Mac 开发中，设置一个 Label 是很常见的事情，但 Mac 中没有直接提供类似 iOS 中的 UILabel 类，只能使用 NSTextField 类；但在使用过程中发现，其中的字无法垂直居中，很是难看。网络上搜了一遍，有用的信息支离破碎，同时几年前的类方法已经被废弃了。
综合一下，参考苹果官方文档，NSTextField 内部有个 cell 对象，默认是 NSTextFieldCell，它负责绘制工作。因此自定义一个 RSVerticallyCenteredTextFieldCell 类继承自 NSTextFieldCell，绘制时设置垂直居中；再自定义一个 RSVerticallyCenteredTextField 类继承自 NSTextField，初始化时设置 cell 为自定义的 Cell 类；最后使用该自定义的 RSVerticallyCenteredTextField 类即可。
RSVerticallyCenteredTextFieldCell.swift
|
class RSVerticallyCenteredTextFieldCell: NSTextFieldCell { |
|
var mIsEditingOrSelecting:Bool = false |
|
|
|
override func drawingRect(forBounds theRect: NSRect) -> NSRect { |
|
//Get the parent's idea of where we should draw |
|
var newRect:NSRect = super.drawingRect(forBounds: theRect) |
|
|
|
// When the text field is being edited or selected, we have to turn off the magic because it screws up |
|
// the configuration of the field editor. We sneak around this by intercepting selectWithFrame and editWithFrame and sneaking a |
|
// reduced, centered rect in at the last minute. |
|
|
|
if !mIsEditingOrSelecting { |
|
// Get our ideal size for current text |
|
let textSize:NSSize = self.cellSize(forBounds: theRect) |
|
|
|
//Center in the proposed rect |
|
let heightDelta:CGFloat = newRect.size.height – textSize.height |
|
if heightDelta > 0 { |
|
newRect.size.height -= heightDelta |
|
newRect.origin.y += heightDelta/2 |
|
} |
|
} |
|
|
|
return newRect |
|
} |
|
override func select(withFrame rect: NSRect, |
|
in controlView: NSView, |
|
editor textObj: NSText, |
|
delegate: Any?, |
|
start selStart: Int, |
|
length selLength: Int)//(var aRect: NSRect, inView controlView: NSView, editor textObj: NSText, delegate anObject: AnyObject?, start selStart: Int, length selLength: Int) |
|
{ |
|
let arect = self.drawingRect(forBounds: rect) |
|
mIsEditingOrSelecting = true; |
|
super.select(withFrame: arect, in: controlView, editor: textObj, delegate: delegate, start: selStart, length: selLength) |
|
mIsEditingOrSelecting = false; |
|
} |
|
|
|
override func edit(withFrame rect: NSRect, |
|
in controlView: NSView, |
|
editor textObj: NSText, |
|
delegate: Any?, |
|
event: NSEvent?) |
|
{ |
|
let aRect = self.drawingRect(forBounds: rect) |
|
mIsEditingOrSelecting = true; |
|
super.edit(withFrame: aRect, in: controlView, editor: textObj, delegate: delegate, event: event) |
|
mIsEditingOrSelecting = false |
|
} |
|
} |
RSVerticallyCenteredTextFieldCell.swiftRSVerticallyCenteredTextField.swift
import Cocoa
class RSVerticallyCenteredTextField: NSTextField {
override func draw(_ dirtyRect: NSRect) {
super.draw(dirtyRect)
}
override init(frame frameRect: NSRect) {
super.init(frame: frameRect)
let cell = RSVerticallyCenteredTextFieldCell(textCell: "")
self.cell = cell
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
参考链接
https://stackoverflow.com/questions/18259899/setting-the-cell-on-nstextfield
let cell = RSVerticallyCenteredTextFieldCell(textCell: “”)
这段代码貌似报错 请问这是swfit 还是 object-c的
赞赞
swift啊，声明一个类对象的变量
赞赞
老哥，我是用分类重写的select和edit方法，但是我发现edit方法没有被调用，select方法只在编辑时被调用，现在我的情况是，只有在编辑状态时可以垂直居中，退出编辑状态时会恢复垂直居上，我该怎么办
赞赞
再多查查吧，苹果开发我只是个半吊子水平，逃。。。
赞赞
这段代码有缺陷，无法设置背景色，背景色被一个白色的覆盖，但是很诡异，找不到这个白色的是个什么东西 ，见鬼
赞赞