From 409e4a355f8e1648956f872da17a5db543ea0d5c Mon Sep 17 00:00:00 2001
From: wimrijnders <wrijnders@gmail.com>
Date: Fri, 29 Sep 2017 20:40:25 +0200
Subject: [PATCH] Network detect clicks on labels (#3410)

* Small refactoring in Label._drawBackground()

* Added size calculation to Label, basic framework for detecting click on label.

* First fully working version of label click.

* Put in extra checks, refactored visibility of labels for more general usage.

* Final fixes to code; added to example and in docs

* Adressed review comments

* Add next attempt to fix Travis unit test bug

* Addressed review issues
---
 docs/network/index.html                       | 20 +++-
 examples/network/labels/labelAlignment.html   | 13 ++-
 lib/network/modules/Canvas.js                 | 11 +--
 lib/network/modules/InteractionHandler.js     |  5 +-
 lib/network/modules/SelectionHandler.js       | 58 ++++++++++++
 lib/network/modules/components/Edge.js        | 93 +++++++++++++++---
 lib/network/modules/components/Node.js        | 36 +++++++
 .../modules/components/edges/util/EdgeBase.js | 19 ++--
 .../components/shared/ComponentUtil.js        | 73 ++++++++++++++
 .../modules/components/shared/Label.js        | 94 +++++++++++++------
 10 files changed, 353 insertions(+), 69 deletions(-)

diff --git a/docs/network/index.html b/docs/network/index.html
index 01af8ad0..2ade8795 100644
--- a/docs/network/index.html
+++ b/docs/network/index.html
@@ -1313,7 +1313,7 @@ var options = {
                 </td>
                 <td>Fired when the user clicks the mouse or taps on a touchscreen device. Passes an object with properties structured as:
 
-                <pre class="prettyprint lang-js">{
+<pre class="prettyprint lang-js">{
   nodes: [Array of selected nodeIds],
   edges: [Array of selected edgeIds],
   event: [Object] original click event,
@@ -1323,6 +1323,24 @@ var options = {
   }
 }
 </pre>
+
+This is the structure common to all events. Specifically for the click event, the following property is added:
+
+<pre class="prettyprint lang-js">{
+...
+  items: [Array of click items],
+}</pre>
+
+Where the click items can be:
+<pre class="prettyprint lang-js">
+  {nodeId:NodeId}            // node with given id clicked on
+  {nodeId:NodeId labelId:0}  // label of node with given id clicked on
+  {edgeId:EdgeId}            // edge with given id clicked on
+  {edge:EdgeId, labelId:0}   // label of edge with given id clicked on
+</pre>
+
+The order of the <code>items</code> array is descending in z-order.
+Thus, to get the topmost item, get the value at index 0.
                 </td>
             </tr>
             <tr><td id="event_doubleClick">doubleClick</td>
diff --git a/examples/network/labels/labelAlignment.html b/examples/network/labels/labelAlignment.html
index dd837ca7..78b47717 100644
--- a/examples/network/labels/labelAlignment.html
+++ b/examples/network/labels/labelAlignment.html
@@ -9,7 +9,7 @@
   <style type="text/css">
     #mynetwork {
       width: 600px;
-      height: 600px;
+      height: 400px;
       border: 1px solid lightgray;
     }
     p {
@@ -25,8 +25,12 @@
 <p>Text-alignment within node labels can be 'left' or 'center', other font alignments not implemented.</p>
 <p>Label alignment (placement of label &quot;box&quot;) for nodes (top, bottom, left, right, inside) is
 planned but not in vis yet.</p>
+<p>The click event is captured and displayed to illustrate how the clicking on labels works.
+You can drag the nodes over each other to see how this influences the click event values.
+</p>
 
 <div id="mynetwork"></div>
+<pre id="eventSpan"></pre>
 
 <script type="text/javascript">
   // create an array with nodes
@@ -53,8 +57,13 @@ planned but not in vis yet.</p>
     nodes: nodes,
     edges: edges
   };
-  var options = {};
+  var options = {physics:false};
   var network = new vis.Network(container, data, options);
+
+    network.on("click", function (params) {
+        params.event = "[original event]";
+        document.getElementById('eventSpan').innerHTML = '<h2>Click event:</h2>' + JSON.stringify(params, null, 4);
+    });
 </script>
 
