Implemented theme icons.

Theme icons are icon widgets that are created with only their name as arguments.
The global static `ICON_LOADER` then searches the currently used icon theme for an icon with that name.
If an icon with that name exists with multiple sizes in the theme, the icon with the best size for the widget is chosen.

examples/todos.rs

@@ -1,7 +1,7 @@
 use iced::{
     button, scrollable, text_input, Align, Application, Button, Checkbox,
     Color, Column, Command, Container, Element, Font, HorizontalAlignment,
-    Length, Row, Scrollable, Settings, Text, TextInput,
+    Icon, Length, Row, Scrollable, Settings, Text, TextInput,
 };
 use serde::{Deserialize, Serialize};
 
@@ -291,12 +291,9 @@ impl Task {
                     .align_items(Align::Center)
                     .push(checkbox)
                     .push(
-                        Button::new(
-                            edit_button,
-                            edit_icon().color([0.5, 0.5, 0.5]),
-                        )
-                        .on_press(TaskMessage::Edit)
-                        .padding(10),
+                        Button::new(edit_button, edit_icon())
+                            .on_press(TaskMessage::Edit)
+                            .padding(10),
                     )
                     .into()
             }
@@ -320,14 +317,11 @@ impl Task {
                     .push(
                         Button::new(
                             delete_button,
-                            Row::new()
-                                .spacing(10)
-                                .push(delete_icon().color(Color::WHITE))
-                                .push(
-                                    Text::new("Delete")
-                                        .width(Length::Shrink)
-                                        .color(Color::WHITE),
-                                ),
+                            Row::new().spacing(10).push(delete_icon()).push(
+                                Text::new("Delete")
+                                    .width(Length::Shrink)
+                                    .color(Color::WHITE),
+                            ),
                         )
                         .on_press(TaskMessage::Delete)
                         .padding(10)
@@ -471,12 +465,24 @@ fn icon(unicode: char) -> Text {
         .size(20)
 }
 
-fn edit_icon() -> Text {
-    icon('\u{F303}')
+fn edit_icon<'a, Message>() -> Element<'a, Message> {
+    if Icon::theme_includes_icon("document-properties") {
+        Icon::from_theme("document-properties")
+            .size(Length::Units(32))
+            .into()
+    } else {
+        icon('\u{F303}').color([0.5, 0.5, 0.5]).into()
+    }
 }
 
-fn delete_icon() -> Text {
-    icon('\u{F1F8}')
+fn delete_icon<'a, Message>() -> Element<'a, Message> {
+    if Icon::theme_includes_icon("edit-delete") {
+        Icon::from_theme("edit-delete")
+            .size(Length::Units(32))
+            .into()
+    } else {
+        icon('\u{F1F8}').color(Color::WHITE).into()
+    }
 }
 
 // Persistence

native/Cargo.toml

@@ -12,3 +12,6 @@ iced_core = { version = "0.1.0", path = "../core", features = ["command"] }
 twox-hash = "1.5"
 raw-window-handle = "0.3"
 unicode-segmentation = "1.6"
+xdg = "2.2"
+rust-ini = "0.13"
+lazy_static = "1.4"

native/src/icon_loader.rs

@@ -0,0 +1,5 @@
+//! A collection of structs to handle themed icons.
+
+mod icon_loader;
+
+pub use icon_loader::*;