如何在PDFView中移动PDFPage上的PDFView？

Question

我正在使用PDFKit和类似的苹果预览应用程序，当添加PDF注释时，我希望用户能够在页面上移动它们。我已经创建了一个example project on Github。

我尝试过对PDFView进行子类化并覆盖func mouseDown(with event: NSEvent)和func mouseDragged(with event: NSEvent)。我可以分享这些代码，但我有种直觉，我觉得我走错了方向。(我想这种感觉是因为我不能让代码工作……)

编辑:我已经将以下代码添加到我的PDFView中。它可以工作，但它不是很优雅。它远没有预览应用的工作方式那么流畅。只是想在这里学习，所以也许有人有更好的方法？

private var annotationBeingDragged:PDFAnnotation?

override func mouseDown(with event: NSEvent) {
    let areaOfInterest = self.areaOfInterest(forMouse: event)
    if areaOfInterest.contains(.annotationArea),
        let currentPage = self.currentPage,
        let annotation = currentPage.annotation(at: self.convert(self.convert(event.locationInWindow, from: nil), to: currentPage)) {

        if annotationBeingDragged == nil {
            annotationBeingDragged = annotation
        } else {
            super.mouseDown(with: event)
        }
    }
    else {
        super.mouseDown(with: event)
    }
}

override func mouseDragged(with event: NSEvent) {

    if let annotation = annotationBeingDragged,
        let currentPage = self.currentPage {
        
            currentPage.removeAnnotation(annotation)
            let currentPoint = self.convert(self.convert(event.locationInWindow, from: nil), to: currentPage)
            annotation.bounds = NSRect(origin: currentPoint, size: annotation.bounds.size)
            currentPage.addAnnotation(annotation)
    }
    else {
        super.mouseDragged(with: event)
    }
}

override func mouseUp(with event: NSEvent) {
    if annotationBeingDragged != nil {
        annotationBeingDragged = nil
        super.mouseDown(with: event)
    }
    else {
        super.mouseUp(with: event)
    }
}

Answer 1

它会在mouseUp方法更改中对代码进行细微更改。

super.mouseDown(with: event)

至

super.mouseUp(with: event)

它的工作很顺利。