Support themeing for plugin icons

manual/creating_plugins.rst

@@ -138,15 +138,23 @@ Getting resources from the plugin ZIP file
 calibre's plugin loading system defines a couple of built-in functions that allow you to conveniently get files from the plugin ZIP file.
 
     **get_resources(name_or_list_of_names)**
-        This function should be called with a list of paths to files inside the ZIP file. For example to access the file icon.png in
+        This function should be called with a list of paths to files inside the
-        the folder images in the ZIP file, you would use: ``images/icon.png``. Always use a forward slash as the path separator,
+        ZIP file. For example to access the file :file:`icon.png` in the folder
-        even on Windows. When you pass in a single name, the function will return the raw bytes of that file or None if the name
+        images in the ZIP file, you would use: ``images/icon.png``. Always use
-        was not found in the ZIP file. If you pass in more than one name then it returns a dict mapping the names to bytes.
+        a forward slash as the path separator, even on Windows. When you pass
-        If a name is not found, it will not be present in the returned dict.
+        in a single name, the function will return the raw bytes of that file
+        or None if the name was not found in the ZIP file. If you pass in more
+        than one name then it returns a dict mapping the names to bytes.  If a
+        name is not found, it will not be present in the returned dict.
+
+    **get_icons(name_or_list_of_names, plugin_name='')**
+        A wrapper for get_resources() that creates QIcon objects
+        from the raw bytes returned by get_resources. If a name is not found
+        in the ZIP file the corresponding QIcon will be null. In order to
+        support icon theme-ing, pass in the human friendly name of your plugin
+        as ``plugin_name``. If the user is using an icon theme with icons for
+        you plugin, they will be loaded preferentially.
 
-    **get_icons(name_or_list_of_names)**
-        A convenience wrapper for get_resources() that creates QIcon objects from the raw bytes returned by get_resources.
-        If a name is not found in the ZIP file the corresponding QIcon will be null.
 
 Enabling user configuration of your plugin
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/calibre/customize/zipplugin.py

@@ -57,38 +57,50 @@ def get_resources(zfp, name_or_list_of_names):
     return ans
 
 
-def get_icons(zfp, name_or_list_of_names):
+def get_icons(zfp, name_or_list_of_names, plugin_name=''):
     '''
     Load icons from the plugin zip file
 
     :param name_or_list_of_names: List of paths to resources in the zip file using / as
                 separator, or a single path
 
+    :param plugin_name: The human friendly name of the plugin, used to load icons from
+                the current theme, if present.
+
     :return: A dictionary of the form ``{name : QIcon}``. Any names
                 that were not found in the zip file will be null QIcons.
                 If a single path is passed in the return value will
                 be A QIcon.
     '''
     from qt.core import QIcon, QPixmap
-    names = name_or_list_of_names
-    ans = get_resources(zfp, names)
-    if isinstance(names, string_or_bytes):
-        names = [names]
-    if ans is None:
     ans = {}
-    if isinstance(ans, string_or_bytes):
+    namelist = [name_or_list_of_names] if isinstance(name_or_list_of_names, string_or_bytes) else name_or_list_of_names
-        ans = dict([(names[0], ans)])
+    failed = set()
+    if plugin_name:
+        for name in namelist:
+            q = QIcon.ic(f'{plugin_name}/{name}')
+            if q.isNull():
+                failed.add(name)
+            else:
+                ans[name] = q
+    else:
+        failed = set(namelist)
+    if failed:
+        from_zfp = get_resources(zfp, list(failed))
+        if from_zfp is None:
+            from_zfp = {}
+        elif isinstance(from_zfp, string_or_bytes):
+            from_zfp = {namelist[0]: from_zfp}
 
-    ians = {}
+        for name in failed:
-    for name in names:
             p = QPixmap()
-        raw = ans.get(name, None)
+            raw = from_zfp.get(name)
             if raw:
                 p.loadFromData(raw)
-        ians[name] = QIcon(p)
+            ans[name] = QIcon(p)
-    if len(names) == 1:
+    if len(namelist) == 1 and ans:
-        ians = ians.pop(names[0])
+        ans = ans.pop(namelist[0])
-    return ians
+    return ans
 
 
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