Macos Cocoa绘图错误:";无效的上下文0x0“;
我试图在我的视窗上画一些漂亮的正方形,但是我得到了一些奇怪的错误。我做错什么了吗 代码如下:Macos Cocoa绘图错误:";无效的上下文0x0“;,macos,swift,cocoa,drawing,nsbezierpath,Macos,Swift,Cocoa,Drawing,Nsbezierpath,我试图在我的视窗上画一些漂亮的正方形,但是我得到了一些奇怪的错误。我做错什么了吗 代码如下: import Foundation import AppKit public class MyWindowView: NSView { private func drawARectAtPoint(point: NSPoint) { let rectToDraw:NSRect = NSMakeRect(point.x, point.y, 200, 200) NSColor.blackC
import Foundation
import AppKit
public class MyWindowView: NSView {
private func drawARectAtPoint(point: NSPoint) {
let rectToDraw:NSRect = NSMakeRect(point.x, point.y, 200, 200)
NSColor.blackColor().setStroke()
var bezier = NSBezierPath(rect: rectToDraw)
bezier.lineWidth = 2
bezier.stroke()
}
override public func mouseDown(theEvent: NSEvent) {
let clickPoint = theEvent.locationInWindow;
self.drawARectAtPoint(clickPoint)
}
}
我将窗口内容视图的类设置为MyWindowView,当我单击该类时,会出现如下错误:
Oct 21 14:57:21 ImageCI[3467]:CGContextSetStrokeColorWithColor:无效上下文0x0。如果要查看回溯,请设置CG_CONTEXT_SHOW_backtrace环境变量。
Oct 21 14:57:21 ImagineCI[3467]:CGContextSaveGState:无效的上下文0x0。如果要查看回溯,请设置CG_CONTEXT_SHOW_backtrace环境变量。
Oct 21 14:57:21 ImagineCI[3467]:CGContextSetLineCap:无效上下文0x0。如果要查看回溯,请设置CG_CONTEXT_SHOW_backtrace环境变量。是的,您需要绘制一个上下文。最佳实践可能是覆盖子类的
drawRect
方法,其中上下文已自动为您设置,类似于:
import Foundation
import AppKit
public class MyWindowView: NSView {
private func drawARectAtPoint(point: NSPoint) {
let rectToDraw:NSRect = NSMakeRect(point.x, point.y, 200, 200)
NSColor.blackColor().setStroke()
var bezier = NSBezierPath(rect: rectToDraw)
bezier.lineWidth = 2
bezier.stroke()
}
private var clickPoint: NSPoint?
override public func mouseDown(theEvent: NSEvent) {
clickPoint = theEvent.locationInWindow
setNeedsDisplayInRect(bounds)
}
override public func drawRect(dirtyRect: NSRect) {
// do all your drawing here
if let clickPoint = clickPoint {
drawARectAtPoint(clickPoint)
}
}
}
不客气!别忘了接受我的回答,谢谢:)