objective-c - Cocoa:如何像在 Mail.app 中一样绘制插入文本？

Question

如何在 Cocoa (OS X) 中绘制这种文本样式？它似乎被用在几个 Apple 应用程序中，包括邮件(如上图所示)和 Xcode 侧边栏中的几个地方。我环顾四周，但未能找到任何建议如何重现这种特定风格的文本的资源。它看起来像一个嵌入的阴影，我的第一个猜测是尝试使用 NSShadow 并将模糊半径设置为负值，但显然只允许使用正值。有什么想法吗？

Answer 1

我有一些代码可以绘制浮雕单元格(我相信最初是 Jonathon Mah 写的)。它可能无法完全满足您的要求，但它会给您一个起点:

@implementation DMEmbossedTextFieldCell

#pragma mark NSCell

- (void)drawInteriorWithFrame:(NSRect)cellFrame inView:(NSView *)controlView;
{
    /* This method copies the three-layer method used by Safari's error page. That's accessible by forcing an
     * error (e.g. visiting <foo://>) and opening the web inspector. */

    // I tried to use NSBaselineOffsetAttributeName instead of shifting the frame, but that didn't seem to work
    const NSRect onePixelUpFrame = NSOffsetRect(cellFrame, 0.0, [NSGraphicsContext currentContext].isFlipped ? -1.0 : 1.0);
    const NSRange fullRange = NSMakeRange(0, self.attributedStringValue.length);

    NSMutableAttributedString *scratchString = [self.attributedStringValue mutableCopy];

    BOOL overDark = (self.backgroundStyle == NSBackgroundStyleDark);
    CGFloat (^whenLight)(CGFloat) = ^(CGFloat b) { return overDark ? 1.0 - b : b; };

    // Layer 1
    [scratchString addAttribute:NSForegroundColorAttributeName value:[NSColor colorWithCalibratedWhite:whenLight(1.0) alpha:1.0] range:fullRange];
    [scratchString drawInRect:cellFrame];

    // Layer 2
    BOOL useGradient = NO; // Safari 5.2 preview has switched to a lighter, solid color look for the detail text. Since we use the same class, use bold-ness to decide
    if (self.attributedStringValue.length > 0) {
        NSFont *font = [self.attributedStringValue attribute:NSFontAttributeName atIndex:0 effectiveRange:NULL];
        if ([[NSFontManager sharedFontManager] traitsOfFont:font] & NSBoldFontMask)
            useGradient = YES;
    }

    NSColor *solidShade = [NSColor colorWithCalibratedHue:200/360.0 saturation:0.03 brightness:whenLight(0.41) alpha:1.0];
    [scratchString addAttribute:NSForegroundColorAttributeName value:solidShade range:fullRange];
    [scratchString drawInRect:onePixelUpFrame];

    // Layer 3 (Safari uses alpha of 0.25)
    [scratchString addAttribute:NSForegroundColorAttributeName value:[NSColor colorWithCalibratedWhite:whenLight(1.0) alpha:0.25] range:fullRange];
    [scratchString drawInRect:cellFrame];
}

@end