all files / lib/features/modeling/behavior/ AdaptiveLabelPositioningBehavior.js

96.08% Statements 49/51
91.67% Branches 11/12
100% Functions 12/12
96.08% Lines 49/51
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import inherits from 'inherits';
 
import {
  getOrientation,
  getMid,
  asTRBL
} from 'diagram-js/lib/layout/LayoutUtil';
 
import {
  substract
} from 'diagram-js/lib/util/Math';
 
import {
  hasExternalLabel
} from '../../../util/LabelUtil';
 
import CommandInterceptor from 'diagram-js/lib/command/CommandInterceptor';
 
 
/**
 * A component that makes sure that external labels are added
 * together with respective elements and properly updated (DI wise)
 * during move.
 *
 * @param {EventBus} eventBus
 * @param {Modeling} modeling
 */
export default function AdaptiveLabelPositioningBehavior(eventBus, modeling) {
 
  CommandInterceptor.call(this, eventBus);
 
  this.postExecuted([
    'connection.create',
    'connection.layout',
    'connection.reconnectEnd',
    'connection.reconnectStart',
    'connection.updateWaypoints'
  ], function(event) {
 
    var context = event.context,
        connection = context.connection;
 
    var source = connection.source,
        target = connection.target;
 
    checkLabelAdjustment(source);
    checkLabelAdjustment(target);
  });
 
 
  this.postExecuted([
    'label.create'
  ], function(event) {
    checkLabelAdjustment(event.context.shape.labelTarget);
  });
 
 
  function checkLabelAdjustment(element) {
 
    // skip non-existing labels
    if (!hasExternalLabel(element)) {
      return;
    }
 
    var optimalPosition = getOptimalPosition(element);
 
    // no optimal position found
    if (!optimalPosition) {
      return;
    }
 
    adjustLabelPosition(element, optimalPosition);
  }
 
  var ELEMENT_LABEL_DISTANCE = 10;
 
  function adjustLabelPosition(element, orientation) {
 
    var elementMid = getMid(element),
        label = element.label,
        labelMid = getMid(label);
 
    var elementTrbl = asTRBL(element);
 
    var newLabelMid;
 
    switch (orientation) {
    case 'top':
      newLabelMid = {
        x: elementMid.x,
        y: elementTrbl.top - ELEMENT_LABEL_DISTANCE - label.height / 2
      };
 
      break;
 
    case 'left':
 
      newLabelMid = {
        x: elementTrbl.left - ELEMENT_LABEL_DISTANCE - label.width / 2,
        y: elementMid.y
      };
 
      break;
 
    case 'bottom':
 
      newLabelMid = {
        x: elementMid.x,
        y: elementTrbl.bottom + ELEMENT_LABEL_DISTANCE + label.height / 2
      };
 
      break;
 
    case 'right':
 
      newLabelMid = {
        x: elementTrbl.right + ELEMENT_LABEL_DISTANCE + label.width / 2,
        y: elementMid.y
      };
 
      break;
    }
 
 
    var delta = substract(newLabelMid, labelMid);
 
    modeling.moveShape(label, delta);
  }
 
}
 
inherits(AdaptiveLabelPositioningBehavior, CommandInterceptor);
 
AdaptiveLabelPositioningBehavior.$inject = [
  'eventBus',
  'modeling'
];
 
 
/**
 * Return the optimal label position around an element
 * or _undefined_, if none was found.
 *
 * @param  {Shape} element
 *
 * @return {String} positioning identifier
 */
function getOptimalPosition(element) {
 
  var labelMid = getMid(element.label);
 
  var elementMid = getMid(element);
 
  var labelOrientation = getApproximateOrientation(elementMid, labelMid);
 
  if (!isAligned(labelOrientation)) {
    return;
  }
 
  var takenAlignments = [].concat(
    element.incoming.map(function(c) {
      return c.waypoints[c.waypoints.length - 2 ];
    }),
    element.outgoing.map(function(c) {
      return c.waypoints[1];
    })
  ).map(function(point) {
    return getApproximateOrientation(elementMid, point);
  });
 
  var freeAlignments = ALIGNMENTS.filter(function(alignment) {
 
    return takenAlignments.indexOf(alignment) === -1;
  });
 
  // NOTHING TO DO; label already aligned a.O.K.
  if (freeAlignments.indexOf(labelOrientation) !== -1) {
    return;
  }
 
  return freeAlignments[0];
}
 
var ALIGNMENTS = [
  'top',
  'bottom',
  'left',
  'right'
];
 
function getApproximateOrientation(p0, p1) {
  return getOrientation(p1, p0, 5);
}
 
function isAligned(orientation) {
  return ALIGNMENTS.indexOf(orientation) !== -1;
}