Add TextEdit::hint_text for showing a weak hint text when empty

CHANGELOG.md

@@ -14,7 +14,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 * Add support for secondary and middle mouse buttons.
 * Add `Label` methods for code, strong, strikethrough, underline and italics.
 * Add `ui.group(|ui| { … })` to visually group some widgets within a frame
-* Text will now wrap at newlines, spaces, dashes, punctuation or in the middle of a words if necessary, in that order of priority.
+* Add `TextEdit::hint_text` for showing a weak hint text when empty.
 * `egui::popup::popup_below_widget`: show a popup area below another widget.
 * Add `Slider::clamp_to_range(bool)`: if set, clamp the incoming and outgoing values to the slider range.
 * Add: `ui.spacing()`, `ui.spacing_mut()`, `ui.visuals()`, `ui.visuals_mut()`.
@@ -22,6 +22,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ### Changed 🔧
 
+* Text will now wrap at newlines, spaces, dashes, punctuation or in the middle of a words if necessary, in that order of priority.
 * `mouse` has be renamed `pointer` everywhere (to make it clear it includes touches too).
 * Most parts of `Response` are now methods, so `if ui.button("…").clicked {` is now `if ui.button("…").clicked() {`.
 * `Response::active` is now gone. You can use `response.dragged()` or `response.clicked()` instead.

egui/src/style.rs

@@ -362,14 +362,14 @@ impl Widgets {
             noninteractive: WidgetVisuals {
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(65)), // window outline
                 bg_fill: Color32::from_gray(30),                     // window background
-                fg_stroke: Stroke::new(1.0, Color32::from_gray(160)), // text color
+                fg_stroke: Stroke::new(1.0, Color32::from_gray(160)), // normal text color
                 corner_radius: 4.0,
                 expansion: 0.0,
             },
             disabled: WidgetVisuals {
                 bg_fill: Color32::from_gray(40), // Should look grayed out
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(70)),
-                fg_stroke: Stroke::new(1.0, Color32::from_gray(140)), // Should look grayed out
+                fg_stroke: Stroke::new(1.0, Color32::from_gray(110)), // Should look grayed out. Also used for "weak" text color.
                 corner_radius: 4.0,
                 expansion: 0.0,
             },
@@ -402,14 +402,14 @@ impl Widgets {
             noninteractive: WidgetVisuals {
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(180)), // window outline
                 bg_fill: Color32::from_gray(220),                     // window background
-                fg_stroke: Stroke::new(1.0, Color32::from_gray(70)),  // text color
+                fg_stroke: Stroke::new(1.0, Color32::from_gray(70)),  // normal text color
                 corner_radius: 4.0,
                 expansion: 0.0,
             },
             disabled: WidgetVisuals {
                 bg_fill: Color32::from_gray(215), // Should look grayed out
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(185)),
-                fg_stroke: Stroke::new(1.0, Color32::from_gray(115)), // Should look grayed out
+                fg_stroke: Stroke::new(1.0, Color32::from_gray(145)), // Should look grayed out. Also used for "weak" text color.
                 corner_radius: 4.0,
                 expansion: 0.0,
             },

egui/src/widgets/text_edit.rs

@@ -123,6 +123,7 @@ impl CCursorPair {
 #[derive(Debug)]
 pub struct TextEdit<'t> {
     text: &'t mut String,
+    hint_text: String,
     id: Option<Id>,
     id_source: Option<Id>,
     text_style: Option<TextStyle>,
@@ -144,6 +145,7 @@ impl<'t> TextEdit<'t> {
     pub fn singleline(text: &'t mut String) -> Self {
         TextEdit {
             text,
+            hint_text: Default::default(),
             id: None,
             id_source: None,
             text_style: None,
@@ -160,6 +162,7 @@ impl<'t> TextEdit<'t> {
     pub fn multiline(text: &'t mut String) -> Self {
         TextEdit {
             text,
+            hint_text: Default::default(),
             id: None,
             id_source: None,
             text_style: None,
@@ -183,6 +186,12 @@ impl<'t> TextEdit<'t> {
         self
     }
 
+    /// Show a faint hint text when the text field is empty.
+    pub fn hint_text(mut self, hint_text: impl Into<String>) -> Self {
+        self.hint_text = hint_text.into();
+        self
+    }
+
     pub fn text_style(mut self, text_style: TextStyle) -> Self {
         self.text_style = Some(text_style);
         self
@@ -268,6 +277,7 @@ impl<'t> TextEdit<'t> {
     fn content_ui(self, ui: &mut Ui) -> Response {
         let TextEdit {
             text,
+            hint_text,
             id,
             id_source,
             text_style,
@@ -511,6 +521,18 @@ impl<'t> TextEdit<'t> {
         ui.painter()
             .galley(response.rect.min, galley, text_style, text_color);
 
+        if text.is_empty() && !hint_text.is_empty() {
+            let font = &ui.fonts()[text_style];
+            let galley = if multiline {
+                font.layout_multiline(hint_text, available_width)
+            } else {
+                font.layout_single_line(hint_text)
+            };
+            let hint_text_color = ui.visuals().weak_text_color();
+            ui.painter()
+                .galley(response.rect.min, galley, text_style, hint_text_color);
+        }
+
         ui.memory().text_edit.insert(id, state);
 
         Response {

egui_demo_lib/src/apps/demo/widget_gallery.rs

@@ -21,7 +21,7 @@ impl Default for WidgetGallery {
             boolean: false,
             radio: Enum::First,
             scalar: 42.0,
-            string: "Hello World!".to_owned(),
+            string: Default::default(),
             color: egui::Color32::LIGHT_BLUE.linear_multiply(0.5),
         }
     }
@@ -66,7 +66,7 @@ impl super::View for WidgetGallery {
             ui.end_row();
 
             ui.label("Text Input:");
-            ui.text_edit_singleline(string);
+            ui.add(egui::TextEdit::singleline(string).hint_text("Write something here"));
             ui.end_row();
 
             ui.label("Checkbox:");