QCAD unresponsive

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andrew
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QCAD unresponsive

Post by andrew » Tue Nov 04, 2014 10:51 am

From a QCAD user:
I am trying to learn to use QCAD 3.7 on a Windows 7 computer. I can get some features to work, but many buttons/menu selections do not respond. For instance, the scroll buttons on the right and bottom sides of the drawing space don't move. Another example: To open a menu button, I have to first "right click" and then "left click" several times on the button to get it to open.

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andrew
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Re: QCAD unresponsive

Post by andrew » Tue Nov 04, 2014 10:53 am

If you are working with large, complex drawings, you might want to reconfigure or disable autosave. Autosave saves the drawing every 5 min by default. QCAD does not respond to any user input during the time it takes to save your drawing, so if your drawing takes more than a few seconds to save, this might become an issue.

You can disable or reconfigure autosave under:
Edit > Application Preferences > Load/Save > Autosave
Screen Shot 2014-11-04 at 10.52.15.png
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phidrho
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Re: QCAD unresponsive

Post by phidrho » Tue Oct 19, 2021 3:28 pm

Are there any possible optimizations on this topic?
In some of my drawings autosave lasts for few minutes, and almost nothing is changed in drawing since last autosave.

If working in DXF (as ASCII text file) maybe some diff approach can be used to save only differences in file.
My DWG is around 6 MB and DXF is around 60MB, which is not small - I understand that, but why does it take so long on modern computer with HDD with write speed of around 100 MB/s and SSD with around 500 MB/s.

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andrew
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Re: QCAD unresponsive

Post by andrew » Tue Oct 19, 2021 4:04 pm

phidrho wrote:
Tue Oct 19, 2021 3:28 pm
Are there any possible optimizations on this topic?
No. Please understand that saving involves more than just streaming data to disk (as in copying an existing file). If you can attach the file, we can tell you more about this specific file.

phidrho
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Re: QCAD unresponsive

Post by phidrho » Tue Oct 19, 2021 6:43 pm

I understand that there is way more job underneath than just dumping data, but I wanted to note that this last step lasts for 2 seconds max on modern computers.

But preprocessing step is way longer than in other software. I have made a video where I compared saving the same drawing in 3 different CADs: AutoCAD, NanoCAD, and QCAD. I have tested saving to DXF2013 and DWG2013 versions, in both cases QCAD needed many times longer processing time and it ended up in bigger files (20 MB bigger in DXF version). I did all testing on SSD drive.
You can see it on video here, I'm sending you the drawing file via PM for testing purposes.

Interesting thing is that NanoCAD also uses Teigha by Open Design Alliance (if I'm not wrong, it's the same library that QCAD also uses for DWG).
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andrew
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Re: QCAD unresponsive

Post by andrew » Tue Oct 19, 2021 7:32 pm

These products use a native DXF/DWG CAD database (such as the OpenDesign libraries).

QCAD uses its own CAD engine and uses OpenDesign only for DXF/DWG import / export. QCAD has to convert all entities to OpenDesign entities and copy them into an OpenDesign database before each save. This is a design choice that allows QCAD to be open source and independent of OpenDesign. Take OpenDesign away and you still have a working CAD system.

Of course, QCAD could also adopt the OpenDesign engine altogether just like NanoCAD, Draftsight and most other Autocad clones and stop being open source. However, that would make QCAD just yet another instance of the already many Autocad clones which it very deliberately tries not to be. I hope that makes sense.

phidrho
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Re: QCAD unresponsive

Post by phidrho » Tue Oct 19, 2021 8:02 pm

Thank you for your thorough answer.
I really appreciate that your project is open source. But I also hope that someday You or someone else will have enough time to rewrite the engine to be much faster at reading/writing. If they made it that fast, I consider it doable (not easy in any way), and the solution is probably in a different approach to the same problem. Similar to QCAD, I am always fascinated by what amazing job people have done with Blender, and it's also fully open source.

Have you considered opening a Google summer of code project, this kind of assignment seems a proper challenge for young and smart students.

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