CGFontGetGlyphBBoxes错误的结果 [英] CGFontGetGlyphBBoxes wrong result

问题描述

我一直在尝试精确测量字形范围，但是此代码可以打印出916 ！！！实际宽度为69。

I have been trying to measure glyph bounds precisely but this code prints out 916!!! The real width of this is 69.

- (void)drawRect:(NSRect)dirtyRect {
        CGContextRef main = [[NSGraphicsContext currentContext] graphicsPort];
        CGContextSetTextMatrix(main, CGAffineTransformIdentity);
        CGGlyph g;
        CGPoint p  = CGPointMake(100, 100);
        CGRect rect = CGRectMake(0, 0, 0, 0);
        CGFontRef font = CGFontCreateWithFontName((CFStringRef)@"Arial");
        g = CGFontGetGlyphWithGlyphName(font, CFSTR("L"));
        CGContextSetFont(main, font);
        CGContextSetTextPosition(main, 0, 0);
        CGContextSetFontSize(main, 200);
        CGContextSetRGBFillColor(main, 0, 0, 1, 1);
        CGContextShowGlyphsAtPositions(main, &g, &p, 1);
        CGFontGetGlyphBBoxes(font, &g, 1, &rect);
        printf("%f", rect.size.width);
    }

推荐答案

您正在使用 CGFontGetGlyphBBoxes ，它以字形空间单位返回大小。要使用此功能，您需要使用每个em的单位和字体大小对其进行缩放。

You are using CGFontGetGlyphBBoxes, which returns the size in glyph space units. To use this, you need to scale it with the units per em and the font size.

CGRect rect;
CGFontRef font = CGFontCreateWithFontName((CFStringRef)@"Arial");
CGFloat fontSize = 200.0;
CGGlyph g = CGFontGetGlyphWithGlyphName(font, CFSTR("L"));
CGFontGetGlyphBBoxes(font, &g, 1, &rect);
CGFloat width = rect.size.Width / CGFontGetUnitsPerEm(font) * fontSize;

使用 [NSFont boundingRectForCGGlyph：]的另一种方法code>。

An alternate way to do it to use [NSFont boundingRectForCGGlyph:].

NSFont *font = [NSFont fontWithName:@"Arial" size:200];
NSRect rect = [font boundingRectForCGGlyph:g];

boundingRectForCGGlyph

返回指定字形的边界矩形，缩放到接收者的大小。

boundingRectForCGGlyph
Returns the bounding rectangle for the specified glyph, scaled to the receiver’s size.

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