Transperent background of plots

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Daniele Dolci

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Apr 11, 2020, 12:11:31 PM4/11/20
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Hi!

I have a main widget with a layout and a gradient as background. I want to add a series of plots with transperent background (basically I would like to only draw the foreground). I am having hardtimes making the background of the plot transperent. I tried lot of things, with this code I was expecting that I would be making all transparent, but it is actually white:

x = [x for x in range(1000)]
y = [x for x in range(1000)]
plotWidget = pg.PlotWidget(title="Ph")
plotWidget.setBackground((0, 0, 0, 0))
plotWidget.getViewBox().setBackgroundColor((0, 0, 0, 0))
self._tab_layout.addWidget(plotWidget, 0, 0)
pen = pg.mkPen(color=(255, 0, 0))
t = plotWidget.plot(x, y, pen=pen)
t.getViewBox().setBackgroundColor((0, 0, 0, 0))

So it looks like this, and I would:

plot1.jpg

And I would like to have it drawn on this background instead:
plot2.jpg


Any idea how to fix this?

Thanks!

Israel Brewster

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Apr 11, 2020, 12:20:06 PM4/11/20
to pyqtgraph
Try:

plotWidget.setBackgroundBrush(QBrush(Qt.transparent, Qt.NoBrush))

There may be some other code needed as well, but that’s at least part of it. you *may* need to do the same for the view box. So you had the right idea, but perhaps not quite right?
---
Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320

On Apr 11, 2020, at 8:11 AM, Daniele Dolci <daniele...@gmail.com> wrote:

Hi!

I have a main widget with a layout and a gradient as background. I want to add a series of plots with transperent background (basically I would like to only draw the foreground). I am having hardtimes making the background of the plot transperent. I tried lot of things, with this code I was expecting that I would be making all transparent, but it is actually white:

x = [x for x in range(1000)]
y = [x for x in range(1000)]
plotWidget = pg.PlotWidget(title="Ph")
plotWidget.setBackground((0, 0, 0, 0))
plotWidget.getViewBox().setBackgroundColor((0, 0, 0, 0))
self._tab_layout.addWidget(plotWidget, 0, 0)
pen = pg.mkPen(color=(255, 0, 0))
t = plotWidget.plot(x, y, pen=pen)
t.getViewBox().setBackgroundColor((0, 0, 0, 0))

So it looks like this, and I would:

<plot1.jpg>

And I would like to have it drawn on this background instead:
<plot2.jpg>


Any idea how to fix this?

Thanks!



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<plot1.jpg><plot2.jpg>

Daniele Dolci
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Apr 11, 2020, 12:37:33 PM4/11/20
to pyqtgraph
Thanks for the fast reply! 

I tried to add that line but didn't work. I then tried to apply it to the plot item and to the view box, but on both I get the error:

plotWidget.getViewBox().setBackgroundBrush(QtGui.QBrush(QtCore.Qt.transparent, QtCore.Qt.NoBrush))
AttributeError: 'ViewBox' object has no attribute 'setBackgroundBrush'

Maybe I misunderstood what you meant by doing the same for the ViewBox?

Thanks again! 
Try:

plotWidget.setBackgroundBrush(QBrush(Qt.transparent, Qt.NoBrush))


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Israel Brewster
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Apr 11, 2020, 1:42:31 PM4/11/20
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No, I mis-spoke with that. I took another look at my code, and realized that I’m not doing *anything* with the view box. So try just doing the setBackgroudBrush on the plotWidget, but *don’t* set the background color on the view box at all. If that doesn’t work, then I’m probably missing something somewhere else in my code that does it…



---
Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320





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Daniele Dolci
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Apr 11, 2020, 1:51:37 PM4/11/20
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So I tried this:

x = [x for x in range(1000)]
y = [x for x in range(1000)]
plotWidget = pg.PlotWidget(title="Ph")
plotWidget.setBackgroundBrush(QtGui.QBrush(QtCore.Qt.transparent, QtCore.Qt.NoBrush))
self._tab_layout.addWidget(plotWidget, 0, 0)
t = plotWidget.plot(x, y)

But the background is still white. I removed all the viewBox stuff and the set colors. I mean, this is very weird. If the plot accepts colors for pen and background in the format of RGBa, why wouldn't the transperency do the trick?

I have also tried using just plotItem, without the widget, but I wasn't able to add it to the layout so I couldn't really finish the test. 

Thanks for your time man, I appreciate!
Cheers,

Israel Brewster
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Apr 11, 2020, 1:58:36 PM4/11/20
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One thought that just occurred to me: I’m using the latest development version of pyqtgraph. Are you by any chance on the release version? That could be the difference, theoretically, if so.



