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Improving graphics interactivity

Matlab release R2018b added the concept of axes-specific toolbars and default axes mouse interactivity. Accelerating MATLAB Performance Plain 2D plot axes have the following default interactions enabled by default: PanInteraction, ZoomInteraction, DataTipInteraction and RulerPanInteraction.

Unfortunately, I find that while the default interactions set is much more useful than the non-interactive default axes behavior in R2018a and earlier, it could still be improved in two important ways:

  1. Performance – Matlab’s builtin Interaction objects are very inefficient. In cases of multiple overlapping axes (which is very common in multi-tab GUIs or cases of various types of axes), instead of processing events for just the top visible axes, they process all the enabled interactions for *all* axes (including non-visible ones!). This is particularly problematic with the default DataTipInteraction – it includes a Linger object whose apparent purpose is to detect when the mouse lingers for enough time on top of a chart object, and displays a data-tip in such cases. Its internal code is both inefficient and processed multiple times (for each of the axes), as can be seen via a profiling session.
  2. Usability – In my experience, RegionZoomInteraction (which enables defining a region zoom-box via click-&-drag) is usually much more useful than PanInteraction for most plot types. ZoomInteraction, which is enabled by default only enables zooming-in and -out using the mouse-wheel, which is much less useful and more cumbersome to use than RegionZoomInteraction. The panning functionality can still be accessed interactively with the mouse by dragging the X and Y rulers (ticks) to each side.

For these reasons, I typically use the following function whenever I create new axes, to replace the default sluggish DataTipInteraction and PanInteraction with RegionZoomInteraction:
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Categories: GUI, Handle graphics, Medium risk of breaking in future versions, Stock Matlab function
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3 Comments

Interesting Matlab puzzle – analysis

Last week I presented a seemingly-innocent Matlab code snippet with several variants, and asked readers to speculate what its outcomes are, and why. Several readers were apparently surprised by the results. In today’s post, I offer my analysis of the puzzle.

The original code snippet was this:

function test
    try
        if (false) or (true)            disp('Yaba');
        else
            disp('Daba');
        end
    catch
        disp('Doo!');
    end
end

With the following variants for the highlighted line #3:

        if (false) or (true)     % variant #1 (original)
        if (true)  or (false)    % variant #2
        if (true)  or (10< 9.9)  % variant #3
        if  true   or  10< 9.9   % variant #4
        if 10> 9.9 or  10< 9.9   % variant #5

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Categories: Medium risk of breaking in future versions, Undocumented feature
Tags: ,
2 Comments

Interesting Matlab puzzle

Here’s a nice little puzzle that came to me from long-time Matlab veteran Andrew Janke:

Without actually running the following code in Matlab, what do you expect its output to be? ‘Yaba’? ‘Daba’? perhaps ‘Doo!’? or maybe it won’t run at all because of a parsing error?

function test
    try
        if (false) or (true)
            disp('Yaba');
        else
            disp('Daba');
        end
    catch
        disp('Doo!');
    end
end

To muddy the waters a bit, do you think that short-circuit evaluation is at work here? or perhaps eager evaluation? or perhaps neither?
Would the results be different if we switched the order of the conditional operands, i.e. (true) or (false) instead of (false) or (true)? if so, how and why?
And does it matter if I used “false” or “10< 9.9” as the “or” conditional?
Are the parentheses around the conditions important? would the results be any different without these parentheses?

In other words, how and why would the results change for the following variants?

        if (false) or (true)     % variant #1
        if (true)  or (false)    % variant #2
        if (true)  or (10< 9.9)  % variant #3
        if  true   or  10< 9.9   % variant #4
        if 10> 9.9 or  10< 9.9   % variant #5

Please post your thoughts in a comment below (expected results and the reason, for the main code snippet above and its variants), and then run the code. You might be surprised at the results, but not less importantly at the reasons. This deceivingly innocuous code snippet leads to interesting insight on Matlab’s parser.

Full marks will go to the first person who posts the correct results and reasoning/interpretation of the variants above (hint: it’s not as trivial as it might look at first glance).

Addendum April 9, 2019: I have now posted my solution/analysis of this puzzle here.

USA visit

I will be travelling in the US (Boston, New York, Baltimore) in May/June 2019. Please let me know (altmany at gmail) if you would like to schedule a meeting or onsite visit for consulting/training, or perhaps just to explore the possibility of my professional assistance to your Matlab programming needs.

Categories: Medium risk of breaking in future versions, Undocumented feature
Tags: ,
20 Comments

Undocumented plot marker types

I wanted to take a break from my miniseries on the Matlab toolstrip to describe a nice little undocumented aspect of plot line markers. Plot line marker types have remained essentially unchanged in user-facing functionality for the past two+ decades, allowing the well-known marker types (.,+,o,^ etc.). Internally, lots of things changed in the graphics engine, particularly in the transition to HG2 in R2014b and the implementation of markers using OpenGL primitives. I suspect that during the massive amount of development work that was done at that time, important functionality improvements that were implemented in the engine were forgotten and did not percolate all the way up to the user-facing functions. I highlighted a few of these in the past, for example transparency and color gradient for plot lines and markers, or various aspects of contour plots.