 </body>
diff --git a/lib/network/modules/Canvas.js b/lib/network/modules/Canvas.js
index 0e53920e..753e56cb 100644
--- a/lib/network/modules/Canvas.js
+++ b/lib/network/modules/Canvas.js
@@ -456,10 +456,8 @@ class Canvas {
 
 
   /**
-   *
-   * @param {object} pos   = {x: number, y: number}
-   * @returns {{x: number, y: number}}
-   * @constructor
+   * @param {point} pos
+   * @returns {point}
    */
   canvasToDOM (pos) {
     return {x: this._XconvertCanvasToDOM(pos.x), y: this._YconvertCanvasToDOM(pos.y)};
@@ -467,9 +465,8 @@ class Canvas {
 
   /**
    *
-   * @param {object} pos   = {x: number, y: number}
-   * @returns {{x: number, y: number}}
-   * @constructor
+   * @param {point} pos
+   * @returns {point}
    */
   DOMtoCanvas (pos) {
     return {x: this._XconvertDOMtoCanvas(pos.x), y: this._YconvertDOMtoCanvas(pos.y)};
diff --git a/lib/network/modules/InteractionHandler.js b/lib/network/modules/InteractionHandler.js
index c8caf412..1e62825b 100644
--- a/lib/network/modules/InteractionHandler.js
+++ b/lib/network/modules/InteractionHandler.js
@@ -1,8 +1,8 @@
 let util = require('../../util');
-
 var NavigationHandler = require('./components/NavigationHandler').default;
 var Popup = require('./../../shared/Popup').default;
 
+
 /**
  * Handler for interactions
  */
@@ -124,6 +124,7 @@ class InteractionHandler {
     }
   }
 
+
   /**
    * handle tap/click event: select/unselect a node
    * @param {Event} event
@@ -150,7 +151,6 @@ class InteractionHandler {
   }
 
 
-
   /**
    * handle long tap event: multi select nodes
    * @param {Event} event
@@ -718,7 +718,6 @@ class InteractionHandler {
       this.body.emitter.emit('hidePopup');
     }
   }
-
 }
 
 export default InteractionHandler;
diff --git a/lib/network/modules/SelectionHandler.js b/lib/network/modules/SelectionHandler.js
index 61a710a4..53c61704 100644
--- a/lib/network/modules/SelectionHandler.js
+++ b/lib/network/modules/SelectionHandler.js
@@ -141,6 +141,13 @@ class SelectionHandler {
     if (oldSelection !== undefined) {
       properties['previousSelection'] = oldSelection;
     }
+
+    if (eventType == 'click') {
+      // For the time being, restrict this functionality to
+      // just the click event.
+      properties.items = this.getClickedItems(pointer);
+    }
+
     this.body.emitter.emit(eventType, properties);
   }
 
@@ -795,6 +802,57 @@ class SelectionHandler {
       }
     }
   }
+
+
+  /**
+   * Determine all the visual elements clicked which are on the given point.
+   *
+   * All elements are returned; this includes nodes, edges and their labels.
+   * The order returned is from highest to lowest, i.e. element 0 of the return
+   * value is the topmost item clicked on.
+   *
+   * The return value consists of an array of the following possible elements:
+   *
+   * - `{nodeId:number}`             - node with given id clicked on
+   * - `{nodeId:number, labelId:0}`  - label of node with given id clicked on
+   * - `{edgeId:number}`             - edge with given id clicked on
+   * - `{edge:number, labelId:0}`    - label of edge with given id clicked on
+   *
+   * ## NOTES
+   *
+   * - Currently, there is only one label associated with a node or an edge,
+   *   but this is expected to change somewhere in the future.
+   * - Since there is no z-indexing yet, it is not really possible to set the nodes and
+   *   edges in the correct order. For the time being, nodes come first.
+   *
+   * @param {point} pointer  mouse position in screen coordinates
+   * @returns {Array.<nodeClickItem|nodeLabelClickItem|edgeClickItem|edgeLabelClickItem>}
+   * @private
+   */ 
+  getClickedItems(pointer) {
+    let point = this.canvas.DOMtoCanvas(pointer);
+    var items = [];
+
+    // Note reverse order; we want the topmost clicked items to be first in the array
+    // Also note that selected nodes are disregarded here; these normally display on top
+    let nodeIndices = this.body.nodeIndices;
+    let nodes = this.body.nodes;
+    for (let i = nodeIndices.length - 1; i >= 0; i--) {
+      let node = nodes[nodeIndices[i]];
+      let ret = node.getItemsOnPoint(point);
+      items.push.apply(items, ret); // Append the return value to the running list.
+    }
+
+    let edgeIndices = this.body.edgeIndices;
+    let edges = this.body.edges;
+    for (let i = edgeIndices.length - 1; i >= 0; i--) {
+      let edge = edges[edgeIndices[i]];
+      let ret = edge.getItemsOnPoint(point);
+      items.push.apply(items, ret); // Append the return value to the running list.
+    }
+
+    return items;
+  }
 }
 
