NET.addAssembly('C:\Yair\Code\NetThread.dll');
data = rand(5e6,1);  % pre-processing (5M elements, ~40MB)
start(My.NetThread('F:\test.data',data));  % start running in parallel
data = fft(data);  % post-processing (.Net I/O runs in parallel)

As with Java, the assembly only needs to be loaded once per Matlab session, not repeatedly. The definition of the .Net class closely follows that of the Java class. Unfortunately, .Net’s System.Threading.Thread class is sealed (non-inheritable), so we cannot extend it as we did in Java. However, we can instantiate an internal Thread object within our class and use it. Here is the corresponding C# source code (thanks to Ronnie Shmuel who assisted):

using System;
using System.IO;
using System.Threading;
namespace My
{
    public class NetThread
    {
        string filename;
        double[] doubleData;
        Thread thread;
        public NetThread(string filename, double[] data)
        {
            this.filename = filename;
            this.doubleData = data;
            thread = new Thread(this.run);
        }
        public void start()
        {
            thread.Start();  // note the capital S in Start()
        }
        private void run()
        {
            try
            {
                BinaryWriter out = new BinaryWriter(
                                   File.Open(filename,FileMode.Create))
                for (int i = 0; i < doubleData.Length; i++)
                {
                    out.Write(doubleData[i]);
                }
                out.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}

Note that C# Thread uses the Start() method (uppercase S), unlike java.lang.Thread that uses start() (lowercase s). Also, while java.lang.Thread.start() always invokes a run() method (the "run" name is predefined), C# Thread.Start() can invoke any delegate method. In this example I chose to name it run() for consistency with the Java example, but in fact I could have named it anything else.
In this example I've used C# source code, but in fact I could also use C++, F# or VB code, since the System.Threading.Thread class behaves very similarly in all of them. Once we compile it in our favorite compiler [hmmm, Microsoft Visual Studio anyway...], the resulting .Net assembly aught to work exactly the same in Matlab.

Compatibility and synchronization

Unlike Java and C++, .Net is not platform-independent: it only works on Windows, so if we need a cross-platform solution then we need to use Java or one of the other alternatives.
Also note that the .Net solution will only work on platforms that installed .Net of a supporting .Net version (Framework). .Net is commonly installed on Win7+, but not for example on XP. On Windows platforms where .Net is not installed, we need to download and install it before we can use any .Net features (duh!). To ensure .NET is supported on our current platform, use the NET.isNETSupported function:

>> NET.isNETSupported  % returns true/false
ans =
     1

As with Java, when compiling a .Net class that should be used within Matlab, we must ensure that we are compiling for a .Net Framework that is equal to or lower than what Matlab will actually use in the target platform, as reported by System.Environment.Version:

% My system uses .Net 4.0, so we should compile for .Net 4.0, not 4.5
>> char(System.Environment.Version.ToString)
ans =
4.0.30319.18034

As with Java threads, .Net threads are most effective when they can run independently of Matlab and of each other. I do not know of any mechanism for data synchronization between .NET threads and Matlab. However, we can use one of the standard IPC mechanisms, as I shall discuss in a future article. For example, it is possible to open a COM connection to the invoking Matlab (serving as an automation server) and then use it in the .Net code.

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Usage syntax

The basic syntax is:

hFig = uiinspect(handle)

Examples:

hFig = uiinspect(0);                         % the root handle
hFig = uiinspect(handle(0));
hFig = uiinspect(gcf);                       % current figure
hFig = uiinspect(handle(gcf));
uiinspect('java.lang.String');               % Java classname
uiinspect(java.lang.String('yes'));          % Java object
uiinspect(get(gcf,'JavaFrame'));             % Java object
uiinspect(classhandle(handle(gcf)));         % UDD class object
uiinspect(findprop(handle(gcf),'MenuBar'));  % UDD property
uiinspect(actxserver('Excel.Application'));  % COM object
uiinspect(Employee)                          % Matlab class object
uiinspect(?handle)                           % Matlab metaclass object
uiinspect('meta.class')                      % Matlab class name
uiinspect(System.DateTime.Now)               % Dot-Net object

uiinspect returns a handle to the created figure window. uiinspect opens a regular Matlab figure window which may be accessed via hFig (unlike Matlab’s methodsview and inspect functions which open Java frame that is not accessible from Matlab).
Unlike Matlab’s functions, multiple uiinspect windows can be opened simultaneously, for different objects. The differentiation is done based on figure title, which contains the inspected object’s name (if available) and its class – reinspecting the same object will reuse the existing figure window, but in all other cases a new figure window will be created.

Main panels

uiinspect includes the following information panels, that shall be described separately below:

• Class information (including superclasses, if applicable)
• Methods (for objects) or graphic handle hierarchy (for Handle Graphics)
• Callbacks (where applicable)
• Inspectable properties
• Other properties plus full meta-data (where applicable)

The panels are fully resizable. We can drag the divider lines up/down or left/right and the contents automatically adjust accordingly. Each panel has a minimal viewable width/height, and the dividers cannot be dragged to squeeze the panels below these minimums – they can only be minimized, which hides the relevant panel entirely. To minimize a panel, simply click the relevant small arrow mark on the divider. The opposite arrow mark next to it maximizes the panel, effectively minimizing the panel on the other side. Once minimized/maximized, the divider can be restored by simply clicking it once, or by dragging it (again, panel minimum sizes apply).
uiinspect only uses Java panels, so implementing the dividers required use of the simple JSplitPane. In a general case where we might wish to embed Matlab graphs in one of the side panels, we would need to employ a more sophisticated solution (see my UISplitPane utility).

