Compute correct widget width for rich text labels

[maweigert]

Currently, the width of label widgets that contain rich text (such as html tags) is computed based on the raw text alone. This may result in excessively large widgets, e.g. when including images.

For instance the following

#download test image 
!wget https://raw.githubusercontent.com/napari/magicgui/master/resources/hotdog.jpg -O very_impressive_flashy_logo_for_my_awesome_napari_plugin.jpg


from magicgui import magicgui

@magicgui(
    label=dict(widget_type='Label', label='<img src="very_impressive_flashy_logo_for_my_awesome_napari_plugin.jpg" width="64">Text'))
def widget(label):
    pass

widget.show()

leads to

The PR fixes how the default size of the label widget is computed for rich text labels. The above code then yields

[tlambert03]

awesome! thanks!

[tlambert03]

bummer ... mightBeRichText doesn't look to be in the Qt namespace in pyside2... we'll have to figure out what's going on there.

[tlambert03]

from the qt source code, looks like all mightBeRichText isn't doing much:

This function uses a fast and therefore simple heuristic. It
mainly checks whether there is something that looks like a tag
before the first line break. Although the result may be correct
for common cases, there is no guarantee.

so we can just use regex and do:

def might_be_rich_text(text):
    import re
    return bool(re.search("<[^\n]+>", text))

[codecov]

Codecov Report

Merging #199 (fc42698) into master (c50a7e2) will increase coverage by 0.02%.
The diff coverage is 60.00%.

@@            Coverage Diff             @@
##           master     #199      +/-   ##
==========================================
+ Coverage   90.07%   90.09%   +0.02%     
==========================================
  Files          29       29              
  Lines        2981     2989       +8     
==========================================
+ Hits         2685     2693       +8     
  Misses        296      296              

Impacted Files	Coverage Δ
magicgui/backends/_qtpy/widgets.py	86.47% <60.00%> (-0.40%)	⬇️
magicgui/application.py	83.14% <0.00%> (+2.24%)	⬆️
magicgui/backends/_qtpy/application.py	100.00% <0.00%> (+2.77%)	⬆️

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[maweigert]

bummer ... mightBeRichText doesn't look to be in the Qt namespace in pyside2... we'll have to figure out what's going on there.

Mhm, seems mightBeRichText lives in different submodules for both backends:

PySide2.QtGui.Qt.mightBeRichText
PyQt5.QtCore.Qt.mightBeRichText

[tlambert03]

thanks!