Add Zoom Actual (1:1 zooming) command to View -> Zoom menu

[mwganson]

Based on a macro from mario52: (Edit: kisolre authored the macro)

https://forum.freecadweb.org/viewtopic.php?p=447004#p454617

Zooms out to a distance such that objects are shown on the screen at their actual size. For example, you can take a ruler and measure a standard Cube to be 10mm across on your screen after executing this command.

Notes:

On my Virtual Machine compile computer (Ubuntu running inside Virtual Box VM, Windows 10 Host) it does not work properly. The Cube measures 15mm approximately. But I think this is due to being in the VM it's not getting the correct physical hardware dimensions. Running the macro gives the same results on the VM, so I don't think it's an error in translation from macro code to the PR. Macro works properly on my Windows 10 host, but I can't test the build there. It needs to be tested.

My skills with Inkscape are limited at best, and that is being generous. The icon, while somewhat serviceable, definitely could use some work.

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[mwganson]

Screenshot here:

https://forum.freecadweb.org/viewtopic.php?f=3&t=43720&p=541833#p541833

[luzpaz]

Added screenshot proposed feature (from the forum thread)

[Syres916]

Tested the command by copying it into ViewFitAll and recompiling, works as expected with a 200mm Cube on a 2560x1440 display using:
OS: Linux Mint 19.3 (X-Cinnamon/cinnamon)
Word size of FreeCAD: 64-bit
Version: 0.20.26201 (Git)
Build type: Release
Branch: master
Hash: 9f2dd4a
Python version: 3.6.9
Qt version: 5.9.5
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedKingdom (en_GB)

[freecadci]

for feature branch PR_5125. Pipeline #394344028 was triggered at fec172b. All CI branch pipelines.

[luzpaz]

@mwganson do you mind adding a comment here on what this equation does?

[mwganson]

I'm going to add a user parameter, default 1.0, that users can use to tweak this if it's not working correctly on their hardware. Usage would be make a default cube of 10 mm, measure after executing zoom actual, divide your measurement by 10 mm and use that for the tweak. For example, if the 10 mm cube measures 15 mm on your ruler, then enter 15 / 10 = 1.5 as the tweak parameter.

[mwganson]

I have added the tweak parameter and the icon file. I think that was why the ci had failed, no icon file. The reason for the forgotten file was the first PR (which I didn't submit) included some unrelated changes, so I deleted that branch and made a new one without the unrelated changes, and neglected to add the icon file in the new branch. Sorry about that. I should have rebuilt to test, but I didn't think I needed to.

Tweak parameter is in BaseApp/Preferences/View and is called ZoomActualTweak. It is a float value. Usage: if the object appears 1.5 x the expected size enter 1.5 as the tweak parameter. Default is 1.0. I was torn between entering as 1.5 or 1/1.5.

Question: Should the tweak parameter be in user preferences dialog? I don't think so because rare should be the case where it is needed. A compromise is to add it to user parameters so it is there already should the user need it.

[mwganson]

User mario52 has corrected me. He was quoting user kisolre, author of original macro. Comments in code corrected.

[adrianinsaval]

It should be documented in the fine tuning wiki page if it's just going to be a parameter

[freecadci]

for feature branch PR_5125. Pipeline #394426909 was triggered at 8e60f96. All CI branch pipelines.

[yorikvanhavre]

This relies on Qt to tell us the display size... Isn't that hazardous somehow? I don't know if I would trust Qt to give the correct result everywhere, always, on all platforms :) I wonder if it's a good idea to add this feature "by default", if it's going to give wrong results for a quantity of users (which I see you are foreseeing it to happen, as you introduced a parameter to fix it)...
Basically, isn't it better to keep as a macro, where users must specifically install it, and therefore are probably more knowing what they are doing?

[luzpaz]

yorik, perhaps the user can also have the ability to add the screen size parameters as an option?

[yorikvanhavre]

yorik, perhaps the user can also have the ability to add the screen size parameters as an option?

Yes, that's the purpose of the ZoomActualTweak parameter. But it won't be clear for many users if you need to set it and how. Many might use this function and get wrong results, and, as you know, complain before looking into the docs :) So I'm wondering if we want the hassle to have to explain many, many times how to use this tool...

[adrianinsaval]

Will it actually fail often? Maybe a warning in the tooltip or a mesage in the status bar when activated could give people the hint to this parameter. Just tested the python macro on windows (PC with a monitor) and it works. Will test on a laptop on windows and linux when I get the chance.

[mwganson]

Another thing I noticed in testing is if the user sets the tweak parameter to 0 it locks up zooming -- can't zoom in or out anymore. I guess a camera height of infinity is asking too much. I had to restart FreeCAD, but I was able to restart in a manner that would have allowed me to save what I was working on. The fix for that would be simple enough, test the tweak parameter to ensure it's greater than 0 or else set it back to the default of 1.0 before using it and send a warning about invalid tweak parameter to the report view. I'll go ahead and add that to it shortly in case we decide to merge this.

[freecadci]

for feature branch PR_5125. Pipeline #395380962 was triggered at 0571623. All CI branch pipelines.

[mwganson]

I've opened a discussion for this and a 3-day poll so we can get a better idea maybe of what the failure rates are and go from there. If it fails too much, then we can just close this and be done. If no failures are reported and we get a big enough sample size, then I say merge.

https://forum.freecadweb.org/viewtopic.php?f=8&t=63258

[wwmayer]

Please note that this function will raise an error if the current camera is not orthographic.

If you e.g. set it to perspective this line
cam.height.setValue(invHeight*25.4/vpDpi)
raises an error that the SoPerspectiveCamera object has no attribute height

[freecadci]

for feature branch PR_5125. Pipeline #398053401 was triggered at 5c1801a. All CI branch pipelines.

[mwganson]

Closing. I agree with yorik. Qt cannot reliably give us the correct dpi / screen size.