[英]Core Text - Get Pixel Coordinates from NSRange
How would I get a CGRect
from an NSRange
for text rendered with Core Text? 我将如何得到
CGRect
从NSRange
与核心文本呈现的文本?
I am using Core Text with an NSAttributedString
. 我正在使用带有
NSAttributedString
Core Text。
It is an absolute pain but can be done. 这是一种绝对的痛苦,但可以做到。
You need to get all of the lines in the frame using CTFrameGetLines()
, check if their character range is in the range you're looking for using CTLineGetStringRange()
, use CTLineGetTypographicBounds()
to find how big the line itself would render as, and use CTLineGetOffsetForStringIndex()
to determine the actual position of the start/end character of the range (if the line is just a subrange of the desired range). 你需要让所有的帧使用线
CTFrameGetLines()
检查他们的字符范围是你要找的使用范围CTLineGetStringRange()
使用CTLineGetTypographicBounds()
找到多大的线本身就呈现为,并使用CTLineGetOffsetForStringIndex()
来确定范围的开始/结束字符的实际位置(如果该行只是所需范围的子范围)。
Combining all of this and adding up offsets and heights and such can get you what you want. 结合所有这些并添加偏移和高度等可以得到你想要的。 Note that
CTLineGetImageBounds()
doesn't work without a graphics context (and, from what I gather, it is pretty expensive anyway) and is not necessary to solve this problem. 请注意,
CTLineGetImageBounds()
在没有图形上下文的情况下不起作用(而且,从我收集的内容来看,它无论如何都非常昂贵)并且不一定要解决这个问题。
FIrst determine the line(s) in which the range you are interested in lies is. 首先确定您感兴趣的范围所在的线。 Then call
CTLineGetOffsetForStringIndex()
to get an offset of a specific string position from the start of the line. 然后调用
CTLineGetOffsetForStringIndex()
以从行的开头获取特定字符串位置的偏移量。 Together with CTLineGetImageBounds()
, it should be possible to calculate a CGPoint
position of the first and last characters in your range. 与
CTLineGetImageBounds()
一起,应该可以计算范围中第一个和最后一个字符的CGPoint
位置。
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