fixing some things

src/view/draw.zig

@@ -0,0 +1,44 @@
+const std = @import("std");
+const mem = std.mem;
+
+const Allocator = mem.Allocator;
+const Matrix = @import("../grome/matrix.zig").Matrix;
+
+/// DoubleBufferWriter manages two buffers for efficient rendering: a display buffer
+/// showing the current screen state, and a write buffer for accumulating changes
+/// that will be committed to the display on the next render cycle. This ABO
+/// approach minimizes unnecessary updates by only diffing changed cells.
+pub fn DoubleBufferWriter(width: usize, height: usize) type {
+    return struct {
+        // display holds the existing data.
+        display: Matrix(Cell, width, height),
+        // write is where we are writing the active changes which will be commited
+        // on the next rendering
+        write: Matrix(Cell, width, height),
+
+        pub fn init(gpa: Allocator, len: usize) DoubleBufferWriter {
+            const display = gpa.alloc(Cell, len);
+            const write = gpa.alloc(Cell, len);
+
+            return .{
+                .display = display,
+                .write = write,
+            };
+        }
+
+        pub fn deinit(self: *@This(), gpa: Allocator) void {
+            gpa.free(self.display);
+            gpa.free(self.write);
+        }
+    };
+}
+
+pub const Cell = struct {
+    char: [8]u8,
+    width: usize,
+
+    /// eql returns
+    pub fn eql(self: *const Cell, b: *const Cell) bool {
+        return mem.eql(u8, self.char, b.char) and self.width == b.width;
+    }
+};