From 3b35c0c630b904f53472d71169bcda7b646e771e Mon Sep 17 00:00:00 2001
From: cossonleo <cossonleo@foxmail.com>
Date: Fri, 5 Nov 2021 11:13:37 +0800
Subject: [PATCH] extract cursor in view calulate

---
 helix-view/src/view.rs | 62 ++++++++++++++++++++----------------------
 1 file changed, 29 insertions(+), 33 deletions(-)

diff --git a/helix-view/src/view.rs b/helix-view/src/view.rs
index f23802616ac4d..6a624ded28362 100644
--- a/helix-view/src/view.rs
+++ b/helix-view/src/view.rs
@@ -85,7 +85,12 @@ impl View {
         self.area.clip_left(OFFSET).clip_bottom(1) // -1 for statusline
     }
 
-    pub fn ensure_cursor_in_view(&mut self, doc: &Document, scrolloff: usize) {
+    //
+    pub fn offset_coords_to_in_view(
+        &self,
+        doc: &Document,
+        scrolloff: usize,
+    ) -> Option<(usize, usize)> {
         let cursor = doc
             .selection(self.id)
             .primary()
@@ -104,50 +109,41 @@ impl View {
 
         let last_col = self.offset.col + inner_area.width.saturating_sub(1) as usize;
 
-        if line > last_line.saturating_sub(scrolloff) {
+        let row = if line > last_line.saturating_sub(scrolloff) {
             // scroll down
-            self.offset.row += line - (last_line.saturating_sub(scrolloff));
+            self.offset.row + line - (last_line.saturating_sub(scrolloff))
         } else if line < self.offset.row + scrolloff {
             // scroll up
-            self.offset.row = line.saturating_sub(scrolloff);
-        }
+            line.saturating_sub(scrolloff)
+        } else {
+            self.offset.row
+        };
 
-        if col > last_col.saturating_sub(scrolloff) {
+        let col = if col > last_col.saturating_sub(scrolloff) {
             // scroll right
-            self.offset.col += col - (last_col.saturating_sub(scrolloff));
+            self.offset.col + col - (last_col.saturating_sub(scrolloff))
         } else if col < self.offset.col + scrolloff {
             // scroll left
-            self.offset.col = col.saturating_sub(scrolloff);
+            col.saturating_sub(scrolloff)
+        } else {
+            self.offset.col
+        };
+        if row == self.offset.row && col == self.offset.col {
+            None
+        } else {
+            Some((row, col))
         }
     }
 
-    pub fn is_cursor_in_view(&mut self, doc: &Document, scrolloff: usize) -> bool {
-        let cursor = doc
-            .selection(self.id)
-            .primary()
-            .cursor(doc.text().slice(..));
-
-        let Position { col, row: line } =
-            visual_coords_at_pos(doc.text().slice(..), cursor, doc.tab_width());
-
-        let inner_area = self.inner_area();
-        let last_line = (self.offset.row + inner_area.height as usize).saturating_sub(1);
-
-        // - 1 so we have at least one gap in the middle.
-        // a height of 6 with padding of 3 on each side will keep shifting the view back and forth
-        // as we type
-        let scrolloff = scrolloff.min(inner_area.height.saturating_sub(1) as usize / 2);
-
-        let last_col = self.offset.col + inner_area.width.saturating_sub(1) as usize;
-
-        if (line > last_line.saturating_sub(scrolloff)) || (line < self.offset.row + scrolloff) {
-            return false;
+    pub fn ensure_cursor_in_view(&mut self, doc: &Document, scrolloff: usize) {
+        if let Some((row, col)) = self.offset_coords_to_in_view(doc, scrolloff) {
+            self.offset.row = row;
+            self.offset.col = col;
         }
+    }
 
-        if (col > last_col.saturating_sub(scrolloff)) || (col < self.offset.col + scrolloff) {
-            return false;
-        }
-        true
+    pub fn is_cursor_in_view(&mut self, doc: &Document, scrolloff: usize) -> bool {
+        self.offset_coords_to_in_view(doc, scrolloff).is_none()
     }
 
     /// Calculates the last visible line on screen