Outside the official Matlab blogs, perhaps the most widely known Matlab-related active blog is BlinkDagger. This blog is certainly worth following, especially for novice Matlab users who could gain fresh angles on regular programming tasks that have a simple solution in Matlab.
In one of their latest posts, BlinkDagger described how to use tooltips in Matlab GUI. In one of this blog’s very first posts, I described how HTML can easily be used with Matlab uicontrols. Let’s now combine these ideas to show how HTML support can easily be used to spice-up the tooltips.
Let’s start with a simple styled multi-line tooltip:
str = '<html><b>line #1</b><br><i><font color="red">line#2'; set(hControl,'tooltipString',str);
Multi-line HTML'ed tooltip
This technique was used to display the informative tooltip for my Java-based data table utility on the Matlab file Exchange:
Multi-line HTML-styled tooltip
Tooltips can also be used to present images, using the HTML <img> tag. However, the image src (filename) needs to be formatted in a URL-compliant format such as ‘http://undocumentedmatlab.com/images/table.png‘ or ‘file:/C:\Yair\Undocumented Matlab\Images\table.png’.
If you try to use a non-URL-format filename, the image will not be displayed. Instead, a placeholder box will appear. For example, let’s take the table screenshot above and try to place its filename directly in the tooltip HTML:
filePath = 'C:\Yair\Undocumented Matlab\Images\table.png'; str = ['<html><center><img src="' filePath '"><br>' filePath]; set(hButton,'tooltipString',str);
Tooltip with invalid HTML img source URL
If we fix filePath to be a valid URL, it now looks as intended:
filePath = 'C:\Yair\Undocumented Matlab\Images\table.png'; filePath = strrep(['file:/' filePath],'\','/'); str = ['<html><center><img src="' filePath '"><br>' ... '<b><font color="blue">' filePath]; set(hButton,'tooltipString',str);
Tooltip with HTML image and caption
Note that the tooltip looks enormous (it’s actually even downsized to fit this post…). This is because our HTML <img> was not limited in size and so the tooltip was created to display the screenshot in its original large size. In order to limit the tooltip size, simply add the height and width attributes to the HTML <img> tag, remembering to preserve the original image aspect ratio.
Now that we know the basics, we can really go wild with HTML and CSS formatting. Have you configured any kick-butt tooltip in your application? If so, please share it here.
Related posts:
- Inactive Control Tooltips & Event Chaining Inactive Matlab uicontrols cannot normally display their tooltips. This article shows how to do this with a combination of undocumented Matlab and Java hacks....
- HTML support in Matlab uicomponents Matlab uicomponents support HTML and CSS, enabling colored items, superscript/subscript, fonts, bold/italic/underline and many other modifications...
- Setting line position in an edit-box uicontrol Matlab uicontrols have many useful features that are only available via Java. Here's how to access them....
- uicontrol side-effect: removing figure toolbar Matlab's built-in uicontrol function has a side-effect of removing the figure toolbar. This was undocumented until lately. This article describes the side-effect behavior and how to fix it....
- Additional uicontrol tooltip hacks Matlab's uicontrol tooltips have several limitations that can be overcome using the control's underlying Java object....
- Uicontrol callbacks This post details undocumented callbacks exposed by the underlying Java object of Matlab uicontrols, that can be used to modify the control's behavior in a multitude of different events...
Tags: BlinkDagger, GUI, HTML, pure Matlab, uicontrol, Undocumented feature
Categories: GUI, Low risk of breaking in future versions, UI controls, Undocumented feature
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on Wednesday, May 27th, 2009 at 12:15 pm PST
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Yair, Could handle2struct/struct2handle pair be extended to cover all java objects?
[...] Yair’s Undocumented Tips on How to Spice up Tooltips [...]
That looks like a really handy feature! On a slightly related note, do you know of any way of forcing a tooltip to display (or update one that is already being displayed)?
@Ben – this was challenging: Until you asked I thought I knew the standard answer, which is “no” – tooltips use the system’s ToolTipManager object that can’t be modified. But then I found this Java hack, which I’m not even sure is documented in Java… Assuming you get the Java reference in jHandle:
The mouse does not even have to be anywhere near the GUI object!
Unfortunately, this hack requires the Java reference of the GUI object, and is not available for Matlab handles. To get a Matlab handle’s underlying Java reference you can use my FindJObj utility on the File Exchange and then use the hack.
@wei – handle2struct/struct2handle are internal Matlab functions that cannot be modified. However, you can easily build your own m-file version that try’s to call the built-in version and if an error is thrown, then the catch segment will create the necessary output object based on inspection of the Java object.
This could be a nice File Exchange submission – care to tackle it?
You can get some pointers by looking at the code within my UIInspect utility on the File Exchange.
Offtopic, sorry, but just wanted to reiterate – great blog idea, you should definitely keep it up. How about a post on systemdependent() ?
@Alan – thanks.
I’ll do a post or two about systemdependent but look at my long TODO list: so little time, so much to do…
[...] Was aber funktioniert ist html, es gibt ein undokumentiertes Feautre, mit dem einfach html eingefügt werden kann – Java machts möglich. [...]