Undocumented Matlab
  • SERVICES
    • Consulting
    • Development
    • Training
    • Gallery
    • Testimonials
  • PRODUCTS
    • IQML: IQFeed-Matlab connector
    • IB-Matlab: InteractiveBrokers-Matlab connector
    • EODML: EODHistoricalData-Matlab connector
    • Webinars
  • BOOKS
    • Secrets of MATLAB-Java Programming
    • Accelerating MATLAB Performance
    • MATLAB Succinctly
  • ARTICLES
  • ABOUT
    • Policies
  • CONTACT
  • SERVICES
    • Consulting
    • Development
    • Training
    • Gallery
    • Testimonials
  • PRODUCTS
    • IQML: IQFeed-Matlab connector
    • IB-Matlab: InteractiveBrokers-Matlab connector
    • EODML: EODHistoricalData-Matlab connector
    • Webinars
  • BOOKS
    • Secrets of MATLAB-Java Programming
    • Accelerating MATLAB Performance
    • MATLAB Succinctly
  • ARTICLES
  • ABOUT
    • Policies
  • CONTACT

ishghandle's undocumented input parameter

March 27, 2013 No Comments

Two weeks ago I wrote about Matlab Handle Graphics (HG) undocumented acceptance of structs as input parameter to some plotting functions. Continuing in a related matter, today I expose an undocumented input parameter for HG’s ishghandle function.
ishghandle is a fully-documented built-in Matlab function that returns a logical flag indicating whether the specified input is a valid HG handle or not. The input could be an invalid handle for several reasons: Perhaps it is not an HG handle in the first place, or perhaps the corresponding HG object has since been deleted (for example, its parent figure window was closed). The usage is very simple:

if ishghandle(myHandle)
    set(myHandle, ...);
end

if ishghandle(myHandle) set(myHandle, ...); end

But what if myHandle could be any of several possible HG types (e.g., plot line, patch or 3D surface) and our logic depends on the type? Of course, we could always add an extra condition to the logic:

if ishghandle(myHandle) && strcmp(get(h,'type'),'surface')
%or: if ishghandle(myHandle) && isa(handle(h),'surface')
    set(myHandle, ...);
end

if ishghandle(myHandle) && strcmp(get(h,'type'),'surface') %or: if ishghandle(myHandle) && isa(handle(h),'surface') set(myHandle, ...); end

There’s an undocumented alternative: we can simply specify the expected type as a second input argument to ishghandle. This is in fact the simplest and fastest alternative:

if ishghandle(myHandle,'surface')
    set(myHandle, ...);
end

if ishghandle(myHandle,'surface') set(myHandle, ...); end


If the second input argument is specified, then ishghandle will only return true if both (1) the input handle is a valid HG handle and (2) if its type is the specified second input argument. ishghandle‘s second input arg is case in-sensitive, so we can enter either ‘surface’, ‘Surface’ or ‘SURFACE’ (unlike the isa function, which is case-sensitive for some unknown reason).
I’ve first came across this ishghandle feature in a post by Sam Roberts. While the second-arg syntax is not very common in the Matlab code corpus, it does appear in several dozen places, for example:

