回顾此问答关于在 Nautilus/GNOME 上预生成缩略图我最近发现,那里发布的所有脚本都无法在 KDE Plasma 5/Dolphin 文件管理器上运行。
有没有什么方法可以在 KDE 上提前生成缩略图,而不必手动浏览每个文件夹?
答案1
介绍
因此,事实证明 KDE 和 GNOME 现在遵循略有不同的缩略图命名和元数据约定。这非常不幸,因为这些问题本应随着自由标准组织。
我已经提交了KDE 的错误报告希望最终能解决这个问题,但目前 KDE 和 GNOME 生成的缩略图彼此不兼容。
缩略图脚本用于弥合 KDE/GNOME 差距
为了解决这种不兼容性,我最终修改 James Henstridge 在上面链接的问答中发布的 Python 脚本。我实现的主要更改是更新生成的缩略图以便被 KDE 识别的功能(通过重命名它们并更新 PNG 元数据块)。
以下是上述脚本的当前修订版本:
#!/usr/bin/python3
"""
Thumbnail generator for KDE/GNOME
Largely based on a script by James Henstridge
(https://askubuntu.com/a/201997)
Unfortunately there seems to be some disagreement between GNOME and KDE
towards how to follow the XDG specs for saving thumbnails. This script
is meant as a workaround to that issue, generating thumbnails that follow
both specifications.
Dependencies: python3 gir1.2-gnomedesktop-3.0 python-pillow
pillow can be installed with `pip install pillow`
You will also need to have the corresponding thumbnailers installed (e.g.
evince-thumbnailer). KDE thumbnailers are not supported. All previews are
generated through GNOME's thumbnail factory and then made compatible with KDE.
Further references:
Thumbnail specifications in KDE/GNOME:
- https://bugs.kde.org/show_bug.cgi?id=393015
- https://api.kde.org/frameworks/kio/html/previewjob_8cpp_source.html
- https://lazka.github.io/pgi-docs/GnomeDesktop-3.0/classes/DesktopThumbnailFactory.html
Setting PNG metadata:
- http://pillow.readthedocs.io/en/5.1.x/PIL.html#PIL.PngImagePlugin.PngInfo
- https://stackoverflow.com/a/10552742/1708932
Copyright: (c) 2012 James Henstridge <https://launchpad.net/~jamesh>
(c) 2018 Glutanimate <https://glutanimate.com/>
License: MIT license
"""
import os
import sys
from hashlib import md5
from PIL import Image
from PIL import PngImagePlugin
import gi
gi.require_version('GnomeDesktop', '3.0')
from gi.repository import Gio, GnomeDesktop
# FIXME: Hardcoding the Thumbnailer to a generic name
# regardless of MIME type might not always work
KDE_THUMBNAILER = "KDE Thumbnail Generator"
def update_name_and_meta(thumb_path, filename, mtime, mime_type, size):
print("Making thumb compatible with KDE...")
abs_path = os.path.abspath(filename)
# The spaces in our URI are not escaped. This is not in accordance
# with the URI RFC2396 which is listed in the freedesktop specs,
# but it's what KDE currently uses
# (cf.: https://bugs.kde.org/show_bug.cgi?id=393015)
kde_uri = "file://" + abs_path
kde_md5 = md5(kde_uri.encode("utf-8")).hexdigest()
thumb_dir = os.path.dirname(thumb_path)
kde_thumb_path = os.path.join(thumb_dir, kde_md5 + ".png")
if os.path.exists(kde_thumb_path):
print("KDE thumb already exists. Skipping")
return
im = Image.open(thumb_path)
# Set PNG metadata chunk
meta = PngImagePlugin.PngInfo()
meta.add_itxt("Software", KDE_THUMBNAILER)
meta.add_text("Thumb::MTime", str(int(mtime)))
meta.add_text("Thumb::Mimetype", mime_type)
meta.add_text("Thumb::Size", str(size))
meta.add_itxt("Thumb::URI", kde_uri)
im.save(kde_thumb_path, "png", pnginfo=meta)
# uncomment this to remove GNOME thumbnails:
# os.remove(thumb_path)
def make_thumbnail(factory, filename):
mtime = os.path.getmtime(filename)
# Use Gio to determine the URI and mime type
f = Gio.file_new_for_path(filename)
uri = f.get_uri()
info = f.query_info(
'standard::content-type', Gio.FileQueryInfoFlags.NONE, None)
mime_type = info.get_content_type()
size = info.get_size()
if factory.lookup(uri, mtime) is not None:
print("FRESH %s" % uri)
return False
if not factory.can_thumbnail(uri, mime_type, mtime):
print("UNSUPPORTED %s" % uri)
return False
thumbnail = factory.generate_thumbnail(uri, mime_type)
if thumbnail is None:
print("ERROR %s" % uri)
return False
factory.save_thumbnail(thumbnail, uri, mtime)
thumb_path = factory.lookup(uri, mtime)
update_name_and_meta(thumb_path, filename, mtime, mime_type, size)
print("OK %s" % uri)
return True
def thumbnail_folder(factory, folder):
for dirpath, dirnames, filenames in os.walk(folder):
for filename in filenames:
make_thumbnail(factory, os.path.join(dirpath, filename))
def main(argv):
factory = GnomeDesktop.DesktopThumbnailFactory()
for filename in argv[1:]:
if os.path.isdir(filename):
thumbnail_folder(factory, filename)
else:
make_thumbnail(factory, filename)
if __name__ == '__main__':
sys.exit(main(sys.argv))
安装
将上面的代码部分复制并粘贴到新文件中,为其选择一个合适的名称(例如thumbnailer
),并将其标记为可执行文件。
依赖项
要使脚本正常工作,您需要安装 GNOME 的 Python 绑定。脚本还依赖于pillow
可通过 进行安装的 Python 库pip
。
以下命令应处理所有依赖关系:
sudo apt install gir1.2-gnomedesktop-3.0 python3-pip
pip3 install pillow
缩略图首先通过 GNOME 的缩略图工厂生成,然后与 KDE 兼容。因此,您仍需要安装所有相应的 GNOME 缩略图模块。不支持 KDE 自己的缩略图模块。例如:要使脚本支持生成 PDF 缩略图,您必须安装evince
。
(我本来很想直接使用 KDE 的 python 绑定,但看起来 pykde4 和 pykde5 都已被废弃多年了)。
用法
一般用法与任何其他缩略图脚本相同。只需使用要生成缩略图的文件或文件夹作为参数来调用它,例如:
thumbnailer /home/Documents
参考
KDE/GNOME 中的缩略图规格:
- https://bugs.kde.org/show_bug.cgi?id=393015
- https://api.kde.org/frameworks/kio/html/previewjob_8cpp_source.html
- https://lazka.github.io/pgi-docs/GnomeDesktop-3.0/classes/DesktopThumbnailFactory.html
设置 PNG 元数据: