introduce tabler-icons for redmine 6.0

app/helpers/hearts_helper.rb

@@ -53,7 +53,11 @@ def heart_link_with_counter_manual(objects, heart_bool, hearted_users_count, use
     objects = Array.wrap(objects)
 
     css = heart_bool ? 'icon icon-heart' : 'icon icon-heart-off'
-    text = content_tag :span, l(:hearts_link_label), :class => 'heart-link-label'
+    if defined? hearts_icon_with_label # redmine >= 6.0
+      text = hearts_icon_with_label('heart', l(:hearts_link_label), css_class: 'heart-link-label')
+    else
+      text = content_tag :span, l(:hearts_link_label), :class => 'heart-link-label'
+    end
     object_type = objects.first.class.to_s.underscore
     object_id = (objects.size == 1) ? objects.first.id : objects.map(&:id).sort
 
@@ -127,4 +131,15 @@ def render_api_heartable_include(heartable, api)
       end
     end
   end
+
+  if defined? IconsHelper # redmine >= 6.0
+    include IconsHelper
+    def hearts_icon_with_label(icon_name, label_text, icon_only: false, size: 18, css_class: nil)
+      label_classes = ["icon-label"]
+      label_classes << "hidden" if icon_only
+      plugin = 'redmine_hearts'
+      sprite_icon(icon_name, size: size, css_class: css_class, plugin: plugin) + content_tag(:span, label_text, class: label_classes.join(' '))
+    end
+  end
+
 end

assets/stylesheets/application.css

@@ -1,8 +1,17 @@
 .icon-heart  { background-image: url(../images/heart.png); }
 .icon-heart-off  { background-image: url(../images/heart_off.png); }
-
 .heart-link-with-count { display: inline-block; }
-.heart-count-number { padding-left: 1ex; }
+.heart-count-number { padding-left: 0.75ex; }
+
+/* redmine >= 6.0 */
+:is(.icon-heart, .icon-heart-off):has(svg.icon-svg) { background-image: none; }
+.icon-heart .icon-svg { fill: #fb8098; stroke: none; }
+.heart-link-with-count:has(svg.icon-svg) { 
+  display: inline-flex;
+  align-items: center;
+  vertical-align: middle;
+}
+
 
 @media screen and (max-width: 899px) {
   .heart-link-with-count > *:nth-child(1) {

config/icon_source.yml

@@ -0,0 +1,2 @@
+- name: heart
+  svg: heart