Class information

The top-left panel displays a label with information about the object’s class and super-classes inheritance (where applicable).
The class name itself is hyper-linked to the class’s documentation: if this is a standard Java class, then to the official online javadoc for this class which opens up in Matlab’s internal web browser. In fact, since different Matlab releases use different JVM versions (1.3 through 1.6), the link points to the documentation page corresponding to the JVM version actually used.
If the class is non-Java, the hyperlink displays the class’s help section in Matlab’s Command Window / console. The panel’s tooltip displays the same information in a slightly different manner.
The hyperlink in the label is actually an optical illusion. In fact, the entire label is hyper-linked, and clicking any part of it will display the relevant documentation (a similar optical illusion is used to display the hyperlink at the footer of the utility window). The illusion is achieved using Matlab’s HTML formatting, where the part of the label string consisting of the class name is underlined. The cursor was dynamically modified to a pointed hand-finger when the mouse hovers over the label, using the following simple Java-based command:

methodsLabel.setCursor(java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));

Special treatment is done to extract the class’s superclass, the interfaces that it implements and any possible class qualifiers (for example, “final”).
For those interested to dig within the code, all this is done in uiinspect‘s getMethodsPane function.
Next to the class label, a checkbox is presented (“Extra”). Clicking this checkbox displays additional meta-data information (qualifiers, interrupts and inheritance) in the methods pane beneath. Not all classes have all these extra meta-data fields – only the relevant extra meta-information fields are displayed. If there are is extra meta-data, then the checkbox is not displayed. This is done in the getMethodsTable function.

Methods or HG hierarchy panel

The utility’s main panel displays either a table of methods (functions) for a class object, or a tree hierarchy for an HG handle.

Class object methods

The methods table takes the information from the getObjMethods function, which is an adaptation of Matlab’s built-in methodsview function. Part of the adaptation is to hyperlink all class references (used in the methods’ inputs, outputs and meta-data), such that clicking them will open new corresponding uiinspect windows.

HG hierarchy tree

For HG handles, getHandleTree creates a Java tree that displays the hierarchy of HG children (as recursively reported by any HG handle’s Children property). For convenience, I have chosen to use the built-in component com.mathworks.hg.peer.UITreePeer that underlies the built-in uitree function. For performance reasons, the tree is not fully evaluated: the inspected handle’s Parent is set as the tree’s Root. The root node is expanded to get all the parent’s Children (i.e., the inspected handle’s siblings), and then the inspected handle’s tree node is again expanded to display its direct descendents.

Callbacks panel

The callbacks panel, computed in getCbsData is based on a reflection of the object’s data as reported by the undocumented built-in classhandle function. I aggregate all the object’s events, as well as all the object property names that end with ‘Fcn’ or ‘Callback’. This takes care (I hope) of all the different manners by which different kinds of objects raise events that are trappable in Matlab callbacks. Specifically, it takes care of Java/Matlab classes as well as HG handles and COM objects. If anyone thinks that I have forgotten something, please let me know.
The getCbsPane function then displays the callbacks data (callbacks’ property name and value) in a Java table (JIDE PropertyTable, JIDE TreeTable, or failing those a simple JTable).

Properties inspector panel

The properties inspection panel, prepared in getPropsPane, is actually composed of two separate panes: the top pane uses the built-in Matlab component com.mathworks.mlwidgets.inspector.PropertyView, which in turn uses JIDE’s PropertyTable. PropertyView is the same component used by Matlab’s standard inspect function (that’s how I came to know it, if anyone wonders).

• PropertyView only displays non-hidden properties. One day when I have time, I intent to add the hidden properties to the resulting JIDE PropertyTable. But for now it only shows non-hidden properties.
• PropertyView causes a Matlab crash on some Matlab releases, in case dbstop if error is active (this can be replicated using Matlab’s standard inspect). I therefore regrettably need to disable this specific dbstop.

I’ve been meaning to do these two fixes ever since I released uiinspect back in 2007, but for now that’s the way it is…
The properties data is retrieved via the getPropsData function. This function uses the built-in Matlab functions meta.class.fromName(className) and metaclass(classObject) to get the class handle of Matlab classes (in getMetaClass); similarly, loadClass loads the class definition for a Java class. I inspect these class handles for their contained properties. I then use the fieldnames function to add static class fields, which are not standard properties (for example, “RED” is a static field of the java.awt.Color class).
From the class handle, I retrieve the full definition of each property. This includes meta-data such as whether the property is regular or hidden (undocumented); settable or not; gettable or not; and any additional qualifiers (e.g., Sealed, Dependent, Constant, Abstract, Transient, Default (factory) value).

Auto-update mechanism

TODO

• cleanup internal functions, remove duplicates etc.
• link property objects to another uiinspect window for these objects
• display object children (& link to them) – COM/Java
• find a way to merge the other-properties table with the inspector table (hidden props + meta-data)
• find a way to use the inspector without disabling dbstop if error
• Fix: some fields generate a Java Exception from: com.mathworks.mlwidgets.inspector.PropertyRootNode$PropertyListener$1$1.run
• Fix: using the “Hide standard callbacks” checkbox sometimes issues Java Exceptions on the console
• Fix: In HG tree view, sometimes the currently-inspected handle is not automatically selected

I would be happy if anyone can help with any of these.

Conclusion

I believe that this has been my longest blog post ever; certainly the one that I have labored most over. This correlates well with the uiinspect utility, which has been one of my most complex tasks. I’m guessing I must have invested 100-200 man-hours developing and improving it over the years.
I hope you find uiinspect as useful and as fun as I do. I believe that its source-code is certainly worth reading if you are interested in any advanced Matlab GUI programming, showing how Java GUI components can be combined in Matlab. Go ahead and download uiinspect from the Matlab file Exchange.

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