Determining NSNaturalTextAlignment's actual text alignment value? - objective-c

Question

I'm currently trying to learn all I can about Cocoa's text "architecture." I've painstakingly learned all about the NSFontDescriptor, NSTextTab, and NSTextView classes, and I think I'm really understanding how it all works. However, there's one thing I can't seem to figure out: NSNaturalTextAlignment. I mean, I get it. I understand that when the font's "script" is RTL, the natural alignment is right, and when it's LTR, the natural alignment is left. All of that makes sense. However, how does one determine the natural direction of the font's script? I ask because of how my little app is set up. I currently have a mini formatting bar with the usual suspects:
NSPopUpButton to choose a font family
NSPopUpButton to choose a typeface
ACustomComboBox to choose a font size
NSSegmentedControl with segments for B, I, U, etc.
After those elements, I have my alignment control, which is also an NSSegmentedControl. In it, I have four options: left, centered, right, and justified. Again, pretty basic stuff. The neat thing about the alignment control is that I've set the tag for each segment to correspond to an NSTextAlignment value. Thus, when the "left" segment is pressed, the selected text aligns to the left. The same thing is true for "centered," "right," and "justified."
The problem is that a lot of the time an attributed string's NSParagraphStyle will return an NSNaturalTextAlignment value.
The documentation states:
The returned value is one of the alignments described in “NSTextAlignment.”
Text using NSNaturalTextAlignment is actually displayed using one of the other alignments, depending on the natural alignment of the text’s script.
Well, I'm glad Apple knows the natural alignment of the text's script, but how I do I find that out? I've currently implemented a really bad solution, but I honestly can't figure out any way around it. The bad solution looks like this:
- (void)updateTextAlignmentDisplayWithParagraphStyle:(NSParagraphStyle *)pStyle
{
NSTextAlignment alignment = pStyle.alignment;
if ( alignment == NSNaturalTextAlignment ) {
// This seems like a horrible way to determine the correct alignment ...
BOOL isRTL = ( self.textEditor.baseWritingDirection == NSWritingDirectionRightToLeft );
if ( isRTL ) {
alignment = NSRightTextAlignment;
} else {
alignment = NSLeftTextAlignment;
}
}
[self.alignmentControl selectSegmentWithTag:alignment];
}
The text view's "base" direction doesn't really tell me anything about the direction of the font itself, but at least it hints at what direction the font might go. I don't know. I just have a feeling there's a super secret NSFontDescriptor attribute which has this information, but I haven't found it. Cocoa gurus, any advice? Thanks in advance!

Answer 1

In the file NSText.h defines
NSNaturalTextAlignment = 4 // Indicates the default alignment for script
I think script is meant in the sense of written text.
You could change your code by using switch (pStyle.alignment or self.textEditor.baseWritingDirection) and add case: for every alignment.
I'm not an expert, but I think, that's what you need to know, to go forward. The info about the alignment maybe part of the Font, but this is speculative! It's also possible, that it is taken from user setting default language for the keyboard. NSLocale in the documentation or Internet might allow to go deeper in this theme.