Failure to edit diverging colormaps: 'PyQt5.QtWidgets' has no attribute 'QFontMetrics'

[pierre-haessig]

Thanks for implementing diverging colormaps (#4). I wanted to test it (using current master) and this is what python -m viscm -t diverging edit gives me. Maybe an issue with Qt API version?

Traceback (most recent call last):
  File "/home/pierre/Programmes/anaconda3/lib/python3.5/runpy.py", line 184, in _run_module_as_main
    "__main__", mod_spec)
  File "/home/pierre/Programmes/anaconda3/lib/python3.5/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/pierre/Programmes/anaconda3/lib/python3.5/site-packages/viscm/__main__.py", line 8, in <module>
    main(sys.argv[1:])
  File "/home/pierre/Programmes/anaconda3/lib/python3.5/site-packages/viscm/gui.py", line 1029, in main
    mainwindow = EditorWindow(figureCanvas, v)
  File "/home/pierre/Programmes/anaconda3/lib/python3.5/site-packages/viscm/gui.py", line 1192, in __init__
    metrics = QtWidgets.QFontMetrics(smoothness_slider_num.font())
AttributeError: module 'PyQt5.QtWidgets' has no attribute 'QFontMetrics'

(also I tested python -m viscm -t diverging-continuous edit which works, but I don't see a diverging luminance. Maybe the definition of diverging-continuous should be clarified.)

[njsmith]

Meh, yes, sounds like a qt version issue, thanks for the report. . And diverging-continuous is that way on purpose yes, see Peter Kovesi's colormaps paper for why this is a useful thing. (Basically: it acts like a diverging map, but with better contrast/discriminibility at the center.) . Note that the current master's save format is unstable, so you may lose any colormaps you make for now.

…

On Jan 4, 2017 2:23 AM, "Pierre Haessig" ***@***.***> wrote: Thanks for implementing diverging colormaps (#4 <#4>). I wanted to test it (using current master) and this is what python -m viscm -t diverging edit gives me. Maybe an issue with Qt API version? Traceback (most recent call last): File "/home/pierre/Programmes/anaconda3/lib/python3.5/runpy.py", line 184, in _run_module_as_main "__main__", mod_spec) File "/home/pierre/Programmes/anaconda3/lib/python3.5/runpy.py", line 85, in _run_code exec(code, run_globals) File "/home/pierre/Programmes/anaconda3/lib/python3.5/site-packages/viscm/__main__.py", line 8, in <module> main(sys.argv[1:]) File "/home/pierre/Programmes/anaconda3/lib/python3.5/site-packages/viscm/gui.py", line 1029, in main mainwindow = EditorWindow(figureCanvas, v) File "/home/pierre/Programmes/anaconda3/lib/python3.5/site-packages/viscm/gui.py", line 1192, in __init__ metrics = QtWidgets.QFontMetrics(smoothness_slider_num.font()) AttributeError: module 'PyQt5.QtWidgets' has no attribute 'QFontMetrics' (also I tested python -m viscm -t diverging-continuous edit which works, but I don't see a diverging luminance. Maybe the definition of diverging-continuous should be clarified.) — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#23>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAlOaAzUCB-DJA_1SqMx5qVJrHkzv_G4ks5rO3MSgaJpZM4Laem-> .

[pierre-haessig]

Excellent article! It may be added as a reference in the README.

Now in terms of terminology, the article uses linear-divergent and divergent-linear, viscm uses diverging-continuous... This is not easy to follow! (adding to the confusion, I would also suggest "diverging-monotonic" as a replacement for "continuous" which is quite ambiguous, or keeping "diverging-linear").

Also, I'm really convinced by Kovesi's explanation about the low discriminibility at the center. Maybe this blue-gray-yellow map, or a close variation, could enter Matplotlib default library?

[akhmerov]

Here's a workaround FWIW

---
 viscm/gui.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/viscm/gui.py b/viscm/gui.py
index edefdfe..a6d2dcf 100644
--- a/viscm/gui.py
+++ b/viscm/gui.py
@@ -1189,7 +1189,11 @@ class EditorWindow(QtWidgets.QMainWindow):
 
             # maximum width
             smoothness_slider_num = QtWidgets.QLabel("1000.00")
-            metrics = QtWidgets.QFontMetrics(smoothness_slider_num.font())
+            try:
+                QFontMetrics = QtWidgets.QFontMetrics
+            except AttributeError:
+                from PyQt5.QtGui import QFontMetrics
+            metrics = QFontMetrics(smoothness_slider_num.font())
             max_width = metrics.width("1000.00")
             smoothness_slider_num.setFixedWidth(max_width)
             smoothness_slider_num.setAlignment(QtCore.Qt.AlignRight)
-- 

[tacaswell]

Can you report this against matplotlib core? It looks like viscm is using the core qt shims.

[tacaswell]

Actually, I think it should always do importing from QtGui. That it works from QtWidgets in pyqt4 is an artifact of how mpl shims over the differences betweer qt4 and qt5 where many things moved from QtGui to the now QtWidgets (by essentially doing QtWidegts = QtGui).

See http://doc.qt.io/qt-4.8/qfontmetrics.html and http://doc.qt.io/qt-5.6/qfontmetrics.html

[stefanv]

This should be fixed now; please re-open if not.