Move all crates into a crates directory (#1940)

crates/egui/src/widgets/mod.rs

@@ -0,0 +1,155 @@
+//! Widgets are pieces of GUI such as [`Label`], [`Button`], [`Slider`] etc.
+//!
+//! Example widget uses:
+//! * `ui.add(Label::new("Text").text_color(color::red));`
+//! * `if ui.add(Button::new("Click me")).clicked() { … }`
+
+use crate::*;
+
+mod button;
+pub mod color_picker;
+pub(crate) mod drag_value;
+mod hyperlink;
+mod image;
+mod label;
+pub mod plot;
+mod progress_bar;
+mod selected_label;
+mod separator;
+mod slider;
+mod spinner;
+pub mod text_edit;
+
+pub use button::*;
+pub use drag_value::DragValue;
+pub use hyperlink::*;
+pub use image::Image;
+pub use label::*;
+pub use progress_bar::ProgressBar;
+pub use selected_label::SelectableLabel;
+pub use separator::Separator;
+pub use slider::*;
+pub use spinner::*;
+pub use text_edit::{TextBuffer, TextEdit};
+
+// ----------------------------------------------------------------------------
+
+/// Anything implementing Widget can be added to a [`Ui`] with [`Ui::add`].
+///
+/// [`Button`], [`Label`], [`Slider`], etc all implement the [`Widget`] trait.
+///
+/// Note that the widgets ([`Button`], [`TextEdit`] etc) are
+/// [builders](https://doc.rust-lang.org/1.0.0/style/ownership/builders.html),
+/// and not objects that hold state.
+///
+/// Tip: you can `impl Widget for &mut YourThing { }`.
+///
+/// `|ui: &mut Ui| -> Response { … }` also implements [`Widget`].
+#[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
+pub trait Widget {
+    /// Allocate space, interact, paint, and return a [`Response`].
+    ///
+    /// Note that this consumes `self`.
+    /// This is because most widgets ([`Button`], [`TextEdit`] etc) are
+    /// [builders](https://doc.rust-lang.org/1.0.0/style/ownership/builders.html)
+    ///
+    /// Tip: you can `impl Widget for &mut YourObject { }`.
+    fn ui(self, ui: &mut Ui) -> Response;
+}
+
+/// This enables functions that return `impl Widget`, so that you can
+/// create a widget by just returning a lambda from a function.
+///
+/// For instance: `ui.add(slider_vec2(&mut vec2));` with:
+///
+/// ```
+/// pub fn slider_vec2(value: &mut egui::Vec2) -> impl egui::Widget + '_ {
+///    move |ui: &mut egui::Ui| {
+///        ui.horizontal(|ui| {
+///            ui.add(egui::Slider::new(&mut value.x, 0.0..=1.0).text("x"));
+///            ui.add(egui::Slider::new(&mut value.y, 0.0..=1.0).text("y"));
+///        })
+///        .response
+///    }
+/// }
+/// ```
+impl<F> Widget for F
+where
+    F: FnOnce(&mut Ui) -> Response,
+{
+    fn ui(self, ui: &mut Ui) -> Response {
+        self(ui)
+    }
+}
+
+/// Helper so that you can do `TextEdit::State::read…`
+pub trait WidgetWithState {
+    type State;
+}
+
+// ----------------------------------------------------------------------------
+
+/// Show a button to reset a value to its default.
+/// The button is only enabled if the value does not already have its original value.
+pub fn reset_button<T: Default + PartialEq>(ui: &mut Ui, value: &mut T) {
+    reset_button_with(ui, value, T::default());
+}
+
+/// Show a button to reset a value to its default.
+/// The button is only enabled if the value does not already have its original value.
+pub fn reset_button_with<T: PartialEq>(ui: &mut Ui, value: &mut T, reset_value: T) {
+    if ui
+        .add_enabled(*value != reset_value, Button::new("Reset"))
+        .clicked()
+    {
+        *value = reset_value;
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+pub fn stroke_ui(ui: &mut crate::Ui, stroke: &mut epaint::Stroke, text: &str) {
+    let epaint::Stroke { width, color } = stroke;
+    ui.horizontal(|ui| {
+        ui.add(DragValue::new(width).speed(0.1).clamp_range(0.0..=5.0))
+            .on_hover_text("Width");
+        ui.color_edit_button_srgba(color);
+        ui.label(text);
+
+        // stroke preview:
+        let (_id, stroke_rect) = ui.allocate_space(ui.spacing().interact_size);
+        let left = stroke_rect.left_center();
+        let right = stroke_rect.right_center();
+        ui.painter().line_segment([left, right], (*width, *color));
+    });
+}
+
+pub(crate) fn shadow_ui(ui: &mut Ui, shadow: &mut epaint::Shadow, text: &str) {
+    let epaint::Shadow { extrusion, color } = shadow;
+    ui.horizontal(|ui| {
+        ui.label(text);
+        ui.add(
+            DragValue::new(extrusion)
+                .speed(1.0)
+                .clamp_range(0.0..=100.0),
+        )
+        .on_hover_text("Extrusion");
+        ui.color_edit_button_srgba(color);
+    });
+}
+
+/// Show a small button to switch to/from dark/light mode (globally).
+pub fn global_dark_light_mode_switch(ui: &mut Ui) {
+    let style: crate::Style = (*ui.ctx().style()).clone();
+    let new_visuals = style.visuals.light_dark_small_toggle_button(ui);
+    if let Some(visuals) = new_visuals {
+        ui.ctx().set_visuals(visuals);
+    }
+}
+
+/// Show larger buttons for switching between light and dark mode (globally).
+pub fn global_dark_light_mode_buttons(ui: &mut Ui) {
+    let mut visuals = ui.ctx().style().visuals.clone();
+    visuals.light_dark_radio_buttons(ui);
+    ui.ctx().set_visuals(visuals);
+}