function onCanvasRelease( event ) {
    /**
     * Raised when the primary mouse button is released or touch ends on the {@link OpenSeadragon.Viewer#canvas} element.
     *
     * @event canvas-release
     * @memberof OpenSeadragon.Viewer
     * @type {object}
     * @property {OpenSeadragon.Viewer} eventSource - A reference to the Viewer which raised this event.
     * @property {OpenSeadragon.MouseTracker} tracker - A reference to the MouseTracker which originated this event.
     * @property {String} pointerType - "mouse", "touch", "pen", etc.
     * @property {OpenSeadragon.Point} position - The position of the event relative to the tracked element.
     * @property {Boolean} insideElementPressed - True if the left mouse button is currently being pressed and was initiated inside the tracked element, otherwise false.
     * @property {Boolean} insideElementReleased - True if the cursor still inside the tracked element when the button was released.
     * @property {Object} originalEvent - The original DOM event.
     * @property {?Object} userData - Arbitrary subscriber-defined object.
     */
    this.raiseEvent( 'canvas-release', {
        tracker: event.eventSource,
        pointerType: event.pointerType,
        position: event.position,
        insideElementPressed: event.insideElementPressed,
        insideElementReleased: event.insideElementReleased,
        originalEvent: event.originalEvent
    });
}
Raised when the primary mouse button is pressed or touch starts on the {@link OpenSeadragon.Viewer#canvas} element.

@event canvas-press
@memberof OpenSeadragon.Viewer
@type {object}
@property {OpenSeadragon.Viewer} eventSource - A reference to the Viewer which raised this event.
@property {OpenSeadragon.MouseTracker} tracker - A reference to the MouseTracker which originated this event.
@property {String} pointerType - "mouse", "touch", "pen", etc.
@property {OpenSeadragon.Point} position - The position of the event relative to the tracked element.
@property {Boolean} insideElementPressed - True if the left mouse button is currently being pressed and was initiated inside the tracked element, otherwise false.
@property {Boolean} insideElementReleased - True if the cursor still inside the tracked element when the button was released.
@property {Object} originalEvent - The original DOM event.
@property {?Object} userData - Arbitrary subscriber-defined object.