Refactor new Rect construction (#575)

* Refactor new Rect construction

Introduces methods that can be chained to construct new Rects
out of pre-existing ones

* Clamp x and y to edges in Rect chop methods

* Rename Rect clipping functions

helix-term/src/ui/editor.rs

@@ -108,13 +108,11 @@ impl EditorView {
 
         self.render_diagnostics(doc, view, inner, surface, theme);
 
-        let area = Rect::new(
+        let statusline_area = view
-            view.area.x,
+            .area
-            view.area.y + view.area.height.saturating_sub(1),
+            .clip_top(view.area.height.saturating_sub(1))
-            view.area.width,
+            .clip_bottom(1); // -1 from bottom to remove commandline
-            1,
+        self.render_statusline(doc, view, statusline_area, surface, theme, is_focused);
-        );
-        self.render_statusline(doc, view, area, surface, theme, is_focused);
     }
 
     /// Get syntax highlights for a document in a view represented by the first line
@@ -528,12 +526,7 @@ impl EditorView {
         let width = 80.min(viewport.width);
         let height = 15.min(viewport.height);
         paragraph.render(
-            Rect::new(
+            Rect::new(viewport.right() - width, viewport.y + 1, width, height),
-                viewport.right() - width,
-                viewport.y as u16 + 1,
-                width,
-                height,
-            ),
             surface,
         );
     }
@@ -572,7 +565,7 @@ impl EditorView {
             theme.get("ui.statusline.inactive")
         };
         // statusline
-        surface.set_style(Rect::new(viewport.x, viewport.y, viewport.width, 1), style);
+        surface.set_style(viewport.with_height(1), style);
         if is_focused {
             surface.set_string(viewport.x + 1, viewport.y, mode, style);
         }
@@ -1001,8 +994,7 @@ impl Component for EditorView {
         surface.set_style(area, cx.editor.theme.get("ui.background"));
 
         // if the terminal size suddenly changed, we need to trigger a resize
-        cx.editor
+        cx.editor.resize(area.clip_bottom(1)); // -1 from bottom for commandline
-            .resize(Rect::new(area.x, area.y, area.width, area.height - 1)); // - 1 to account for commandline
 
         for (view, is_focused) in cx.editor.tree.views() {
             let doc = cx.editor.document(view.doc).unwrap();

helix-term/src/ui/markdown.rs

@@ -13,7 +13,7 @@ use helix_core::{
     Rope,
 };
 use helix_view::{
-    graphics::{Color, Rect, Style},
+    graphics::{Color, Margin, Rect, Style},
     Theme,
 };
 
@@ -207,8 +207,11 @@ impl Component for Markdown {
             .wrap(Wrap { trim: false })
             .scroll((cx.scroll.unwrap_or_default() as u16, 0));
 
-        let area = Rect::new(area.x + 1, area.y + 1, area.width - 2, area.height - 2);
+        let margin = Margin {
-        par.render(area, surface);
+            vertical: 1,
+            horizontal: 1,
+        };
+        par.render(area.inner(&margin), surface);
     }
 
     fn required_size(&mut self, viewport: (u16, u16)) -> Option<(u16, u16)> {

helix-term/src/ui/menu.rs

@@ -304,14 +304,6 @@ impl<T: Item + 'static> Component for Menu<T> {
             },
         );
 
-        // // TODO: set bg for the whole row if selected
-        // if line == self.cursor {
-        //     surface.set_style(
-        //         Rect::new(area.x, area.y + i as u16, area.width - 1, 1),
-        //         selected,
-        //     )
-        // }
-
         for (i, _) in (scroll..(scroll + win_height).min(len)).enumerate() {
             let is_marked = i >= scroll_line && i < scroll_line + scroll_height;
 

helix-term/src/ui/picker.rs

@@ -19,7 +19,7 @@ use helix_core::Position;
 use helix_view::{
     document::canonicalize_path,
     editor::Action,
-    graphics::{Color, CursorKind, Rect, Style},
+    graphics::{Color, CursorKind, Margin, Rect, Style},
     Document, Editor,
 };
 
@@ -90,23 +90,26 @@ impl<T: 'static> Component for FilePicker<T> {
             area.width
         };
 
-        let picker_area = Rect::new(area.x, area.y, picker_width, area.height);
+        let picker_area = area.with_width(picker_width);
         self.picker.render(picker_area, surface, cx);
 
         if !render_preview {
             return;
         }
 
-        let preview_area = Rect::new(area.x + picker_width, area.y, area.width / 2, area.height);
+        let preview_area = area.clip_left(picker_width);
 
         // don't like this but the lifetime sucks
         let block = Block::default().borders(Borders::ALL);
 
         // calculate the inner area inside the box
-        let mut inner = block.inner(preview_area);
+        let inner = block.inner(preview_area);
         // 1 column gap on either side
-        inner.x += 1;
+        let margin = Margin {
-        inner.width = inner.width.saturating_sub(2);
+            vertical: 1,
+            horizontal: 0,
+        };
+        let inner = inner.inner(&margin);
 
         block.render(preview_area, surface);
 
@@ -282,15 +285,11 @@ impl<T> Picker<T> {
 //  - score all the names in relation to input
 
 fn inner_rect(area: Rect) -> Rect {
-    let padding_vertical = area.height * 10 / 100;
+    let margin = Margin {
-    let padding_horizontal = area.width * 10 / 100;
+        vertical: area.height * 10 / 100,
-
+        horizontal: area.width * 10 / 100,
-    Rect::new(
+    };
-        area.x + padding_horizontal,
+    area.inner(&margin)
-        area.y + padding_vertical,
-        area.width - padding_horizontal * 2,
-        area.height - padding_vertical * 2,
-    )
 }
 
 impl<T: 'static> Component for Picker<T> {
@@ -410,7 +409,7 @@ impl<T: 'static> Component for Picker<T> {
 
