Add Link widget (#1506)

This looks like a Hyperlink, but doesn't do anything when clicked.
Or rather: it lets the user decide what happens on click.

Closes #1152

Author: emilk

CHANGELOG.md

@@ -14,6 +14,7 @@ NOTE: [`epaint`](epaint/CHANGELOG.md), [`eframe`](eframe/CHANGELOG.md), [`egui_w
 * Added `Ui::push_id` to resolve id clashes ([#1374](https://github.com/emilk/egui/pull/1374)).
 * Added `Frame::outer_margin`.
 * Added `Painter::hline` and `Painter::vline`.
+* Added `Link` and `ui.link`  ([#1506](https://github.com/emilk/egui/pull/1506)).
 
 ### Changed 🔧
 * `ClippedMesh` has been replaced with `ClippedPrimitive` ([#1351](https://github.com/emilk/egui/pull/1351)).
@@ -27,7 +28,7 @@ NOTE: [`epaint`](epaint/CHANGELOG.md), [`eframe`](eframe/CHANGELOG.md), [`egui_w
 * Renamed the feature `serialize` to `serde` ([#1467](https://github.com/emilk/egui/pull/1467)).
 
 ### Fixed 🐛
-* Fixed ComboBoxes always being rendered left-aligned ([#1304](https://github.com/emilk/egui/pull/1304)).
+* Fixed `ComboBox`:es always being rendered left-aligned ([#1304](https://github.com/emilk/egui/pull/1304)).
 * Fixed ui code that could lead to a deadlock ([#1380](https://github.com/emilk/egui/pull/1380)).
 * Text is darker and more readable in bright mode ([#1412](https://github.com/emilk/egui/pull/1412)).
 * Fixed `Ui::add_visible` sometimes leaving the `Ui` in a disabled state. ([#1436](https://github.com/emilk/egui/issues/1436)).

egui/src/data/output.rs

@@ -466,7 +466,7 @@ impl WidgetInfo {
 
         // TODO: localization
         let widget_type = match typ {
-            WidgetType::Hyperlink => "link",
+            WidgetType::Link => "link",
             WidgetType::TextEdit => "text edit",
             WidgetType::Button => "button",
             WidgetType::Checkbox => "checkbox",

egui/src/lib.rs

@@ -494,7 +494,8 @@ pub mod special_emojis {
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub enum WidgetType {
     Label, // TODO: emit Label events
-    Hyperlink,
+    /// e.g. a hyperlink
+    Link,
     TextEdit,
     Button,
     Checkbox,

egui/src/ui.rs

@@ -1227,14 +1227,40 @@ impl Ui {
         Label::new(text.into().weak()).ui(self)
     }
 
-    /// Shortcut for `add(Hyperlink::new(url))`
+    /// Looks like a hyperlink.
+    ///
+    /// Shortcut for `add(Link::new(text))`.
+    ///
+    /// ```
+    /// # egui::__run_test_ui(|ui| {
+    /// if ui.link("Documentation").clicked() {
+    ///     // …
+    /// }
+    /// # });
+    /// ```
+    ///
+    /// See also [`Link`].
+    #[must_use = "You should check if the user clicked this with `if ui.link(…).clicked() { … } "]
+    pub fn link(&mut self, text: impl Into<WidgetText>) -> Response {
+        Link::new(text).ui(self)
+    }
+
+    /// Link to a web page.
+    ///
+    /// Shortcut for `add(Hyperlink::new(url))`.
+    ///
+    /// ```
+    /// # egui::__run_test_ui(|ui| {
+    /// ui.hyperlink("https://www.egui.rs/");
+    /// # });
+    /// ```
     ///
     /// See also [`Hyperlink`].
     pub fn hyperlink(&mut self, url: impl ToString) -> Response {
         Hyperlink::new(url).ui(self)
     }
 
-    /// Shortcut for `add(Hyperlink::new(url).text(label))`
+    /// Shortcut for `add(Hyperlink::new(url).text(label))`.
     ///
     /// ```
     /// # egui::__run_test_ui(|ui| {

egui/src/widgets/hyperlink.rs

@@ -1,5 +1,69 @@
 use crate::*;
 
