Position signature help above to not block completion

helix-term/src/commands/lsp.rs

@@ -12,8 +12,8 @@ use helix_view::editor::Action;
 use crate::{
     compositor::{self, Compositor},
     ui::{
-        self, lsp::SignatureHelp, overlay::overlayed, FileLocation, FilePicker, Popup, Prompt,
-        PromptEvent,
+        self, lsp::SignatureHelp, overlay::overlayed, popup, FileLocation, FilePicker, Popup,
+        Prompt, PromptEvent,
     },
 };
 
@@ -633,9 +633,10 @@ pub fn signature_help(cx: &mut Context) {
             };
             contents.set_active_param_range(active_param_range());
 
-            let mut popup = Popup::new(SignatureHelp::ID, contents);
             let old_popup = compositor.find_id::<Popup<SignatureHelp>>(SignatureHelp::ID);
-            popup.set_position(old_popup.and_then(|p| p.position()));
+            let popup = Popup::new(SignatureHelp::ID, contents)
+                .position(old_popup.and_then(|p| p.get_position()))
+                .position_bias(popup::PositionBias::Above);
             compositor.replace_or_push(SignatureHelp::ID, popup);
         },
     );

helix-term/src/ui/mod.rs

@@ -6,7 +6,7 @@ mod markdown;
 pub mod menu;
 pub mod overlay;
 mod picker;
-mod popup;
+pub mod popup;
 mod prompt;
 mod spinner;
 mod text;

helix-term/src/ui/popup.rs

@@ -11,12 +11,19 @@ use helix_view::graphics::{Margin, Rect};
 // TODO: share logic with Menu, it's essentially Popup(render_fn), but render fn needs to return
 // a width/height hint. maybe Popup(Box<Component>)
 
+#[derive(PartialEq)]
+pub enum PositionBias {
+    Above,
+    Below,
+}
+
 pub struct Popup<T: Component> {
     contents: T,
     position: Option<Position>,
     margin: Margin,
     size: (u16, u16),
     child_size: (u16, u16),
+    position_bias: PositionBias,
     scroll: usize,
     auto_close: bool,
     id: &'static str,
@@ -32,21 +39,28 @@ impl<T: Component> Popup<T> {
                 horizontal: 0,
             },
             size: (0, 0),
+            position_bias: PositionBias::Below,
             child_size: (0, 0),
             scroll: 0,
             auto_close: false,
             id,
         }
     }
 
-    pub fn set_position(&mut self, pos: Option<Position>) {
+    pub fn position(mut self, pos: Option<Position>) -> Self {
         self.position = pos;
+        self
     }
 
-    pub fn position(&self) -> Option<Position> {
+    pub fn get_position(&self) -> Option<Position> {
         self.position
     }
 
+    pub fn position_bias(mut self, bias: PositionBias) -> Self {
+        self.position_bias = bias;
+        self
+    }
+
     pub fn margin(mut self, margin: Margin) -> Self {
         self.margin = margin;
         self
@@ -75,13 +89,23 @@ impl<T: Component> Popup<T> {
             rel_x = rel_x.saturating_sub((rel_x + width).saturating_sub(viewport.width));
         }
 
-        // TODO: be able to specify orientation preference. We want above for most popups, below
-        // for menus/autocomplete.
-        if viewport.height > rel_y + height {
-            rel_y += 1 // position below point
-        } else {
-            rel_y = rel_y.saturating_sub(height) // position above point
-        }
+        let can_put_below = viewport.height > rel_y + height;
+        let can_put_above = rel_y.checked_sub(height).is_some();
+        let final_pos = match self.position_bias {
+            PositionBias::Below => match can_put_below {
+                true => PositionBias::Below,
+                false => PositionBias::Above,
+            },
+            PositionBias::Above => match can_put_above {
+                true => PositionBias::Above,
+                false => PositionBias::Below,
+            },
+        };
+
+        rel_y = match final_pos {
+            PositionBias::Above => rel_y.saturating_sub(height),
+            PositionBias::Below => rel_y + 1,
+        };
 
         (rel_x, rel_y)
     }