         // -- Render the input bar:
 
-        let area = Rect::new(inner.x + 1, inner.y, inner.width - 1, 1);
+        let area = inner.clip_left(1).with_height(1);
 
         let count = format!("{}/{}", self.matches.len(), self.options.len());
         surface.set_stringn(
@@ -434,8 +433,8 @@ impl<T: 'static> Component for Picker<T> {
         }
 
         // -- Render the contents:
-        // subtract the area of the prompt (-2) and current item marker " > " (-3)
+        // subtract area of prompt from top and current item marker " > " from left
-        let inner = Rect::new(inner.x + 3, inner.y + 2, inner.width - 3, inner.height - 2);
+        let inner = inner.clip_top(2).clip_left(3);
 
         let selected = cx.editor.theme.get("ui.text.focus");
 
@@ -474,7 +473,7 @@ impl<T: 'static> Component for Picker<T> {
         let inner = block.inner(area);
 
         // prompt area
-        let area = Rect::new(inner.x + 1, inner.y, inner.width - 1, 1);
+        let area = inner.clip_left(1).with_height(1);
 
         self.prompt.cursor(area, editor)
     }

helix-view/src/graphics.rs

@@ -24,7 +24,7 @@ pub struct Margin {
 }
 
 /// A simple rectangle used in the computation of the layout and to give widgets an hint about the
-/// area they are supposed to render to.
+/// area they are supposed to render to. (x, y) = (0, 0) is at the top left corner of the screen.
 #[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
 pub struct Rect {
     pub x: u16,
@@ -92,6 +92,57 @@ impl Rect {
         self.y.saturating_add(self.height)
     }
 
+    // Returns a new Rect with width reduced from the left side.
+    // This changes the `x` coordinate and clamps it to the right
+    // edge of the original Rect.
+    pub fn clip_left(self, width: u16) -> Rect {
+        let width = std::cmp::min(width, self.width);
+        Rect {
+            x: self.x.saturating_add(width),
+            width: self.width.saturating_sub(width),
+            ..self
+        }
+    }
+
+    // Returns a new Rect with width reduced from the right side.
+    // This does _not_ change the `x` coordinate.
+    pub fn clip_right(self, width: u16) -> Rect {
+        Rect {
+            width: self.width.saturating_sub(width),
+            ..self
+        }
+    }
+
+    // Returns a new Rect with height reduced from the top.
+    // This changes the `y` coordinate and clamps it to the bottom
+    // edge of the original Rect.
+    pub fn clip_top(self, height: u16) -> Rect {
+        let height = std::cmp::min(height, self.height);
+        Rect {
+            y: self.y.saturating_add(height),
+            height: self.height.saturating_sub(height),
+            ..self
+        }
+    }
+
+    // Returns a new Rect with height reduced from the bottom.
+    // This does _not_ change the `y` coordinate.
+    pub fn clip_bottom(self, height: u16) -> Rect {
+        Rect {
+            height: self.height.saturating_sub(height),
+            ..self
+        }
+    }
+
+    pub fn with_height(self, height: u16) -> Rect {
+        // new height may make area > u16::max_value, so use new()
+        Self::new(self.x, self.y, self.width, height)
+    }
+
+    pub fn with_width(self, width: u16) -> Rect {
+        Self::new(self.x, self.y, width, self.height)
+    }
+
     pub fn inner(self, margin: &Margin) -> Rect {
         if self.width < 2 * margin.horizontal || self.height < 2 * margin.vertical {
             Rect::default()
@@ -495,6 +546,40 @@ mod tests {
         assert_eq!(rect.height, 100);
     }
 
+    #[test]
+    fn test_rect_chop_from_left() {
+        let rect = Rect::new(0, 0, 20, 30);
+        assert_eq!(Rect::new(10, 0, 10, 30), rect.clip_left(10));
+        assert_eq!(
+            Rect::new(20, 0, 0, 30),
+            rect.clip_left(40),
+            "x should be clamped to original width if new width is bigger"
+        );
+    }
+
+    #[test]
+    fn test_rect_chop_from_right() {
+        let rect = Rect::new(0, 0, 20, 30);
+        assert_eq!(Rect::new(0, 0, 10, 30), rect.clip_right(10));
+    }
+
+    #[test]
+    fn test_rect_chop_from_top() {
+        let rect = Rect::new(0, 0, 20, 30);
+        assert_eq!(Rect::new(0, 10, 20, 20), rect.clip_top(10));
+        assert_eq!(
+            Rect::new(0, 30, 20, 0),
+            rect.clip_top(50),
+            "y should be clamped to original height if new height is bigger"
+        );
+    }
+
+    #[test]
+    fn test_rect_chop_from_bottom() {
+        let rect = Rect::new(0, 0, 20, 30);
+        assert_eq!(Rect::new(0, 0, 20, 20), rect.clip_bottom(10));
+    }
+
     fn styles() -> Vec<Style> {
         vec![
             Style::default(),

helix-view/src/view.rs

@@ -83,12 +83,7 @@ impl View {
     pub fn inner_area(&self) -> Rect {
         // TODO: not ideal
         const OFFSET: u16 = 7; // 1 diagnostic + 5 linenr + 1 gutter
-        Rect::new(
+        self.area.clip_left(OFFSET).clip_bottom(1) // -1 for statusline
-            self.area.x + OFFSET,
-            self.area.y,
-            self.area.width - OFFSET,
-            self.area.height.saturating_sub(1), // -1 for statusline
-        )
     }
 
     pub fn ensure_cursor_in_view(&mut self, doc: &Document, scrolloff: usize) {