+/// Clickable text, that looks like a hyperlink.
+///
+/// To link to a web page, use [`Hyperlink`], [`Ui::hyperlink`] or [`Ui::hyperlink_to`].
+///
+/// See also [`Ui::link`].
+///
+/// ```
+/// # egui::__run_test_ui(|ui| {
+/// // These are equivalent:
+/// if ui.link("Documentation").clicked() {
+///     // …
+/// }
+///
+/// if ui.add(egui::Link::new("Documentation")).clicked() {
+///     // …
+/// }
+/// # });
+/// ```
+#[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
+pub struct Link {
+    text: WidgetText,
+}
+
+impl Link {
+    pub fn new(text: impl Into<WidgetText>) -> Self {
+        Self { text: text.into() }
+    }
+}
+
+impl Widget for Link {
+    fn ui(self, ui: &mut Ui) -> Response {
+        let Link { text } = self;
+        let label = Label::new(text).sense(Sense::click());
+
+        let (pos, text_galley, response) = label.layout_in_ui(ui);
+        response.widget_info(|| WidgetInfo::labeled(WidgetType::Link, text_galley.text()));
+
+        if response.hovered() {
+            ui.ctx().output().cursor_icon = CursorIcon::PointingHand;
+        }
+
+        if ui.is_rect_visible(response.rect) {
+            let color = ui.visuals().hyperlink_color;
+            let visuals = ui.style().interact(&response);
+
+            let underline = if response.hovered() || response.has_focus() {
+                Stroke::new(visuals.fg_stroke.width, color)
+            } else {
+                Stroke::none()
+            };
+
+            ui.painter().add(epaint::TextShape {
+                pos,
+                galley: text_galley.galley,
+                override_text_color: Some(color),
+                underline,
+                angle: 0.0,
+            });
+        }
+
+        response
+    }
+}
+
 /// A clickable hyperlink, e.g. to `"https://github.com/emilk/egui"`.
 ///
 /// See also [`Ui::hyperlink`] and [`Ui::hyperlink_to`].
@@ -42,15 +106,9 @@ impl Hyperlink {
 
 impl Widget for Hyperlink {
     fn ui(self, ui: &mut Ui) -> Response {
-        let Hyperlink { url, text } = self;
-        let label = Label::new(text).sense(Sense::click());
+        let Self { url, text } = self;
 
-        let (pos, text_galley, response) = label.layout_in_ui(ui);
-        response.widget_info(|| WidgetInfo::labeled(WidgetType::Hyperlink, text_galley.text()));
-
-        if response.hovered() {
-            ui.ctx().output().cursor_icon = CursorIcon::PointingHand;
-        }
+        let response = ui.add(Link::new(text));
         if response.clicked() {
             let modifiers = ui.ctx().input().modifiers;
             ui.ctx().output().open_url = Some(crate::output::OpenUrl {
@@ -64,26 +122,6 @@ impl Widget for Hyperlink {
                 new_tab: true,
             });
         }
-
-        if ui.is_rect_visible(response.rect) {
-            let color = ui.visuals().hyperlink_color;
-            let visuals = ui.style().interact(&response);
-
-            let underline = if response.hovered() || response.has_focus() {
-                Stroke::new(visuals.fg_stroke.width, color)
-            } else {
-                Stroke::none()
-            };
-
-            ui.painter().add(epaint::TextShape {
-                pos,
-                galley: text_galley.galley,
-                override_text_color: Some(color),
-                underline,
-                angle: 0.0,
-            });
-        }
-
         response.on_hover_text(url)
     }
 }

egui_demo_lib/src/apps/demo/widget_gallery.rs

@@ -141,6 +141,12 @@ impl WidgetGallery {
         }
         ui.end_row();
 
+        ui.add(doc_link_label("Link", "link"));
+        if ui.link("Click me!").clicked() {
+            *boolean = !*boolean;
+        }
+        ui.end_row();
+
         ui.add(doc_link_label("Checkbox", "checkbox"));
         ui.checkbox(boolean, "Checkbox");
         ui.end_row();