As I was deliberating the topic of my weekly article, a new CSSM newsreader thread arrived today to immediately conclude the debate: The CSSM poster asked how Matlab labels can be modified to display non-ASCII characters such as the ∀ or β math symbols.
As you may recall, unlike axes text labels that support Tex/Latex, and unlike other uicontrols like buttons or listboxes that support HTML, text labels (uicontrol(‘Style’,'text’,…)) do not support text formatting or special symbols.
In the above-mentioned thread, Matt Whitaker, a longstanding CSSM contributor and a Matlab-Java veteran gave a solution that shows how seemingly difficult questions sometimes have simple solutions right beneath our noses. His solution was to simply replace the uicontrol label with a Java JLabel:
%show the 'for all' and 'beta' symbols labelStr = '<html>∀β <b>bold</b> <i><font color="red">label</html>'; jLabel = javaObjectEDT('javax.swing.JLabel',labelStr); [hcomponent,hcontainer] = javacomponent(jLabel,[100,100,40,20],gcf);
Math symbols and HTML support in a Java JLabel
Note that the standard Matlab text uicontrol itself is very limited in the amount of customization it supports, even when accessing its underlying Java object using the FindJObj utility. This underlying Java object is a com.mathworks.hg.peer.utils.MultilineLabel extension of Swing’s bland javax.swing.JComponent. In fact, aside from some font and color customizations (also available via the Matlab HG properties), the most useful properties that are accessible only via the Java object are few. These include Border, HorizontalAlignment, VerticalAlignment and LineWrap. This is a very short list compared to the long list of corresponding undocumented properties in the other uicontrols.
Related posts:
- Customizing uicontrol border Matlab uicontrol borders can easily be modified - this article shows how...
- Customizing listbox & editbox scrollbars Matlab listbox and multi-line editbox uicontrols have pre-configured scrollbars. This article shows how they can be customized....
- Customizing uitree nodes – part 1 This article describes how to customize specific nodes of Matlab GUI tree controls created using the undocumented uitree function...
- Customizing help popup contents The built-in HelpPopup, available since Matlab R2007b, has a back-door that enables displaying arbitrary text, HTML and URL web-pages....
- Customizing uitree nodes – part 2 This article shows how Matlab GUI tree nodes can be customized with checkboxes and similar controls...
- Customizing uitree This article describes how to customize Matlab GUI tree controls created using the undocumented uitree function...
I don’t know if this is obvious as I don’t know Java, but you can change the gray background of the JLabel by defining a java.awt.Color object and using setBackground:
mycolor = javaObjectEDT(‘java.awt.Color’, rgb_code)
setBackground(jLabel, mycolor);
The rgb_code is an integer that seems to be correspond to RGB as follows:
256^2*(0-255 red level) + 256*(0-255 green level) + (0-255 blue level)
So black = 0, and white is 256^2*255 + 256*255 + 255. You can cobble together highlighted sentences using this technique by aligning multiple JLabel objects in the figure.
@Nick – JLabel’s Background and Foreground properties, and their corresponding getXYZ(),setXYZ() accessor methods, are common to all Java Swing components, together with several other basic properties (and their accessor methods).
In this particular case, java.awt.Color can be constructed in several ways:
1) Color(int) – the single integer RGB value you have reported in your comment
2) Color(float,float,float) – accepts three values between 0.0-1.0 (R,G,B)
3) Color(float,float,float,float) – as #2 above, with an additional 0.0-1.0 value for transparency (alpha)
4) Color(int, int, int) – as #2 above but the RGB values are specified as integer values between 0-255. There is also a fourth value for alpha, as in #3 above
5) Color.red etc. – there are several predefined static values: black, blue, cyan, darkGray, gray, green, lightGray, magenta, orange, pink, red, white, and yellow