Toolbar icons are too large particularly in dark theme

[CAM-Gerlach]

Problem Description

Originally noticed on #8020 and part of the broader #8068 .

The size of the icons in the toolerbar, already a bit overly large (IMO) compared to other IDEs in the normal light theme, has become almost comical in the dark theme; this makes the chrome bigger, looks less polished, makes them not all fit on one line anymore while they fit quite comfortably before, and is a substantial UI inconsistency between themes. Therefore, it should be reduced to a common size at least as small as the current light theme.

Tested on Python 3.6.6, Windows 8.1 x64 and PyQt/Qt 5.9.6.

[jnsebgosselin]

In addition, should we add an option to select the icon size (large or small)? This option is available in may software.

[CAM-Gerlach]

@jnsebgosselin Sure, if you don't mind. "Large" can be the size we have currently in the light theme (32px) , while "Small" should be the standard size in most applications that still use toolbars (24 px); that's generally how I've seen it done anyway.

[jnsebgosselin]

Maybe we should use the sizes provided by the pixel metrics to set the icon size instead of using hard coded values.

import sys
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import (QApplication, QStyle)
app = QApplication(sys.argv)
style = app.style()
print(style.pixelMetric(QStyle.PM_LargeIconSize))
print(style.pixelMetric(QStyle.PM_SmallIconSize))
print(style.pixelMetric(QStyle.PM_ToolBarIconSize))
app.exec_()

This results in 32, 16, 24 on my laptop with Windows 10.

[CAM-Gerlach]

Great thinking! Yeah; ToolBarIconSize would correspond to the "Small" size for the toolbar that I suggest, while LargeIconSize is the current size in the light theme that I suggest for "large" (and the dark theme is even larger than that).

[ccordoba12]

Maybe we should use the sizes provided by the pixel metrics to set the icon size instead of using hard coded values.

@jnsebgosselin, that's a really neat idea!! Could you prepare a PR for it? Thanks!

[jnsebgosselin]

Maybe we should use the sizes provided by the pixel metrics to set the icon size instead of using hard coded values.

@jnsebgosselin, that's a really neat idea!! Could you prepare a PR for it? Thanks!

Sure thing.

What about the idea to add an option in the preferences where users can switch between 'large', 'normal', and 'small' size icons?

[ccordoba12]

Sure, I'd like that too. Please go ahead with it.

[CAM-Gerlach]

FYI, icons in the toolbars of individual panels are also ~50% larger, which makes the minimum width of things like e.g. the outline explorer awkwardly large. We could probably just fix them at the size they are in the standard theme, since too much smaller and they'd be almost impossible to see, but too much larger and they'd constrain the minimum panel width.

[ccordoba12]

This seems fixed in QDarkStyle 2.6.1. @CAM-Gerlach, please confirm and close if that's the case.

@jnsebgosselin, please open a new issue for your proposed changes, in case you still want to implement them.

[CAM-Gerlach]

Yup, looking good. Thanks @ccordoba12

[dpizetta]

Oh, nice, I would ask for small icons :) more space for texting!