我正在开发一个生成矩形的 macOS 应用程序。我可以用鼠标左键LMB单独移动矩形的点。操作原理:当我用LMB拖动1个点时,其他3个点会同时跟随它,并具有相同的偏移量。
如何同时移动矩形的所有四个点?
构造元素的代码:
enum RectPoint {
case point1(point: CGPoint)
case point2(point: CGPoint)
case point3(point: CGPoint)
case point4(point: CGPoint)
func pointCoord() -> [CGPoint] {
switch self {
case .point1(let point): return [point]
case .point2(let point): return [point]
case .point3(let point): return [point]
case .point4(let point): return [point]
}
}
}
class SpecialView: NSView {
var array: [RectPoint] = []
private var trackVertex: RectPoint?
private var trackVertexIndex: Int?
private var trackElementIndex: Int?
private func updateDragging(point: CGPoint) {
guard let trackVertex = self.trackVertex,
let trackVertexIndex = self.trackVertexIndex,
let trackElementIndex = self.trackElementIndex
else { return }
let newVertex = trackVertex.debugReleaseChecking(point,
atElementIndex: trackElementIndex)
array[trackVertexIndex] = newVertex
self.needsDisplay = true
}
}
以下是拖动点的方法:
func mouseDragged(event: NSEvent) {
var point = self.convertPoint(event.locationInWindow, fromView: nil)
updateDragging(point)
}
基本上,您需要计算应用于跟踪点的偏移并将该偏移应用于所有其他点。最简单的方法是分离计算和更新,因此更新始终在所有点上运行。
要计算偏移量,只需从新点 x 和 y 中减去当前点 x 和 y。
大致如下:
func mouseDragged(event: NSEvent) {
let eventPoint = self.convertPoint(event.locationInWindow, fromView: nil)
let trackingPoint = XXX
let xOffset = eventPoint.x - trackingPoint.x
let yOffset = eventPoint.y - trackingPoint.y
for point in allPoints {
point.x += xOffset
point.y += yOffset
}
}