Multi-line tooltips

Yair Altman — Thu, 03 Nov 2011 02:05:36 +0000

I often use tooltips in my Matlab GUIs. They are a fantastically intuitive and unobtrusive visual helper for users to understand the GUI. In this blog, I have already posted several articles about how to tweak tooltip contents (here, here, and here). Today I would like to expand on one of the aspects that were already covered, namely that of multi-line tooltips.

Basic multi-line tooltips

The basic multi-line tooltip consists of a simple string that includes the newline character. for example:

set(hControl, 'TooltipString', ['this is line 1' 10 'and this is line 2'])

Or better (platform independent):

set(hControl, 'TooltipString', sprintf('this is line 1\nand this is line 2'))

A simple multi-line tooltip string

As can be seen, this is very simple to set up. Unfortunately, the font cannot be customized. Which leads us to:

HTML-rendered multi-line tooltips

Tooltips, like most other Matlab controls, supports HTML rendering. This is a natural corollary of the fact that Java Swing, on which all Matlab controls are based, automatically supports HTML. All we need to do is to add ‘‘ at the very beginning of our tooltip string, and then we can embed HTML tags within the rest of the string:

set(hControl, 'tooltipString', 'line #1
line#2');

Multi-line HTML'ed tooltip

And a more sophisticated example, used within my createTable utility on the File Exchange:

A more complex multi-line HTML-based tooltip

Note that there is no need to close the final HTML tags in the tooltip string, although it’s not an error to do so (as I have done above).

The problem with formatted multi-line tooltip

Unfortunately, none of these two methods work when we wish to display formatted multi-line tooltips. For example, suppose that we wish to display struct data in a tooltip:

>> myData = struct('a',pi, 'b',-4, 'very_long_field_name','short txt')
myData =
                       a: 3.14159265358979
                       b: -4
    very_long_field_name: 'short txt'
>> myDataStr = evalc('disp(myData)');
>> set(hControl, 'TooltipString', myDataStr);

Badly-formatted multi-line tooltip

If we try to use HTML, the result looks even worse, because if the HTML-renderer detects a newline character embedded in the string, it simply uses the regular (non-HTML) renderer:

set(hControl, 'TooltipString', ['' myDataStr ''])

Failure to parse a string using HTML

Even if we fix this by replacing all line-separators with ‘

‘, we still get a badly-formatted tooltip, because HTML ignores all white spaces:

>> myDataStr2 = strrep(myDataStr, sprintf('\n'), '
');
>> set(hControl, 'TooltipString', ['' myDataStr2 ''])

Badly-formatted multi-line tooltip

(you can see that it’s HTML-formatted by the fact that the tooltip contents do not have internal margins like in the non-HTML tooltip above)

Fixed-width font multi-line tooltips

We now recall the HTML

tag, which tells HTML not to ignore white-spaces. In most web browsers, it also defaults to using a fixed-width font. Unfortunately, this is not the case here:

set(hControl, 'TooltipString', ['

' myDataStr2])

Still not quite right...

Which brings us to the final customization of the day, namely explicitly forcing the tooltip to use a fixed-width font:

set(hControl, 'TooltipString', ['

' myDataStr2 ''])

Finally - a well-formatted multi-line tooltip

Even more powerful customizations can be achieved using CSS rather than pure HTML. This will be discussed a future article.

The post Multi-line tooltips appeared first on Undocumented Matlab.

Tooltip – Undocumented Matlab

Multi-line tooltips

Basic multi-line tooltips

HTML-rendered multi-line tooltips

The problem with formatted multi-line tooltip

Fixed-width font multi-line tooltips

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