1 files changed, 73 insertions, 0 deletions
diff --git a/helix-term/src/ui/overlay.rs b/helix-term/src/ui/overlay.rs
new file mode 100644
index 00000000..9f522e35
--- /dev/null
+++ b/helix-term/src/ui/overlay.rs
@@ -0,0 +1,73 @@
+use crossterm::event::Event;
+use helix_core::Position;
+use helix_view::{
+    graphics::{CursorKind, Rect},
+    Editor,
+};
+use tui::buffer::Buffer;
+
+use crate::compositor::{Component, Context, EventResult};
+
+/// Contains a component placed in the center of the parent component
+pub struct Overlay<T> {
+    /// Child component
+    pub content: T,
+    /// Function to compute the size and position of the child component
+    pub calc_child_size: Box<dyn Fn(Rect) -> Rect>,
+}
+
+/// Surrounds the component with a margin of 5% on each side, and an additional 2 rows at the bottom
+pub fn overlayed<T>(content: T) -> Overlay<T> {
+    Overlay {
+        content,
+        calc_child_size: Box::new(|rect: Rect| clip_rect_relative(rect.clip_bottom(2), 90, 90)),
+    }
+}
+
+fn clip_rect_relative(rect: Rect, percent_horizontal: u8, percent_vertical: u8) -> Rect {
+    fn mul_and_cast(size: u16, factor: u8) -> u16 {
+        ((size as u32) * (factor as u32) / 100).try_into().unwrap()
+    }
+
+    let inner_w = mul_and_cast(rect.width, percent_horizontal);
+    let inner_h = mul_and_cast(rect.height, percent_vertical);
+
+    let offset_x = rect.width.saturating_sub(inner_w) / 2;
+    let offset_y = rect.height.saturating_sub(inner_h) / 2;
+
+    Rect {
+        x: rect.x + offset_x,
+        y: rect.y + offset_y,
+        width: inner_w,
+        height: inner_h,
+    }
+}
+
+impl<T: Component + 'static> Component for Overlay<T> {
+    fn render(&mut self, area: Rect, frame: &mut Buffer, ctx: &mut Context) {
+        let dimensions = (self.calc_child_size)(area);
+        self.content.render(dimensions, frame, ctx)
+    }
+
+    fn required_size(&mut self, (width, height): (u16, u16)) -> Option<(u16, u16)> {
+        let area = Rect {
+            x: 0,
+            y: 0,
+            width,
+            height,
+        };
+        let dimensions = (self.calc_child_size)(area);
+        let viewport = (dimensions.width, dimensions.height);
+        let _ = self.content.required_size(viewport)?;
+        Some((width, height))
+    }
+
+    fn handle_event(&mut self, event: Event, ctx: &mut Context) -> EventResult {
+        self.content.handle_event(event, ctx)
+    }
+
+    fn cursor(&self, area: Rect, ctx: &Editor) -> (Option<Position>, CursorKind) {
+        let dimensions = (self.calc_child_size)(area);
+        self.content.cursor(dimensions, ctx)
+    }
+}