在核心文本中查找文本的边界矩形

发布于 2024-08-31 11:43:06 字数 784 浏览 7 评论 0原文

我试图在核心文本中找到一行文本的边界。为简单起见，假设它只有一个字符。目前我正在使用以下方法：

line = CTLineCreateWithAttributedString(attrString);
rect = CTLineGetImageBounds(line, context);

它在大多数情况下都有效，但对于某些字符，例如数学斜体 d （Unicode：0x1D451）或数学斜体 q （Unicode：0x1D45E），宽度有点短。

我尝试使用 CTLineGetTypgraphicBounds() 或 CTFramesetterSuggestFrameSizeWithConstraints，但它们也没有帮助（我认为它们使用字形的提前来查找宽度，而不是其图形宽度。）字体本身不是斜体，我也无法使用倾斜角度来纠正这个问题。

我尝试直接访问字形并使用 CTFontCreatePathForGlyph()，但失败了，因为 CGGlyph 和 UniChar 都是 16 位，而我需要 32 位字符。

有谁知道我做错了什么吗？如果是这样，正确的方法是什么？

更新：

为了确保这不是与字体相关的问题，我使用了不同的字体。即使对于 Arial Italic 中的 ASCII 字符也存在该问题。

更新：

忽略我之前的更新！事实证明，这个问题（Arial Italic 的问题）是我自己的错误。但第一个问题仍然存在。

原文

I'm trying to find the boundaries of a line of text in Core Text. For simplicity, assume it has a single character.
At the moment I'm using the following method:

line = CTLineCreateWithAttributedString(attrString);
rect = CTLineGetImageBounds(line, context);

It works most of the times, but for some characters, like math italic d (Unicode: 0x1D451) or math italic q (Unicode: 0x1D45E), the width is a bit short.

I tried using CTLineGetTypographicBounds() or CTFramesetterSuggestFrameSizeWithConstraints, but they didn't help either (I think they use glyph's advance to find the width, not its graphical width.) As the font itself isn't italic, I also can't use slant angle to correct this.

I tried accessing the glyphs directly and using CTFontCreatePathForGlyph(), but failed as CGGlyph and UniChar are both 16-bits and I need 32-bit characters.

Does anyone know if I'm doing anything wrong? If so, what's the right way?

Update:

To make sure it's not a problem related to the font, I used different fonts. The problem exists even for ASCII characters in Arial Italic.

Update:

Ignore my previous update! It turns out this one (problem with Arial Italic) was my own bug. The first problem still stands though.

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