mod(renderer): dynamic clear of size for widgets to improve render performance

src/render.zig

@@ -128,12 +128,19 @@ pub fn Direct(comptime _: bool) type {
             _ = this;
             _ = size;
         }
+
         pub fn clear(this: *@This(), size: Size) !void {
             _ = this;
-            const anchor = size.anchor;
-            // NOTE: clear entire screen for the first content (derived from the anchor being at the very left-top)
-            if (anchor.col == 1 and anchor.row == 1) {
-                try terminal.clearScreen();
+            std.debug.assert(1028 > size.cols);
+            var buf: [1028]u8 = undefined;
+            @memset(buf[0..], ' ');
+            for (0..size.rows) |r| {
+                const row: u16 = @truncate(r);
+                try terminal.setCursorPosition(.{
+                    .col = size.anchor.col,
+                    .row = size.anchor.row + row,
+                });
+                _ = try terminal.write(buf[0..size.cols]);
             }
         }