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我试图在我的 NSTextView 子类中显示不可见的字符,例如换行符。像覆盖 NSLayoutManager 的 drawGlyph 方法这样的常用方法是一个坏主意,因为它太慢并且不能在多页布局中正常工作。

我想要做的是覆盖 NSLayoutManager 的 setGlyph 方法,这样它将用“¶”字形替换不可见的“\n”字形,用“∙”替换“”。

它适用于“”空间字形,但对换行符没有影响。

public override func setGlyphs(_ glyphs: UnsafePointer<CGGlyph>, properties props: UnsafePointer<NSGlyphProperty>, characterIndexes charIndexes: UnsafePointer<Int>, font aFont: Font, forGlyphRange glyphRange: NSRange) {
    var substring = (self.currentTextStorage.string as NSString).substring(with: glyphRange)

    // replace invisible characters with visible
    if PreferencesManager.shared.shouldShowInvisibles == true {
        substring = substring.replacingOccurrences(of: " ", with: "\u{00B7}")
        substring = substring.replacingOccurrences(of: "\n", with: "u{00B6}")
    }

    // create a CFString
    let stringRef = substring as CFString
    let count = CFStringGetLength(stringRef)

    // convert processed string to the C-pointer
    let cfRange = CFRangeMake(0, count)
    let fontRef = CTFontCreateWithName(aFont.fontName as CFString?, aFont.pointSize, nil)
    let characters = UnsafeMutablePointer<UniChar>.allocate(capacity: MemoryLayout<UniChar>.size * count)
    CFStringGetCharacters(stringRef, cfRange, characters)

    // get glyphs for the pointer of characters
    let glyphsRef = UnsafeMutablePointer<CGGlyph>.allocate(capacity: MemoryLayout<CGGlyph>.size * count)
    CTFontGetGlyphsForCharacters(fontRef, characters, glyphsRef, count)

    // set those glyphs
    super.setGlyphs(glyphsRef, properties:props, characterIndexes: charIndexes, font: aFont, forGlyphRange: glyphRange)
}

然后我想出了一个主意:看起来 NSTypesetter 将新行字符范围标记为根本不应该处理的字符范围。所以我继承了 NSTypesetter 并覆盖了一个方法:

override func setNotShownAttribute(_ flag: Bool, forGlyphRange glyphRange: NSRange) {
    let theFlag = PreferencesManager.shared.shouldShowInvisibles == true ? false : true
    super.setNotShownAttribute(theFlag, forGlyphRange: glyphRange)
}

但它不起作用。NSLayoutManager 仍然不会为换行符生成一个字形,无论我创建什么字形。

我究竟做错了什么?

4

2 回答 2

4

正如我所知道的,该类的 NSTypesetter 的 setNotShownAttribute: 的默认实现不会更改其字形存储中已生成的字形。因此,调用 super 不会产生任何效果。我只需要在调用 super 之前手动替换字形。

因此,显示不可见字符的最有效实现(您将在缩放视图时看到差异)是这样的:

这种方法的局限性:如果你的应用程序必须在文本视图中有多种字体,那么这种方法可能不是一个好主意,因为那些显示的不可见字符的字体也会不同。这不是您可能想要实现的目标。

  1. 子类 NSLayoutManager 并覆盖 setGlyphs 以显示空格字符:

    public override func setGlyphs(_ glyphs: UnsafePointer<CGGlyph>, properties props: UnsafePointer<NSGlyphProperty>, characterIndexes charIndexes: UnsafePointer<Int>, font aFont: Font, forGlyphRange glyphRange: NSRange) {
        var substring = (self.currentTextStorage.string as NSString).substring(with: glyphRange)
    
        // replace invisible characters with visible
        if PreferencesManager.shared.shouldShowInvisibles == true {
            substring = substring.replacingOccurrences(of: " ", with: "\u{00B7}")
        }
    
        // create a CFString
        let stringRef = substring as CFString
        let count = CFStringGetLength(stringRef)
    
        // convert processed string to the C-pointer
        let cfRange = CFRangeMake(0, count)
        let fontRef = CTFontCreateWithName(aFont.fontName as CFString?, aFont.pointSize, nil)
        let characters = UnsafeMutablePointer<UniChar>.allocate(capacity: MemoryLayout<UniChar>.size * count)
        CFStringGetCharacters(stringRef, cfRange, characters)
    
        // get glyphs for the pointer of characters
        let glyphsRef = UnsafeMutablePointer<CGGlyph>.allocate(capacity: MemoryLayout<CGGlyph>.size * count)
        CTFontGetGlyphsForCharacters(fontRef, characters, glyphsRef, count)
    
