Add documentation

crates/egui/src/containers/modal.rs

@@ -3,24 +3,68 @@ use crate::{
 };
 use emath::{Align2, Vec2};
 
+/// A modal dialog.
+/// Similar to a [`crate::Window`] but centered and with a backdrop that
+/// blocks input to the rest of the UI.
+///
+/// You can show multiple modals on top of each other. The top most modal will always be
+/// the most recently shown one.
 pub struct Modal {
     pub area: Area,
     pub backdrop_color: Color32,
     pub frame: Option<Frame>,
 }
 
 impl Modal {
+    /// Create a new Modal. The id is passed to the area.
     pub fn new(id: Id) -> Self {
         Self {
-            area: Area::new(id)
-                .sense(Sense::hover())
-                .anchor(Align2::CENTER_CENTER, Vec2::ZERO)
-                .order(Order::Foreground),
+            area: Self::default_area(id),
             backdrop_color: Color32::from_black_alpha(100),
             frame: None,
         }
     }
 
+    /// Returns an area customized for a modal.
+    /// Makes these changes to the default area:
+    /// - sense: hover
+    /// - anchor: center
+    /// - order: foreground
+    pub fn default_area(id: Id) -> Area {
+        Area::new(id)
+            .sense(Sense::hover())
+            .anchor(Align2::CENTER_CENTER, Vec2::ZERO)
+            .order(Order::Foreground)
+    }
+
+    /// Set the frame of the modal.
+    ///
+    /// Default is [`Frame::popup`].
+    #[inline]
+    pub fn frame(mut self, frame: Frame) -> Self {
+        self.frame = Some(frame);
+        self
+    }
+
+    /// Set the backdrop color of the modal.
+    ///
+    /// Default is `Color32::from_black_alpha(100)`.
+    #[inline]
+    pub fn backdrop_color(mut self, color: Color32) -> Self {
+        self.backdrop_color = color;
+        self
+    }
+
+    /// Set the area of the modal.
+    ///
+    /// Default is [`Modal::default_area`].
+    #[inline]
+    pub fn area(mut self, area: Area) -> Self {
+        self.area = area;
+        self
+    }
+
+    /// Show the modal.
     pub fn show<T>(self, ctx: &Context, content: impl FnOnce(&mut Ui) -> T) -> ModalResponse<T> {
         let (is_top_modal, any_popup_open) = ctx.memory_mut(|mem| {
             mem.set_modal_layer(self.area.layer());
@@ -33,7 +77,6 @@ impl Modal {
             inner: (inner, backdrop_response),
             response,
         } = self.area.show(ctx, |ui| {
-            // TODO: Is screen_rect the right thing to use here?
             let mut backdrop = ui.new_child(UiBuilder::new().max_rect(ui.ctx().screen_rect()));
             let backdrop_response = backdrop_ui(&mut backdrop, self.backdrop_color);
 
@@ -81,11 +124,20 @@ fn backdrop_ui(ui: &mut Ui, color: Color32) -> Response {
     response
 }
 
+/// The response of a modal dialog.
 pub struct ModalResponse<T> {
+    /// The response of the modal contents
     pub response: Response,
+
+    /// The response of the modal backdrop
     pub backdrop_response: Response,
+
+    /// The inner response from the content closure
     pub inner: T,
+
+    /// Is this the top most modal?
     pub is_top_modal: bool,
+
     /// Is there any popup open?
     /// We need to check this before the modal contents are shown, so we can know if any popup
     /// was open when checking if the escape key was clicked.

crates/egui/src/memory/mod.rs

@@ -515,6 +515,7 @@ pub(crate) struct Focus {
 
     /// The top-most modal layer from the previous frame.
     top_modal_layer: Option<LayerId>,
+
     /// The top-most modal layer from the current frame.
     top_modal_layer_current_frame: Option<LayerId>,