  • %matlabroot%/toolbox/matlab/graph2d/plotedit.m: if any(ishghandle(varargin{1}, 'figure'))
  • %matlabroot%/toolbox/matlab/graph2d/subplot.m: if ~ishghandle(h, 'axes')
  • %matlabroot%/toolbox/matlab/graph3d/camlight.m: ...any(ishghandle(args{1},'light'))
  • %matlabroot%/toolbox/matlab/graph3d/colordef.m: ...~ishghandle(arg1, 'figure') && ~ishghandle(arg1, 'root')
  • %matlabroot%/toolbox/matlab/graph3d/objbounds.m: if (ishghandle(h(i),'surface') || ishghandle(h(i),'line') || ishghandle(h(i),'image'))
  • %matlabroot%/toolbox/matlab/graph3d/objbounds.m: elseif ishghandle(h(i),'patch')
  • %matlabroot%/toolbox/matlab/graphics/@graphics/@pan/schema.m: ... ~ishghandle(valueProposed,'uicontextmenu')
  • %matlabroot%/toolbox/matlab/scribe/selectobject.m: if ~ishghandle(obj,'axes') && ~ishghandle(obj,'figure') && ~ishghandle(obj,'uipanel')
  • %matlabroot%/toolbox/matlab/uitools/@uitools/@uimode/createuimode.m: ... ishghandle(figureState.LastObject,'uicontrol') || ishghandle(figureState.LastObject,'uitable')
  • %matlabroot%/toolbox/matlab/uitools/private/javacomponentundoc_helper.m: ishghandle(hParent, 'uicontainer') || ishghandle(hParent, 'uiflowcontainer') || ishghandle(hParent, 'uigridcontainer') ... ishghandle(hParent, 'uitoolbar') ... ishghandle(hParent, 'uisplittool') || ishghandle(hParent, 'uitogglesplittool') ... ishghandle(hParent, 'hgjavacomponent')
  • %matlabroot%/toolbox/matlab/uitools/winmenu.m: ... ~ishghandle(h,'uimenu')
  • %matlabroot%/toolbox/matlab/guide/guidemfile.m: mychildren(ishghandle(mychildren,'hggroup')) = [];

Did you happen to notice any other stock Matlab function with undocumented input arguments? If so, please write a short comment about it below.

Related posts:

  1. Undocumented scatter plot behavior – The scatter plot function has an undocumented behavior when plotting more than 100 points: it returns a single unified patch object handle, rather than a patch handle for each specific point as it returns with 100 or less points....
  2. Editbox data input validation – Undocumented features of Matlab editbox uicontrols enable immediate user-input data validation...
  3. IP address input control – A built-in JIDE control can be used in Matlab GUI for IP-address entry/display. ...
  4. Undocumented scatter plot jitter – Matlab's scatter plot can automatically jitter data to enable better visualization of distribution density. ...
  5. HG's undocumented parameters interface – Some HG functions also accept inputs parameters in a struct fields rather than the normal P-V pairs format. ...
  6. Undocumented plot marker types – Undocumented plot marker styles can easily be accesses using a hidden plot-line property. ...
Handle graphics Pure Matlab Undocumented feature
Print Print
« Previous
Next »
Leave a Reply
HTML tags such as <b> or <i> are accepted.
Wrap code fragments inside <pre lang="matlab"> tags, like this:
<pre lang="matlab">
a = magic(3);
disp(sum(a))
</pre>
I reserve the right to edit/delete comments (read the site policies).
Not all comments will be answered. You can always email me (altmany at gmail) for private consulting.

Click here to cancel reply.

Useful links
  •  Email Yair Altman
  •  Subscribe to new posts (email)
  •  Subscribe to new posts (feed)
  •  Subscribe to new posts (reader)
  •  Subscribe to comments (feed)
 
Accelerating MATLAB Performance book
Recent Posts

Speeding-up builtin Matlab functions – part 3

Improving graphics interactivity

Interesting Matlab puzzle – analysis

Interesting Matlab puzzle

Undocumented plot marker types

Matlab toolstrip – part 9 (popup figures)

Matlab toolstrip – part 8 (galleries)

Matlab toolstrip – part 7 (selection controls)

Matlab toolstrip – part 6 (complex controls)

Matlab toolstrip – part 5 (icons)

Matlab toolstrip – part 4 (control customization)

Reverting axes controls in figure toolbar

Matlab toolstrip – part 3 (basic customization)

Matlab toolstrip – part 2 (ToolGroup App)