        // set those glyphs
        super.setGlyphs(glyphsRef, properties:props, characterIndexes: charIndexes, font: aFont, forGlyphRange: glyphRange)
    }
    
  2. 子类 NSATSTypesetter 并将其分配给您的 NSLayoutManager 子类。子类将显示换行符,并确保每个不可见的字符都用不同的颜色绘制:

    class CustomTypesetter: NSATSTypesetter {
    
        override func setNotShownAttribute(_ flag: Bool, forGlyphRange glyphRange: NSRange) {
            var theFlag = flag
    
            if PreferencesManager.shared.shouldShowInvisibles == true   {
                theFlag = false
    
                // add new line glyphs into the glyph storage
                var newLineGlyph = yourFont.glyph(withName: "paragraph")
                self.substituteGlyphs(in: glyphRange, withGlyphs: &newLineGlyph)
    
                // draw new line char with different color
                self.layoutManager?.addTemporaryAttribute(NSForegroundColorAttributeName, value: NSColor.invisibleTextColor, forCharacterRange: glyphRange)
            }
    
            super.setNotShownAttribute(theFlag, forGlyphRange: glyphRange)
        }
    
        /// Currently hadn't found any faster way to draw space glyphs with different color
        override func setParagraphGlyphRange(_ paragraphRange: NSRange, separatorGlyphRange paragraphSeparatorRange: NSRange) {
            super.setParagraphGlyphRange(paragraphRange, separatorGlyphRange: paragraphSeparatorRange)
    
            guard PreferencesManager.shared.shouldShowInvisibles == true else { return }
    
            if let substring = (self.layoutManager?.textStorage?.string as NSString?)?.substring(with: paragraphRange) {
                let expression = try? NSRegularExpression.init(pattern: "\\s", options: NSRegularExpression.Options.useUnicodeWordBoundaries)
                let sunstringRange = NSRange(location: 0, length: substring.characters.count)
    
                if let matches = expression?.matches(in: substring, options: NSRegularExpression.MatchingOptions.withoutAnchoringBounds, range: sunstringRange) {
                    for match in matches {
                        let globalSubRange = NSRange(location: paragraphRange.location + match.range.location, length: 1)
                        self.layoutManager?.addTemporaryAttribute(NSForegroundColorAttributeName, value: Color.invisibleText, forCharacterRange: globalSubRange)
                    }
                }
            }
        }
    }
    
  3. 要显示/隐藏不可见字符,只需调用:

    let storageRange = NSRange(location: 0, length: currentTextStorage.length)
    layoutManager.invalidateGlyphs(forCharacterRange: storageRange, changeInLength: 0, actualCharacterRange: nil)
    layoutManager.ensureGlyphs(forGlyphRange: storageRange)
    
于 2016-09-17T16:18:24.583 回答
3

这可能已经超出了这个问题的用处,但我是通过谷歌来到这里的。

至少在 macOS 10.14 上进行测试时,-[NSLayoutManager setNotShownAttribute:forGlyphAtIndex:]能够在生成该索引的字形后更改其值。关键是它会setNotShownAttribute:YES在布局行结束时无条件地为换行符字形。完成后你会得到-[NSLayoutManagerDelegate layoutManager:shouldUseAction:forControlCharacterAtIndex:],你可以在那里重置它:

- (NSControlCharacterAction)layoutManager:(NSLayoutManager *)layoutManager shouldUseAction:(NSControlCharacterAction)action forControlCharacterAtIndex:(NSUInteger)characterIndex {
  if (layoutManager.showsInvisibleCharacters && (action & NSControlCharacterActionLineBreak)) {
    [layoutManager setNotShownAttribute:NO forGlyphAtIndex:[layoutManager glyphIndexForCharacterAtIndex:characterIndex]];
  }

  return action;
}
func layoutManager(_ layoutManager: NSLayoutManager, shouldUse action: NSLayoutManager.ControlCharacterAction, forControlCharacterAt characterIndex: Int) -> NSLayoutManager.ControlCharacterAction {
  if layoutManager.showsInvisibleCharacters, action.contains(.lineBreak) {
    let glyphIndex = layoutManager.glyphIndexForCharacter(at: characterIndex)
    layoutManager.setNotShownAttribute(false, forGlyphAt: glyphIndex)
  }

  return action
}

您会注意到我showsInvisibleCharacters在示例中使用了它,它实际上适用于内置方法,即使它没有该字符的映射,产生“我不知道”字形:

换行符字形未知替换

使用-[NSLayoutManagerDelegate layoutManager:shouldGenerateGlyphs:properties:characterIndexes:font:forGlyphRange:,您可以使其完美运行:

换行符自定义替换

于 2019-02-20T04:58:31.780 回答