bugGNU Octave - Bugs: bug #55418, Speed issue with uicontrols


bug #55418: Speed issue with uicontrols

Submitted by:  Guillaume <gyom>
Submitted on:  Tue 08 Jan 2019 11:41:51 AM UTC  
Category:  Plotting with OpenGL Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Regression
Status:  Confirmed Assigned to:  None
Originator Name:  Guillaume Open/Closed:  Open
Release:  dev Operating System:  GNU/Linux

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Wed 09 Jan 2019 07:54:30 AM UTC, comment #3: 

The main problem is that some properties rely on the the widget being actually built to be correct. Lets take an example: suppose the extent property of uicontrol objects would work properly :-), i.e. computed and set from the GUI thread once the string is parsed and displayed by Qt.

h = uicontrol ("style", "text", "My string is long and I would lke to know if it fits in one line");
ext = get (h, "extent");

If I wait for a drawnow before creating the uicontrol, then ext will be wrong since the widget has not been created at the time the "extent" is queried.

This problem is tricky and I'll take a look at it once Octave 5 is released.

Pantxo Diribarne <pantxo>
Project Member
Tue 08 Jan 2019 06:06:35 PM UTC, comment #2: 

Thanks for the feedback; I prefer reliable to fast. I marked it as regression but that's something to look at after the 5.0 release. That said, can you think of ways to accelerate it? For example, would it help if a redraw was only performed at the end of the sequence?

Guillaume <gyom>
Tue 08 Jan 2019 03:22:20 PM UTC, comment #1: 

Confirmed, the whole sequence takes ~1s in Octave 4.4.1 while it takes ~5s in Octave 5.
This is most probably due to the fact that Widgets are now created synchronously (the interpreter waits for Widget n to be created in the GUI thread before creating Widget n+1). This change made the Qt toolkit much more reliable but also much slower for creation/deletion of GUI elements.

Pantxo Diribarne <pantxo>
Project Member
Tue 08 Jan 2019 11:41:51 AM UTC, original submission:  

I notice a significant difference in speed between 4.4.1 and 5.0.1 when displaying and deleting uicontrols. The following script runs nearly instantaneously in Matlab and Octave 4.4.1 but is much slower with current Octave dev.

h = figure ();
for i=0.02:0.08:0.94
    for j=0.02:0.08:0.94
        uicontrol (...
            "Parent", h, ...
            "Units", "normalized", ...
            "Position", [i j 0.06 0.06]);
delete (findobj (h, "Type", "uicontrol"));

Guillaume <gyom>


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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-01-08 pantxo StatusNone => Confirmed

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