Fortunately, Matlab usually exposes the internal objects that we can customize and which enable these extra features, in hidden properties of the top-level graphics handle. For example, the standard Matlab plot-line handle has a hidden property called MarkerHandle that we can access. This returns an internal object that enables marker transparency and color gradients. We can also use this object to set the marker style to a couple of formats that are not available in the top-level object:

>> x=1:10; y=10*x; hLine=plot(x,y,'o-'); box off; drawnow;
>> hLine.MarkerEdgeColor = 'r';
 
>> set(hLine, 'Marker')'  % top-level marker styles
ans =
  1×14 cell array
    {'+'} {'o'} {'*'} {'.'} {'x'} {'square'} {'diamond'} {'v'} {'^'} {'>'} {'<'} {'pentagram'} {'hexagram'} {'none'}
 
>> set(hLine.MarkerHandle, 'Style')'  % low-level marker styles
ans =
  1×16 cell array
    {'plus'} {'circle'} {'asterisk'} {'point'} {'x'} {'square'} {'diamond'} {'downtriangle'} {'triangle'} {'righttriangle'} {'lefttriangle'} {'pentagram'} {'hexagram'} {'vbar'} {'hbar'} {'none'}

We see that the top-level marker styles directly correspond to the low-level styles, except for the low-level ‘vbar’ and ‘hbar’ styles. Perhaps the developers forgot to add these two styles to the top-level object in the enormous upheaval of HG2. Luckily, we can set the hbar/vbar styles directly, using the line’s MarkerHandle property:

hLine.MarkerHandle.Style = 'hbar';
set(hLine.MarkerHandle, 'Style','hbar');  % alternative

hLine.MarkerHandle.Style='hbar'

hLine.MarkerHandle.Style='hbar'

hLine.MarkerHandle.Style='vbar'

hLine.MarkerHandle.Style='vbar'

USA visit

I will be travelling in the US in May/June 2019. Please let me know (altmany at gmail) if you would like to schedule a meeting or onsite visit for consulting/training, or perhaps just to explore the possibility of my professional assistance to your Matlab programming needs.

Categories: Handle graphics, Hidden property, Low risk of breaking in future versions, Stock Matlab function, Undocumented feature
Tags: , , , ,
1 Comment

Matlab toolstrip – part 9 (popup figures)

In previous posts I showed how we can create custom Matlab app toolstrips using various controls. Today I will show how we can incorporate popup forms composed of Matlab figures into our Matlab toolstrip. These are similar in concept to drop-down and gallery selectors, in the sense that when we click the toolstrip button a custom popup is displayed. In the case of a popup form, this is a fully-customizable Matlab GUI figure.

Popup figure in Matlab toolstrip

Toolstrips can be a bit complex to develop so I’m proceeding slowly, with each post in the miniseries building on the previous posts. Continue reading

Categories: Figure window, GUI, High risk of breaking in future versions, Java, Undocumented feature
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4 Comments

Matlab toolstrip – part 8 (galleries)

In previous posts I showed how we can create custom Matlab app toolstrips using various controls (buttons, checkboxes, drop-downs, lists etc.). Today I will show how we can incorporate gallery panels into our Matlab toolstrip.

Toolstrip Gallery (in-line & drop-down)

Toolstrips can be a bit complex to develop so I’m proceeding slowly, with each post in the miniseries building on the previous posts. I encourage you to review the earlier posts in the Toolstrip miniseries before reading this post.
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Categories: Figure window, GUI, High risk of breaking in future versions, Undocumented feature
Tags: , , ,
5 Comments

Matlab toolstrip – part 7 (selection controls)

In previous posts I showed how we can create custom Matlab app toolstrips using controls such as buttons, checkboxes, sliders and spinners. Today I will show how we can incorporate even more complex selection controls into our toolstrip: lists, drop-downs, popups etc.

Toolstrip SplitButton with dynamic popup and static sub-menu

Toolstrip SplitButton with dynamic popup and static sub-menu

Toolstrips can be a bit complex to develop so I’m proceeding slowly, with each post in the miniseries building on the previous posts. I encourage you to review the earlier posts in the Toolstrip miniseries before reading this post.
Continue reading

Categories: Figure window, GUI, High risk of breaking in future versions, Undocumented feature
Tags: , , ,
6 Comments

Matlab toolstrip – part 6 (complex controls)

In previous posts I showed how we can create custom Matlab app toolstrips using simple controls such as buttons and checkboxes. Today I will show how we can incorporate more complex controls into our toolstrip: button groups, edit-boxes, spinners, sliders etc.

Some custom Toolstrip Controls

Toolstrips can be a bit complex to develop so I’m proceeding slowly, with each post in the miniseries building on the previous posts. I encourage you to review the earlier posts in the Toolstrip miniseries before reading this post.
Continue reading

Categories: Figure window, GUI, High risk of breaking in future versions, UI controls, Undocumented feature
Tags: , , ,
4 Comments

Matlab toolstrip – part 5 (icons)

In a previous post I showed how we can create custom Matlab app toolstrips. Toolstrips can be a bit complex to develop so I’m trying to proceed slowly, with each post in the miniseries building on the previous posts. I encourage you to review the earlier posts in the Toolstrip miniseries before reading this post. Today’s post describes how we can set various icons, based on the toolstrip created in the previous posts:

Toolstrip example (basic controls)

Toolstrip example (basic controls)


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Categories: GUI, High risk of breaking in future versions, Java, Undocumented feature
Tags: , , , ,
2 Comments

Matlab toolstrip – part 4 (control customization)

In a previous post I showed how we can create custom Matlab app toolstrips. Toolstrips can be a bit complex to develop so I’m trying to proceed slowly, with each post in the miniseries building on the previous posts. I encourage you to review the earlier posts in the Toolstrip miniseries before reading this post. In today’s post we continue the discussion of the toolstrip created in the previous post:

Toolstrip example (basic controls)

Toolstrip example (basic controls)

Today’s post will show how to attach user-defined functionality to toolstrip components, as well as some additional customizations. At the end of today’s article, you should be able to create a fully-functional custom Matlab toolstrip. Continue reading

Categories: Figure window, GUI, High risk of breaking in future versions, UI controls, Undocumented feature
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