NSAttributedString上的模糊图像(NSTextAttachment)

Question

我正在使用NSAttributedString将图像包含在字符串中.但是,图像有时会模糊,就像在非整数帧上绘制一样.

我试图确保每个NSTextAttachment的边界是整数大小,但这似乎没有帮助.关于如何确保它不模糊的任何提示？

参见随附的截图,第一辆公交车并不模糊,但第二辆公交车是模糊的.

Answer 1

我通过在 NSAttributedString 上添加一个类别来修复此问题。

基本上，您需要获取 NSTextAttachment 的框架并添加其 X 坐标缺少的小数部分，以使其很好地舍入。

- (void)applyBlurrinessFixToAttachments {
    [self enumerateAttribute:NSAttachmentAttributeName inRange:NSMakeRange(0, self.length) options:0 usingBlock:^(id value, NSRange range, BOOL *stop) {
        if (![value isKindOfClass:[NSTextAttachment class]]) {
            return;
        }
        NSTextAttachment *attachment = (NSTextAttachment*)value;
        CGRect bounds = attachment.bounds;
        CGRect attributedStringRect = [self boundingRectForCharacterRange:range];

        double integral;
        double fractional = modf(attributedStringRect.origin.x, &integral);
        if (fractional > 0) {
            double roundedXOrigin = 1.0 - fractional;

            // If X coordinate starts at 0.7, add 0.3 to it
            bounds.origin.x += roundedXOrigin;
            attachment.bounds = bounds;
        }
    }];
}

- (CGRect)boundingRectForCharacterRange:(NSRange)range {
    NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:self];
    NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
    [textStorage addLayoutManager:layoutManager];
    NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:CGSizeMake(CGFLOAT_MAX, CGFLOAT_MAX)];
textContainer.lineFragmentPadding = 0;
    [layoutManager addTextContainer:textContainer];

    NSRange glyphRange;
    [layoutManager characterRangeForGlyphRange:range actualGlyphRange:&glyphRange];

    return [layoutManager boundingRectForGlyphRange:glyphRange inTextContainer:textContainer];
}