/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */


#include "nsIDOMMouseEvent.idl"

/**
 * The nsIDOMSimpleGestureEvent interface is the datatype for all
 * Mozilla-specific simple gesture events in the Document Object Model.
 *
 * The following events are generated:
 *
 * MozSwipeGestureMayStart - Generated when the user starts a horizontal
 * swipe across the input device, but before we know whether the user
 * is actually scrolling past a scroll edge.
 * This event asks two questions:  Should a swipe really be started, and
 * in which directions should the user be able to swipe?  The first
 * question is answered by event listeners by calling or not calling
 * preventDefault() on the event.  Since a swipe swallows all scroll
 * events, the default action of the swipe start event is *not* to
 * start a swipe. Call preventDefault() if you want a swipe to be
 * started. Doing so won't necessarily result in a swipe being started,
 * it only communicates an intention. Once Gecko determines whether a
 * swipe should actually be started, it will send a MozSwipeGestureStart
 * event.
 * The second question (swipe-able directions) is answered in the
 * allowedDirections field.
 *
 * MozSwipeGestureStart - This event signals the start of a swipe.
 * It guarantees a future MozSwipeGestureEnd event that will signal
 * the end of a swipe animation.
 *
 * MozSwipeGestureUpdate - Generated periodically while the user is
 * continuing a horizontal swipe gesture.  The "delta" value represents
 * the current absolute gesture amount.  This event may even be sent
 * after a MozSwipeGesture event fired in order to allow for fluid
 * completion of a swipe animation.  The direction value is meaningless
 * on swipe update events.
 *
 * MozSwipeGestureEnd - Generated when the swipe animation is completed.
 *
 * MozSwipeGesture - Generated when the user releases a swipe across
 * across the input device.  This event signals that the actual swipe
 * operation is complete, even though the animation might not be finished
 * yet.  This event can be sent without accompanying start / update / end
 * events, and it can also be handled on its own if the consumer doesn't
 * want to handle swipe animation events.
 * Only the direction value has any significance, the delta value is
 * meaningless.
 *
 * MozMagnifyGestureStart - Generated when the user begins the magnify
 * ("pinch") gesture.  The "delta" value represents the initial
 * movement.
 *
 * MozMagnifyGestureUpdate - Generated periodically while the user is
 * continuing the magnify ("pinch") gesture.  The "delta" value
 * represents the movement since the last MozMagnifyGestureStart or
 * MozMagnifyGestureUpdate event.
 *
 * MozMagnifyGesture - Generated when the user has completed the
 * magnify ("pinch") gesture.  If you only want to receive a single
 * event when the magnify gesture is complete, you only need to hook
 * this event and can safely ignore the MozMagnifyGestureStart and the
 * MozMagnifyGestureUpdate events. The "delta" value is the cumulative
 * amount represented by the user's gesture.
 *
 * MozRotateGestureStart - Generated when the user begins the rotation
 * gesture.  The "delta" value represents the initial rotation.
 *
 * MozRotateGestureUpdate - Generated periodically while the user is
 * continuing the rotation gesture.  The "delta" value represents the
 * rotation since the last MozRotateGestureStart or
 * MozRotateGestureUpdate event.
 *
 * MozRotateGesture - Generated when the user has completed the
 * rotation gesture.  If you only want to receive a single event when
 * the rotation gesture is complete, you only need to hook this event
 * and can safely ignore the MozRotateGestureStart and the
 * MozRotateGestureUpdate events.  The "delta" value is the cumulative
 * amount of rotation represented by the user's gesture.
 *
 * MozTapGesture - Generated when the user executes a two finger
 * tap gesture on the input device. Client coordinates contain the
 * center point of the tap.
 * (XXX On OS X, only Lion (10.7) and up)
 *
 * MozPressTapGesture - Generated when the user executes a press
 * and tap two finger gesture (first finger down, second finger down,
 * second finger up, first finger up) on the input device.
 * Client coordinates contain the center pivot point of the action.
 * (XXX Not implemented on Mac)
 *
 * MozEdgeUIGesture - Generated when the user swipes the display to
 * invoke edge ui.
 * (XXX Win8 only)
 *
 * Default behavior:
 *
 * Some operating systems support default behaviors for gesture events
 * when they are not handled by the application. Consumers should
 * use event.preventDefault() to prevent default behavior when
 * consuming events.
 */