 export default SelectionHandler;
diff --git a/lib/network/modules/components/Edge.js b/lib/network/modules/components/Edge.js
index ab5988e5..f66fc53d 100644
--- a/lib/network/modules/components/Edge.js
+++ b/lib/network/modules/components/Edge.js
@@ -531,7 +531,7 @@ class Edge {
     // draw everything
     this.edgeType.drawLine(ctx, values, this.selected, this.hover, viaNode);
     this.drawArrows(ctx, arrowData, values);
-    this.drawLabel (ctx, viaNode);
+    this.drawLabel(ctx, viaNode);
   }
 
   /**
@@ -572,15 +572,24 @@ class Edge {
         var point = this.edgeType.getPoint(0.5, viaNode);
         ctx.save();
 
-        // if the label has to be rotated:
-        if (this.options.font.align !== "horizontal") {
-          this.labelModule.calculateLabelSize(ctx, this.selected, this.hover, point.x, point.y);
-          ctx.translate(point.x, this.labelModule.size.yLine);
-          this._rotateForLabelAlignment(ctx);
+        let rotationPoint = this._getRotation(ctx);
+        if (rotationPoint.angle != 0) {
+          ctx.translate(rotationPoint.x, rotationPoint.y);
+          ctx.rotate(rotationPoint.angle);
         }
 
         // draw the label
         this.labelModule.draw(ctx, point.x, point.y, this.selected, this.hover);
+
+/*
+        // Useful debug code: draw a border around the label
+        // This should **not** be enabled in production!
+        var size = this.labelModule.getSize();; // ;; intentional so lint catches it
+        ctx.strokeStyle = "#ff0000";
+        ctx.strokeRect(size.left, size.top, size.width, size.height);
+        // End  debug code
+*/
+
         ctx.restore();
       }
       else {
@@ -603,6 +612,36 @@ class Edge {
   }
 
 
+  /**
+   * Determine all visual elements of this edge instance, in which the given
+   * point falls within the bounding shape.
+   *
+   * @param {point} point
+   * @returns {Array.<edgeClickItem|edgeLabelClickItem>} list with the items which are on the point
+   */
+  getItemsOnPoint(point) {
+    var ret = [];
+
+    if (this.labelModule.visible()) {
+      let rotationPoint = this._getRotation();
+      if (ComponentUtil.pointInRect(this.labelModule.getSize(), point, rotationPoint)) {
+        ret.push({edgeId:this.id, labelId:0});
+      }
+    }
+
+    let obj = {
+      left: point.x,
+      top: point.y
+    };
+
+    if (this.isOverlappingWith(obj)) {
+      ret.push({edgeId:this.id});
+    }
+
+    return ret;
+  }
+
+
   /**
    * Check if this object is overlapping with the provided object
    * @param {Object} obj   an object with parameters left, top
@@ -628,22 +667,46 @@ class Edge {
   }
 
