From fb23445e1d86337c0434231e4221e1cf43ce5c48 Mon Sep 17 00:00:00 2001
From: Alexandre Bury <alexandre.bury@gmail.com>
Date: Mon, 26 Oct 2020 12:30:00 -0700
Subject: [PATCH] Add Cursive::screen_size based on last layout phase

---
 cursive-core/src/cursive.rs          | 15 ++++++++++++++-
 cursive-core/src/cursive_run.rs      |  2 ++
 cursive-core/src/view/scroll/core.rs |  1 +
 cursive-core/src/view/scroll/raw.rs  | 16 +++++-----------
 4 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/cursive-core/src/cursive.rs b/cursive-core/src/cursive.rs
index 752881f..7f56aed 100644
--- a/cursive-core/src/cursive.rs
+++ b/cursive-core/src/cursive.rs
@@ -19,6 +19,8 @@ use crate::{
 
 static DEBUG_VIEW_NAME: &str = "_cursive_debug_view";
 
+type RootView = views::OnEventView<views::ScreensView<views::StackView>>;
+
 /// Central part of the cursive library.
 ///
 /// It initializes ncurses on creation and cleans up on drop.
@@ -30,7 +32,7 @@ pub struct Cursive {
     theme: theme::Theme,
 
     // The main view
-    root: views::OnEventView<views::ScreensView<views::StackView>>,
+    root: RootView,
 
     menubar: views::Menubar,
 
@@ -42,6 +44,8 @@ pub struct Cursive {
     cb_source: Receiver<Box<dyn FnOnce(&mut Cursive) + Send>>,
     cb_sink: Sender<Box<dyn FnOnce(&mut Cursive) + Send>>,
 
+    last_size: Vec2,
+
     // User-provided data.
     user_data: Box<dyn Any>,
 
@@ -84,6 +88,7 @@ impl Cursive {
                 views::StackView::new(),
             )),
             menubar: views::Menubar::new(),
+            last_size: Vec2::zero(),
             needs_clear: true,
             running: true,
             cb_source,
@@ -96,7 +101,15 @@ impl Cursive {
         cursive
     }
 
+    /// Returns the screen size given in the last layout phase.
+    ///
+    /// Note: this will return `(0, 0)` before the first layout phase.
+    pub fn screen_size(&self) -> Vec2 {
+        self.last_size
+    }
+
     pub(crate) fn layout(&mut self, size: Vec2) {
+        self.last_size = size;
         let offset = if self.menubar.autohide { 0 } else { 1 };
         let size = size.saturating_sub((0, offset));
         self.root.layout(size);
diff --git a/cursive-core/src/cursive_run.rs b/cursive-core/src/cursive_run.rs
index 9093f1c..e1c88c9 100644
--- a/cursive-core/src/cursive_run.rs
+++ b/cursive-core/src/cursive_run.rs
@@ -9,6 +9,8 @@ const INPUT_POLL_DELAY_MS: u64 = 30;
 ///
 /// You can get one from `Cursive::runner`, then either call `.run()`, or
 /// manually `.step()`.
+///
+/// The `C` type is usually either `Cursive` or `&mut Cursive`.
 pub struct CursiveRunner<C> {
     siv: C,
     backend: Box<dyn backend::Backend>,
diff --git a/cursive-core/src/view/scroll/core.rs b/cursive-core/src/view/scroll/core.rs
index c5944b8..738e0fb 100644
--- a/cursive-core/src/view/scroll/core.rs
+++ b/cursive-core/src/view/scroll/core.rs
@@ -305,6 +305,7 @@ impl Core {
                             && (self.offset.y + self.available_size().y
                                 < self.inner_size.y) =>
                     {
+                        // No `min` check here - we allow going over the edge.
                         self.offset.y += 5;
                     }
                     Event::Ctrl(Key::Down) | Event::Key(Key::Down)
diff --git a/cursive-core/src/view/scroll/raw.rs b/cursive-core/src/view/scroll/raw.rs
index c8c18b7..be498a9 100644
--- a/cursive-core/src/view/scroll/raw.rs
+++ b/cursive-core/src/view/scroll/raw.rs
@@ -210,19 +210,13 @@ where
 }
 
 /// Implements `View::on_event` on the given model.
-pub fn on_event<Model, GetScroller, OnEvent, ImportantArea>(
+pub fn on_event<Model: ?Sized>(
     event: Event,
     model: &mut Model,
-    mut get_scroller: GetScroller,
-    mut on_event: OnEvent,
-    mut important_area: ImportantArea,
-) -> EventResult
-where
-    Model: ?Sized,
-    GetScroller: FnMut(&mut Model) -> &mut scroll::Core,
-    OnEvent: FnMut(&mut Model, Event) -> EventResult,
-    ImportantArea: FnMut(&Model, Vec2) -> Rect,
-{
+    mut get_scroller: impl FnMut(&mut Model) -> &mut scroll::Core,
+    mut on_event: impl FnMut(&mut Model, Event) -> EventResult,
+    mut important_area: impl FnMut(&Model, Vec2) -> Rect,
+) -> EventResult {
     let mut relative_event = event.clone();
     let inside = get_scroller(model).is_event_inside(&mut relative_event);
     let result = if inside {