Add support for touch and hold gesture

CHANGES.md

@@ -12,6 +12,7 @@ Change Log
 ##### Additions :tada:
 * `Resource.fetchImage` now has a `flipY` option to vertically flip an image during fetch & decode. It is only valid when `ImageBitmapOptions` is supported by the browser. [#7579](https://github.com/AnalyticalGraphicsInc/cesium/pull/7579)
 * Added `backFaceCulling` and `normalShading` options to `PointCloudShading`. Both options are only applicable for point clouds containing normals. [#7399](https://github.com/AnalyticalGraphicsInc/cesium/pull/7399)
+* Added support for touch and hold gesture. The touch and hold delay can be customized by updating `ScreenSpaceEventHandler.touchHoldDelayMilliseconds`. [#7286](https://github.com/AnalyticalGraphicsInc/cesium/pull/7286)
 
 ##### Fixes :wrench:
 * Fixed the value for `BlendFunction.ONE_MINUS_CONSTANT_COLOR`. [#7624](https://github.com/AnalyticalGraphicsInc/cesium/pull/7624)

Source/Core/ScreenSpaceEventHandler.js

@@ -133,6 +133,14 @@ define([
         return (getTimestamp() - screenSpaceEventHandler._lastSeenTouchEvent) > ScreenSpaceEventHandler.mouseEmulationIgnoreMilliseconds;
     }
 
+    function checkPixelTolerance(startPosition, endPosition, pixelTolerance) {
+        var xDiff = startPosition.x - endPosition.x;
+        var yDiff = startPosition.y - endPosition.y;
+        var totalPixels = Math.sqrt(xDiff * xDiff + yDiff * yDiff);
+
+        return totalPixels < pixelTolerance;
+    }
+
     function handleMouseDown(screenSpaceEventHandler, event) {
         if (!canProcessMouseEvent(screenSpaceEventHandler)) {
             return;
@@ -193,11 +201,7 @@ define([
 
             if (defined(clickAction)) {
                 var startPosition = screenSpaceEventHandler._primaryStartPosition;
-                var xDiff = startPosition.x - position.x;
-                var yDiff = startPosition.y - position.y;
-                var totalPixels = Math.sqrt(xDiff * xDiff + yDiff * yDiff);
-
-                if (totalPixels < screenSpaceEventHandler._clickPixelTolerance) {
+                if (checkPixelTolerance(startPosition, position, screenSpaceEventHandler._clickPixelTolerance)) {
                     Cartesian2.clone(position, mouseClickEvent.position);
 
                     clickAction(mouseClickEvent);
@@ -398,11 +402,13 @@ define([
     var touchClickEvent = {
         position : new Cartesian2()
     };
+    var touchHoldEvent = {
+        position : new Cartesian2()
+    };
 
     function fireTouchEvents(screenSpaceEventHandler, event) {
         var modifier = getModifier(event);
         var positions = screenSpaceEventHandler._positions;
-        var previousPositions = screenSpaceEventHandler._previousPositions;
         var numberOfTouches = positions.length;
         var action;
         var clickAction;
@@ -411,6 +417,12 @@ define([
         if (numberOfTouches !== 1 && screenSpaceEventHandler._buttonDown[MouseButton.LEFT]) {
             // transitioning from single touch, trigger UP and might trigger CLICK
             screenSpaceEventHandler._buttonDown[MouseButton.LEFT] = false;
+
+            if(defined(screenSpaceEventHandler._touchHoldTimer)) {
+                clearTimeout(screenSpaceEventHandler._touchHoldTimer);
+                screenSpaceEventHandler._touchHoldTimer = undefined;
+            }
+
             action = screenSpaceEventHandler.getInputAction(ScreenSpaceEventType.LEFT_UP, modifier);
 
             if (defined(action)) {
@@ -419,25 +431,23 @@ define([
                 action(touchEndEvent);
             }
 
-            if (numberOfTouches === 0) {
+            if (numberOfTouches === 0 && !screenSpaceEventHandler._isTouchHolding) {
                 // releasing single touch, check for CLICK
                 clickAction = screenSpaceEventHandler.getInputAction(ScreenSpaceEventType.LEFT_CLICK, modifier);
 
                 if (defined(clickAction)) {
                     var startPosition = screenSpaceEventHandler._primaryStartPosition;
-                    var endPosition = previousPositions.values[0];
-                    var xDiff = startPosition.x - endPosition.x;
-                    var yDiff = startPosition.y - endPosition.y;
-                    var totalPixels = Math.sqrt(xDiff * xDiff + yDiff * yDiff);
-
-                    if (totalPixels < screenSpaceEventHandler._clickPixelTolerance) {
+                    var endPosition = screenSpaceEventHandler._previousPositions.values[0];
+                    if(checkPixelTolerance(startPosition, endPosition, screenSpaceEventHandler._clickPixelTolerance)) {
                         Cartesian2.clone(screenSpaceEventHandler._primaryPosition, touchClickEvent.position);
 
                         clickAction(touchClickEvent);
                     }
                 }
             }
 
+            screenSpaceEventHandler._isTouchHolding = false;
+
             // Otherwise don't trigger CLICK, because we are adding more touches.
         }
 
