From 9b9ff934d2352ad082383c61adc069dc0ca0212d Mon Sep 17 00:00:00 2001
From: Niklas Kiefer <niklas.kiefer@camunda.com>
Date: Wed, 19 Jun 2019 08:02:00 +0200
Subject: [PATCH] feat(snapping): snap to task mid on center interaction

Closes #1086
---
 lib/features/snapping/BpmnConnectSnapping.js  | 48 ++++++++++++++---
 .../snapping/BpmnConnectSnappingSpec.js       | 53 +++++++++++++++++++
 2 files changed, 94 insertions(+), 7 deletions(-)

diff --git a/lib/features/snapping/BpmnConnectSnapping.js b/lib/features/snapping/BpmnConnectSnapping.js
index bb41deec..f1b1c99a 100644
--- a/lib/features/snapping/BpmnConnectSnapping.js
+++ b/lib/features/snapping/BpmnConnectSnapping.js
@@ -11,7 +11,10 @@ import {
 
 import { is } from '../../util/ModelUtil';
 
-import { some } from 'min-dash';
+import {
+  every,
+  some
+} from 'min-dash';
 
 import { isAny } from '../modeling/util/ModelingUtil';
 
@@ -21,6 +24,8 @@ var BOUNDARY_TO_HOST_THRESHOLD = 40;
 
 var TARGET_BOUNDS_PADDING = 20;
 
+var TARGET_CENTER_PADDING = 20;
+
 var AXES = [ 'x', 'y' ];
 
 var abs = Math.abs;
@@ -55,7 +60,7 @@ export default function BpmnConnectSnapping(eventBus, rules) {
     });
 
     if (target && connectionAttrs) {
-      snapInsideTarget(event, target);
+      snapInsideTarget(event, target, getTargetBoundsPadding(target));
     }
 
     if (target && isAnyType(connectionAttrs, [
@@ -72,6 +77,10 @@ export default function BpmnConnectSnapping(eventBus, rules) {
         snapToPosition(event, mid(target));
       }
 
+      if (is(target, 'bpmn:Task')) {
+        snapTargetMidOnCenter(event, target);
+      }
+
       if (is(source, 'bpmn:BoundaryEvent') && target === source.host) {
         snapBoundaryEventLoop(event, source, target);
       }
@@ -103,16 +112,16 @@ BpmnConnectSnapping.$inject = [
   'rules'
 ];
 
-function snapInsideTarget(event, target) {
+function snapInsideTarget(event, target, padding) {
 
   AXES.forEach(function(axis) {
     var matchingTargetDimension = getDimensionForAxis(axis, target),
         newCoordinate;
 
-    if (event[axis] < target[axis] + TARGET_BOUNDS_PADDING) {
-      newCoordinate = target[axis] + TARGET_BOUNDS_PADDING;
-    } else if (event[axis] > target[axis] + matchingTargetDimension - TARGET_BOUNDS_PADDING) {
-      newCoordinate = target[axis] + matchingTargetDimension - TARGET_BOUNDS_PADDING;
+    if (event[axis] < target[axis] + padding) {
+      newCoordinate = target[axis] + padding;
+    } else if (event[axis] > target[axis] + matchingTargetDimension - padding) {
+      newCoordinate = target[axis] + matchingTargetDimension - padding;
     }
 
     if (newCoordinate) {
@@ -121,6 +130,23 @@ function snapInsideTarget(event, target) {
   });
 }
 
+// snap to target mid if event position in center area
+function snapTargetMidOnCenter(event, target) {
+
+  var isCenter = every(AXES, function(axis) {
+    var coordinate = event[axis],
+        matchingTargetDimension = getDimensionForAxis(axis, target);
+
+    return coordinate > target[axis] + TARGET_CENTER_PADDING
+      && coordinate < target[axis] + matchingTargetDimension - TARGET_CENTER_PADDING;
+  });
+
+  if (isCenter) {
+    snapToPosition(event, mid(target));
+  }
+
+}
+
 // snap outside of Boundary Event surroundings
 function snapBoundaryEventLoop(event, source, target) {
   var sourceMid = mid(source),
@@ -171,3 +197,11 @@ function isAnyType(attrs, types) {
 function getDimensionForAxis(axis, element) {
   return axis === 'x' ? element.width : element.height;
 }
+
+function getTargetBoundsPadding(target) {
+  if (is(target, 'bpmn:Task')) {
+    return 10;
+  } else {
+    return TARGET_BOUNDS_PADDING;
+  }
+}
diff --git a/test/spec/features/snapping/BpmnConnectSnappingSpec.js b/test/spec/features/snapping/BpmnConnectSnappingSpec.js
index 2e82825c..c9034166 100644
--- a/test/spec/features/snapping/BpmnConnectSnappingSpec.js
+++ b/test/spec/features/snapping/BpmnConnectSnappingSpec.js
@@ -142,6 +142,59 @@ describe('features/snapping - BpmnConnectSnapping', function() {
       });
 
 
+      describe('Task target', function() {
+
+        it('should snap to task mid',
+          inject(function(connect, dragging, elementRegistry) {
+
+            // given
+            var startEvent = elementRegistry.get('StartEvent_1'),
+                task = elementRegistry.get('Task_1'),
+                taskGfx = elementRegistry.getGraphics(task);
+
+            // when
+            connect.start(canvasEvent({ x: 210, y: 60 }), startEvent);
+
+            dragging.hover({ element: task, gfx: taskGfx });
+
+            dragging.move(canvasEvent({ x: 300, y: 300 }));
+
+            dragging.end();
+
+            // then
+            var waypoints = startEvent.outgoing[0].waypoints;
+
+            expect(waypoints[3].y).to.eql(300);
+          })
+        );
+
+
+        it('should snap to grid point',
+          inject(function(connect, dragging, elementRegistry) {
+
+            // given
+            var startEvent = elementRegistry.get('StartEvent_1'),
+                task = elementRegistry.get('Task_1'),
+                taskGfx = elementRegistry.getGraphics(task);
+
+            // when
+            connect.start(canvasEvent({ x: 210, y: 60 }), startEvent);
+
+            dragging.hover({ element: task, gfx: taskGfx });
+
+            dragging.move(canvasEvent({ x: 300, y: 260 }));
+
+            dragging.end();
+
+            // then
+            var waypoints = startEvent.outgoing[0].waypoints;
+
+            expect(waypoints[3].y).to.eql(270);
+          })
+        );
+      });
+
+
       it('should snap event if close to target bounds',
         inject(function(connect, dragging, elementRegistry) {