Matlab toolstrip – part 1

Categories
  • Desktop (45)
  • Figure window (59)
  • Guest bloggers (65)
  • GUI (165)
  • Handle graphics (84)
  • Hidden property (42)
  • Icons (15)
  • Java (174)
  • Listeners (22)
  • Memory (16)
  • Mex (13)
  • Presumed future risk (394)
    • High risk of breaking in future versions (100)
    • Low risk of breaking in future versions (160)
    • Medium risk of breaking in future versions (136)
  • Public presentation (6)
  • Semi-documented feature (10)
  • Semi-documented function (35)
  • Stock Matlab function (140)
  • Toolbox (10)
  • UI controls (52)
  • Uncategorized (13)
  • Undocumented feature (217)
  • Undocumented function (37)
Tags
ActiveX (6) AppDesigner (9) Callbacks (31) Compiler (10) Desktop (38) Donn Shull (10) Editor (8) Figure (19) FindJObj (27) GUI (141) GUIDE (8) Handle graphics (78) HG2 (34) Hidden property (51) HTML (26) Icons (9) Internal component (39) Java (178) JavaFrame (20) JIDE (19) JMI (8) Listener (17) Malcolm Lidierth (8) MCOS (11) Memory (13) Menubar (9) Mex (14) Optical illusion (11) Performance (78) Profiler (9) Pure Matlab (187) schema (7) schema.class (8) schema.prop (18) Semi-documented feature (6) Semi-documented function (33) Toolbar (14) Toolstrip (13) uicontrol (37) uifigure (8) UIInspect (12) uitools (20) Undocumented feature (187) Undocumented function (37) Undocumented property (20)
Recent Comments
  • Jianfei (30 days 23 hours ago): I have tried the MathWorks CheckBoxList in Matlab 2015b. For whatever the reason, I can’t change the font properties. I can change the font color, but changing font properties...
  • Donato Coppola (36 days 19 hours ago): Hi Yair, I have a problem with the double format. When I run the treeTable function, the numbers in double format cells are displayed with comma as decimal separator. How can...
  • Kim (42 days 9 hours ago): Yair, the following didn’t work for me either: jh.setBorderPainted(false); Regards, Kim
  • Adil (44 days 11 hours ago): Thank you for the blog, it was useful for me. I have a file named App_project.mlapp.zip and when I extract it through Winzip it gives all the files exactly as you described above. I...
  • Mr Ashley Trowell (46 days 20 hours ago): Thank you so much for this analysis. Also, I find it somewhat horrifying. The take away seems to be to use && / || and NOT and / or. Thanks a bunch! ~Ashley
  • Matt (51 days 22 hours ago): Late reply I know, but you can call custom shortcuts with alt-#. Hold down Alt to see what number is assigned to the shortcuts you’ve created. Now if there was a way to create a...
  • James (59 days 17 hours ago): Is there a way to change the location of the window? They pop up at random locations and the user has to chase them down.
  • Robin (60 days 1 hour ago): Hi Yair, This has been a great help. With the removal of com.mathworks sometime in the future (as announced in R2020b), is there an alternative? For me, just getting a preference...
  • Eric Dziekonski (81 days 22 hours ago): This is fantastic! Thanks everyone! To get access to CEF on 2019b, I had to take the advise of Jeffery Devereux and Xiangrui Li. warning off MATLAB:structOnObject % suppress...
  • Yair Altman (82 days 4 hours ago): jPanel1.setParent(jPanel2) will reparent jPanel1 (and similarly any Java component/container) inside jPanel2 (any Java container). While this might work, it seems to me to be an...
  • Eivind (82 days 19 hours ago): Hi, Thanks for a great function! I was trying to put the main panel of my figure into a scrollable panel with the goal of zooming into the panel using shift+scroll and scrolling up...
  • Yair Altman (97 days 5 hours ago): There is no direct way to replicate the CW in a GUI window, you’ll need to display the text in the GUI using your program logic. Here is one possible implementation that...
  • Sunki Reddy Gunugu (99 days 3 hours ago): hi 1.i would like to know how the error in command window of matlab is captured and displayed in the GUI with the same color in CW 2. Is their any way to replicate the...
  • Matthias Brenneis (101 days 21 hours ago): Hi, thank you so much for the inspiring work and comments! My issue is: As soon as the panel gets an axes, the panel is no longer transparent: f =...
  • Collin (121 days 19 hours ago): Yair, In 2020a Mathworks added this semi-useful class matlab.ui.internal.JavaMigrati onTools Which contains static methods to call javacomponent, actxcontrol or to get an...
Contact us
Undocumented Matlab © 2009 - Yair Altman
Scroll to top