@@ -469,6 +479,25 @@ define([
                 action(touchStartEvent);
             }
 
+            screenSpaceEventHandler._touchHoldTimer = setTimeout(function() {
+                if(!screenSpaceEventHandler.isDestroyed()) {
+                    screenSpaceEventHandler._touchHoldTimer = undefined;
+                    screenSpaceEventHandler._isTouchHolding = true;
+
+                    clickAction = screenSpaceEventHandler.getInputAction(ScreenSpaceEventType.RIGHT_CLICK, modifier);
+
+                    if (defined(clickAction)) {
+                        var startPosition = screenSpaceEventHandler._primaryStartPosition;
+                        var endPosition = screenSpaceEventHandler._previousPositions.values[0];
+                        if(checkPixelTolerance(startPosition, endPosition, screenSpaceEventHandler._holdPixelTolerance)) {
+                            Cartesian2.clone(screenSpaceEventHandler._primaryPosition, touchHoldEvent.position);
+
+                            clickAction(touchHoldEvent);
+                        }
+                    }
+                }
+            }, ScreenSpaceEventHandler.touchHoldDelayMilliseconds);
+
             event.preventDefault();
         }
 
@@ -669,6 +698,7 @@ define([
             RIGHT: false
         };
         this._isPinching = false;
+        this._isTouchHolding = false;
         this._lastSeenTouchEvent = -ScreenSpaceEventHandler.mouseEmulationIgnoreMilliseconds;
 
         this._primaryStartPosition = new Cartesian2();
@@ -680,9 +710,12 @@ define([
 
         this._removalFunctions = [];
 
+        this._touchHoldTimer = undefined;
+
         // TODO: Revisit when doing mobile development. May need to be configurable
         // or determined based on the platform?
         this._clickPixelTolerance = 5;
+        this._holdPixelTolerance = 25;
 
         this._element = defaultValue(element, document);
 
@@ -799,5 +832,13 @@ define([
      */
     ScreenSpaceEventHandler.mouseEmulationIgnoreMilliseconds = 800;
 
+    /**
+     * The amount of time, in milliseconds, before a touch on the screen becomes a
+     * touch and hold.
+     * @type {Number}
+     * @default 1500
+     */
+    ScreenSpaceEventHandler.touchHoldDelayMilliseconds = 1500;
+
     return ScreenSpaceEventHandler;
 });

Specs/Core/ScreenSpaceEventHandlerSpec.js

@@ -1207,6 +1207,89 @@ defineSuite([
         expect(action).not.toHaveBeenCalled();
     });
 
+    it('handles touch and hold gesture', function() {
+        jasmine.clock().install();
+
+        var delay = ScreenSpaceEventHandler.touchHoldDelayMilliseconds;
+
+        var eventType = ScreenSpaceEventType.RIGHT_CLICK;
+
+        var action = createCloningSpy('action');
+        handler.setInputAction(action, eventType);
+
+        expect(handler.getInputAction(eventType)).toEqual(action);
+
+        // start, then end
+        function simulateInput(timeout) {
+            var touchStartPosition = {
+                clientX : 1,
+                clientY : 2
+            };
+            var touchEndPosition = {
+                clientX : 1,
+                clientY : 2
+            };
+
+            if (usePointerEvents) {
+                DomEventSimulator.firePointerDown(element, combine({
+                    pointerType : 'touch',
+                    pointerId : 1
+                }, touchStartPosition));
+                jasmine.clock().tick(timeout);
+                DomEventSimulator.firePointerUp(element, combine({
+                    pointerType : 'touch',
+                    pointerId : 1
+                }, touchEndPosition));
+            } else {
+                DomEventSimulator.fireTouchStart(element, {
+                    changedTouches : [combine({
+                        identifier : 0
+                    }, touchStartPosition)]
+                });
+                jasmine.clock().tick(timeout);
+                DomEventSimulator.fireTouchEnd(element, {
+                    changedTouches : [combine({
+                        identifier : 0
+                    }, touchEndPosition)]
+                });
+            }
+        }
+
+        simulateInput(delay + 1);
+
+        expect(action.calls.count()).toEqual(1);
+        expect(action).toHaveBeenCalledWith({
+            position : new Cartesian2(1, 2)
+        });
+
+        // Should not be fired if hold delay is less than touchHoldDelayMilliseconds.
+        action.calls.reset();
+
+        simulateInput(delay - 1);
+
+        expect(action).not.toHaveBeenCalled();
+
+        // Should not be fired after removal.
+        action.calls.reset();
+
+        handler.removeInputAction(eventType);
+
+        simulateInput(delay + 1);
+
+        expect(action).not.toHaveBeenCalled();
+
+        // Should not fire click action if touch and hold is triggered.
+        eventType = ScreenSpaceEventType.LEFT_CLICK;
+
+        handler.setInputAction(action, eventType);
+
+        simulateInput(delay + 1);
+
+        expect(action).not.toHaveBeenCalled();
+
+        jasmine.clock().uninstall();
+    });
+
     it('treats touch cancel as touch end for touch clicks', function() {
         var eventType = ScreenSpaceEventType.LEFT_CLICK;