 
-  /**
-   * Rotates the canvas so the text is most readable
-   * @param {CanvasRenderingContext2D} ctx
+  /** 
+   * Determine the rotation point, if any.
+   *
+   * @param {CanvasRenderingContext2D} [ctx] if passed, do a recalculation of the label size
+   * @returns {rotationPoint} the point to rotate around and the angle in radians to rotate
    * @private
    */
-  _rotateForLabelAlignment(ctx) {
+  _getRotation(ctx) {
+    let viaNode = this.edgeType.getViaNode();
+    let point = this.edgeType.getPoint(0.5, viaNode);
+
+    if (ctx !== undefined) {
+      this.labelModule.calculateLabelSize(ctx, this.selected, this.hover, point.x, point.y);
+    }
+
+    let ret = {
+      x: point.x,
+      y: this.labelModule.size.yLine,
+      angle: 0
+    };
+
+    if (!this.labelModule.visible()) {
+      return ret;  // Don't even bother doing the atan2, there's nothing to draw
+    }
+
+    if (this.options.font.align === "horizontal") {
+      return ret;  // No need to calculate angle
+    }
+
     var dy = this.from.y - this.to.y;
     var dx = this.from.x - this.to.x;
-    var angleInDegrees = Math.atan2(dy, dx);
+    var angle = Math.atan2(dy, dx);  // radians
 
-    // rotate so label it is readable
-    if ((angleInDegrees < -1 && dx < 0) || (angleInDegrees > 0 && dx < 0)) {
-      angleInDegrees = angleInDegrees + Math.PI;
+    // rotate so that label is readable
+    if ((angle < -1 && dx < 0) || (angle > 0 && dx < 0)) {
+      angle += Math.PI;
     }
+    ret.angle = angle;
 
-    ctx.rotate(angleInDegrees);
+    return ret;
   }
 
 
diff --git a/lib/network/modules/components/Node.js b/lib/network/modules/components/Node.js
index 3484bc7a..f4b70e11 100644
--- a/lib/network/modules/components/Node.js
+++ b/lib/network/modules/components/Node.js
@@ -508,6 +508,16 @@ class Node {
   }
 
 
+  /**
+   * Get the current dimensions of the label
+   *
+   * @return {rect}
+   */
+  getLabelSize() {
+    return this.labelModule.size();
+  }
+
+
   /**
    * Adjust the value range of the node. The node will adjust it's size
    * based on its value.
@@ -553,6 +563,7 @@ class Node {
     this.shape.updateBoundingBox(this.x,this.y,ctx);
   }
 
+
   /**
    * Recalculate the size of this node in the given canvas
    * The 2d context of a HTML canvas can be retrieved by canvas.getContext("2d");
@@ -564,6 +575,30 @@ class Node {
   }
 
 
+  /**
+   * Determine all visual elements of this node instance, in which the given
+   * point falls within the bounding shape.
+   *
+   * @param {point} point
+   * @returns {Array.<nodeClickItem|nodeLabelClickItem>} list with the items which are on the point
+   */
+  getItemsOnPoint(point) {
+    var ret = [];
+
+    if (this.labelModule.visible()) {
+      if (ComponentUtil.pointInRect(this.labelModule.getSize(), point)) {
+        ret.push({nodeId:this.id, labelId:0});
+      }
+    }
+
+    if (ComponentUtil.pointInRect(this.shape.boundingBox, point)) {
+      ret.push({nodeId:this.id});
+    }
+
+    return ret;
+  }
+
+
   /**
    * Check if this object is overlapping with the provided object
    * @param {Object} obj   an object with parameters left, top, right, bottom
@@ -578,6 +613,7 @@ class Node {
     );
   }
 
+
   /**
    * Check if this object is overlapping with the provided object
    * @param {Object} obj   an object with parameters left, top, right, bottom
diff --git a/lib/network/modules/components/edges/util/EdgeBase.js b/lib/network/modules/components/edges/util/EdgeBase.js
index e703e7a5..59b1e67a 100644
--- a/lib/network/modules/components/edges/util/EdgeBase.js
+++ b/lib/network/modules/components/edges/util/EdgeBase.js
@@ -388,10 +388,11 @@ class EdgeBase {
 
 
   /**
-   * Calculate the distance between a point (x3,y3) and a line segment from
-   * (x1,y1) to (x2,y2).
-   * x3,y3 is the point.
+   * Calculate the distance between a point (x3,y3) and a line segment from (x1,y1) to (x2,y2).
+   * (x3,y3) is the point.
+   *
    * http://stackoverflow.com/questions/849211/shortest-distancae-between-a-point-and-a-line-segment
+   *
    * @param {number} x1
    * @param {number} y1
    * @param {number} x2
@@ -401,7 +402,6 @@ class EdgeBase {
    * @param {Node} via
    * @param {Array} values
    * @returns {number}
-   * @private
    */
   getDistanceToEdge(x1, y1, x2, y2, x3, y3, via, values) {  // eslint-disable-line no-unused-vars
     let returnValue = 0;
@@ -415,17 +415,10 @@ class EdgeBase {
       returnValue = Math.abs(Math.sqrt(dx * dx + dy * dy) - radius);
     }
 