[builtinclass, uuid(d78656ab-9d68-4f03-83f9-7c7bee071aa7)]
interface nsIDOMSimpleGestureEvent : nsIDOMMouseEvent
{
  /* Swipe direction constants */
  const unsigned long DIRECTION_UP = 1;
  const unsigned long DIRECTION_DOWN = 2;
  const unsigned long DIRECTION_LEFT = 4;
  const unsigned long DIRECTION_RIGHT = 8;

  /* Rotational direction constants */
  const unsigned long ROTATION_COUNTERCLOCKWISE = 1;
  const unsigned long ROTATION_CLOCKWISE = 2;

  /* Read-write value for swipe events.
   *
   * Reports the directions that can be swiped to; multiple directions
   * should be OR'ed together.
   *
   * The allowedDirections field is designed to be set on SwipeGestureMayStart
   * events by event listeners.  Its value after event dispatch determines
   * the behavior of the swipe animation that might be about to begin.
   * Specifically, if the user swipes in a direction that can't be swiped
   * to, the animation will have a bounce effect.
   * Future SwipeGestureUpdate, SwipeGesture and SwipeGestureEnd events
   * will carry the allowDirections value that was set on the SwipeMayStart
   * event.  Changing this field on non-SwipeGestureMayStart events doesn't
   * have any effect.
   */
  attribute unsigned long allowedDirections;

  /* Direction of a gesture. Diagonals are indicated by OR'ing the
   * applicable constants together.
   *
   * Swipes gestures may occur in any direction.
   *
   * Magnify gestures do not have a direction.
   *
   * Rotation gestures will be either ROTATION_COUNTERCLOCKWISE or
   * ROTATION_CLOCKWISE.
   */
  readonly attribute unsigned long direction;

  /* Delta value for magnify, rotate and swipe gestures.
   *
   * For rotation, the value is in degrees and is positive for
   * clockwise rotation and negative for counterclockwise
   * rotation.
   *
   * For magnification, the value will be positive for a "zoom in"
   * (i.e, increased magnification) and negative for a "zoom out"
   * (i.e., decreased magnification).  The particular units
   * represented by the "delta" are currently implementation specific.
   *
   * XXX - The units for measuring magnification are currently
   * unspecified because the units used by Mac OS X are currently
   * undocumented.  The values are typically in the range of 0.0 to
   * 100.0, but it is only safe currently to rely on the delta being
   * positive or negative.
   *
   * For swipe start, update and end events, the value is a fraction
   * of one "page".  If the resulting swipe will have DIRECTION_LEFT, the
   * delta value will be positive; for DIRECTION_RIGHT, delta is negative.
   * If this seems backwards to you, look at it this way:  If the current
   * page is pushed to the right during the animation (positive delta),
   * the page left to the current page will be visible after the swipe
   * (DIRECTION_LEFT).
   *
   * Units on Windows represent the difference between the initial
   * and current/final width between the two touch points on the input
   * device and are measured in pixels.
   */
  readonly attribute double delta;

  /* Click count value for taps. */
  readonly attribute unsigned long clickCount;

  void initSimpleGestureEvent(in DOMString typeArg,
                              in boolean canBubbleArg,
                              in boolean cancelableArg,
                              in nsIDOMWindow viewArg,
                              in long detailArg,
                              in long screenXArg,
                              in long screenYArg,
                              in long clientXArg,
                              in long clientYArg,
                              in boolean ctrlKeyArg,
                              in boolean altKeyArg,
                              in boolean shiftKeyArg,
                              in boolean metaKeyArg,
                              in unsigned short buttonArg,
                              in nsIDOMEventTarget relatedTargetArg,
                              in unsigned long allowedDirectionsArg,
                              in unsigned long directionArg,
                              in double deltaArg,
                              in unsigned long clickCount);
};