---
Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320





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Daniele Dolci
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Apr 11, 2020, 2:06:50 PM4/11/20
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I would assume I am on the latest version, I installed it today. One difference perhaps might be the operative system? I am using raspbian OS.

To install it I used 

sudo apt install python3-pyqtgraph

So I assume it gets the latest one, or not?
Israel Brewster
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Apr 11, 2020, 2:09:40 PM4/11/20
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Nope, that would be the latest *release* version, which would be 0.10. I’m using the latest *development* version that you can get from source forge. So yeah, that *could* be why my code isn’t working for you (though I don’t guarantee it).

There have been a lot of changes between the last release and the current development (like compatibility with PySide2, which is why I use the development). I keep wondering when they will make a new release, but it hasn’t happened yet.



---
Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320





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Daniele Dolci
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Apr 11, 2020, 3:42:11 PM4/11/20
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Alright, tomorrow I will try download the development version then and give it a try. 

I will let you know how it goes, thanks!

Cheers,
Daniele Dolci
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Apr 12, 2020, 11:22:03 AM4/12/20
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Hi!

I gave it a try but still same result. I uninstalled everything with 

sudo pip3 uninstall pyqtgraph 


and made sure that under dist-packages there was nothing left. Then I tried to download it from source forge but with no much success, finally, as is read here https://github.com/pyqtgraph/pyqtgraph , I used the command:


or, actually, 
 
sudo pip3 install git+https://github.com/pyqtgraph/pyqtgraph@develop

Any other idea of what I could try? 

Cheers,
Israel Brewster
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Apr 12, 2020, 11:51:38 AM4/12/20
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I’ll have to find some time to go back over my code and see what I’m missing then, because it’s working for me. Dunno off the top of my head. Sorry!



---
Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320




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Daniele Dolci
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Apr 12, 2020, 11:59:37 AM4/12/20
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I understand, I appreciated the help you gave so far. Is it possible it has to do with some css? 

Thanks!


To view this discussion on the web visit https://groups.google.com/d/msgid/pyqtgraph/2FCF8E91-6628-4A0B-83B3-0B24F22CB62D%40alaska.edu.




-- 
Daniele Dolci
Technical Director & Python Developer
Vetralla, Italy
Skype: dolci.daniele
Portfolio (YouTube): https://youtu.be/IMZdW4ikjok
=======================================
Insanity:  doing the same thing over and over again and expecting different results. 
- Albert Einstein - 



Israel Brewster
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Apr 12, 2020, 1:16:12 PM4/12/20
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So here’s a short snippet of code that works for me to get a plot with a transparent background:

from PySide2.QtWidgets import QApplication, QDialog, QVBoxLayout
from PySide2.QtGui import QBrush
from PySide2.QtCore import Qt
import pyqtgraph as pg

if __name__ == "__main__":
    app=QApplication()
    dialog=QDialog()
    dialog.setStyleSheet('background-color:#050’)
    
    layout=QVBoxLayout(dialog)
    dialog.setLayout(layout)
    
    vals=list(range(100))
    
    plotWidget=pg.PlotWidget(dialog)
    plotWidget.setBackgroundBrush(QBrush(Qt.transparent,Qt.NoBrush))
    plotWidget.plot(vals)
    
    layout.addWidget(plotWidget)
    
    dialog.show()
    
    app.exec_()



---
Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320




Message has been deleted
Daniele Dolci
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Apr 12, 2020, 3:35:20 PM4/12/20
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Hi! It was actually easier than I expected. A couple of css line did the trick. Just set the objectName of the plot widget and then I could assign a background-color: rgba(x, x, x, 0);



plots.jpg




Thanks anyway for the help! 



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-- 
Daniele Dolci
Technical Director & Python Developer
Vetralla, Italy
Skype: dolci.daniele
Portfolio (YouTube): https://youtu.be/IMZdW4ikjok
=======================================
Insanity:  doing the same thing over and over again and expecting different results. 
- Albert Einstein - 




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Israel Brewster
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Apr 12, 2020, 3:50:59 PM4/12/20
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Interesting. As you can see from my code snipet, I didn’t have to do any of that. But as long as it works, right? :-) Good job figuring it out!



---
Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320




On Apr 12, 2020, at 11:35 AM, Daniele Dolci <daniele...@gmail.com> wrote:

Hi! It was actually easier than I expected. A couple of css line did the trick. Just set the objectName of the plot widget and then I could assign a background-color: rgba(x, x, x, 0);



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<plots.jpg>

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