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当水平调整包含nstextview的大小时,如何停止nsscrollview从滚动到顶部?

nsscrollview nstextview macos cocoa

Lyndsey Ferguson · 技术社区 · 15 年前

我有一个nstextview,我想显示一个水平滚动条。除了垂直滚动条有问题外,在互联网上跟踪一些线索后,大部分信息都能正常工作。

我所做的是找到最长行的宽度(以给定字体的像素为单位),然后适当地调整nstextcontainer和nstextview的大小。这样,水平滚动条代表宽度,向右滚动将滚动到最长文本行的末尾。

完成这项工作后,我注意到我的nsscrollview会在键入时显示和隐藏垂直滚动条。我已经通过在调整大小之前将autohidescrolls设置为no,然后将其设置为yes来“修复”这个问题。但是,在我键入垂直滚动条时仍然存在另一个问题拇指跳到滚动条的顶部,然后在键入时返回到正确的位置。我键入“a”<space>,它跳到顶部,我再次按<space>,它跳回到正确的位置。

有什么想法吗?

以下是一些示例代码:

- (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];
        }
    }   
}

1 回复 | 直到 15 年前

Lyndsey Ferguson 15 年前

多亏了罗斯·卡特 post 上 Cocoa-Dev list ,我解决了这个问题。

a.您必须设置文本视图以支持水平滚动:

- (void)awakeFromNib {
    [myTextView setHorizontallyResizable:YES];
    NSSize tcSize = [[myTextView textContainer] containerSize];
    tcSize.width = FLT_MAX;
    [[myTextView textContainer] setContainerSize:tcSize];
    [[myTextView textContainer] setWidthTracksTextView:NO];
}

b.文本视图更改时必须更新其宽度,否则水平滚动条无法正确更新:

- (void)textDidChange:(NSNotification *)notification
{
    [self updateTextViewWidth];
}

- (CGFloat)longestLineOfText
{
    CGFloat longestLineOfText = 0.0;

    NSLayoutManager* layoutManager = [myTextView layoutManager];

    NSRange lineRange;
    NSUInteger glyphIndex = 0;
    NSUInteger glyphCount = [layoutManager numberOfGlyphs];
    while (glyphIndex < glyphCount) {

        NSRect lineRect = [layoutManager lineFragmentUsedRectForGlyphAtIndex:glyphIndex
                                                              effectiveRange:&lineRange
                                                     withoutAdditionalLayout:YES];

        longestLineOfText = max(longestLineOfText, lineRect.size.width);

        glyphIndex = NSMaxRange(lineRange);
    }

    return longestLineOfText;

}

// ----------------------------------------------------------------------------

- (void)updateTextViewWidth
{
    static CGFloat previousLongestLineOfText = 0.0;

    CGFloat currentLongestLineOfText = [self longestLineOfText];
    if (currentLongestLineOfText != previousLongestLineOfText) {
        previousLongestLineOfText = currentLongestLineOfText;

        NSTextContainer* container = [myTextView textContainer];
        CGFloat padding = [container lineFragmentPadding];

        NSRect frame = [myTextView frame];
        frame.size.width = currentLongestLineOfText + padding * 2;
        [myTextView setFrame:frame];
    }
}