你如何划分一个NSAttributedString的_outside_？ [英] How do you stroke the _outside_ of an NSAttributedString?

问题描述

我在 NSAttributedString 对象上使用 NSStrokeWidthAttributeName ，在文本绘制时放置大纲。问题是笔划在文本的填充区域内。当文本小（例如，1像素厚）时，抚摸使得文本难以阅读。我真正想要的是在外面的中风。

I've been using NSStrokeWidthAttributeName on NSAttributedString objects to put an outline around text as it's drawn. The problem is that the stroke is inside the fill area of the text. When the text is small (e.g. 1 pixel thick), the stroking makes the text hard to read. What I really want is a stroke on the outside. Is there any way to do that?

我尝试了一个没有偏移和模糊的 NSShadow 它太模糊，很难看到。

I've tried an NSShadow with no offset and a blur, but it's too blurry and hard to see. If there was a way to increase the size of the shadow without any blur, that would work too.

推荐答案

虽然有可能会有其他方式，一种方法来完成这一点是首先绘制字符串只有一个笔画，然后绘制字符串只有一个填充，直接overt之前绘制的东西。 （Adobe InDesign实际上有这个内置的，它将看起来只适用于外面的字母，这有助于可读性）。

While there may be other ways, one way to accomplish this is to first draw the string with only a stroke, then draw the string with only a fill, directly overtop of what was previously drawn. (Adobe InDesign actually has this built-in, where it will appear to only apply the stroke to the outside of letter, which helps with readability).

这只是一个示例视图（显示了如何完成此操作）（受 http：// developer.apple.com/library/mac/#qa/qa2008/qa1531.html ）：

This is just an example view that shows how to accomplish this (inspired by http://developer.apple.com/library/mac/#qa/qa2008/qa1531.html):

首先设置属性：

@implementation MDInDesignTextView

static NSMutableDictionary *regularAttributes = nil;
static NSMutableDictionary *indesignBackgroundAttributes = nil;
static NSMutableDictionary *indesignForegroundAttributes = nil;

- (void)drawRect:(NSRect)frame {
    NSString *string = @"Got stroke?";
    if (regularAttributes == nil) {
        regularAttributes = [[NSMutableDictionary
    dictionaryWithObjectsAndKeys:
        [NSFont systemFontOfSize:64.0],NSFontAttributeName,
        [NSColor whiteColor],NSForegroundColorAttributeName,
        [NSNumber numberWithFloat:-5.0],NSStrokeWidthAttributeName,
        [NSColor blackColor],NSStrokeColorAttributeName, nil] retain];
    }

    if (indesignBackgroundAttributes == nil) {
        indesignBackgroundAttributes = [[NSMutableDictionary
        dictionaryWithObjectsAndKeys:
        [NSFont systemFontOfSize:64.0],NSFontAttributeName,
        [NSNumber numberWithFloat:-5.0],NSStrokeWidthAttributeName,
        [NSColor blackColor],NSStrokeColorAttributeName, nil] retain];
    }

    if (indesignForegroundAttributes == nil) {
        indesignForegroundAttributes = [[NSMutableDictionary
        dictionaryWithObjectsAndKeys:
        [NSFont systemFontOfSize:64.0],NSFontAttributeName,
        [NSColor whiteColor],NSForegroundColorAttributeName, nil] retain];
    }

    [[NSColor grayColor] set];
    [NSBezierPath fillRect:frame];

    // draw top string
    [string drawAtPoint:
        NSMakePoint(frame.origin.x + 200.0, frame.origin.y + 200.0)
        withAttributes:regularAttributes];

    // draw bottom string in two passes
    [string drawAtPoint:
        NSMakePoint(frame.origin.x + 200.0, frame.origin.y + 140.0)
        withAttributes:indesignBackgroundAttributes];
    [string drawAtPoint:
        NSMakePoint(frame.origin.x + 200.0, frame.origin.y + 140.0)
        withAttributes:indesignForegroundAttributes];
}

@end

现在，它不是完美的，因为字形有时会落在分数边界上，但是，它肯定看起来比默认更好。

Now, it's not perfect, since the glyphs will sometimes fall on fractional boundaries, but, it certainly looks better than the default.

如果性能是一个问题，总是看下降到一个稍低的水平，如CoreGraphics或CoreText。

If performance is an issue, you could always look into dropping down to a slightly lower level, such as CoreGraphics or CoreText.

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