Question

我有多行NSTexField，用于显示静态文本，每次显示窗口时可能有不同的长度。此NSTextField具有高度约束，将其限制为两行。

我想设置行为，NSTextField只会水平增长，它将填充这两条水平线。现在，当我将水平压缩阻力设置得更高时，文本字段宽度会增长很多，以便在一行上显示所有文本。这可能只能通过使用自动布局约束来实现，还是必须以某种方式计算nstextfield宽度？

我尝试在superview中重载“layout”方法。但它没有像我期望的那样工作。

- (void)layout
{
    [self solveLayoutForView:self];
}

- (void)solveLayoutForView:(NSView*)view
{
    for (NSView* subView in [view subviews])
    {
        if (subView.subviews.count)
            [self solveLayoutForView:subView];
        else
        {
            NSLayoutConstraint* height = [subView constraintForAttribute:NSLayoutAttributeHeight];

            if (height && height.constant > 17 && [subView isKindOfClass:[NSTextField class]]) // seems like multiline nstextfield
            {
                NSTextField* textField = (NSTextField*)subView;

                textField.preferredMaxLayoutWidth = 0;
                [super layout];
                textField.preferredMaxLayoutWidth = NSWidth([textField alignmentRectForFrame:textField.frame]);
                [super layout];
            }
        }
    }
}

Answer 1

我最终自己计算了它。我在NSTextField的子类中重载setStringValue。如果我需要跳过这个计算，那么“PreferGrowingHorizontally”是一个子类属性（例如：如果我希望它水平增长）

- (void)setStringValue:(NSString *)stringValue
{
    BOOL changed = ![self.stringValue isEqualToString:stringValue] ? YES : NO;

    [super setStringValue:stringValue];

    if (stringValue.length && changed)
    {
        if (self.frame.size.height > 17 && self.preferGrowingHorizontally)
            [self compensateWidth];
    }
}

- (void)compensateWidth
{
    float requiredHeight = FLT_MAX;
    int widthCompensation = 0;

    while (requiredHeight > self.frame.size.height)
        requiredHeight = [self heightForStringDrawing:self.stringValue Font:self.font Width:self.frame.size.width + widthCompensation++];

    if (--widthCompensation)
    {
        NSLayoutConstraint* width = [self constraintForAttribute:NSLayoutAttributeWidth];
        if (width)
            width.constant = self.frame.size.width + widthCompensation;

        NSLog(@"requiredHeight: %f width compensation: %d for textField: %@", requiredHeight, widthCompensation, self.stringValue);
    }
}

- (float)heightForStringDrawing:(NSString*)myString Font:(NSFont*)myFont Width:(float)myWidth
{
    NSTextStorage *textStorage = [[[NSTextStorage alloc] initWithString:myString] autorelease];
    NSTextContainer *textContainer = [[[NSTextContainer alloc] initWithContainerSize:NSMakeSize(myWidth, FLT_MAX)] autorelease];

    NSLayoutManager *layoutManager = [[[NSLayoutManager alloc] init] autorelease];
    [layoutManager addTextContainer:textContainer];
    [textStorage addLayoutManager:layoutManager];
    [textStorage addAttribute:NSFontAttributeName value:myFont
                        range:NSMakeRange(0, [textStorage length])];
    [textContainer setLineFragmentPadding:0.0];
    textContainer.lineBreakMode = NSLineBreakByWordWrapping;

    (void) [layoutManager glyphRangeForTextContainer:textContainer];
    return [layoutManager usedRectForTextContainer:textContainer].size.height;
}

填充所有行后，NSTextField（多行）水平增长

1 个答案: