How to stop NSScrollView from scrolling to top when horizontally resizing contained NSTextView?
How to stop NSScrollView from scrolling to top when horizontally resizing contained NSTextView?
- Subject: How to stop NSScrollView from scrolling to top when horizontally resizing contained NSTextView?
- From: Lyndsey Ferguson <email@hidden>
- Date: Mon, 16 Nov 2009 16:33:25 -0500
Hello Everyone,
I have a NSTextView for which I want to display a horizontal scroll
bar. Following some leads on the internet, I have most of it working
except that I am having problems with the vertical scroll bar.
What I have done is to find the width of the longest line (in pixels
with the given font) and then I resize the NSTextContainer and the
NSTextView appropriately. This way the horizontal scroll bar is
representative of the width and scrolling to the right will scroll to
the end of the longest line of text.
After doing this work, I noticed that my NSScrollView would show and
hide the vertical scroll bar as I typed. I've 'fixed' this problem by
setting autohidesScrollers to NO before the resize and then YES
afterwards. However, there still remains another problem where, as I
type, the vertical scrollbar thumb jumps to the top of the scrollbar
and back to the proper place as I type. I type 'a' <space>, it jumps
to the top, I press the <space> again and it jumps back to the proper
location.
Any thoughts?
Here is some sample code:
- (CGFloat)longestLineOfText
{
CGFloat longestLineOfText = 0.0;
NSRange lineRange;
NSString* theScriptText = [myTextView string];
NSDictionary* attributesDict = [NSDictionary
dictionaryWithObject:scriptFont forKey:NSFontAttributeName];
//scriptFont is a instance variable
NSUInteger characterIndex = 0;
NSUInteger stringLength = [theScriptText length];
while (characterIndex < stringLength) {
lineRange = [theScriptText
lineRangeForRange:NSMakeRange(characterIndex, 0)];
NSSize lineSize = [[theScriptText
substringWithRange:lineRange] sizeWithAttributes:attributesDict];
longestLineOfText = max(longestLineOfText, lineSize.width);
characterIndex = NSMaxRange(lineRange);
}
return longestLineOfText;
}
// ----------------------------------------------------------------------------
- (void)updateMyTextViewWidth
{
static CGFloat previousLongestLineOfText = 0.0;
CGFloat currentLongestLineOfText = [self longestLineOfText];
if (currentLongestLineOfText != previousLongestLineOfText) {
BOOL shouldStopBlinkingScrollBar = (previousLongestLineOfText
< currentLongestLineOfText);
previousLongestLineOfText = currentLongestLineOfText;
NSTextContainer* container = [myTextView textContainer];
NSScrollView* scrollView = [myTextView enclosingScrollView];
if (shouldStopBlinkingScrollBar) {
[scrollView setAutohidesScrollers:NO];
}
CGFloat padding = [container lineFragmentPadding];
NSSize size = [container containerSize];
size.width = currentLongestLineOfText + padding * 2;
[container setContainerSize:size];
NSRect frame = [myTextView frame];
frame.size.width = currentLongestLineOfText + padding * 2;
[myTextView setFrame:frame];
if (shouldStopBlinkingScrollBar) {
[scrollView setAutohidesScrollers:YES];
}
}
}
--
Lyndsey Ferguson
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