Add icon cache (closes #5)

README.md

@@ -161,7 +161,18 @@ Material Desing Icons are loaded from the default URL:
 MD_ICONS_BASE_URL = 'https://cdn.jsdelivr.net/npm/@mdi/[email protected]/'
 ```
 
-You can change it to your desired location by overriding this setting.        
+You can change it to your desired location by overriding this setting.       
+
+### Configure icon cache
+
+To avoid rendering icons multiple times, configure the icon cache directory:
+
+```
+BS_ICONS_CACHE = os.path.join(STATIC_ROOT, 'icon_cache')
+```
+
+This will ensure that icons will be rendered only once with their individual svg properties 
+and stored to a local file. On each subsequent use the icon will be simply loaded from file.
 
 ## Example App
 
@@ -194,8 +205,9 @@ This project is licensed under the MIT License - see the
   as long as you don't want to use MDI.
 * django-bootstrap-icons 0.6.0 (Mai 2021): Update default bootstrap icons CDN to version 1.5.0
 * django-bootstrap-icons 0.6.1 (June 2021): Fix path building on windows (#3)
+* django-bootstrap-icons 0.6.2 (June 2021): Add icon cache to avoid multiple redering of same icon (#5)
 
-## Migration
+## Migration from 0.2
 
 If you had installed an earlier version of this package, you have to change some things:
 

django_bootstrap_icons/templatetags/bootstrap_icons.py

@@ -9,7 +9,6 @@
 from django.template import Library
 from django.utils.html import format_html
 
-
 register = Library()
 
 
@@ -54,7 +53,7 @@ def render_svg(content, size, color, extra_classes):
         svg[0].setAttribute('width', size)
         svg[0].setAttribute('height', size)
 
-    if not 'color' in svg[0].attributes:
+    if 'color' not in svg[0].attributes:
         svg[0].setAttribute('fill', "currentColor")
     if color:
         svg[0].setAttribute('fill', color)
@@ -82,6 +81,44 @@ def custom_icon(icon_name, size=None, color=None, extra_classes=None):
     return format_html(render_svg(content, size, color, extra_classes))
 
 
+def icon(icon_path, icon_name, size=None, color=None, extra_classes=None):
+    """
+    Manage caching of bootstrap icons
+    :param str icon_path: icon path given by CDN
+    :param str icon_name: Name of custom icon to render
+    :param str size: size of custom icon to render
+    :param str color: color of custom icon to render
+    :param str extra_classes: String of classes to add to icon
+    """
+    cache_path = getattr(
+        settings,
+        'BS_ICONS_CACHE',
+        None
+    )
+    cache_file = None
+
+    if cache_path:
+        if not os.path.exists(cache_path):
+            os.makedirs(cache_path)
+        cache_name = f'{icon_name}_{size}_{color}_{extra_classes}.svg'
+        cache_file = os.path.join(cache_path, cache_name)
+        if os.path.exists(cache_file):
+            # icon exists in cache, use that
+            return open(cache_file, 'r').read()
+
+    # cached icon doesn't exist or no cache configured, create and return icon
+    resp = requests.get(icon_path)
+    if resp.status_code >= 400:
+        return f"Icon <{icon_path}> does not exist"
+
+    content = xml.dom.minidom.parseString(resp.text)
+    svg = render_svg(content, size, color, extra_classes)
+    # if cache configured write icon to cache
+    if cache_path and cache_file:
+        open(cache_file, 'w').write(svg)
+    return svg
+
+
 @register.simple_tag
 def bs_icon(icon_name, size=None, color=None, extra_classes=None):
     """
@@ -100,12 +137,10 @@ def bs_icon(icon_name, size=None, color=None, extra_classes=None):
         'https://cdn.jsdelivr.net/npm/[email protected]/',
     )
     icon_path = f'{base_url}icons/{icon_name}.svg'
-    resp = requests.get(icon_path)
-    if resp.status_code >= 400:
-        return f"Icon <{icon_path}> does not exist"
 
-    content = xml.dom.minidom.parseString(resp.text)
-    return format_html(render_svg(content, size, color, extra_classes))
+    svg = icon(icon_path, icon_name, size, color, extra_classes)
+    resp = format_html(svg)
+    return resp
 
 
 @register.simple_tag
@@ -120,25 +155,23 @@ def md_icon(icon_name, size=None, color=None, extra_classes=None):
     if icon_name is None:
         return ''
 
+    # set some classes, so one can style the icons globally
+    if extra_classes is None:
+        extra_classes = f'mdi mdi-{icon_name}'
+    else:
+        extra_classes = f'mdi mdi-{icon_name} {extra_classes}'
+
+    # Set same size for mdi like bi
+    if size is None:
+        size = '20'
+
     base_url = getattr(
         settings,
         'MD_ICONS_BASE_URL',
         'https://cdn.jsdelivr.net/npm/@mdi/[email protected]/'
     )
     icon_path = f'{base_url}svg/{icon_name}.svg'
-    resp = requests.get(icon_path)
-    if resp.status_code >= 400:
-        return f"Icon <{icon_path}> does not exist"
 
-    # Set same size for mdi like bi
-    if size is None:
-        size = '20'
-
-    # set some classes, so one can style the icons globally
-    if extra_classes is None:
-        extra_classes = f'mdi mdi-{icon_name}'
-    else:
-        extra_classes = f'mdi mdi-{icon_name} {extra_classes}'
-
-    content = xml.dom.minidom.parseString(resp.text)
-    return format_html(render_svg(content, size, color, extra_classes))
+    svg = icon(icon_path, icon_name, size, color, extra_classes)
+    resp = format_html(svg)
+    return resp

setup.py

@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name='django-bootstrap-icons',
-    version='0.6.1',
+    version='0.6.2',
     packages=setuptools.find_packages(),
     include_package_data=True,
     description='A quick way to add Bootstrap Icons with Django template tags.',