-    if (this.labelModule.size.left < x3 &&
-      this.labelModule.size.left + this.labelModule.size.width > x3 &&
-      this.labelModule.size.top < y3 &&
-      this.labelModule.size.top + this.labelModule.size.height > y3) {
-      return 0;
-    }
-    else {
-      return returnValue;
-    }
+    return returnValue;
   }
 
+
   /**
    *
    * @param {number} x1
diff --git a/lib/network/modules/components/shared/ComponentUtil.js b/lib/network/modules/components/shared/ComponentUtil.js
index b8961192..95dfeb8f 100644
--- a/lib/network/modules/components/shared/ComponentUtil.js
+++ b/lib/network/modules/components/shared/ComponentUtil.js
@@ -1,3 +1,23 @@
+/**
+ * Definitions for param's in jsdoc.
+ * These are more or less global within Network. Putting them here until I can figure out
+ * where to really put them
+ * 
+ * @typedef {string|number} Id
+ * @typedef {Id} NodeId
+ * @typedef {Id} EdgeId
+ * @typedef {Id} LabelId
+ *
+ * @typedef {{x: number, y: number}} point
+ * @typedef {{left: number, top: number, width: number, height: number}} rect
+ * @typedef {{x: number, y:number, angle: number}} rotationPoint
+ *   - point to rotate around and the angle in radians to rotate. angle == 0 means no rotation
+ * @typedef {{nodeId:NodeId}} nodeClickItem
+ * @typedef {{nodeId:NodeId, labelId:LabelId}} nodeLabelClickItem
+ * @typedef {{edgeId:EdgeId}} edgeClickItem
+ * @typedef {{edgeId:EdgeId, labelId:LabelId}} edgeLabelClickItem
+ */
+
 let util = require("../../../../util");
 
 /**
@@ -49,6 +69,59 @@ class ComponentUtil {
 
     return value;
   }
+
+
+  /**
+   * Check if the point falls within the given rectangle.
+   *
+   * @param {rect} rect
+   * @param {point} point
+   * @param {rotationPoint} [rotationPoint] if specified, the rotation that applies to the rectangle.
+   * @returns {boolean}  true if point within rectangle, false otherwise
+   * @static
+   */
+  static pointInRect(rect, point, rotationPoint) {
+    if (rect.width <= 0 || rect.height <= 0) {
+      return false;  // early out
+    }
+
+    if (rotationPoint !== undefined) {
+      // Rotate the point the same amount as the rectangle
+      var tmp = {
+        x: point.x - rotationPoint.x,
+        y: point.y - rotationPoint.y
+      };
+
+      if (rotationPoint.angle !== 0) {
+        // In order to get the coordinates the same, you need to 
+        // rotate in the reverse direction
+        var angle = -rotationPoint.angle;
+
+        var tmp2 = {
+          x: Math.cos(angle)*tmp.x - Math.sin(angle)*tmp.y,
+          y: Math.sin(angle)*tmp.x + Math.cos(angle)*tmp.y
+        };
+        point = tmp2;
+      } else {
+        point = tmp;
+      }
+
+      // Note that if a rotation is specified, the rectangle coordinates
+      // are **not* the full canvas coordinates. They are relative to the
+      // rotationPoint. Hence, the point coordinates need not be translated
+      // back in this case.
+    }
+
+    var right  = rect.x + rect.width;
+    var bottom = rect.y + rect.width;
+
+    return (
+      rect.left < point.x &&
+      right     > point.x &&
+      rect.top  < point.y &&
+      bottom    > point.y
+    );
+  }
 }
 
 export default ComponentUtil;
diff --git a/lib/network/modules/components/shared/Label.js b/lib/network/modules/components/shared/Label.js
index ab17918a..abbc31da 100644
--- a/lib/network/modules/components/shared/Label.js
+++ b/lib/network/modules/components/shared/Label.js
@@ -51,7 +51,7 @@ class Label {
     this.baseSize = undefined;
     this.fontOptions = {};      // instance variable containing the *instance-local* font options
     this.setOptions(options);
-    this.size = {top: 0, left: 0, width: 0, height: 0, yLine: 0}; // could be cached
+    this.size = {top: 0, left: 0, width: 0, height: 0, yLine: 0};
     this.isEdgeLabel = edgelabel;
   }
 
