NSLayoutManager/NSTextContainer忽略比例因子

Question

我正在尝试使用以下方法测量给定恒定宽度的NSAttributedString的高度：

-(CGFloat)calculateHeightForAttributedString:(NSAttributedString*)attributedNotes {
    CGFloat scrollerWidth = [NSScroller scrollerWidthForControlSize:NSRegularControlSize scrollerStyle:NSScrollerStyleLegacy];
    CGFloat width = self.tableView.frame.size.width - self.cellNotesWidthConstraint - scrollerWidth;
    // http://www.cocoabuilder.com/archive/cocoa/54083-height-of-string-with-fixed-width-and-given-font.html
    NSTextView *tv = [[NSTextView alloc] initWithFrame:NSMakeRect(0, 0, width - 20, 1e7)];
    tv.font = [NSFont userFontOfSize:32];
    [tv.textStorage setAttributedString:attributedNotes];
    [self setScaleFactor:[self convertSliderValueToFontScale:self.fontScaleSlider] forTextView:tv];

    [tv.layoutManager glyphRangeForTextContainer:tv.textContainer];
    [tv.layoutManager ensureLayoutForTextContainer:tv.textContainer];

    return [tv.layoutManager usedRectForTextContainer:tv.textContainer].size.height + 10.0f; // add a little bit of a buffer
}

基本上，宽度是表格视图的大小减去滚动条和用于显示其他信息的每个单元格的一小部分。只要文本比例(通过convertSliderValueToFontScale:)是1.0，这种方法就能很好地工作。但是，如果我更改比例因子，则usedRectForTextContainer的结果是不正确的--就好像没有考虑比例因子一样。

在NSTextView上的setScaleFactor:forTextView:中按如下方式设置比例(标量是实际缩放量)：

[textView scaleUnitSquareToSize:NSMakeSize(scaler, scaler)];

有什么办法解决这个问题吗？

编辑:我在这里有一个样例项目可以尝试：Github。奇怪的是，如果规模小于0，事情就会正常工作，有时它们似乎随机地在4.XXX范围内工作……

Answer 1

答案很简单:将NSTextView添加为与NSTextView具有相同框架的NSClipView的子视图。

最终的高度函数如下：

-(CGFloat)calculateHeightForAttributedString:(NSAttributedString*)attributedNotes {
    CGFloat width = self.textView.frame.size.width;
    // http://www.cocoabuilder.com/archive/cocoa/54083-height-of-string-with-fixed-width-and-given-font.html
    NSTextView *tv = [[NSTextView alloc] initWithFrame:NSMakeRect(0, 0, width, 1e7)];
    tv.horizontallyResizable = NO;
    tv.font = [NSFont userFontOfSize:32];
    tv.alignment = NSTextAlignmentLeft;
    [tv.textStorage setAttributedString:attributedNotes];
    [self setScaleFactor:self.slider.floatValue forTextView:tv];

    // In order for usedRectForTextContainer: to be accurate with a scale, you MUST
    // set the NSTextView as a subview of an NSClipView!
    NSClipView *clipView = [[NSClipView alloc] initWithFrame:NSMakeRect(0, 0, width, 1e7)];
    [clipView addSubview:tv];

    [tv.layoutManager glyphRangeForTextContainer:tv.textContainer];
    [tv.layoutManager ensureLayoutForTextContainer:tv.textContainer];
    return [tv.layoutManager usedRectForTextContainer:tv.textContainer].size.height;
}