working on things

src/view/draw.zig

@@ -1,7 +1,7 @@
 const std = @import("std");
 const mem = std.mem;
 
-const grome = @import("root");
+const grome = @import("../root.zig");
 
 const Allocator = mem.Allocator;
 const Matrix = grome.matrix.Matrix;
@@ -15,20 +15,27 @@ const Rect = grome.matrix.Rect;
 /// approach minimizes unnecessary updates by only diffing changed cells.
 pub const DoubleBuffer = struct {
     // display holds the existing data.
-    display: Matrix(Cell),
+    a: Matrix(Cell),
     // write is where we are writing the active changes which will be commited
     // on the next rendering
-    write: Matrix(Cell),
+    b: Matrix(Cell),
+
+    // Front and back hold pointers to a and b, they will switch back and forth
+    // based on what is needed.
+    front: *Matrix(Cell),
+    back: *Matrix(Cell),
 
     pub fn init(gpa: Allocator, size: Rect) !DoubleBuffer {
-        const display = try gpa.alloc(Cell, size.area());
-        errdefer gpa.free(display);
+        var a = try Matrix(Cell).init(gpa, .{ .char = [_]u8{' '} ** 8, .width = 1 }, size);
+        errdefer a.deinit(gpa);
 
-        const write = try gpa.alloc(Cell, size.area());
+        var b = try Matrix(Cell).init(gpa, .{ .char = [_]u8{' '} ** 8, .width = 1 }, size);
 
         return .{
-            .display = display,
-            .write = write,
+            .a = a,
+            .b = b,
+            .front = &a,
+            .back = &b,
         };
     }
 
@@ -37,19 +44,23 @@ pub const DoubleBuffer = struct {
         gpa.free(self.write);
     }
 
-    pub fn frame(m: Matrix, loc: Point, size: Rect) Frame {
-        return .init(m, loc, size);
+    pub fn frame(self: *@This(), loc: Point, size: Rect) SubMatrix(Cell) {
+        return .init(self.back, loc, size);
     }
-};
 
-/// Frame is a location in the matrix so you can change things if you want
-pub const Frame = struct {
-    data: SubMatrix(Cell),
+    pub fn render(self: *@This(), w: *std.Io.Writer) !usize {
+        std.mem.swap(*Matrix(Cell), &self.front, &self.back);
 
-    pub fn init(m: Matrix, loc: Point, size: Rect) Frame {
-        return .{
-            .data = SubMatrix(Cell).init(m, loc, size),
-        };
+        var i = try w.write("\\033[H\\033[2J");
+        var iter = self.front.row_iterator();
+        while (iter.next()) |row| {
+            for (row) |cell| {
+                i += try cell.render(w);
+            }
+            i += try w.write("\n");
+        }
+
+        return i;
     }
 };
 
@@ -61,4 +72,8 @@ pub const Cell = struct {
     pub fn eql(self: *const Cell, b: *const Cell) bool {
         return mem.eql(u8, self.char, b.char) and self.width == b.width;
     }
+
+    pub fn render(self: *const @This(), w: *std.Io.Writer) !usize {
+        return w.write(self.char[0..self.width]);
+    }
 };