@@ -439,42 +439,21 @@ class Label {
 
     // update the size cache if required
     this.calculateLabelSize(ctx, selected, hover, x, y, baseline);
-    this._drawBackground(ctx, this.size.left, this.size.top);
+    this._drawBackground(ctx);
     this._drawText(ctx, x, this.size.yLine, baseline, viewFontSize);
-
   }
 
+
   /**
    * Draws the label background
    * @param {CanvasRenderingContext2D} ctx
-   * @param {number} x
-   * @param {number} y
    * @private
    */
-  _drawBackground(ctx, x, y) {
+  _drawBackground(ctx) {
     if (this.fontOptions.background !== undefined && this.fontOptions.background !== "none") {
       ctx.fillStyle = this.fontOptions.background;
-
-      let lineMargin = 2;
-
-      if (this.isEdgeLabel) {
-        switch (this.fontOptions.align) {
-          case 'middle':
-            ctx.fillRect(-this.size.width * 0.5, -this.size.height * 0.5, this.size.width, this.size.height);
-            break;
-          case 'top':
-            ctx.fillRect(-this.size.width * 0.5, -(this.size.height + lineMargin), this.size.width, this.size.height);
-            break;
-          case 'bottom':
-            ctx.fillRect(-this.size.width * 0.5, lineMargin, this.size.width, this.size.height);
-            break;
-          default:
-            ctx.fillRect(x, y - 0.5*lineMargin, this.size.width, this.size.height);
-            break;
-        }
-      } else {
-        ctx.fillRect(x, y - 0.5*lineMargin, this.size.width, this.size.height);
-      }
+      let size = this.getSize();
+      ctx.fillRect(size.left, size.top, size.width, size.height);
     }
   }
 
@@ -489,7 +468,6 @@ class Label {
    * @private
    */
   _drawText(ctx, x, y, baseline = 'middle', viewFontSize) {
-
     [x, y] = this._setAlignment(ctx, x, y, baseline);
 
     ctx.textAlign = 'left';
@@ -608,6 +586,46 @@ class Label {
   }
 
 
+  /**
+   * Get the current dimensions of the label
+   *
+   * @return {rect}
+   */
+  getSize() {
+    let lineMargin = 2;
+    let x = this.size.left;                 // default values which might be overridden below
+    let y = this.size.top - 0.5*lineMargin; // idem
+
+    if (this.isEdgeLabel) {
+      const x2 = -this.size.width * 0.5;
+
+      switch (this.fontOptions.align) {
+        case 'middle':
+          x = x2;
+          y = -this.size.height * 0.5
+          break;
+        case 'top':
+          x = x2;
+          y = -(this.size.height + lineMargin);
+          break;
+        case 'bottom':
+          x = x2;
+          y = lineMargin;
+          break;
+      }
+    }
+
+    var ret = {
+      left  : x,
+      top   : y,
+      width : this.size.width,
+      height: this.size.height,
+    };
+
+    return ret;
+  }
+
+
   /**
    *
    * @param {CanvasRenderingContext2D} ctx
@@ -744,6 +762,26 @@ class Label {
 
     this.labelDirty = false;
   }
+
+
+  /**
+   * Check if this label is visible
+   *
+   * @return {boolean} true if this label will be show, false otherwise
+   */
+  visible() {
+    if ((this.size.width === 0 || this.size.height === 0)
+      || this.elementOptions.label === undefined) {
+      return false;  // nothing to display
+    }
+
+    let viewFontSize = this.fontOptions.size * this.body.view.scale;
+    if (viewFontSize < this.elementOptions.scaling.label.drawThreshold - 1) {
+      return false;  // Too small or too far away to show
+    }
+
+    return true;
+  }
 }
 
 export default Label;