Split parts of helix-term into helix-view.

It still largely depends on term for some types but I plan to change
that later.

1 files changed, 48 insertions, 0 deletions

diff --git a/helix-view/src/view.rs b/helix-view/src/view.rs
new file mode 100644
index 00000000..3f7a9974
--- /dev/null
+++ b/helix-view/src/view.rs
@@ -0,0 +1,48 @@
+use anyhow::Error;
+
+use std::path::PathBuf;
+
+use crate::theme::Theme;
+use helix_core::State;
+
+pub struct View {
+    pub state: State,
+    pub first_line: u16,
+    pub size: (u16, u16),
+    pub theme: Theme, // TODO: share one instance
+}
+
+impl View {
+    pub fn open(path: PathBuf, size: (u16, u16)) -> Result<View, Error> {
+        let mut state = State::load(path)?;
+        let theme = Theme::default();
+        state.syntax.as_mut().unwrap().configure(theme.scopes());
+
+        let view = View {
+            state,
+            first_line: 0,
+            size, // TODO: pass in from term
+            theme,
+        };
+
+        Ok(view)
+    }
+
+    pub fn ensure_cursor_in_view(&mut self) {
+        let cursor = self.state.selection().cursor();
+        let line = self.state.doc().char_to_line(cursor) as u16;
+        let document_end = self.first_line + self.size.1.saturating_sub(1) - 1;
+
+        let padding = 5u16;
+
+        // TODO: side scroll
+
+        if line > document_end.saturating_sub(padding) {
+            // scroll down
+            self.first_line += line - (document_end.saturating_sub(padding));
+        } else if line < self.first_line + padding {
+            // scroll up
+            self.first_line = line.saturating_sub(padding);
+        }
+    }
+}