewBox", [-width / 2, -height / 2, width, height])
-      .select("g")
-      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
+      .select("g");
+
+    function zoomed(e) {
+      let { transform } = e;
+      svg.attr("transform", transform);
+    }
+
+    d3.select(container).call(
+      d3
+        .zoom()
+        .scaleExtent([0.1, 2])
+        .on("zoom", zoomed)
+    );
 
     runSimulation();
   });
@@ -85,7 +96,6 @@
     runSimulation();
   }
   // now it's safe to stop vomitting 🤮
-
 </script>
 
 <style>
@@ -104,6 +114,7 @@
       {#each nodes as task}
         <GraphNode
           {task}
+          on:taskClick
           on:click={nodeClick(task)}
           on:hoveringChange={nodeHover(task)} />
       {/each}

frontend/src/GraphEdge.svelte

@@ -1,8 +1,6 @@
 <script lang="ts">
     import type { SimulationLinkDatum } from "d3";
   
-    import { onMount } from "svelte";
-  
     import type { TaskDescriptor } from "./task-loader";
   
     export let edge: SimulationLinkDatum<TaskDescriptor>;

frontend/src/GraphNode.svelte

@@ -1,17 +1,15 @@
 <script lang="ts">
   import { createEventDispatcher, onMount } from "svelte";
-
   import type { TaskDescriptor } from "./task-loader";
 
   export let task: TaskDescriptor;
   let hovering: boolean = false;
   let text_element: SVGTextElement;
 
-  const eventDispatcher = createEventDispatcher()
-
   $: cx = task === undefined || task.x === undefined ? 0 : task.x;
   $: cy = task === undefined || task.y === undefined ? 0 : task.y;
   
+  const eventDispatcher = createEventDispatcher()
   function enter() {
     hovering = true;
     eventDispatcher("hoveringChange", hovering)
@@ -26,6 +24,7 @@
     eventDispatcher("click", e)
   }
 
+  // automatically size the bubbles to fit the text
   let ellipse_rx = 20;
   let ellipse_ry = 20;
   onMount(() => {