/*

See LICENSE folder for this sample’s licensing information.

Abstract:

NSAccessibilityElement subclass for outline view items.

*/

import Cocoa

class CustomOutlineViewAccessibilityRowElement: NSAccessibilityElement {

    var disclosureTriangleCenterPoint = CGPoint()

    var canDisclose = false

    /**

     Override activation point to calculate it's position in screen coordinates relative to it's parent.

     This is necessary to support the window moving.

     */

    override func accessibilityActivationPoint() -> NSPoint {

        var result = NSPoint()

        if let parentView = accessibilityParent() as? CustomOutlineView {

            result = NSAccessibilityPointInView(parentView, disclosureTriangleCenterPoint)

        }

        return result

    }

    /** Override accessibilityDisclosed setter to update the the node this element represents

    This allows an accessibility client to expand or collapse a row in an outline

    (rather than just being able to read that state)

    VoiceOver, for example, exposes this via the Control+Command+\ command.

    */

    override func setAccessibilityDisclosed(_ accessibilityDisclosed: Bool) {

        if let parentView = accessibilityParent() as? CustomOutlineView {

            super.setAccessibilityDisclosed(accessibilityDisclosed)

            parentView.setExpandedStatus(expanded: accessibilityDisclosed, rowIndex: accessibilityIndex())

        }

    }

    // Disallow calling accessibilityDisclosed setter on elements that can't disclose (leaf nodes).

    override func isAccessibilitySelectorAllowed(_ selector: Selector) -> Bool {

        if selector == #selector(setAccessibilityDisclosed) {

            return canDisclose

        }

        return super.isAccessibilitySelectorAllowed(selector)

    }

    override func accessibilityRole() -> NSAccessibilityRole? {

        return NSAccessibilityRole.row

    }

    override func accessibilitySubrole() -> NSAccessibilitySubrole? {

        return NSAccessibilitySubrole.outlineRow

    }

}