Re: Scrolling Behavior of NSTextView
Re: Scrolling Behavior of NSTextView
- Subject: Re: Scrolling Behavior of NSTextView
- From: Martin Wierschin <email@hidden>
- Date: Mon, 7 Jun 2010 14:29:59 -0700
On 2010.06.07, at 2:10 PM, Paul Sanders wrote:
I encountered a wired behavior of NSTextView. I tried to use the
following statement to scroll to top:
[[_scrollView documentView] scrollPoint:NSMakePoint(0, 0)];
where the *documentView* is a NSTextView. But it seems when the
window is in
certain size, the scroll-to-top behavior does not take effect. Then
I added
a seemingly irrelevant statement before the above statement, by
accidental,
so the fragment become the follows:
[[[_scrollView documentView] layoutManager]
glyphRangeForTextContainer:[[self dictionaryContent] textContainer]];
[[_scrollView documentView] scrollPoint:NSMakePoint(0, 0)];
The complete source code is at http://techsingular.net/dict_mac/dict_mac.dmg
The problem happens when you search for "灵" or "神" through this
dictionary program.
I haven't looked at your code so I don't know what is going on in
detail but [NSLayoutManager glyphRangeForTextContainer:] performs
layout, if it hasn't been done already, which is probably why it is
affecting the results you get. Until layout has been performed, the
Cocoa text system doesn't know the size of the text (in terms of the
amount of space it will take up on the display) and so (I surmise)
scrollPoint: doesn't work as expected.
You're right about triggering layout, but there's no reason the text
system should have any trouble with NSMakePoint(0,0). NSTextView and
the Cocoa layout system always use a flipped coordinate system, so the
origin is always top-left.
Perhaps the problem is that once layout completes (or during layout),
you (or Cocoa) is automatically scrolling the text view somewhere
else? I'd break in the debugger to see if anything else is triggering
unwanted scrolling.
~Martin
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