Fix half and whole page movements

src/buffer/Cursor.zig

@@ -103,6 +103,24 @@ pub fn move_page_down(self: *Self, root: Buffer.Root, view: *const View, metrics
     self.move_right_no_target(root, metrics) catch return;
 }
 
+pub fn move_half_page_up(self: *Self, root: Buffer.Root, view: *const View, metrics: Metrics) void {
+    const half_view_rows = @divTrunc(view.rows, 2);
+    self.row = if (self.row > half_view_rows) self.row - half_view_rows else 0;
+    self.follow_target(root, metrics);
+    self.move_left_no_target(root, metrics) catch return;
+    self.move_right_no_target(root, metrics) catch return;
+}
+
+pub fn move_half_page_down(self: *Self, root: Buffer.Root, view: *const View, metrics: Metrics) void {
+    const half_view_rows = @divTrunc(view.rows, 2);
+    if (root.lines() > self.row + half_view_rows) {
+        self.row += half_view_rows;
+    } else self.move_buffer_last(root, metrics);
+    self.follow_target(root, metrics);
+    self.move_left_no_target(root, metrics) catch return;
+    self.move_right_no_target(root, metrics) catch return;
+}
+
 pub fn move_to(self: *Self, root: Buffer.Root, row: usize, col: usize, metrics: Metrics) !void {
     if (row < root.lines()) {
         self.row = row;

src/keybind/builtin/helix.json

@@ -11,8 +11,8 @@
         "press": [
             ["ctrl+b", "move_scroll_page_up"],
             ["ctrl+f", "move_scroll_page_down"],
-            ["ctrl+u", "page_cursor_half_up"],
+            ["ctrl+u", "move_scroll_half_page_up"],
-            ["ctrl+d", "page_cursor_half_down"],
+            ["ctrl+d", "move_scroll_half_page_down"],
             ["ctrl+c", "toggle_comment"],
             ["ctrl+i", "jump_forward"],
             ["ctrl+o", "jump_back"],
@@ -253,10 +253,10 @@
         "line_numbers": "relative",
         "cursor": "block",
         "press": [
-            ["ctrl+b", "move_scroll_page_up"],
+            ["ctrl+b", "select_page_up"],
-            ["ctrl+f", "move_scroll_page_down"],
+            ["ctrl+f", "select_page_down"],
-            ["ctrl+u", "page_cursor_half_up"],
+            ["ctrl+u", "select_half_page_up"],
-            ["ctrl+d", "page_cursor_half_down"],
+            ["ctrl+d", "select_half_page_down"],
 
             ["ctrl+c", "toggle_comment"],
 

src/tui/editor.zig

@@ -1955,6 +1955,14 @@ pub const Editor = struct {
         cursor.move_page_down(root, view, metrics);
     }
 
+    fn move_cursor_half_page_up(root: Buffer.Root, cursor: *Cursor, view: *const View, metrics: Buffer.Metrics) !void {
+        cursor.move_half_page_up(root, view, metrics);
+    }
+
+    fn move_cursor_half_page_down(root: Buffer.Root, cursor: *Cursor, view: *const View, metrics: Buffer.Metrics) !void {
+        cursor.move_half_page_down(root, view, metrics);
+    }
+
     pub fn primary_click(self: *Self, y: c_int, x: c_int) !void {
         if (self.fast_scroll)
             try self.push_cursor()
@@ -2889,6 +2897,30 @@ pub const Editor = struct {
     }
     pub const move_scroll_page_down_meta = .{ .description = "Move and scroll page down" };
 
+    pub fn move_scroll_half_page_up(self: *Self, _: Context) Result {
+        if (self.screen_cursor(&self.get_primary().cursor)) |cursor| {
+            const root = try self.buf_root();
+            self.with_cursors_and_view_const(root, move_cursor_half_page_up, &self.view) catch {};
+            const new_cursor_row = self.get_primary().cursor.row;
+            self.update_scroll_dest_abs(if (cursor.row > new_cursor_row) 0 else new_cursor_row - cursor.row);
+        } else {
+            return self.move_half_page_up(.{});
+        }
+    }
+    pub const move_scroll_half_page_up_meta = .{ .description = "Move and scroll half a page up" };
+
+    pub fn move_scroll_half_page_down(self: *Self, _: Context) Result {
+        if (self.screen_cursor(&self.get_primary().cursor)) |cursor| {
+            const root = try self.buf_root();
+            self.with_cursors_and_view_const(root, move_cursor_half_page_down, &self.view) catch {};
+            const new_cursor_row = self.get_primary().cursor.row;
+            self.update_scroll_dest_abs(if (cursor.row > new_cursor_row) 0 else new_cursor_row - cursor.row);
+        } else {
+            return self.move_half_page_down(.{});
+        }
+    }
+    pub const move_scroll_half_page_down_meta = .{ .description = "Move and scroll half a page down" };
+
     pub fn smart_move_begin(self: *Self, _: Context) Result {
         const root = try self.buf_root();
         try self.with_cursors_const(root, smart_move_cursor_begin);
@@ -2927,6 +2959,23 @@ pub const Editor = struct {
     }
     pub const move_page_down_meta = .{ .description = "Move cursor page down" };
 
+    pub fn move_half_page_up(self: *Self, _: Context) Result {
+        try self.send_editor_jump_source();
+        const root = try self.buf_root();
+        try self.with_cursors_and_view_const(root, move_cursor_page_up, &self.view);
+        self.clamp();
+    }
+    pub const move_half_page_up_meta = .{ .description = "Move cursor half a page up" };
+
+    pub fn move_half_page_down(self: *Self, _: Context) Result {
+        try self.send_editor_jump_source();
+        const root = try self.buf_root();
+        try self.with_cursors_and_view_const(root, move_cursor_page_down, &self.view);
+        self.clamp();
+        try self.send_editor_jump_destination();
+    }
+    pub const move_half_page_down_meta = .{ .description = "Move cursor half a page down" };
+
     pub fn move_buffer_begin(self: *Self, _: Context) Result {
         try self.send_editor_jump_source();
         self.cancel_all_selections();
@@ -3095,6 +3144,24 @@ pub const Editor = struct {
     }
     pub const select_page_down_meta = .{ .description = "Select page down" };
 
+    pub fn select_half_page_up(self: *Self, _: Context) Result {
+        try self.send_editor_jump_source();
+        const root = try self.buf_root();
+        try self.with_selections_and_view_const(root, move_cursor_half_page_up, &self.view);
+        self.clamp();
+        try self.send_editor_jump_destination();
+    }
+    pub const select_half_page_up_meta = .{ .description = "Select half a page up" };
+
+    pub fn select_half_page_down(self: *Self, _: Context) Result {
+        try self.send_editor_jump_source();
+        const root = try self.buf_root();
+        try self.with_selections_and_view_const(root, move_cursor_half_page_down, &self.view);
+        self.clamp();
+        try self.send_editor_jump_destination();
+    }
+    pub const select_half_page_down_meta = .{ .description = "Select half a page down" };
+
     pub fn select_all(self: *Self, _: Context) Result {
         try self.send_editor_jump_source();
         self.cancel_all_selections();