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设置 NSTextField 垂直居中

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
}
}
view raw RSVerticallyCenteredTextFieldCell.swift hosted with ❤ by GitHub
RSVerticallyCenteredTextFieldCell.swift

RSVerticallyCenteredTextField.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

分类：Mac

Tagged as: ,

5 replies ›

  1. let cell = RSVerticallyCenteredTextFieldCell(textCell: “”)
    这段代码貌似报错 请问这是swfit 还是 object-c的

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  2. 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

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  3. 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

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